EP1033420B1 - Process and apparatus for electrochemically graining a support for light-sensitive layers - Google Patents

Process and apparatus for electrochemically graining a support for light-sensitive layers Download PDF

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Publication number
EP1033420B1
EP1033420B1 EP00104028A EP00104028A EP1033420B1 EP 1033420 B1 EP1033420 B1 EP 1033420B1 EP 00104028 A EP00104028 A EP 00104028A EP 00104028 A EP00104028 A EP 00104028A EP 1033420 B1 EP1033420 B1 EP 1033420B1
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EP
European Patent Office
Prior art keywords
electrode
alternating
phase current
substrate
electrolyte bath
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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EP00104028A
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German (de)
French (fr)
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EP1033420A1 (en
Inventor
Georg Haby
Raimund Dr. Haas
Uwe Gartmann
Günter Dr. Hultzsch
Klaus Dr. Joerg
Jörg Kaden
Hermann Idstein
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Agfa Gevaert NV
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Agfa Gevaert NV
Agfa Gevaert AG
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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
    • C25F7/00—Constructional parts, or assemblies thereof, of cells for electrolytic removal of material from objects; Servicing or operating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41N—PRINTING PLATES OR FOILS; MATERIALS FOR SURFACES USED IN PRINTING MACHINES FOR PRINTING, INKING, DAMPING, OR THE LIKE; PREPARING SUCH SURFACES FOR USE AND CONSERVING THEM
    • B41N3/00—Preparing for use and conserving printing surfaces
    • B41N3/03—Chemical or electrical pretreatment
    • B41N3/034—Chemical or electrical pretreatment characterised by the electrochemical treatment of the aluminum support, e.g. anodisation, electro-graining; Sealing of the anodised layer; Treatment of the anodic layer with inorganic compounds; Colouring of the anodic layer
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
    • C25F3/00—Electrolytic etching or polishing
    • C25F3/02—Etching
    • C25F3/04—Etching of light metals

Definitions

  • the invention relates to a method and a device for electrochemically roughening a Support for light-sensitive layers, the surface of which is electrochemical or mechanical and then electrochemically in an aqueous electrolyte bath by applying an alternating or Three-phase current is roughened on the opposite electrodes, the carrier is continuously passed through the electrolyte bath.
  • the Material of the carrier which is processed in plate or tape form, is a metal, in particular Aluminum.
  • the roughening of, for example, aluminum strips for the production of Printing plates are made mechanically, chemically or electrochemically or in a combination of these Roughening.
  • the aim is to ensure that the water supply and liability of the aluminum surface used a certain structure and photosensitive layer Has uniformity.
  • the surface structures When mechanically roughened, the surface structures have pyramid-like shapes, and have different orientations in the longitudinal and transverse directions on (anisotropy) while electrochemically roughened aluminum surfaces a sponge-like Structure with many wells and depressions with uniform geometry in longitudinal and Have transverse direction (isotropy).
  • the surface of the not roughened Print plate carrier shows a non-linear behavior electrically.
  • Cause of this non-linear Behavior can consist of both organic and inorganic material Layers.
  • the aluminum oxide layer is particularly useful for aluminum printing plate supports on the surface is a layer that remains non-linear until complete removal behave
  • the resistance of the surface of the printing plate carrier decreases. Assigns part of the Surface has a lower resistance, so the current flows preferentially through this part of the Surface, and not through the part of the surface that has higher resistance. The higher one Current now leads to a further decrease in resistance. This drop is bigger than that Reduction of the resistance at the points on the surface through which a lower current flows. This further increases the differences in the surface resistance.
  • the current density changes depending on the surface resistance of the carrier electrical cross-cuts on the carrier, which are visible in strip form.
  • the Stripes correspond to the current distribution, which is determined by the shape of the inlet electrode. On beat the alternating or three-phase current applied to the electrodes, i.e. depending on whether there is first a If there is a positive or negative half-wave, the cross-strokes occur.
  • the cross passages in strip form reduce the visual impression and, in the case of a particularly strong expression, also the Quality of the product.
  • the formation of these transverse or current strips increases with a high current density in the electrolyte bath at the beginning of the electrochemical roughening.
  • the electrical behavior of the Pressure plate carrier and the electrolyte is at the beginning of the roughening, as already above was mentioned not linear and changes with increasing roughening.
  • the decrease in Uniformity of the optical impression and the reduction of the print quality, in particular pronounced shape of the cross passages is very useful when mapping high-resolution screens disadvantageous.
  • the surface of the Printing plate carrier can, as described in DE 38 42 454 C2, with an additional layer be provided.
  • This additional layer eliminates material irregularities balanced, which essentially cause stains. This creates the formation of horizontal stripes although also weakened, the cause of the horizontal stripes is not eliminated, which in the steep Increase in current density when the carrier enters the effective range of the AC electrode lies. Even with a uniform coating, transverse stiffeners form depending on whether first the positive or negative half-wave of the alternating current flows.
  • the effort technical equipment is large, since usually an additional one for the application of an oxide layer Electrolyte is required.
  • the same electrolyte can also be used to reduce the expenditure are used, however, the electrolytes suitable for roughening are usually for one Oxidation or the application of other layers is not suitable or only suitable to a limited extent.
  • DE 3910 450 C2 describes a process for the production of a printing plate support, in using the printing plate support surface electrochemically in an acid electrolyte an AC current is roughened, which has a frequency of 80 to 120 Hz, and in which the ratio of anode time to period time is 0.25 to 0.20.
  • Such a process requires a high level of circuitry complexity because of the large power output implemented and causes problems in the distribution of the current to the individual electrodes.
  • a roughening of the printing plate carrier at certain transport speeds as in EP 0 585 586 B1 are proposed, although it supplies a constant loading of each part the printing plate support with positive and negative half-waves of the alternating current of the same size, but does not take into account that transverse stripes essentially due to the upcoming half-waves Entry into the zone of AC roughening are formed.
  • the known methods and devices take into account or reduce the formation of Horizontal stripes during the complete passage of the printing plate support through the AC roughening zone, do not, however, prevent horizontal stripes from appearing when the Form the pressure plate carrier in the effective range of the AC or three-phase electrodes, because the current density, i.e. the current per unit area on the printing plate carrier, of different sizes is
  • the current density in the electrolyte bath increases in the course a period of alternating or three-phase current less than 20% of the maximum current density.
  • a device for performing the method is characterized in that one in the Electrolytic bath arranged alternating or three-phase electrode is rounded such that its distance to a carrier transported through the electrolyte bath at an entry point into a Roughening zone of the electrolyte bath is larger than within the roughening zone and that from one predetermined distance from the entry point the distance of the AC or three-phase electrode to the carrier is constant.
  • the rounded outline of the AC or three-phase electrode a parabolic section, which is followed by a straight section.
  • the first AC or three-phase electrode divided into electrode sections and the individual electrode sections consist of materials with different electrical conductivities. Expediently between the Electrode sections and another AC or three-phase electrode insulating plates arranged.
  • the advantage of the invention is that the shape, the choice of material and / or the different total resistances from ohmic and / or inductive and capacitive Resistances of the AC or three-phase electrode increase the current density over the course of a Period of the alternating or three-phase current is less than or equal to 20% of the maximum current density, so that there are no cross-cuts or only a very weak formation of cross-cuts.
  • Fig. 1 shows schematically a device known in the prior art, which consists of a Electrolyte bath 1, through which a band-shaped carrier 2 in the transport direction A moved through.
  • the electrolyte in the electrolyte bath 1 can, for example, dilute aqueous Nitric, sulfuric or hydrochloric acid. It can also be a combination of 2 or 3 acids can be used. Of course, other acid baths are also available to those skilled in the art are common, suitable for the electrolyte bath 1.
  • the electrolytic bath can also be used Chemicals such as Contain salts or surfactants.
  • the carrier is before electrochemical roughening pretreated by an acidic or alkaline pretreatment to To remove impurities and "natural" oxide formed in the air.
  • the carrier 2 can, before it enters the electrolyte bath 1 occurs, be mechanically or chemically roughened in a suitable form.
  • the facilities for mechanical roughening of the surfaces of the carrier 2 are also not shown. such Plants and facilities include described in DE-A 19 62 729 and DE-B 19 62 728 and shown.
  • the corresponding three windings on the The primary side of the three-phase transformer 6 are not shown via lines L1, L2, L3 Control transformers powered by a common power transformer for three-phase current are connected. It is also possible that the lines L1, L2, L3, omitting the Control transformers, directly connected to the power transformer. Will not be further measures taken result in the case of high transport speeds of the carrier 2 electric shocks or electrical cross-shocks, which correspond to the high current density increase in the Electrolytes between the first three-phase electrode 3 and the carrier 2 are caused.
  • at 2 which are also known in the prior art, are in a Electrolytic bath 1 two alternating current electrodes 7 and 8, one with a secondary winding U2 AC transformer 9 are connected. It also applies here that the high Current density increase in the electrolyte between the first AC electrode 7 and the carrier 2 Electric shocks or electrical cross-shocks at high carrier speeds occur when no further action is taken.
  • each the first AC or three-phase electrode by shaping or special Selection of materials with different conductivities and / or electrode sections with different electrical properties due to ohmic, inductive and capacitive Resistors connected to the electrode sections are designed so that the increase in Current density over a period of alternating or three-phase current less than 20% of maximum current density
  • a slight change in the alternating or three-phase current occurs because of the small different conductivity on the surface of the carrier barely noticeable. Those Surface parts of the carrier that are not due to the originally applied alternating or three-phase current or have just experienced a small drop in resistance will be with the same current density acts like those parts of the surface where the reduction in resistance is somewhat greater was. Because of the slight change in alternating or three-phase current, there is only one slight distinction in the absolute values of the conductivities of different surface parts of the carrier. The conductivities differ from each other, but because of the small differences in current, these differences are not very noticeable. In other words this means that the enhancement or the reduction of the conductivities at different Surface parts of the carrier are not sufficient to form cross-strikes or is the formation of cross-cuts so low that it is hardly recognizable
  • FIG. 3 is the first embodiment of the device according to the invention only shows a first AC or three-phase electrode 10 in an electrolyte bath 1.
  • the first AC or three-phase electrode 10 is rounded or curved, in Contrary to the respective first three-phase or alternating current electrode 3 or 7 according to the devices known for the roughening of supports 2, as are known in the prior art 1 and 2 are shown schematically.
  • the three-phase or AC electrodes generally have an elongated rectangular cross section. As before, this leads to It was stated above that the increase in current density between these electrodes and the carrier 2 is very large when the carrier 2 enters the roughening zone and this to the unwanted cross-blows. If from an AC or three-phase electrode in the further Course of the description, it is to be understood that this electrode either with three-phase current or with alternating current, as is shown in FIGS. 1 and 2 has been described.
  • the alternating or three-phase electrode 10 immersed in the electrolytic bath 1 is rounded off in such a way that its distance d 1 to the carrier 2 transported through the electrolytic bath 1 is greater at an entry point B than within the roughening zone.
  • the distance of the AC or three-phase electrode 10 from the carrier 2 decreases in the transport direction A of the carrier 2, as can be seen from the distances d 2 and d 3 .
  • the resistance predetermined by the electrolyte located therebetween is greater than at the points with the distances d 2 and d 3 . Accordingly, the current densities then increase with increasing distances d 2 and d 3 .
  • the rounded outline of the AC or three-phase electrode 10 is composed of a parabolic section C and an adjoining rectilinear section D.
  • the curve of the AC or three-phase electrode 10 can also have a curve shape other than a parabolic shape.
  • the reduction in the electrical resistance in the electrolyte between the AC or three-phase electrode 10 and the carrier 2 leads to a gradual increase in the current density. Due to the large distance d 1 of the AC or three-phase electrode 10 from the carrier 2 at the beginning of the roughening zone, less current flows than is the case with the smaller distance d 2 or d 3 . Due to the small increase, the characteristics of points with low and higher surface resistance are less than with a steep increase in current density.
  • a second embodiment of the device according to the invention is shown schematically in FIG. 4 shown.
  • a first AC or three-phase electrode is in electrode sections 21, 22, 23 divided.
  • the electrode sections can be configured in such a way that those facing the carrier 2 Surfaces 18, 19, 20 flat or sawtooth-shaped cross-section, formed from rectangles or Trapezoids, e.g. quickly dissipate the gas bubbles generated in the electrolyte bath.
  • the carrier 2 is transported through the electrolyte bath 1 in the transport direction A.
  • the A further alternating or three-phase electrode 4 follows electrode sections 21, 22, 23 Electrode sections 21, 22, 23 are made of materials that are different electrical Can have conductivities to each other and to the AC or three-phase electrode 4 have different conductivity.
  • the third embodiment of the device according to the invention shown in FIG. 5 comprises a first AC or three-phase electrode, which is divided into electrode sections 31, 32, 33, the are electrically isolated from each other.
  • the carrier 2 is in the transport direction A by the Electrolyte bath 1 transported through. Another is connected to the electrode sections 31, 32, 33 AC or three-phase electrode 4. If the electrode sections and the electrode 4 with Three-phase current is applied, there is still another, not shown, in the electrolyte bath 1 Three-phase electrode available.
  • Each of the electrode sections 31, 32, 33 is fixed or variable ohmic resistor 12, 13, 14 connected in series (as shown) or in parallel are switched. Depending on whether it is AC or three-phase electrodes, the are Resistors 12, 13, 14 via a connection 11 with an alternating or not shown Three-phase source connected.
  • the current density per unit area of the individual electrode sections 31, 32, 33 is less than the current density per unit area of the AC or three-phase electrode 4.
  • the specific ohmic resistance of the electrode sections 31, 32, 33, the electrolyte and the fixed or variable resistors 12, 13, 14 determine the respective current density in Electrolytes between the surfaces 18, 19 and 20 and the carrier 2.
  • a fourth embodiment of the device is shown schematically in FIG. 6.
  • the formation of the first AC or three-phase electrode is similar to that of the second and third embodiments.
  • This first AC or three-phase electrode is divided into electrode sections 24, 25, 26 which are arranged isolated from each other in the electrolytic bath 1.
  • a of the carrier 2 connects a further AC or three-phase electrode 27.
  • Between the electrode sections and the further electrode 27 are insulating plates 28, 29 and 30.
  • Each of the Electrode sections 24, 25, 26 are connected to electrical components 34, 35, 36, each of which contains an ohmic resistor and / or inductive and capacitive resistor.
  • Electrode sections 24, 25, 26 are made up of the reactances of the inductors and Capacities in the components 34, 35, 36 together, which are indicated schematically in Fig. 6, and the ohmic resistors.
  • the AC resistance is equal to the root from the sum of the squares of ohmic resistance and reactance.
  • the through the Reactive power caused by reactive currents is not converted into heat.
  • Fig. 7 shows a fifth embodiment of the device in which the first change or Three-phase electrode 40 is formed in one piece in the electrolyte bath 1 and an elongated rectangular Has cross-section.
  • the carrier 2 is in the transport direction A through the electrolyte bath 1 below of perforated elements 38, 39; 41, 42; 43, 44 passed through.
  • These perforated elements are in Fig. 8 executed as pairs for the purpose of adjustability. You are between the first AC or three-phase electrode 40 and the carrier 2.
  • the pairs of elements are as in Fig. 8 shown, slidable against each other.
  • the plates can be moved in such a way that the Transport direction A of the carrier 2 first pair of elements 38, 39 a smaller coverage of the Row of holes 47, 48, as the next successive pair of elements 41, 42. B ei the third pair the elements 43, 44 is then, for example, full coverage of the rows of holes 47, 48, so that then the current density in the electrolyte between the AC or three-phase electrode 40 and the carrier 2 is largest.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
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Description

Die Erfindung betrifft ein Verfahren und eine Vorrichtung zum elektrochemischen Aufrauhen eines Trägers für lichtempfindliche Schichten, dessen Oberfläche elektrochemisch oder mechanisch und anschließend elektrochemisch in einem wäßrigen Elektrolytbad durch Anlegen eines Wechsel- oder Drehstromes an dem Träger gegenüberliegenden Elektroden aufgerauht wird, wobei der Träger kontinuierlich durch das Elektrolytbad hindurchgeführt wird.The invention relates to a method and a device for electrochemically roughening a Support for light-sensitive layers, the surface of which is electrochemical or mechanical and then electrochemically in an aqueous electrolyte bath by applying an alternating or Three-phase current is roughened on the opposite electrodes, the carrier is continuously passed through the electrolyte bath.

Derartige Träger werden für die Herstellung vorsensibilisierter Druckplatten verwendet, wobei das Material der Träger, die in Platten- oder Bandform verarbeitet werden, ein Metall ist, insbesondere Aluminium. Die Aufrauhung von beispielsweise Aluminiumbändern für die Herstellung von Druckplatten erfolgt mechanisch, chemisch oder elektrochemisch oder in Kombination dieser Aufrauhverfahren. Dabei wird angestrebt, daß die für die Wasserführung und die Haftung der lichtempfindlichen Schicht benutzte Aluminiumoberfläche eine bestimmte Struktur und Gleichmäßigkeit aufweist. Beim mechanischen Aufrauhen besitzen die Oberflächenstrukturen pyramidenähnliche Formen, und weisen unters chiedliche Orientierungen in Längs-und Querrichtung auf(Anisotropie) während elektrochemisch aufgerauhte Aluminiumoberflächen eine schwammartige Struktur mit vielen Näpfchen und Vertiefungen mit gleichformiger Geometrie in Längs- und Querrichtung (Isotropie) haben.Such carriers are used for the production of presensitized printing plates, the Material of the carrier, which is processed in plate or tape form, is a metal, in particular Aluminum. The roughening of, for example, aluminum strips for the production of Printing plates are made mechanically, chemically or electrochemically or in a combination of these Roughening. The aim is to ensure that the water supply and liability of the aluminum surface used a certain structure and photosensitive layer Has uniformity. When mechanically roughened, the surface structures have pyramid-like shapes, and have different orientations in the longitudinal and transverse directions on (anisotropy) while electrochemically roughened aluminum surfaces a sponge-like Structure with many wells and depressions with uniform geometry in longitudinal and Have transverse direction (isotropy).

B ei der Aufrauhung von Druckplattenträgern in einem Elektrolyten mittels Wechselstrom in einem kontinuierlichen Verfahren entstehen, insbesondere bei niedrigen Frequezen und hohen Bandgeschwindigkeiten, Querstreifen, die auch Querschläge genannt werden. B roughening of printing plate supports in an electrolyte using alternating current in one continuous processes arise, especially at low frequencies and high belt speeds, Horizontal stripes, which are also called cross-cuts.

Diese Querschläge entstehen beim Eintritt oder kurz vor dem Eintritt des Druckplattenträgers in den Wirkungsbereich der ersten Wechselstromelektrode. Die Oberfläche des nicht aufgerauhten Druckplattenträgers zeigt elektrisch ein nichtlineares Verhalten. Ursache dieses nichtlinearen Verhaltens können sowohl aus organischem als auch aus anorganischem Material bestehende Schichten sein. Insbesondere bei Druckplattenträgers aus Aluminium stellt die Aluminiumoxidschicht auf der Oberfläche eine Schicht dar, die sich bis zur vollständigen Abtragung nichtlinear verhältThese cross-cuts occur when the pressure plate carrier enters or shortly before it enters the Effective range of the first AC electrode. The surface of the not roughened Print plate carrier shows a non-linear behavior electrically. Cause of this non-linear Behavior can consist of both organic and inorganic material Layers. The aluminum oxide layer is particularly useful for aluminum printing plate supports on the surface is a layer that remains non-linear until complete removal behave

Erst wenn die Schichten auf der Oberfläche abgetragen sind, stellt sich ein Verhalten ein, bei dem die Stromdichte nur von der Spannung, und nicht noch zusätzlich von der Beschaffenheit der Oberfläche abhängig ist.Only when the layers on the surface have been removed does a behavior occur in which the current density only from the voltage, and not additionally from the nature of the Surface is dependent.

In Abhängigkeit davon, ob durch einen Teil der Oberfläche zunächst ein positiver oder negativer Strom fließt, nimmt der Widerstand der Oberfläche des Druckplattenträgers ab. Weist ein Teil der Oberfläche einen geringeren Widerstand auf, so fließt der Strom bevorzugt durch diesen Teil der Oberfläche, und nicht durch den Teil der Oberfläche, der höheren Widerstand besitzt. Der höhere Strom führt nun zu einer weiteren Absenkung des Widerstandes. Diese Absenkung ist größer als die Absenkung des Widerstandes an den Stellen der Oberfläche, durch die ein geringerer Strom fließt. Dadurch werden die Unterschiede im Widerstand der Oberfläche weiter verstärkt.Depending on whether through a part of the surface initially a positive or negative Current flows, the resistance of the surface of the printing plate carrier decreases. Assigns part of the Surface has a lower resistance, so the current flows preferentially through this part of the Surface, and not through the part of the surface that has higher resistance. The higher one Current now leads to a further decrease in resistance. This drop is bigger than that Reduction of the resistance at the points on the surface through which a lower current flows. This further increases the differences in the surface resistance.

Durch die unterschiedliche Verteilung der Stromdichte über die Querschnittsfläche und die Änderung der Stromdichte in Abhängigkeit von dem Oberflächenwiderstand des Trägers bilden sich elektrische Querschläge auf dem Träger aus, die in Streifenform sichtbar sind. Die Streifen entsprechen der Stromverteilung, die durch die Form der Einlaufelektrode vorgegeben ist. Im Takt des Wechsel- oder Drehstroms, der an den Elektroden anliegt, d.h. jenachdem, ob zunächst eine positive oder negative Halbwelle anliegt, entstehen die Querschläge. Due to the different distribution of the current density over the cross-sectional area and the The current density changes depending on the surface resistance of the carrier electrical cross-cuts on the carrier, which are visible in strip form. The Stripes correspond to the current distribution, which is determined by the shape of the inlet electrode. On beat the alternating or three-phase current applied to the electrodes, i.e. depending on whether there is first a If there is a positive or negative half-wave, the cross-strokes occur.

Die in Streifenform vorliegenden Querschläge, allgemein auch als Quer- oder Stromstreifen bezeichnet, vermindern den optischen Eindruck und bei besonders starker Ausprägung auch die Qualität des Produktes. Die Ausbildung dieser Quer- oder Stromstreifen steigt bei hoher Stromdichte im Elektrolytbad zu Beginn der elektrochemischen Aufrauhung an. Das elektrische Verhalten des Druckplattenträgers und des Elektrolyten ist am Anfang der Aufrauhung, wie schon voranstehend erwähnt wurde, nicht linear und ändert sich mit fortschreitender Aufrauhung. Die Verminderung der Gleichmäßigkeit des optischen Eindrucks und die Verminderung der Druckqualität, bei besonders stark ausgeprägter Form der Querschläge, ist bei der Abbildung von hochauflösenden Raster sehr nachteilig.The cross passages in strip form, generally also as transverse or stream strips referred to, reduce the visual impression and, in the case of a particularly strong expression, also the Quality of the product. The formation of these transverse or current strips increases with a high current density in the electrolyte bath at the beginning of the electrochemical roughening. The electrical behavior of the Pressure plate carrier and the electrolyte is at the beginning of the roughening, as already above was mentioned not linear and changes with increasing roughening. The decrease in Uniformity of the optical impression and the reduction of the print quality, in particular pronounced shape of the cross passages, is very useful when mapping high-resolution screens disadvantageous.

Zur Vermeidung dieser Querschläge sind verschiedene Verfahren bekannt. Die Oberfläche des Druckplattenträgers kann, wie in DE 38 42 454 C2 beschrieben, mit einer zusätzlichen Schicht versehen werden. Durch diese zusätzliche Schicht werden Ungleichmäßigkeiten im Material ausgeglichen, die im wesentlichen Flecken verursachen. Die Bildung von Querstreifen wird dadurch zwar auch abgeschwächt, jedoch wird die Ursache der Querstreifen nicht beseitigt, die in dem steilen Anstieg der Stromdichte bei Eintritt des Trägers in den Wirkungsbereich der Wechselstromelektrode liegt. Auch bei gleichmäßiger Beschichtung bilden sich Quersteifen in Abhängigkeit davon aus, ob zunächst die positive oder negative Halbwelle des Wechselstroms fließt. Der Aufwand an technischen Einrichtungen ist groß, da für die Aufbringung einer Oxidschicht meist ein zusätzlicher Elektrolyt erforderlich ist. Zwar kann auch zur Verringerung des Aufwandes derselbe Elektrolyt verwendet werden, jedoch sind die für die Aufrauhung geeigneten Elektrolyten meist für eine Oxidation oder das Aufbringen anderer Schichten nicht oder nur bedingt geeignet.Various methods are known for avoiding these cross-cuts. The surface of the Printing plate carrier can, as described in DE 38 42 454 C2, with an additional layer be provided. This additional layer eliminates material irregularities balanced, which essentially cause stains. This creates the formation of horizontal stripes although also weakened, the cause of the horizontal stripes is not eliminated, which in the steep Increase in current density when the carrier enters the effective range of the AC electrode lies. Even with a uniform coating, transverse stiffeners form depending on whether first the positive or negative half-wave of the alternating current flows. The effort technical equipment is large, since usually an additional one for the application of an oxide layer Electrolyte is required. The same electrolyte can also be used to reduce the expenditure are used, however, the electrolytes suitable for roughening are usually for one Oxidation or the application of other layers is not suitable or only suitable to a limited extent.

In derDE 3910 450 C2 ist ein Verfahren zur Herstellung eines Druckplattenträgers beschrieben, bei dem die Druckplattenträgeroberfläche elektrochemisch in einem Säurelektrolyt unter Verwendung eines Wechselstroms aufgerauht wird,der eine Frequenz von 80 bis 120 Hz aufweist, und bei dem das Verhältnis von Anodenzeit zur Periodenzeit 0,25 bis 0,20 beträgt. Ein derartiges Verfahren erfordert einen hohen schaltungstechnischen Aufwand wegen der großen umgesetzten Stromleistung und bereitet Probleme bei der Verteilung des Stroms auf die einzelnen Elektroden.DE 3910 450 C2 describes a process for the production of a printing plate support, in using the printing plate support surface electrochemically in an acid electrolyte an AC current is roughened, which has a frequency of 80 to 120 Hz, and in which the ratio of anode time to period time is 0.25 to 0.20. Such a process requires a high level of circuitry complexity because of the large power output implemented and causes problems in the distribution of the current to the individual electrodes.

Eine Aufrauhung mit Wechselstrom höherer, variabler Frequenz, wie sie in DE 39 10 213 A1 beschrieben ist führt zu einer Verringerung der Intensität der Querstreifen, erfordert jedoch einen hohen Aufwand an elektrotechnischen Einrichtungen und schränkt den Frequenzbereich des Wechselstroms ein, der für eine optimale Gestaltung der Oberfläche des Druckplattenträgers genutzt werden kann.Roughening with alternating current of higher, variable frequency, as described in DE 39 10 213 A1 leads to a reduction in the intensity of the horizontal stripes, but requires one high expenditure on electrical engineering equipment and limits the frequency range of the AC, which is used for an optimal design of the surface of the printing plate carrier can be.

Eine Aufrauhung des Druckplattenträgers bei bestimmten Transportgeschwindigkeiten, wie sie in derEP 0 585 586 B1 vorgeschlagen werden, liefert zwar eine konstante Beaufschlagung jedes Teiles des Druckplattenträgers mit gleich großen positiven und negativen Halbwellen des Wechselstromes, berücksichtigt aber nicht, daß Querstreifen im wesentlichen durch die anstehenden Halbwellen bei Eintritt in die Zone der Wechselstromaufrauhung gebildet werden.A roughening of the printing plate carrier at certain transport speeds, as in EP 0 585 586 B1 are proposed, although it supplies a constant loading of each part the printing plate support with positive and negative half-waves of the alternating current of the same size, but does not take into account that transverse stripes essentially due to the upcoming half-waves Entry into the zone of AC roughening are formed.

Die bekannten Verfahren und Vorrichtungen berücksichtigen bzw. vermindern die Bildung von Querstreifen während des vollständigen Durchlaufes des Druckplattenträgers durch die Wechselstromaufrauhungszone, verhindern jedoch nicht, daß sich Querstreifen schon beim Eintritt des Druckplattenträgers in den Wirkungsbereich der Wechsel- oder Drehstromelektroden ausbilden, da die Stromdichte, d.h. der Strom pro Flächeneinheit auf dem Druckplattenträger, unterschiedlich groß istThe known methods and devices take into account or reduce the formation of Horizontal stripes during the complete passage of the printing plate support through the AC roughening zone, do not, however, prevent horizontal stripes from appearing when the Form the pressure plate carrier in the effective range of the AC or three-phase electrodes, because the current density, i.e. the current per unit area on the printing plate carrier, of different sizes is

Demnach ist es Aufgabe der vorliegenden Erfindung, ein Verfahren der eingangs beschriebenen Art und eine Vorrichtung zur Durchführung des Verfahrens so zu verbessern, daß die Bildung von Querschlägen verhindert oder minimiert wird.It is therefore an object of the present invention to provide a method of the type described in the introduction and to improve an apparatus for performing the method so that the formation of Crossing is prevented or minimized.

Diese Aufgabe wird nach einem Verfahren gemäß des Oberbegriffs des Anspruchs 1 in der Weise gelöst, daß an einer Eintrittsstelle des Trägers in die Aufrauhzone die Stromdichte im Elektrolyten zwischen einer ersten Wechsel- oder Drehstromelektrode und dem Träger niedriger als eine maximale Stromdichte für die Aufrauhung ist und daß die Stromdichte mitzunehmender Entfernung von der Eintrittsstelle innerhalb des Bereichs der ersten Wechsel- oder Drehstromelektrode kontinuierlich auf die maximale Stromdichte ansteigt.This object is achieved by a method according to the preamble of claim 1 solved that the current density in the electrolyte at an entry point of the carrier in the roughening zone between a first AC or three-phase electrode and the carrier lower than one is the maximum current density for the roughening and that the current density increases with distance from the entry point within the area of the first AC or three-phase electrode continuously increases to the maximum current density.

In Ausgestaltung des Verfahrens beträgt der Anstieg der Stromdichte im Elektrolytbad im Verlauf einer Periode des Wechsel- oder Drehstroms weniger als 20% der maximalen Stromdichte.In an embodiment of the method, the current density in the electrolyte bath increases in the course a period of alternating or three-phase current less than 20% of the maximum current density.

Die weitere Ausgestaltung des Verfahrens ergibt sich aus den Merkmalen der Patentansprüche 3 bis 8.The further embodiment of the method results from the features of claims 3 to 8th.

Eine Vorrichtung zur Durchführung des Verfahrens zeichnet sich dadurch aus, daß eine in dem Elektrolytbad angeordnete Wechsel- oder Drehstromelektrode derart abgerundet ist, daß ihr Abstand zu einem durch das Elektrolytbad hindurchtransportierten Träger an einer Eintrittsstelle in eine Aufrauhzone des Elekrolytbades größer ist als innerhalb der Aufrauhzone und daß ab einer vorgegebenen Entfernung von der Eintrittsstelle der Abstand der Wechsel- oder Drehstromelektrode zu dem Träger konstant ist.A device for performing the method is characterized in that one in the Electrolytic bath arranged alternating or three-phase electrode is rounded such that its distance to a carrier transported through the electrolyte bath at an entry point into a Roughening zone of the electrolyte bath is larger than within the roughening zone and that from one predetermined distance from the entry point the distance of the AC or three-phase electrode to the carrier is constant.

In Weitergestaltung der Vorrichtung weist der abgerundete Umriß der Wechsel- oder Drehstromelektrode einen parabelförmigen Abschnitt auf, an den ein geradliniger Abschnitt anschließt.In a further development of the device, the rounded outline of the AC or three-phase electrode a parabolic section, which is followed by a straight section.

In einer weiteren Ausführungsform der Vorrichtung ist die erste Wechsel- oder Drehstromelektrode in Elektrodenabschnitte unterteilt und bestehen die einzelnen Elektrodenabschnitte aus Materialien mit unterschiedlichen elektrischen Leitfähigkeiten. Zweckmäßigerweise sind zwischen den Elektrodenabschnitten und einer weiteren Wechsel- oder Drehstromelektrode Isolierplatten angeordnet. In a further embodiment of the device, the first AC or three-phase electrode divided into electrode sections and the individual electrode sections consist of materials with different electrical conductivities. Expediently between the Electrode sections and another AC or three-phase electrode insulating plates arranged.

Die weitere Ausgestaltung der Ausführungsformen der erfindungsgemäßen Vorrichtung ergeben sich aus den Merkmalen der Patentansprüche 13 bis 17.The further embodiment of the embodiments of the device according to the invention result from the features of claims 13 to 17.

Mit der Erfindung wird der Vorteil erzielt, daß durch die Formgebung, die Materialauswahl und/oder die unterschiedlichen Gesamtwiderstände aus ohmschen und/oder induktiven und kapazitiven Widerständen der Wechsel- oder Drehstromelektrode der Anstieg der Stromdichte im Verlauf einer Periode des Wechsel- oder Drehstroms kleiner/gleich 20 % der maximalen Stromdichte ist, so daß es zu keinen Querschlägen oder nur zu einer sehr schwachen Ausbildung von Querschlägen kommt.The advantage of the invention is that the shape, the choice of material and / or the different total resistances from ohmic and / or inductive and capacitive Resistances of the AC or three-phase electrode increase the current density over the course of a Period of the alternating or three-phase current is less than or equal to 20% of the maximum current density, so that there are no cross-cuts or only a very weak formation of cross-cuts.

Die Erfindung wird im folgenden anhand von zeichnerisch dargestellten Ausführungsformen näher erläutert.The invention is explained in more detail below with the aid of embodiments shown in the drawings explained.

Es zeigen

Fig. 1 und 2
schematisch Vorrichtungen zum elektrochemischen Aufrauhen mit Wechsel- oder Drehstrom gemäß dem Stand der Technik,
Fig. 3
schematisch eine Wechsel- oder Drehstromelektrode einer ersten Ausführungsform der Vorrichtung nach der Erfindung
Fig. 4
schematisch eine zweite Ausführungsform der Wechsel- oder Drehstromelektrode, die Elektrodenabschnitte aus unterschiedlich leitfähigen Materialien aufweist, in einer erfindungsgemäßen Vorrichtung,
Fig. 5
eine dritte Ausführungsform der Wechsel- oder Drehstromelektrode, deren Elektrodenschnitte mit festen oder variablen ohmschen Widerständen verbunden sind, in einer erfindungsgemäßen Vorrichtung,
Fig. 6
eine vierte Ausführungsform der Wechsel- oder Drehstromelektrode, deren Elektrodenabschnitte mit Gesamtwiderständen aus ohmschen und/oder induktiven oder kapazitiven Widerständen verbunden sind, in einer erfindungsgemäßen Vorrichtung,
Fig. 7
eine fünfte Ausführungsform einer Wechsel- oder Drehstromelektrode mit Paaren von gelochten Elementen, die zwischen der Elektrode und einem durch das Elektrolytbad hindurchtransportierten Träger in der erfindungsgemäßen Vorrichtung angeordnet sind, und
Fig. 8
eine Draufsicht auf ein Paar von gelochten Platten, die zwischen einer Wechsel- oder Drehstromelektrode und einem Träger angeordnet sind.
Show it
1 and 2
schematically devices for electrochemical roughening with alternating or three-phase current according to the prior art,
Fig. 3
schematically an AC or three-phase electrode of a first embodiment of the device according to the invention
Fig. 4
schematically a second embodiment of the AC or three-phase electrode, which has electrode sections made of differently conductive materials, in a device according to the invention,
Fig. 5
a third embodiment of the AC or three-phase electrode, the electrode sections of which are connected to fixed or variable ohmic resistors, in a device according to the invention,
Fig. 6
a fourth embodiment of the AC or three-phase electrode, the electrode sections of which are connected to total resistances made of ohmic and / or inductive or capacitive resistors, in a device according to the invention,
Fig. 7
a fifth embodiment of an AC or three-phase electrode with pairs of perforated elements, which are arranged between the electrode and a carrier transported through the electrolyte bath in the device according to the invention, and
Fig. 8
a plan view of a pair of perforated plates, which are arranged between an AC or three-phase electrode and a carrier.

Fig. 1 zeigt schematisch eine im Stand der Technik bekannte Vorrichtung, die aus einem Elektrolytbad 1 besteht, durch das sich ein bandförmiger Träger 2 in Transportrichtung A hindurchbewegt. Der Elektrolyt in dem Elektrolytbad 1 kann beispielsweise verdünnte wäßrige Salpeter-, Schwefel- oder Chlorwasserstoffsäure sein. Es kann auch eine Kombination von 2 oder 3 Säuren verwendet werden. Selbstverständlich sind auch andere Säurebäder, die dem Fachmann geläufig sind, für das Elektrolytbad 1 geeignet. Neben Säure kann das Elektrolytbad weitere Chemikalien, wie z.B. Salze oder Tenside enthalten.In der Regel wird der Träger vor dem elektrochemischen Aufrauhen durch eine saure oder alkalische Vorbeize vorbehandelt, um Walzöle, Verunreinigungen sowie an der Luft gebildetes "natürliches" Oxid abzutragen. Die hierfür verwendete Einrichtung ist nicht dargestellt. Der Träger 2 kann, bevor er in das Elektrolytbad 1 eintritt, in geeigneter Form mechanisch oder chemisch aufgerauht werden. Die Einrichtungen zum mechanischen Aufrauhen der Oberflächen des Trägers 2 sind ebenfalls nicht dargestellt. Derartige Anlagen bzw. Einrichtungen sind u.a. in der DE-A 19 62 729 und der DE-B 19 62 728 beschrieben und dargestellt. Im Elektrolytbad 1 selbst findet nur eine elektrochemische Aufrauhung der Oberfläche des Trägers 2 statt. Im Abstand zu dem Träger 2 sind in dem Elektrolytbad 1 Elektroden 3, 4, 5 angeordnet, die an drei nicht näher bezeichneten Wicklungen einer Sekundärseite eines Drehstromtransformators 6 angeschlossen sind. Die entsprechenden drei Wicklungen auf der Primärseite des Drehstromtransformators 6 sind über Leitungen L1, L2, L3 an nicht gezeigten Regeltransformatoren, die von einem gemeinsamen Leistungstransformator für Drehstrom gespeist werden, angeschlossen. Ebenso ist es möglich, daß die Leitungen L1, L2, L3, unter Weglassung der Regeltransformatoren, direkt mit dem Leistungstransformator verbunden sind. Werden keine weiterenMaßnahmen getroffen, so ergeben sich bei hohen Transportgeschwindigkeiten des Trägers 2 Stromschläge bzw. elektrische Querschläge, die entsprechend dem hohen Stromdichteanstieg im Elektrolyten zwischen der ersten Drehstromelektrode 3 und dem Träger 2 verursacht werden. Bei der gleichfalls im Stand der Technik bekannten Vorrichtung gemäß Fig. 2 befinden sich in einem Elektrolytbad 1 zwei Wechselstromelektroden 7 und 8, die mit einer Sekundärwicklung U2 eines Wechselstromtransformators 9 verbunden sind. Hier gilt gleichfalls, daß durch den hohen Stromdichteanstieg im Elektrolyten zwischen der ersten Wechselstromelektrode 7 und dem Träger 2 bei hohen Transportgeschwindigkeiten des Trägers Stromschläge bzw. elektrische Querschläge auftreten, wenn keine weiteren Maßnahmen getroffen werden.Fig. 1 shows schematically a device known in the prior art, which consists of a Electrolyte bath 1, through which a band-shaped carrier 2 in the transport direction A moved through. The electrolyte in the electrolyte bath 1 can, for example, dilute aqueous Nitric, sulfuric or hydrochloric acid. It can also be a combination of 2 or 3 acids can be used. Of course, other acid baths are also available to those skilled in the art are common, suitable for the electrolyte bath 1. In addition to acid, the electrolytic bath can also be used Chemicals such as Contain salts or surfactants. Usually the carrier is before electrochemical roughening pretreated by an acidic or alkaline pretreatment to To remove impurities and "natural" oxide formed in the air. The one for this device used is not shown. The carrier 2 can, before it enters the electrolyte bath 1 occurs, be mechanically or chemically roughened in a suitable form. The facilities for mechanical roughening of the surfaces of the carrier 2 are also not shown. such Plants and facilities include described in DE-A 19 62 729 and DE-B 19 62 728 and shown. In the electrolyte bath 1 itself there is only an electrochemical roughening of the Surface of the carrier 2 instead. There are electrodes in the electrolyte bath 1 at a distance from the carrier 2 3, 4, 5 arranged on three windings of a secondary side of an unspecified Three-phase transformer 6 are connected. The corresponding three windings on the The primary side of the three-phase transformer 6 are not shown via lines L1, L2, L3 Control transformers powered by a common power transformer for three-phase current are connected. It is also possible that the lines L1, L2, L3, omitting the Control transformers, directly connected to the power transformer. Will not be further measures taken result in the case of high transport speeds of the carrier 2 electric shocks or electrical cross-shocks, which correspond to the high current density increase in the Electrolytes between the first three-phase electrode 3 and the carrier 2 are caused. at 2, which are also known in the prior art, are in a Electrolytic bath 1 two alternating current electrodes 7 and 8, one with a secondary winding U2 AC transformer 9 are connected. It also applies here that the high Current density increase in the electrolyte between the first AC electrode 7 and the carrier 2 Electric shocks or electrical cross-shocks at high carrier speeds occur when no further action is taken.

Zur Vermeidung dieser Querschläge werden bei den erfindungsgemäßen Vorrichtungen gemäß den Fig. 3 bis 7 jeweils die erste Wechsel- oder Drehstromelektrode durch Formgebung oder besondere Auswahl von Werkstoffen mit unterschiedlichen Leitfähigkeiten und/oder Elektrodenabschnitten mit unterschiedlichen elektrischen Eigenschaften infolge ohmscher, induktiver und kapazitiver Widerstände, die mit den Elektrodenabschnitten verbunden sind, so gestaltet , daß der Anstieg der Stromdichte im Verlauf einer Periode des Wechsel- oder Drehstromes kleiner als 20 % der maximalen Stromdichte istTo avoid these cross-blows in the devices according to the invention according to 3 to 7 each the first AC or three-phase electrode by shaping or special Selection of materials with different conductivities and / or electrode sections with different electrical properties due to ohmic, inductive and capacitive Resistors connected to the electrode sections are designed so that the increase in Current density over a period of alternating or three-phase current less than 20% of maximum current density

Eine geringe Veränderung des Wechsel- oder Drehstroms macht sich, wegen der geringen unterschiedlichen Leitfähigkeit an der Oberfläche des Trägers kaum bemerkbar. Diejenigen Oberflächenteile des Trägers, die durch den ursprünglich angelegten Wechsel-oder Drehstrom keine oder nur eine kleine Widerstandsherabsetzung erfahren haben, werden mit der gleichen Stromdichte beaufschlagt, wie diejenigen Oberflächenteile, bei denen die Widerstandsreduzierung etwas größer war. Wegen der geringfügigen Änderung des Wechsel- oder Drehstromes kommt es nur zu einer geringfügigen Unterscheidung in denAbsolutwerten der Leitfähigkeiten verschiedener Oberflächenteile des Trägers. Zwar unterscheiden sich die Leitfähigkeiten voneinander, jedoch aufgrund der geringen Stromänderung machen sich diese Unterschiede nicht stark bemerkbar. Mit anderen Worten bedeutet dies, daß die Verstärkung oder auch die Reduzierung der Leitfähigkeiten an verschiedenen Oberflächenteilen des Trägers zur Bildung von Quers chlägen nicht ausreicht bzw. ist die Ausbildung von Querschlägen so gering, daß sie kaum erkennbar istA slight change in the alternating or three-phase current occurs because of the small different conductivity on the surface of the carrier barely noticeable. Those Surface parts of the carrier that are not due to the originally applied alternating or three-phase current or have just experienced a small drop in resistance will be with the same current density acts like those parts of the surface where the reduction in resistance is somewhat greater was. Because of the slight change in alternating or three-phase current, there is only one slight distinction in the absolute values of the conductivities of different surface parts of the carrier. The conductivities differ from each other, but because of the small differences in current, these differences are not very noticeable. In other words this means that the enhancement or the reduction of the conductivities at different Surface parts of the carrier are not sufficient to form cross-strikes or is the formation of cross-cuts so low that it is hardly recognizable

Bei der Fig. 3 dargestellten ersten Ausführungsform der erfindungsgemäßen Vorrichtung ist vergrößert nur eine erste Wechsel- oder Drehstromelektrode 10 in einem Elektrolytbad 1 gezeigt. Die erste Wechsel- oder Drehstromelektrode 10 ist abgerundet bzw. gekrümmt geformt, im Gegensatz zu der jeweiligen ersten Drehstrom- bzw. Wechselstromelektrode 3 bzw. 7 gemäß den im Stand der Technik bekannten Vorrichtungen für die Aufrauhung von Trägern 2, wie sie in den Fig. 1 und 2 schematisch dargestellt sind. Die dort gezeigten Drehstrom-bzw. Wechselstromelektroden besitzen im allgemeinen einen länglichen rechteckigen Querschnitt. Dies führt dazu, wie schon voranstehend dargelegt wurde, daß der Anstieg der Stromdichte zwischen diesen Elektroden und dem Träger 2 beim Eintritt des Trägers 2 in die Aufrauhzone sehr groß ist und diese zu den unerwünschten Querschlägenführt. Wenn von einer Wechsel- oder Drehstromelektrode im weiteren Verlauf der Beschreibung die Rede ist, so ist darunter zu verstehen, daß diese Elektrode entweder mit Drehstrom bzw. mit Wechselstrom beaufschlagt ist, wie dies anhand der Fig. 1 und 2 beschrieben wurde.3 is the first embodiment of the device according to the invention only shows a first AC or three-phase electrode 10 in an electrolyte bath 1. The first AC or three-phase electrode 10 is rounded or curved, in Contrary to the respective first three-phase or alternating current electrode 3 or 7 according to the devices known for the roughening of supports 2, as are known in the prior art 1 and 2 are shown schematically. The three-phase or AC electrodes generally have an elongated rectangular cross section. As before, this leads to It was stated above that the increase in current density between these electrodes and the carrier 2 is very large when the carrier 2 enters the roughening zone and this to the unwanted cross-blows. If from an AC or three-phase electrode in the further Course of the description, it is to be understood that this electrode either with three-phase current or with alternating current, as is shown in FIGS. 1 and 2 has been described.

Die in das Elektrolybad 1 eintauchende Wechsel- oder Drehstromelektrode 10 ist derart abgerundet, daß ihr Abstand d1 zu dem durch das Elektrolytbad 1 hindurchtransportierten Träger 2 an einer Eintrittsstelle B größer ist als innerhalb der Aufrauhzone. Der Abstand der Wechsel- oder Drehstromelektrode 10 von dem Träger 2 nimmt in Transportrichtung A des Trägers 2 ab, wie dies durch die Abstände d2 und d3 erkennbar ist. An der Eintrittsstelle B, mit dem Abstand d1 zwischen der Wechsel- oder Drehstromelektrode 10 und dem Träger 2 ist der durch den dazwischen befindlichen Elektrolyten vorgegebene Widerstand größer als an den Stellen mit den Abständen d2 und d3. Dementsprechend gilt dann, daß die Stromdichten mit geringer werdenden Abständen d2 und d3 ansteigen. An der Stelle des Abstandes d3 erreicht die Stromdichte ihren Maximalwert und bleibt von da an konstant, da dieser Abstand d3 konstant bleibt. Der abgerundete Umriß der Wechsel- oder Drehstromelektrode 10 setzt sich aus einem parabelförmigen Abschnitt C und einen daran anschließenden geradlinigen Abschnitt D an. Selbstverständlich kann die Rundung der Wechsel- oder Drehstromelektrode 10 auch einen anderen Kurvenverlauf als einen parabelförmigen Verlauf aufweisen.The alternating or three-phase electrode 10 immersed in the electrolytic bath 1 is rounded off in such a way that its distance d 1 to the carrier 2 transported through the electrolytic bath 1 is greater at an entry point B than within the roughening zone. The distance of the AC or three-phase electrode 10 from the carrier 2 decreases in the transport direction A of the carrier 2, as can be seen from the distances d 2 and d 3 . At the entry point B, with the distance d 1 between the AC or three-phase electrode 10 and the carrier 2, the resistance predetermined by the electrolyte located therebetween is greater than at the points with the distances d 2 and d 3 . Accordingly, the current densities then increase with increasing distances d 2 and d 3 . At the point of the distance d 3 , the current density reaches its maximum value and remains constant from then on, since this distance d 3 remains constant. The rounded outline of the AC or three-phase electrode 10 is composed of a parabolic section C and an adjoining rectilinear section D. Of course, the curve of the AC or three-phase electrode 10 can also have a curve shape other than a parabolic shape.

Die Verringerung des elektrischen Widerstandes im Elektrolyten zwischen der Wechsel- oder Drehstromelektrode 10 und dem Träger 2 führt zu einem allmählichen Anstieg der Stromdichte. Durch den großen Abstand d1 der Wechsel- oder Drehstromelektrode 10 vom Träger 2 am Beginn der Aufrauhzone fließt weniger Strom als dies bei dem kleineren Abstand d2 bzw. d3 der Fall ist. Durch den geringen Anstieg ist die Ausprägung von Stellen mit niedrigem und höherem Oberflächenwiderstand geringer als bei steilem Anstieg der Stromdichte.The reduction in the electrical resistance in the electrolyte between the AC or three-phase electrode 10 and the carrier 2 leads to a gradual increase in the current density. Due to the large distance d 1 of the AC or three-phase electrode 10 from the carrier 2 at the beginning of the roughening zone, less current flows than is the case with the smaller distance d 2 or d 3 . Due to the small increase, the characteristics of points with low and higher surface resistance are less than with a steep increase in current density.

Eine zweite Ausführungsform der erfindungsgemäßen Vorrichtung ist in Fig. 4 schematisch dargestellt. Eine erste Wechsel- oder Drehstromelektrode ist in Elektrodenabschnitte 21, 22, 23 unterteilt. Die Elektrodenabschnitte können so ausgestaltet sein, daß die dem Träger 2 zugewandten Flächen 18, 19, 20 ebenen oder sägezahnförmigen Querschnitt, gebildet aus Rechtecken oder Trapezen, aufweisen, um z.B. die im Elektrolytbad entstehenden Gasbläschen schnell abzuleiten. Der Träger 2 wird in Transportrichtung A durch das Elektrolytbad 1 hindurchtransportiert. Den Elektrodenabschnitten 21, 22 , 23 folgt eine weitere Wechsel- oder Drehstromelektrode 4. Die Elektrodenabschnitte 21, 22, 23 bestehen aus Materialien, die unterschiedliche elektrische Leitfähigkeiten untereinander haben können und gegenüber der Wechsel- oder Drehstromelektrode 4 eine unterschiedliche Leitfähigkeit besitzen. A second embodiment of the device according to the invention is shown schematically in FIG. 4 shown. A first AC or three-phase electrode is in electrode sections 21, 22, 23 divided. The electrode sections can be configured in such a way that those facing the carrier 2 Surfaces 18, 19, 20 flat or sawtooth-shaped cross-section, formed from rectangles or Trapezoids, e.g. quickly dissipate the gas bubbles generated in the electrolyte bath. The carrier 2 is transported through the electrolyte bath 1 in the transport direction A. The A further alternating or three-phase electrode 4 follows electrode sections 21, 22, 23 Electrode sections 21, 22, 23 are made of materials that are different electrical Can have conductivities to each other and to the AC or three-phase electrode 4 have different conductivity.

Die in Fig. 5 dargestellte dritte Ausführungsform der erfindungsgemäßen Vorrichtung umfaßt eine erste Wechsel- oder Drehstromelektrode, die in Elektrodenabschnitte 31, 32, 33 unterteilt ist, die voneinander elektrisch isoliert sind. Der Träger 2 wird in Transportrichtung A durch das Elektrolytbad 1 hindurchtransportiert. An die Elektrodenabschnitte 31, 32, 33 schließt eine weitere Wechsel- oder Drehstromelektrode 4 an. Falls die Elektrodenabschnitte und die Elektrode 4 mit Drehstrom beaufschlagt werden, ist im Elektrolytbad 1 noch eine weitere, nicht gezeigte Drehstromelektrode vorhanden. Jeder der Elektrodenabschnitte 31, 32, 33 ist mit einem festen oder variablen ohmschen Widerstand 12, 13, 14 verbunden, die in Reihe (wie gezeigt) oder parallel geschaltet sind. Je nachdem, ob es sich um Wechsel- oder Drehstromelektroden handelt, sind die Widerstände 12, 13, 14 über einen Anschluß 11 mit einer nicht gezeigten Wechsel- oder Drehstromquelle verbunden.The third embodiment of the device according to the invention shown in FIG. 5 comprises a first AC or three-phase electrode, which is divided into electrode sections 31, 32, 33, the are electrically isolated from each other. The carrier 2 is in the transport direction A by the Electrolyte bath 1 transported through. Another is connected to the electrode sections 31, 32, 33 AC or three-phase electrode 4. If the electrode sections and the electrode 4 with Three-phase current is applied, there is still another, not shown, in the electrolyte bath 1 Three-phase electrode available. Each of the electrode sections 31, 32, 33 is fixed or variable ohmic resistor 12, 13, 14 connected in series (as shown) or in parallel are switched. Depending on whether it is AC or three-phase electrodes, the are Resistors 12, 13, 14 via a connection 11 with an alternating or not shown Three-phase source connected.

Zwischen den Elektrodenabschnitten 31, 32, 33 und der Elektrode 4 sind Isolierplatten 15, 16, 17 angeordnet, die verhindern, daß zu hohe Ströme über den Elektrolyten zwischen den Elektrodenabs chnitten fließen. Die Stromdichte je Flächeneinheit der einzelnen Elektrodenabschnitte 31, 32, 33 ist geringer als die Stromdichte je Flächeneinheit der Wechsel- oder Drehstromelektrode 4. Der spezifische ohmsche Widerstand der Elektrodenabschnitte 31, 32, 33, des Elektrolyten und die festen bzw. variablen Widerstände 12, 13, 14 bestimmen die jeweilige Stromdichte im Elektrolyten zwischen den Flächen 18, 19 und 20 und dem Träger 2. Durch die entsprechende Auswahl dieser Widerstände werden die Stromdichten so eingestellt, daß der durch Teile der Oberfläche des Trägers 2 fließende Strom weitgehend unabhängig von dem Oberflächenwiderstand des Trägers 2 an den betreffenden Stellen ist. Durch die Auswahl der festen Widerstände bzw. die Einstellung der variablen Widerstände 12, 13, 14 werden die Querschläge minimiert.There are insulating plates 15, 16, 17 between the electrode sections 31, 32, 33 and the electrode 4 arranged to prevent excessive currents over the electrolyte between the Cut off electrode sections. The current density per unit area of the individual electrode sections 31, 32, 33 is less than the current density per unit area of the AC or three-phase electrode 4. The specific ohmic resistance of the electrode sections 31, 32, 33, the electrolyte and the fixed or variable resistors 12, 13, 14 determine the respective current density in Electrolytes between the surfaces 18, 19 and 20 and the carrier 2. By the corresponding Selection of these resistors, the current densities are set so that the by parts of the Surface of the carrier 2 flowing current largely independent of the surface resistance of the carrier 2 at the relevant points. By selecting the fixed resistors or the Setting the variable resistors 12, 13, 14 minimizes the cross-wake.

Eine vierte Ausführungsform der Vorrichtung zeigt schematisch Fig. 6. Die Ausbildung der ersten Wechsel- oder Drehstromelektrode ist ähnlich derjenigen der zweiten und dritten Ausführungsform. Diese erste Wechsel- oder Drehstromelektrode ist in Elektrodenabschnitte 24, 25, 26 unterteilt, die im Elektrolytbad 1 isoliert voneinander angeordnet sind. In Transportrichtung A des Trägers 2 schließt eine weitere Wechsel-oder Drehstromelektrode 27 an. Zwischen den Elektrodenabschnitten und der weiteren Elektrode 27 befinden sich Isolierplatten 28, 29 und 30. Jeder der Elektrodenabschnitte 24,25,26 ist mit elektrischen Bauteilen 34,35,36 verbunden, von denen jedes einen ohmschen Widerstand und/oder induktiven und kapazitiven Widerstand enthält. Das Bauteil 34 aus ohmschen und/oder induktiven und kapazitiven Widerstand des Elektrodenabschnittes 24 ist mit den Bauteilen 35, 36 der übrigen Elektrodenabschnitte 25,26 in Reihe oder parallel geschaltet und mit diesen zusammen über einen Anschluß 37 mit einer Wechsel- oder Drehstromquelle verbunden. Die für den Stromfluß im Elektrolytbad 1 maßgebenden Widerstände der Elektrodenabschnitte 24, 25, 26 setzen sich aus den Blindwiderständen der Induktivitäten und Kapazitäten in den Bauteilen 34, 35, 36 zusammen, die in Fig. 6 schematisch angedeutet sind, und den ohmschen Widerständen. Bekannterweise ist der Wechselstromwiderstand gleich der Wurzel aus der Summe der Quadrate aus ohmschem Widerstand und Blindwiderständen. Die durch die Blindströme verursachte Blindleistung wird nicht in Wärme umgesetzt. Bei Änderung des Oberflächenwiderstandes des Träges 2, der im wesentlichen ein ohmscher Widerstand ist, wird die Änderung des Blindwiderstandes geringer sein als dies bei einem rein ohmschen Gesamtwiderstand des einzelnen Bauteils der Fall wäre.A fourth embodiment of the device is shown schematically in FIG. 6. The formation of the first AC or three-phase electrode is similar to that of the second and third embodiments. This first AC or three-phase electrode is divided into electrode sections 24, 25, 26 which are arranged isolated from each other in the electrolytic bath 1. In the direction of transport A of the carrier 2 connects a further AC or three-phase electrode 27. Between the electrode sections and the further electrode 27 are insulating plates 28, 29 and 30. Each of the Electrode sections 24, 25, 26 are connected to electrical components 34, 35, 36, each of which contains an ohmic resistor and / or inductive and capacitive resistor. The component 34 of ohmic and / or inductive and capacitive resistance of the electrode section 24 connected in series or in parallel with the components 35, 36 of the remaining electrode sections 25, 26 and together with these via a connection 37 with an AC or three-phase source connected. The decisive resistances for the current flow in the electrolytic bath 1 Electrode sections 24, 25, 26 are made up of the reactances of the inductors and Capacities in the components 34, 35, 36 together, which are indicated schematically in Fig. 6, and the ohmic resistors. As is known, the AC resistance is equal to the root from the sum of the squares of ohmic resistance and reactance. The through the Reactive power caused by reactive currents is not converted into heat. When changing the Surface resistance of the support 2, which is essentially an ohmic resistance, is the Change in reactance may be less than with a purely ohmic total resistance of the individual component would be the case.

Fig. 7 zeigt eine fünfte Ausführungsform der Vorrichtung, bei der die erste Wechsel- oder Drehstromelektrode 40 im Elektrolytbad 1 einteilig ausgebildetistund einen länglichen rechteckigen Querschnitt aufweist. Der Träger 2 wird in Transportrichtung A durch das Elektrolytbad 1 unterhalb von gelochten Elementen 38, 39; 41, 42; 43, 44 hindurchgeführt. Diese gelochten Elemente sind in Fig. 8 als Paare zum Zwecke der Verstellbarkeit ausgeführt. Sie befinden sich zwischen der ersten Wechsel- oder Drehstromelektrode 40 und dem Träger 2. Die Paare von Elementen sind wie in Fig. 8 gezeigt, gegeneinander verschiebbar. Die Elemente 38,39; 41,42; 43,44 bestehen beispielsweise aus Platten, die Lochreihen 47, 48 aufweisen. In der Ausgangsstellung der Elemente decken sich die Lochreihen 47, 48. Wird die der Wechsel- oder Drehstromelektrode 40 zugewandte Platte 38, 41 bzw. 43 eines Elementenpaares quer zur Transportrichtung A des Trägers 2 verschoben, so überdecken sich die Lochreihen 47, 48 nur noch teilweise oder auch nicht, wie dies anhand der einzelnen Löcher 45 einer Lochreihe 47 und der Löcher 46 einer Lochreihe 48, die in Fig. 8 gestrichelt angedeutet sind, erkennbar ist. Durch die teilweise Überdeckung der Lochreihen 47, 48 wird der Querschnitt der von den Löchern freigegebenen Öffnungen kleiner. Der kleinere Querschnitt für den leitfähigen Elektrolyten führt zu einem größeren ohmschen Widerstand und somit zu einer geringeren Stromdichte im Elektrolytbad 1 zwischen der Elektrode 40 und dem Träger 2. Im Betrieb kann die Verschiebung der Platten in der Weise erfolgen, daß das in Transportrichtung A des Trägers 2 erste Paar von Elementen 38, 39 eine kleinere Überdeckung der Lochreihen 47, 48 aufweist, als das nächstfolgende Paar von Elementen 41, 42. B ei dem dritten Paar der Elemente 43, 44 liegt dann beispielsweise volle Überdeckung der Lochreihen 47, 48 vor, so daß dann die Stromdichte in dem Elektrolyten zwischen der Wechsel- oder Drehstromelektrode 40 und dem Träger 2 am größten ist.Fig. 7 shows a fifth embodiment of the device in which the first change or Three-phase electrode 40 is formed in one piece in the electrolyte bath 1 and an elongated rectangular Has cross-section. The carrier 2 is in the transport direction A through the electrolyte bath 1 below of perforated elements 38, 39; 41, 42; 43, 44 passed through. These perforated elements are in Fig. 8 executed as pairs for the purpose of adjustability. You are between the first AC or three-phase electrode 40 and the carrier 2. The pairs of elements are as in Fig. 8 shown, slidable against each other. The elements 38.39; 41.42; For example, 43.44 from plates that have rows of holes 47, 48. In the starting position of the elements, the Row of holes 47, 48. If the plate 38, 41 facing the AC or three-phase electrode 40 or 43 of a pair of elements displaced transversely to the transport direction A of the carrier 2, see above The rows of holes 47, 48 only partially or not overlap, as is shown in FIG individual holes 45 of a row of holes 47 and the holes 46 of a row of holes 48, which are shown in FIG. 8 are indicated by dashed lines, is recognizable. Due to the partial coverage of the rows of holes 47, 48 the cross section of the openings exposed by the holes becomes smaller. The smaller one Cross section for the conductive electrolyte leads to a greater ohmic resistance and thus to a lower current density in the electrolyte bath 1 between the electrode 40 and the Carrier 2. In operation, the plates can be moved in such a way that the Transport direction A of the carrier 2 first pair of elements 38, 39 a smaller coverage of the Row of holes 47, 48, as the next successive pair of elements 41, 42. B ei the third pair the elements 43, 44 is then, for example, full coverage of the rows of holes 47, 48, so that then the current density in the electrolyte between the AC or three-phase electrode 40 and the carrier 2 is largest.

Claims (17)

  1. A method for electrochemically roughening a substrate for light-sensitive layers, the surface of said substrate being roughened electrochemically, or mechanically and subsequently electrochemically, in an aqueous electrolyte bath by the application of an alternating or three-phase current to electrodes opposite the substrate while the substrate is transported continuously through the electrolyte bath, characterised in that at an entry point of the substrate into the roughening zone, the current density in the electrolyte bath between the first alternating or three-phase current electrode and the substrate is less than a maximum current density for the roughening, and in that the current density within the range of the first alternating or three-phase current electrode increases continuously up to the maximum current density with increasing distance from the entry point.
  2. A method according to claim 1, wherein the increase in current density in the electrolyte bath over the course of one period of the alternating or three-phase current amounts to less than 20% of the maximum current density.
  3. A method according to claim 1, wherein the spacing of the first alternating or three-phase current electrode from the substrate decreases continuously from the entry point into the roughening zone in the transport direction of the substrate until a predetermined constant spacing is attained.
  4. A method according to claim 1, wherein the first alternating or three-phase current electrode is subdivided into electrode portions of different materials, whose specific electrical conductivities differ from one another.
  5. A method according to claim 1, wherein the first alternating or three-phase current electrode is subdivided into electrode portions, and wherein each electrode portion is connected to a fixed or variable ohmic resistor, the size of the resistors being selected such that the current density in the electrolyte bath increases in the transport direction of the substrate.
  6. A method according to claim 1, wherein the first alternating or three-phase current electrode is subdivided into electrode portions, and wherein each electrode portion is connected to ohmic and/or inductive and capacitive resistances, the total resistance of the individual electrode portions comprising ohmic resistances and reactances comprising inductances and capacitances being selected such that the current density in the electrolyte bath increases in the transport direction of the substrate.
  7. A method according to claim 1 wherein perforated elements or pairs of perforated elements, the conductivity of which is selected to be less than the conductivity of the electrolyte bath, are positioned between the first alternating or three-phase current electrode and the substrate.
  8. A method according to claim 7, wherein the elements of a pair are shiftable one with respect to the other.
  9. An apparatus for applying the method according to one or more of claims 1 to 3, wherein an alternating or three-phase current electrode (10) disposed in said electrolyte bath (1) has a rounded outline such that its spacing (d1) from a substrate (2) being passed through the electrolyte bath is greater at an entry point (B) into a roughening zone of the electrolyte bath than within the roughening zone, and wherein beyond a predetermined distance from the entry point (B) the spacing of the alternating or three-phase current electrode from said substrate (2) is constant.
  10. An apparatus according to claim 9, wherein the curved outline of the alternating or three-phase current electrode (10) has a parabolic portion (C) which is adjoined by a straight portion (D).
  11. An apparatus for applying the method according to any of claims 1 to 4, wherein the first alternating or three-phase current electrode is subdivided into electrode portions (21, 22, 23), and wherein the individual electrode portions comprise materials of different electrical conductivities
  12. An apparatus according to claim 11, wherein the electrode portions (21, 22, 23) and a further alternating or three-phase current electrode (4) adjoin one another.
  13. An apparatus for applying the method according to one or more of claims 1 to 3 and 5, wherein the first alternating or three-phase current electrode is subdivided into electrode portions (31, 32, 33) and wherein each of said electrode portions (31, 32, 33) is connected to a fixed or variable ohmic resistor (12, 13, 14), said resistors (12, 13, 14) being connected to an alternating or three-phase current source.
  14. An apparatus according to claim 13, wherein insulating plates (15, 16, 17) are disposed between the electrode portions (31, 32, 33) and a further alternating or three-phase current electrode (4) and wherein the current density per unit of surface area of the individual electrode portions (31, 32, 33) is less than that of the alternating or three-phase current electrode (4).
  15. An apparatus for applying the method according to one or more of claims 1 to 3, 5 and 6, wherein the first alternating or three-phase current electrode is subdivided into electrode portions (24, 25, 26) which are insulated from one another, wherein each of the electrode portions (24, 25, 26) is connected to an electrical component (34, 35, 36), each of which has an ohmic resistance and/or inductive and capacitive resistances, said component (34) having ohmic and/or inductive and capacitive resistances of each electrode portion (24) being connected in series with or parallel to the other components (35, 36) of the other electrode portions (25, 26) and being connected with them to an alternating or three-phase current source.
  16. An apparatus for applying the method according to one or more of claims 1 to 3, 7 and 8, wherein pairs of perforated elements (38, 39, 41, 42, 43, 44) are disposed between a first alternating or three-phase current electrode (40) and a substrate (2), wherein the pairs of elements are spaced apart one from the other, and wherein the elements of each pair are shiftable one with respect to the other.
  17. An apparatus according to claim 16, wherein said elements (38, 39, 41, 42, 43, 44) comprise plates presenting rows of perforations (47, 48) that coincide at an initial position and wherein one plate is shiftable with respect to the other plate of a pair transversally to the transport direction (A) of the substrate (2) to such an extent that said rows of perforations (47, 48) coincide only in part or not at all.
EP00104028A 1999-03-02 2000-02-26 Process and apparatus for electrochemically graining a support for light-sensitive layers Expired - Lifetime EP1033420B1 (en)

Applications Claiming Priority (2)

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DE19908884 1999-03-02
DE19908884A DE19908884C1 (en) 1999-03-02 1999-03-02 Method and device for electrochemically roughening a support for photosensitive layers

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EP1033420B1 true EP1033420B1 (en) 2004-01-28

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JP2000303200A (en) 2000-10-31
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US6423206B1 (en) 2002-07-23

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