DE2422918C3 - Planographic printing plate and process for making same - Google Patents

Description

The invention relates to a planographic printing plate and a method for producing these planographic printing plates

Aluminum surface.

The technology of surface treatment and tempering of aluminum and its alloys is a complex and well-developed area, as shown in the work of S. Wernick »Surface Treatment and Finishing of Aluminum and Ils Alloys ", Robert Draper Ltd ^ Teddington, England (1956), and by G. H. Kis s t η "Finishing of Aluminum", Reinhold Publishing Corporation, New York, emerges thereby it is recognized that electroplating Electroplating on aluminum and thus the possible Production of planographic printing plates requires unusual treatment steps to achieve the necessary adhesion to achieve. The best known processes for plating aluminum are the galvanizing processes and the

J5 Anodic Oxydierea In the last-mentioned process, in which the plating or electroplating over an anodically deposited oxide layer is carried out on the aluminum substrate, efforts are made to produce continuously galvanized or electro- plated coatings.

It is therefore an object of the invention to produce improved planographic printing plates, in which in particular Due to their surface structure, an extended printing period is possible and their production

«S is simple, continuous and economically possible.

This object is achieved according to the invention by an aluminum substrate, a porous anodic oxide layer on the substrate and electrolytically deposited, randomly distributed discrete metal islands with an in one or more pores of the oxide layer anchored FuUleil, wherein the Metallinscln from the foot part extend beyond the surface of the oxide layer, so that there is one anodized surface with discontinuous electroplated areas and one thereon applied photosensitive layer.

The electrolytically deposited chromium-plated chromium can advantageously be used to increase the durability exist, and in order to create a ready-to-use printing area, it can be advantageous not to use metal inserts covered part of the oxide layer to be sealed.

The Metallinscln have one to improve the adhesiveness of the sealing layer Diameter of the portion exceeding the diameter and the photosensitive layer may be made of any one of

Diazo resin be formed.

The process according to the invention for the production of the laughter pressure plates is advantageously characterized in that a) the aluminum substrate is first used

Production of an unsealed, porous anodic oxide layer is anodically oxidized, that b) thereafter by Electrolytic deposition: randomly distributed discrete metal islands, each with one in one or more pores the oxide layer anchored foot part are applied, the metal islands from the foot part over the The surface of the oxide layer protrude and daQ c) the oxide layer applied a photosensitive layer with the metal islands protruding above the surface of the photosensitive layer.

The according to the invention can be particularly economical Processes are carried out in that the treatment is carried out continuously and that aluminum substrate is used in the form of a strip. Those not covered by the electrolytic deposit Sections of the oxide layer are sealed after the metallic deposition.

In detail, the method according to the invention In a particularly simple device carried out in that the aluminum strip in a cell is anodically oxidized, with an electrically conductive roller in front of its entry into the cell Contact is made, and that the anodically oxidized strip is then inserted into a galvanizing cell! will, after leaving the Electroplating cell is in contact with an electrically conductive roller

Further advantageous refinements of the method according to the invention can be found in the further Subclaims.

For the person skilled in the art it is surprising Printing plate according to the invention particularly advantageous that a improved !: Adhesion of the photosensitive layer is present and thereby the planographic printing plates a have a significantly longer service life than conventional plates with smooth surfaces. Of the mechanical abrasion of the photosensitive layer is greatly reduced and the area between the Melullin can serve as a reservoir for this.

In the following, preferred exemplary embodiments of the invention are explained in more detail with reference to the drawings. Show it

F i g. I to 6 photomicrographs of chromium in the form of metal islands with bubble-like, undercut Form electrolytically in the pores of an unsealed, anodized aluminum surface has been deposited,

Figures 7-12 are photomicrographs of copper used in Form of metal islands with bubble-like, undercut configuration electrolytically in the pores of a unsealed, anodized aluminum surface has been deposited,

13 is an enlarged scale Section to illustrate one of the Metallinscln anchored in a pore of the anodic oxide layer is and protrudes in a bubble-like, undershot shape over its surface, and

14a to 14e are schematic representations of various Ways by which eir. Aluminum strips according to the method according to the invention can be continuously anodized and plated or galvanized.

In the drawings, and particularly in FIG Fluid pressure split in the form of an aluminum substrate 18 with an unsealed, porous Children's oxide layer 16 shown, electrolytic Deposited metal cells each have a base or root part 12 which is contained in one or more pores 14 the oxide layer 16 is anchored. These islands extend from the root part 12 in a bubble-like, undercut Configuration 10 via the interface of the

5 oxide layer 16 addition. This bubble-like undercut configuration is shown in greater detail in FIGS illustrates which is made using an electron microscope at magnifications of 300. 1000 and 3000 obtained photomicrographs

lu len. In the examples shown, chromium was on Electrolytically deposited for a period of 30s (Fig. 1 to 3) and 150s (Fig. 4 to 6). Copper was electrolytically applied for a period of 30s (Fig. 7 to 9) and 60s (Fig. 10 to 15) In any case, the chromium or copper is deposited in an indiscriminate distribution in the form of discrete Metal islands are deposited, each of which is in one or more pores of the anodized oxide layer is anchored and Iri is more bubble-like, undercut; r shape extends beyond the surface of the oxide layer.

The electrolytic formation of Metal islands, which are separated from each other and each of which has a bubble-like and undercut design is. The invention takes advantage of this phenomenon by taking advantage of the fact that the discrete rental islands are firmly anchored in the pores of the anodic oxide layer and that the The portion of these metal islands protruding from the surface of the oxide layer generally has a larger surface Diameter than the anchored root part in the pores of the oxide layer.

Virtually any platable metal can be coated onto an anodized aluminum article to form a discontinuous galvanized surface according to the invention. Examples of suitable metals are copper, tin, silver, nickel, gold, rhodium, chromium and alloys and Mixtures of the aforementioned and similar metals.

The planographic printing plate according to the invention with one anodically oxidized surface and one discontinuous galvanized surface can be done using conventional anodizing and plating or electroplating processes are produced, but is preferably produced by the method according to the invention. One major factor of the electroplating process is the electroplating time, which depends on the desired Density of the individual metal plates is chosen. However, the plating time must not be so long.

that bridging or contact between the adjacent metal islands caused will.

The planographic printing plate of the present invention is preferred continuously anodized and galvanized by direct current; into the aluminum in one kaihotischen Konlaktzellc is applied, which a Plallable metal! contains, being on the aluminum before entering the cell under the action of the direct current introduced into the contact cell itself

t> o anodic oxide coating is formed. In the Contact cell is the platable metal in the pores of the previously formed oxide coating in the form the described Mctallin & cln deposited.

In other words: An aluminum! 'Will rush

hi continuously anodically oxidized by being continuously through a treatment cell having a cathode connected to a direct current source and from this / hurry continuously into a

cathodic contact cell is introduced, in which one platable metal anode connected to the same direct current source is arranged. DC becomes applied to the strip in the treatment cell, so that on the strip before its fin run into the ! contact cell forms an anodic oxide coating. Inner Alb In the contact cell, the plable metal is then deposited in the pores of the oxide coating in the form of the described discrete Meiallinseln deposited.

On the aluminum strip running into the cathodic contact cell, an anodic, oxidized coating is already formed before it runs into this cell. As a result, a platable metal such as copper, nickel, / ink or the like can be used for the anode of the contact / parts. In this way, the pressure applied in the Kontaktzclle the Aluminiumstreilen DC for forming the .modischen oxide coating on the strip in front of his l'.inliiuf in the Kontaktzclle also to deposit the ιλ can - ιιIii "if'jhuTjin Mot: TLTC of Hpr Anr. \ fin in Hpn Prirpn rip *: Jn

oxide coating formed on the strip can be used before the strip enters the contact cell. Here, the direct current from a power source is effectively used to perform two operations used, namely once to form an oxide coating on the strip before it enters the Contact cells and, on the other hand, for the deposition of the said metal on the previously formed oxide coating, while the aluminum strip passes through the contact cells. Since the process carried out in the contact cell th process a discontinuously galvanized surface in the form of the described metal islands is deposited can be conventional, continuously operating Electroplating process to increase the size and density of individual metal objects. « which form the discontinuous, galvanized surface.

In Iig. 14 are different embodiments of the Process according to the invention for continuous anodic oxidation and plating or electroplating · »(> Ren shown by aluminum strips. According to Fig. 14a a contact cell is connected to a treatment cell for anodic oxidation, and both cells are with rollers for guiding the aluminum strip through the cells in the direction indicated by the arrows Mistake.

Each cell has a container that contains a flectrolyte. In the treatment cell there is one Cathode connected to a direct current source in the manner shown. In the contact cell there is a V) Anode is provided, which iM connected to the same direct current source. The aluminum strip passes through continuously the handling cell and then the contact cell, as shown in the drawing. Of the Direct current for anodic oxidation is introduced into the strip in the contact cell. On the An anodic oxide coating forms there under the effect of the in the cell on the strips Strip of applied direct current before the strip enters the contact cell. The same current causes Mi also the deposition of the platable metal from the anode in the contact cell in the pores of the previously formed oxide coating in the form of discrete, discontinuous metal islands, the. how mentioned, a bubble-like, undercut shape t * ~ < own.

The aluminum tire can be used before the anodic Oxidizing according to known methods, cleaned, degreased and otherwise chemically and / or in the usual way mechanically pretreated, and after It can be electroplated, sealed, colored or otherwise according to conventional aluminum surfaces surface treatment processes are post-treated. The strip is generally used conventional winding and conveying devices under a continuous treatment process threw.

According to Fig. 14b. i-d the aluminum strip through Application of a direct current to the 'ι ι nium in the Kalhodischen Bchandlungszelle anodise! oxidized where by forming an anodic oxide coating on the strip prior to its fin run into the cell. The stripe then passes through an electroplating bath, the electroplating current being applied by means of a contact roller which contacts the strip immediately after its exit from the electroplating cell. At this In a special embodiment, the procedure is first started by - /! g «u / nicp Hariiirrh in gear gpspl7l_ Hall Bare aluminum strips pulled through the three Bchandlungs cells and with the contact roller on The end of the electroplating cell is contacted. Then the electroplating current is switched on first, so that a certain anodic oxidation is formed on the bare aluminum strip. Once the If the oxidation process is switched on, the strip entering the electroplating bath becomes discontinuousί Plated surface in the form of the discrete metal elements described. This start-up procedure is necessary if the galvanizing contact is made via a contact roller and here plating odci Electroplating is carried out in a separate electroplating cell, e.g. B. in the even closer / ii explanatory method according to FIGS. 14c and 14c In addition, this approach is in accordance with the method according to Fig. 14b and 14b are advantageous.

According to Fig. 14c, the aluminum strip is in a Treatment cell is anodically oxidized, with it being electroconductive before the fin run into the cell Roller is in contact. The strip then runs into a plating cell. in which he after leaving this cell is contacted with an electrically conductive roller. That of the cell to the anodic Oxidation upstream contact roller introduces the current into the strip, while that of the electroplating cell downstream contact roller introduces the electroplating current.

14d is similar to that. 14b. where the treatment *, - cell and the electroplating cells are combined into one cell.

In the arrangement according to FIG Aluminum strips are anodically oxidized as a result is first passed through a contact cell and then through a cell for anodic oxidation. Of the anodically oxidized strip is then passed through an electroplating cell using the electroplating current is applied to the strip via an electrically conductive contact roller, which follows the strip whose exit from the electroplating cell contacted. The method according to FIG. 14e is, as is the case with the Embodiment according to FIG. 14b. with bare aluminum set in motion.

The invention enables the manufacture of planographic printing plates by applying a seal on the oxide layer which adheres to this layer and which protrudes beyond the surface of the oxide layer surrounded by uninterrupted metal islands. The flat printing

24 22 91h

Plates are produced in such a way that a photosensitive layer enclosing the intersected metal islands Layer is applied to the oxide layer.

Suitable photosensitive or radiation-sensitive substances, which can be used for the manufacture of planographic printing plates according to the invention are dichromatic Colloids. Photopolymers such as diazo resins and the like. These and other photochemicals are ira individuals in Kosar, »Lightsensitivi: Systems«, in John Wiley and Sons, Inc., New York (1965).

The following examples are intended to explain the invention further without restricting it in any way.

Chromium and copper were electroplated onto an anodised aluminum surface, with a discontinuous electroplated surface of discrete metal islands with a bubble-like, undercut configuration, as shown in FIGS. 1 to 12 illustrated. Cleaned aluminum plates were anodically oxidized in an electrolyte which contained 280 g sulfuric acid per liter of water. The anodic oxidizing carried out at a temperature of 40 ⁰ C and a current density of about 30 A per 0.09 m ² for a period of about 54 s.

After the formation of the anodic oxide layer, the chrome plating was carried out in an electrolyte of 250 g of chromic acid per liter of water together with 2.5 g of sulfuric acid per liter of water. The electroplating was carried out at a temperature of 40-45 ° C for a period of 60 to 120 seconds using a current density of 125 A per 0.09 m ² . The results are shown in Figs.

Copper plating was done in a similar manner to J5 and the results are shown in Figs. 7 to 12 shown.

In another embodiment it has been found possible according to the invention to use aluminum strips continuously to oxidize anodically and either with a discontinuously galvanized metal surface of the to provide the type described or, if desired, to apply a continuous electroplating coating. In the process used for this purpose, the aluminum strip is continuously electrolytic in one Cell anodically oxidized, one cathode connected to a direct current source and one with the same Direct current source connected, the cell upstream of the contact roller, which has an electrical Makes contact with the aluminum strip before it enters the cell itself. Then the anodically oxidized strips by electrolytic deposition or precipitation of a platable Plated or electroplated metal in an electroplating cell, this cell being connected to a second direct current source connected anode made of the platable metal and one downstream of the cell, to the same Has power source connected contact roller, which after the galvanized aluminum strips contacted his exit from the Galvariisierzelle.

This embodiment is illustrated in Figure 14c. As mentioned, it is necessary to start the process in the wines that first Bare aluminum strips passed through the cells for anodic oxidation and electroplating cells so that <: r the contact roller upstream of the cell for the anodic oxidation and that of the Electroplating cell touches downstream contact roller. The electroplating current is introduced into the electroplating cell, causing some plating of the bare aluminum strip occurs. In the course of the anodic oxidation in the covering cell, the in the strip entering the electroplating bath is already anodically oxidized, whereupon it is replaced with a discontinuous or continuous galvanized metal surface is plated.

The device for the continuous treatment of the aluminum strip according to the method shown in FIG. 14c shown Embodiment Weiiil a cell for continuous anodic oxidation of the aluminum strip with a cathode connected to a power source and one of this cell upstream, connected to the same power source and a contact roller Electroplating cell for the continuous electrolytic deposition of a plating metal on the anodically oxidized aluminum strips, this cell with an at eim; second power source connected Anode made of a metal that can be plated and connected to a downstream electroplating cell second power source connected contact roller is provided.

It is also possible to use the anodic oxydati'.ii to be carried out continuously with a single or multi-phase alternating current and then the strip to be galvanized continuously with direct current. When using an alternating current for continuous Oxidation is the strip in the cell bipolar, while the electrode in the cell is to each other and to Stripes have opposite polarity.

For this purpose 4 sheets of drawings

Claims (12)

Claims; 1. Planographic printing plate, marked through an aluminum substrate, a porous anodic oxide layer on the substrate, and electrolytically deposited, randomly distributed discrete metal islands with one in one or more pores of the Oxide layer anchored foot part, whereby the metal islands from the foot part over the surface of the oxide layer so that there is an anodized surface with discontinuous electroplating areas and one thereon applied photosensitive layer 2. Planographic printing plate according to claim 1, characterized characterized in that the electrodeposited metal islands are made of chromium. 3. Planographic printing plate according to claim 1, characterized in that the not of metal islands covered part of the oxide layer is sealed 4. Planographic printing plate according to claim 1, characterized in that the Metallinscln one the Have the diameter of the foot part exceeding diameter. 5. Planographic printing plate according to claim 4, characterized in that the photosensitive layer is formed from a diazo resin 6. A method for producing the revenge printing plates with an aluminum surface according to claim 1, characterized in that a) the aluminum substrate is initially used to produce an unsealed, porous anodic oxide layer is anodically oxidized, that b) then by electrolytic deposition randomly distributed discrete metal islands with each a foot part anchored in one or more pores of the oxide layer are broken, the Metal islands protrude from the foot part over the surface of the oxide layer un ^ that c) on the Oxide layer a photosensitive layer is applied, with the metal islands over the Protrude from the surface of the photosensitive layer. 7. The method according to claim 6, characterized in that the treatment is carried out continuously and the aluminum substrate in the form of a strip is used. 8. The method according to claim 6, characterized in that the not of the electrulytic Deposition-covered sections of the oxide layer are sealed. 9. The method according to claim 7, characterized in that the aluminum strip is in a cell is anodically oxidized, with an electrically conductive roller in front of its entry into the cell Contact is, and that the anodically oxidized strip is then in an electroplating cell is introduced, and after its exit from the electroplating cell with an electrically conductive Toilet is in contact. 10. The method according to claim 7, characterized in that the aluminum strip in the manner is anodically oxidized that it is initially through a first contact cell with a downstream cell for anodic oxidation is passed through, and that the strip is then passed through an electroplating / eile, wherein it is after its exit from the electroplating line is in contact with an electrically conductive roller. 11. The method according to claim 7, characterized draws that the aluminum strip by applying a direct current to the aluminum in a cathodic contact cell is anodically oxidized, being deposited on the aluminum before entering the cell forms an oxide coating, and that the anodized strip then passes through a Electroplating bath and after its exit from the electroplating bath with an electrically conductive Roller is contacted. 12. The method according to claim 11, characterized in that the contact cell and the Electroplating bath are combined in the same cell.