EP0095581B1 - Process for the post treatment of aluminium oxide layers with aqueous solutions containing alkalisilicate, and its use in the manufacture of offset printing platen supports - Google Patents

Description

The invention relates to an aftertreatment process for roughened and anodically oxidized aluminum, in particular of support materials for offset printing plates with aqueous solutions containing alkali silicate.

Carrier materials for offset printing plates are provided either directly by the consumer or by the manufacturer of precoated printing plates on one or both sides with a radiation-sensitive layer (reproduction layer), with the aid of which a printing image of a template is generated in a photomechanical way. After this printing form has been produced from the printing plate, the layer support carries the image areas which will guide the color during later printing and at the same time forms the hydrophilic image background for the lithographic printing process at the areas which are later free of image (non-image areas).

• - Die nach der Belichtung relativ löslicher gewordenen Teile der lichtempfindlichen Schicht müssen durch eine Entwicklung leicht zur Erzeugung der hydrophilen Nichtbildstellen rückstandsfrei vom Träger zu entfernen sein.
• - Der in den Nichtbildstellen freigelegte Träger muß eine große Affinität zu Wasser besitzen, d. h. stark hydrophil sein, um beim lithographischen Druckvorgang schnell und dauerhaft Wasser aufzunehmen und gegenüber der fetten Druckfarbe ausreichend abstoßend zu wirken.
• - Die Haftung der lichtempfindlichen Schicht vor bzw. der druckenden Teile der Schicht nach der Belichtung muß in einem ausreichenden Maß gegeben sein.

The following requirements must therefore be placed on a layer support for reproduction layers for the production of offset printing plates:

• - The parts of the photosensitive layer which have become relatively more soluble after exposure must be easy to remove from the support without residue by development to produce the hydrophilic non-image areas.
• - The carrier exposed in the non-image areas must have a great affinity for water, ie be highly hydrophilic, in order to absorb water quickly and permanently during the lithographic printing process and to be sufficiently repellent to the bold printing ink.
• - The adhesion of the light-sensitive layer before or the printing parts of the layer after exposure must be sufficient.

Aluminum, steel, copper, brass or zinc, but also plastic films or paper can be used as the base material for such layers. These raw materials are processed by suitable operations such as. B. grain, matt chrome plating, surface oxidation and / or application of an intermediate layer in layer support for offset printing plates. Aluminum, which is probably the most frequently used base material for offset printing plates today, is roughened on the surface by known methods by dry brushing, wet brushing, sandblasting, chemical and / or electrochemical treatment. In order to increase the abrasion resistance, the roughened substrate can also be subjected to an anodization step to build up a thin oxide layer.

• In der DE-PS 907 147 (=US-PS 2 714 066), der DE-AS 14 71 707 (=US―PS 3 181 461 und US-PS 3 280 734) oder der DE-OS 25 32 769 (= US-PS 3 902 976) werden Verfahren zur Hydrophilierung von Druckplattenträgermaterialien auf der Basis von. gegebenenfalls anodisch oxidiertem Aluminium beschrieben, in denen diese Materialien ohne oder mit Einsatz von elektrischem Strom mit wäßriger Natriumsilikat-Lösung behandelt werden.
• Aus der DE-PS 11 34 093 (= US-PS 3 276 868) und der DE-PS 16 21 478 (= US-PS 4153 461) ist es bekannt, Polyvinylphosphonsäure oder Mischpolymerisate auf der Basis von Vinylphosphonsäure, Acrylsäure und Vinylacetat zur Hydrophilierung von Druckplattenträgermaterialien auf der Basis von gegebenenfalls anodisch oxidiertem Aluminium einzusetzen.

In practice, the support materials are often subjected to a further treatment step, in particular anodically oxidized support materials based on aluminum, to improve the layer adhesion, to increase the hydrophilicity and / or to facilitate the developability of the light-sensitive layers, before the application of a light-sensitive layer for example the following methods:

• In DE-PS 907 147 (= US-PS 2 714 066), DE-AS 14 71 707 (= US ― PS 3 181 461 and US-PS 3 280 734) or DE-OS 25 32 769 (= US Pat. No. 3,902,976) describes processes for the hydrophilization of printing plate support materials based on. optionally described anodized aluminum, in which these materials are treated with aqueous sodium silicate solution without or with the use of electric current.
• From DE-PS 11 34 093 (= US-PS 3 276 868) and DE-PS 16 21 478 (= US-PS 4153 461) it is known to use polyvinylphosphonic acid or copolymers based on vinylphosphonic acid, acrylic acid and vinyl acetate Hydrophilization of printing plate support materials based on anodized aluminum, if necessary.

Although these post-treatment processes often lead to sufficient results, they cannot meet all, often very complex, requirements for a printing plate support material, as are currently placed on high-performance printing plates in practice.

• - der Zusatz von Tensiden mit nichtionogenen und anionogenen Bausteinen, gegebenenfalls auch noch von Gelatine, zu wäßrigen Silikatlösung für die Tauchbehandlung von Druckplattenträgern aus Aluminium und anschließendes Erhitzen aus der JP-OS 55 109 693 (veröffentlicht am 23. August 1980) oder der JP-OS 55 082 695 (veröffentlicht am 21. Juni 1980),
• - der Zusatz einer Kombination aus nichtionogenen und anionogenen Tensiden zu wäßrigen Alkalisilikatlösungen für die Tauchbehandlung von Druckplattenträgern aus Aluminium bei 80 bis 100°C aus der FR-PS 1 162 653,
• - der Zusatz von wasserlöslichen organischen Polymeren wie Polyvinylalkohol, Polyacrylsäure, Polyacrylamid, Polysacchariden oder Polystyrolsulfonsäure zu wäßrigen Alkalisilikatlösungen für die Tachbehandlung von Aluminium bei mehr als 40°C aus der EP-OS 0 016 298, diese Behandlung wird speziell für Aluminiumbehälter angewandt,
• - ein dreistufiges Verfahren zur Erzeugung einer hydrophilen Haftschicht auf Druckplattenträgern aus Aluminium nach der DE-AS 11 18 009 (= US-PS 2,922,717) mit a) einer chemischen oder mechanischen Aufrauhung, b) einer Tauchbehandlung bei mehr als 85°C in einer wäßrigen Alkalisilikatlösung und c) einer abschließenden Tauchbehandlung bei Raumtemperatur in einer wäßrigen Citronen- oder Weinsäurelösung zur Neutralisation des in b) erzeugten Alkalis, oder
• - die härtende Nachbehandlung von durch Tauchbehandlung in wäßrigen Alkalisilikatlösungen hergestellten Silikatschichten auf Druckplattenträgern aus Aluminium mit einer wäßrigen Ca(N0₃)₂-Lösung nach den US-PS 2,882,153 und US-PS 2,882,154.

For example, after treatment with alkali silicates, which lead to good developability and hydrophilicity, a certain deterioration in the shelf life of reproductive layers applied thereon must be accepted. In the treatment of carriers with water-soluble organic polymers, their good solubility, particularly in aqueous alkaline developers, as are used predominantly for the development of positive-working reproduction layers, leads to a weakening of the hydrophilizing effect. The alkali resistance, which is required in particular when using high-performance developers in the field of positive-working reproduction layers, is not sufficient. Occasionally, depending on the chemical composition of the reproduction layers, there is a fog in the non-image areas, which should be caused by absorptive effects. Modifications of the silicating processes have also been described in the prior art, for example:

• - The addition of surfactants with non-ionic and anionogenic building blocks, possibly also of gelatin, to aqueous silicate solution for the immersion treatment of aluminum printing plate supports and subsequent heating from JP-OS 55 109 693 (published on August 23, 1980) or JP- OS 55 082 695 (published June 21, 1980),
• the addition of a combination of nonionic and anionogenic surfactants to aqueous alkali silicate solutions for the immersion treatment of printing plate supports made of aluminum at 80 to 100 ° C. from FR-PS 1 162 653,
• the addition of water-soluble organic polymers such as polyvinyl alcohol, polyacrylic acid, polyacrylamide, polysaccharides or polystyrene sulfonic acid to aqueous alkali silicate solutions for the tachy treatment of aluminum at more than 40 ° C. from EP-OS 0 016 298, this treatment is used especially for aluminum containers,
• - A three-stage process for producing a hydrophilic adhesive layer on printing plate supports made of aluminum according to DE-AS 11 18 009 (= US Pat. No. 2,922,717) with a) a chemical or mechanical roughening, b) an immersion treatment at more than 85 ° C in an aqueous Alkali silicate solution and c) a final immersion treatment at room temperature in an aqueous citric or tartaric acid solution to neutralize the alkali produced in b), or
• - The curing aftertreatment of silicate layers produced by immersion treatment in aqueous alkali silicate solutions on printing plate supports made of aluminum with an aqueous Ca (N0 ₃ ) ₂ solution according to US Pat. No. 2,882,153 and US Pat. No. 2,882,154.

Even these modified processes do not yet result in silicate layers on printing plate supports made of aluminum which are so technically improved that they would fully meet the requirements described above.

DE-AS 21 62 674 (= US Pat. No. 3,838,023) discloses a process for compacting anodically oxidized aluminum with aqueous solutions by immersion treatment at at least 90 ° C. The suitable aqueous solutions should contain at a pH of 5 to 6 citric acid, tartaric acid, gallic acid, sugar acid or their alkali, ammonium or alkaline earth salts; an application in the printing plate field is not mentioned.

The anodic oxidation process of aluminum supports for offset printing plates according to US Pat. No. 3,756,826 is carried out as an alternative to silicating with aqueous solutions of hydroxydi- or tricarboxylic acids such as tartaric acid, citric acid or malic acid in a one-step process.

DE-OS 22 23 850 (= US ― PS 3,824,159) describes a method for coating aluminum moldings, sheets, castings or foils (including for offset printing plates, but especially for capacitors), in which anodic oxidation in an aqueous electrolyte from an alkali silicate and an organic complexing agent. The complexing agents include amines, amino acids and sulfonic acids.

Phenols and glycols also salts of organic carboxylic acids such as maleic acid, fumaric acid, citric acid or tartaric acid. This anodic oxidation reaction is generated directly on the aluminum, ie without the formation of an aluminum oxide layer in the meantime by anodic oxidation in H ₂ SO ₄ or H ₃ PO ₄ . The electrolyte concentrations should preferably be between 0.1 and 15% by weight for the silicate and between 1 and 12% by weight for the complexing agent. The preferred process parameters are: the temperature between 15 and 40 ° C, the coating time between 0.5 and 5 min, the current density between 0.5 and 3 A / dm ² . A printing plate support material was in Example 9 in an electrolyte containing 9.2% by weight of sodium silicate, 6.3% by weight of monoethanolamine and 0.9% by weight of sodium potassium tartrate at a current density of 3 A / dm2 for 15 min and anodized at 45 to 50 ° C.

The process for the production of grain-like or grained surfaces on aluminum according to DE-AS 26 51 346 (GB-PS 1,523,030) is carried out directly on aluminum with alternating current in an electrolyte which is 0.01 to 0.5 mol / l in aqueous solution contains an alkali or alkaline earth metal hydroxide or salt and optionally 0.01 to 0.5 mol / 1 of a barrier layer former. After this surface treatment, a coloring treatment is carried out, optionally after previous anodic oxidation. To the barrier layer formers u. a. also include citric acid, tartaric acid, succinic acid, lactic acid, malic acid or their salts.

No anodic oxidation of the aluminum is carried out before the grain-like or grained surface is produced. The aluminum substrate to be treated is hung vertically in the electrolytic bath in order to achieve the desired grain. In Example 5, an aqueous electrolyte with a content of 10 g / l of Na orthosilicate and 30 g / l of Na tartrate was used at a current density of 3 A / dm ² for 15 minutes. The products produced in this way are said to be suitable for the production of window frames, wall panels (paneling) and decorative moldings for vehicles or household articles.

However, these known anodic oxidation processes or surface structuring with electrolytes with a content of organic acids or their salts - if they can be transferred to printing plate supports made of aluminum at all or are sensible for them - do not yet lead to a surface which is suitable for high-performance printing plates.

The object of the present invention is to propose a method for the aftertreatment of flat aluminum, which can be carried out in addition to anodic oxidation of the aluminum and leads to a surface on the aluminum oxide thus produced, which in particular meets the practical requirements of a high-performance printing plate described at the outset.

The invention is based on the known process for the production of plate, sheet or strip materials based on chemically, mechanically and / or electrochemically roughened and anodically oxidized aluminum or one of its alloys, the aluminum oxide layers of which are post-treated with an aqueous alkali silicate solution. The process according to the invention is then characterized in that the aftertreatment with an aqueous alkali silicate Solution is carried out, which additionally contains at least one aliphatic hydroxy mono-, di- or tricarboxylic acid, an aliphatic dicarboxylic acid or a water-soluble salt of these acids. Materials treated in this way are used in particular as supports for offset printing plates.

The aliphatic carboxylic acids which can be used in the process according to the invention include, in particular, hydroxytricarboxylic acids such as citric acid, hydroxydicarboxylic acids such as tartaric or malic acid, hydroxymonocarboxylic acids such as glycolic, lactic or gluconic acid or dicarboxylic acids such as oxalic, malonic, maleic or succinic acid. The corresponding water-soluble salts such as alkali or ammonium salts are preferably used, since they only slightly change the pH of the aqueous alkali silicate solution; this should suitably be in the range from 11.5 to 13.5, in particular from 12.0 to 13.0. The lowering of the pH of the aqueous alkali silicate solution, which usually takes place when the free acids are used, can be brought back to higher pH values by adding bases such as aqueous NaOH solution.

The treatment can be carried out as an immersion treatment or electrochemically, the latter procedure often bringing an increase in the resistance to alkali. The electrochemical process variant is carried out in particular with direct or alternating current, trapezoidal, rectangular or triangular current or overlapping forms of these types of current; the current density is generally 0.1 to 10 A / dm ² . The treatment of the materials can be carried out batchwise or continuously in modern conveyor systems, the treatment times are expediently in the range of 5 to _'120 seconds and the treatment temperature at 15 to 80 ° C, especially at 40 to 75 ° C. The aqueous solution generally contains 1 to 50 g / l, in particular 5 to 30 g / l, of an alkali silicate (such as sodium metasilicate or the sodium and silicate contained in the "water glass") and 3 to 50 g / l I, in particular 5 to 20 g / I, one of the acids and / or salts mentioned above. The weight ratio of silicate to acid / salt is preferably in the range from 1: 1 to 4: 1.

• - "Reinaluminium" (DIN-Werkstoff Nr. 3.0255), d. h. bestehend aus ≥99,5% AI und den folgenden zulässigen Beimengungen von (maximale Summe von 0,5%) 0,3% Si, 0,4% Fe, 0,03% Ti, 0.02% Cu, 0,07% Zn und 0,03% Sonstigem, oder
• - "AI-Legierung 3003" (vergleichbar mit DIN-Werkstoff Nr. 3.0515), d. h. bestehend aus s 98,5% Al, den Legierungsbestandteilen 0 bis 0,3% Mg und 0,8 bis 1,5% Mn und den folgenden Zulässigen Beimengungen von 0,5% Si, 0,5% Fe, 0,2% Ti, 0,2% Zn, 0,1% Cu und 0,15% Sonstigem.

Suitable base materials for use in the process according to the invention, in particular for the production of printing plate supports, include those made of aluminum or one of its alloys such as

• - "Pure aluminum" (DIN material no. 3.0255), ie consisting of ≥99.5% AI and the following admissible admixtures of (maximum sum of 0.5%) 0.3% Si, 0.4% Fe, 0 , 03% Ti, 0.02% Cu, 0.07% Zn and 0.03% other, or
• - "AI alloy 3003" (comparable to DIN material no. 3.0515), ie consisting of s 98.5% Al, the alloy components 0 to 0.3% Mg and 0.8 to 1.5% Mn and the following Permissible admixtures of 0.5% Si, 0.5% Fe, 0.2% Ti, 0.2% Zn, 0.1% Cu and 0.15% other.

The aluminum support materials for printing plates encountered in practice are mechanically (e.g. by brushing and / or with abrasive treatments), chemically (e.g. by etching agents) or electrochemically (e.g. by AC treatment in aqueous HCI and / or HN0 ₃ before applying the light-sensitive layer Solutions) roughened. Aluminum printing plates with electrochemical roughening are used in particular for the present invention.

In general, the process parameters in the roughening stage are in the following ranges: the temperature of the electrolyte between 20 and 60 ° C, the active substance (acid, salt) concentration between 5 and 100 g / I, the current density between 15 and 130 A / dm ² , the residence time between 10 and 100 sec and the electrolyte flow rate in continuous processes on the surface of the workpiece to be treated between 5 and 100 cm / sec; AC is usually used as the type of current, but modified types of current such as AC with different amplitudes of the current strength are also possible for the anode and cathode currents. The average roughness depth R _{z of} the roughened surface is in the range from about 1 to 15 μm, in particular in the range from 2 to 8 μm. The roughness depth is determined in accordance with DIN 4768 in the version from October 1970, the roughness depth R _z is then the arithmetic mean of the individual roughness depths of five adjacent individual measuring sections.

• - Bern, 1948, Seite 760; Praktische Galvanotechnik, Eugen G. Leuze Verlag - Saulgau, 1970, Seite 395 ff und Seiten 518/519; W. Hübner und C. T. Speiser, Die Praxis der anodischen Oxidation des Aluminiums, Aluminium Verlag - Düsseldorf, 1977, 3. Auflage, Seiten 137 ff):
• - Das Gleichstrom-Schwefelsäure-Verfahren, bei dem in einem wäßrigen "Elektrolyten aus üblicherweise ca. 230 g H₂S0₄ pro 1 I Lösung bei 10° bis 22°C und einer Stromdichte von 0,5 bis 2,5 Aldm² während 10 bis 60 min anodisch oxidiert wird. Die Schwefelsäurekonzentration in der wäßrigen Elektrolytlösung kann dabei auch bis auf 8 bis 10 Gew.-% H₂S0₄ (ca. 100 g H₂SO₄/l) verringert oder auch auf 30 Gew.-% (365 g H₂SO₄/l) und mehr erhöht werden.
• - Die "Hartanodisierung" wird mit einem wäßrigen, H_IS0₄ enthaltenden Elektrolyten einer Konzentration von 166 g H₂SO₄/ l (oder ca. 230 g H₂SO₄/) bei einer Betriebstemperatur von 0° bis 5°C, bei einer Stromdichte von 2 bis 3 A/dm², einer steigenden Spannung von etwa 25 bis 30 V zu Beginn und etwa 40 bis 100 V gegen Ende der Behandlung und während 30 bis 200 min durchgeführt.

After the electrochemical roughening process, an anodic oxidation of the aluminum then follows in a further process step, for example to improve the abrasion and adhesion properties of the surface of the carrier material. The usual electrolytes such as H ₂ S0 ₄ , H ₃ P0 ₄ , H ₂ C ₂ 0 ₄ , amidosulfonic acid, sulfosuccinic acid, sulfosalicylic acid or mixtures thereof can be used for anodic oxidation. Reference is made, for example, to the following standard methods for the use of aqueous electrolytes containing H ₂ SO ₄ for the anodic oxidation of aluminum (see, for example, BM Schenk, material aluminum and its anodic oxidation, Francke Verlag

• - Bern, 1948, page 760; Practical electroplating, Eugen G. Leuze Verlag - Saulgau, 1970, page 395 ff and pages 518/519; W. Hübner and CT Speiser, The Practice of Anodic Oxidation of Aluminum, Aluminum Verlag - Düsseldorf, 1977, 3rd edition, pages 137 ff):
• - The direct current sulfuric acid process, in which in an aqueous "electrolyte from usually about 230 g H ₂ S0 ₄ per 1 I solution at 10 ° to 22 ° C and a current density of 0.5 to 2.5 Aldm ² during 10 is oxidized to 60 min anodically. the sulfuric acid concentration in the aqueous electrolyte solution can also be reduced to 8 to 10 wt .-% H ₂ S0 ₄ (100 g H ₂ SO ₄ / l) reduced or even to 30 weight % (365 g H ₂ SO ₄ / l) and more can be increased.
• - The "hard anodizing" is carried out with an aqueous electrolyte containing H _I S0 _{4 with} a concentration of 166 g H ₂ SO ₄ / l (or approx. 230 g H ₂ SO ₄ /) at an operating temperature of 0 ° to 5 ° C, at a current density of 2 to 3 A / dm ² , a rising voltage of about 25 to 30 V at the beginning and about 40 to 100 V towards the end of the treatment and for 30 to 200 min.

In addition to the processes for anodic oxidation of aluminum already mentioned in the previous paragraph, the following processes can also be used, for example: the anodic oxidation of aluminum in an aqueous H ₂ S0 _4- containing electrolyte, the Al ³⁺ ion content of which is more than is set as 12 g / l (according to DE-OS 28 11 396 = US-PS 4211 619), in an aqueous electrolyte containing H ₂ S0 ₄ and H ₂ P0 ₄ (according to DE-OS 27 07 810 = US -PS 4,049,504) or in an aqueous, H _Z SO _4, H ₂ P0 ₄ and Al3 ⁺ ion-containing electrolyte (according to DE-OS 28 36 803 = US-PS 4,229,226). Direct current is preferably used for the anodic oxidation, however alternating current or a combination of these types of current (eg direct current with superimposed alternating current) can also be used; the electrolyte is in particular an aqueous solution containing H ₃ PO ₄ . The layer weights of aluminum oxide range from 1 to 10 g / m ² , corresponding to a layer thickness of approximately 0.3 to 3.0 µm.

In principle, all layers are suitable as light-sensitive layers which, after exposure, optionally with subsequent development and / or fixation, provide an imagewise surface from which printing can take place. They are either applied to the substrate by the manufacturer of presensitized printing plates or directly by the consumer.

• Positiv-arbeitende o-Chinondiazid-, bevorzugt o-Naphthochinondiazid-Verbindungen, die beispielsweise in den DE-PSen 854 890, 865 109, 879, 203, 894 959, 938 233, 1 109521, 1 144 705, 1 188 606, 1 120 273 und 1 124817 beschrieben werden.
• Negativ-arbeitende Kondensationsprodukte aus aromatischen Diazoniumsalzen und Verbindungen mit aktiven Carbonylgruppen, bevorzugt Kondensationsprodukte aus Diphenylamindiazoniumsalzen und Formaldehyd, die beispielsweise in den DE-PSen 596 731, 1 138 399, 1 138 400, 1 138 401, 1 142 871, 1 154 123, den US-PSen 2 679 498 und 3 050 502 und der GB-PS 712 606 beschrieben werden.
• Negativ-arbeitende Mischkondensationsprodukte aromatischer Diazoniumverbindungen, beispielsweise nach der DE-OS 20 24 244, die mindestens je eine Einheit der allgemeinen Typen A(-D)_n und B verbunden durch ein zweibindiges, von einer kondensationsfähigen Carbonylverbindung abgeleitetes Zwischenglied aufweisen. Dabei sind diese Symbole wie folgt definiert: A ist der Rest einer mindestens zwei aromatische carbo- und/oder heterocyclische Kerne enthaltenden Verbindung, die in saurem Medium an mindestens einer Position zur Kondensation mit einer aktiven Carbonylverbindung befähigt ist. D ist eine an ein aromatisches Kohlenstoffatom von A gebundene Diazoniumsalzgruppe; n ist eine ganze Zahl von 1 bis 10; und B der Rest einer von Diazoniumgruppen freien Verbindung, die in saurem Medium an mindestens einer Position des Moleküls zur Kondensation mit einer aktiven Carbonylverbindung befähigt ist.
• Positiv-arbeitende Schichten nach der DE-OS 26 10 842, die eine bei Bestrahlung Säure abspaltende . Verbindung, eine Verbindung, die mindestens eine durch Säure abspaltbare C―O―C-Gruppe aufweist (z. B. eine Orthocarbonsäureestergruppe oder eine Carbonsäureamidacetalgruppe) und gegebenenfalls ein Bindemittel enthalten.
• Negativ-arbeitende Schichten aus photopolymerisierbaren Monomeren, Photoinitiatoren, Bindemitteln und gegebenenfalls weiteren Zusätzen. Als Monomere werden dabei beispielsweise Acryl- und Methacrylsäureester oder Umsetzungsprodukte von Diisocyanaten mit Partialestern mehrwertiger Alkohole eingesetzt, wie es beispielsweise in den US-PSen 2 760 863 und 3 060 023 und den DE-OSen 20 64 079 und 23 61 041 beschrieben wird. Als Photoinitiatoren eignen sich u. a. Benzoin, Benzoinether, Mehrkernchinone, Acridinderivate, Phenazinderivate, Chinoxalinderivate, Chinazolinderivate oder synergistische Mischungen verschiedener Ketone. Als Bindemittel können eine Vielzahl löslicher organischer Polymere Einsatz finden, z. B. Polyamide, Polyester, Alkydharze, Polyvinylalkohol, Polyvinylpyrrolidon, Polyethylenoxid, Gelatine oder Celluloseether.
• Negativ-arbeitende Schichten gemäß der DE-OS 30 36 077, die als lichtempfindliche Verbindung ein Diazoniumsalz-Polykondensationsprodukt oder eine organische Azidoverbindung und als Bindemittel ein hochmolekulares Polymeres mit seitenständigen Alkenylsulfonyl- oder Cycloalkenylsulfonylurethan-Gruppen enthalten.

In addition to the layers containing silver halides used in many fields, various others are also known, such as e.g. As described in "Light-Sensitive Systems" by Jaromir Kosar, John Wiley & sons Verlag, New York 1965: the chromate and dichromate-containing colloid layers (Kosar, Chapter 2); the layers containing unsaturated compounds in which these compounds are isomerized, rearranged, cyclized or crosslinked during exposure (Kosar, Chapter 4); the layers containing photopolymerizable compounds, in which monomers or prepolymers optionally polymerize during exposure by means of an initiator (Kosar, Chapter 5); and the layers containing o-diazo-quinones such as naphthoquinonediazides, p-diazo-quinones or diazonium salt condensates (Kosar, Chapter 7). The suitable layers also include the electrophotographic layers, ie those which contain an inorganic or organic photoconductor. In addition to the light-sensitive substances, these layers can of course also other components such. B. contain resins, dyes or plasticizers. In particular, the following light-sensitive compositions or compounds can be used in the coating of the carrier materials produced by the process according to the invention:

• Positive-working o-quinonediazide, preferably o-naphthoquinonediazide compounds, which are described, for example, in DE-PS 854 890, 865 109, 879, 203, 894 959, 938 233, 1 109521, 1 144 705, 1 188 606, 1 120 273 and 1 124817.
• Negative-working condensation products from aromatic diazonium salts and compounds with active carbonyl groups, preferably condensation products from diphenylamine diazonium salts and formaldehyde, which are described, for example, in DE-PS 596 731, 1 138 399, 1 138 400, 1 138 401, 1 142 871, 1 154 123, U.S. Patents 2,679,498 and 3,050,502 and British Pat. No. 712,606.
• Negative-working mixed condensation products of aromatic diazonium compounds, for example according to DE-OS 20 24 244, which each have at least one unit of the general types A (-D) _n and B connected by a double-bonded intermediate member derived from a condensable carbonyl compound. These symbols are defined as follows: A is the remainder of a compound containing at least two aromatic carbocyclic and / or heterocyclic nuclei, which is capable of condensing with an active carbonyl compound in an acidic medium at at least one position. D is a diazonium salt group attached to an aromatic carbon atom of A; n is an integer from 1 to 10; and B is the remainder of a compound free of diazonium groups and capable of condensing with an active carbonyl compound in an acidic medium at at least one position on the molecule.
• Positive-working layers according to DE-OS 26 10 842, which releases an acid when irradiated. Compound, a compound which has at least one C ― O ― C group which can be split off by acid (for example an orthocarboxylic acid ester group or a carboxylic acid amide acetal group) and optionally contains a binder.
• Negative working layers made of photopolymerizable monomers, photoinitiators, binders and optionally other additives. The monomers used here are, for example, acrylic and methacrylic acid esters or reaction products of diisocyanates with partial esters of polyhydric alcohols, as described, for example, in US Pat. Nos. 2,760,863 and 3,060,023 and DE-OSes 20 64 079 and 23 61 041. Suitable photoinitiators include benzoin, benzoin ethers, multinuclear quinones, acridine derivatives, phenazine derivatives, quinoxaline derivatives, quinazoline derivatives or synergistic mixtures of various ketones. A variety of soluble organic polymers can be used as binders, e.g. B. polyamides, polyesters, alkyd resins, polyvinyl alcohol, polyvinyl pyrrolidone, polyethylene oxide, gelatin or cellulose ether.
• Negative working layers according to DE-OS 30 36 077, which contain a diazonium salt polycondensation product or an organic azido compound as a photosensitive compound and a high molecular weight polymer with pendant alkenylsulfonyl or cycloalkenylsulfonylurethane groups as a binder.

It can also be photoconductive layers such as z. B. in DE-PSen 11 17391, 15 22 497, 1572312, 2322046 and 2322047 are described, to those produced according to the invention Carrier materials are applied, which creates highly light-sensitive, electrophotographic printing plates.

The coated offset printing plates obtained from the carrier materials provided according to the invention are converted into the desired printing form in a known manner by imagewise exposure or irradiation and washing out the non-image areas with a developer, preferably an aqueous developer solution. Surprisingly, offset printing plates, the base support materials of which have been post-treated by the processes according to the invention, are distinguished from such plates in which the same base material has been post-treated with aqueous solutions containing only silicates, by improved hydrophilicity of the non-image areas, a lower tendency to color fog binding, improved alkali resistance and Achieve a steeper gradation (measured with a halftone step part).

In the above description and the following examples,% data always mean% by weight, unless stated otherwise. Parts by weight relate to parts by volume in the ratio of g to cm ³ . The following methods for determining parameters were used in the examples:

The hydrophilicity of the carrier materials produced according to the invention is checked using wetting angle measurements in relation to a drop of water placed on it, the angle between the carrier surface and a tangent through the point of contact of the drop being determined, it is generally between 0 and 90 °. The smaller the angle, the better the wetting.

Zinc certificate (according to US Pat. No. 3,940,321, columns 3 and 4, lines 29 to 68 and lines 1 to 8):

The rate at which the layer dissolves in an alkaline zincate solution is used as a measure of the alkali resistance of an aluminum oxide layer. The layer is more alkali-resistant the longer it takes to dissolve it. The layer thicknesses should be roughly comparable, since of course they also represent a parameter for the dissolution rate. A drop of a solution of 500 ml of distilled H ₂ O, 480 g of KOH and 80 g of zinc oxide is placed on the surface to be examined and the period of time until the appearance of metallic zinc is determined, which can be seen from the darkening of the examination site.

Gravimetric removal (alkali resistance)

The sample of a defined size protected on the back by a layer of lacquer is moved in a bath containing an aqueous solution of 6 g / l of NaOH. The weight loss experienced in this bath is determined gravimetrically and is given in g / m ² . Times of 1, 2, 4 or 8 minutes are selected as the treatment time in the alkaline bath.

Examples 1 to 3 and comparative examples V to V4

An aluminum foil is electrochemically roughened in dilute aqueous HN0 ₃ solution with alternating current and anodically oxidized in dilute aqueous H ₃ SO ₄ solution with direct current. The subsequent treatment is carried out either only with Na ₂ SiO ₃ . 5H ₂ 0 (comparative examples V2, V3), carried out only with KN tartrate (comparative example V4) or with a mixture of the two components (examples 1 to 3) and compared with a film without any aftertreatment (comparative example V1). The test conditions and results can be found in the table below.

Examples 4 to 15 and comparative examples V5 to V16

An aluminum foil is roughened electrochemically in a dilute aqueous HCl or NHO ₃ solution using alternating current and anodically oxidized in a dilute aqueous H ₂ S0 ₄ or H ₃ P0 ₄ solution. The subsequent treatment is carried out either only with Na ₂ SiO ₃ . 5 H ₂ 0 (V5 to V16) or with a mixture of silicate and KN-tartrate (Examples 4 to 15) and compared with foils without any aftertreatment (V1 and V17). The test conditions and results can be found in the table below, the effective temperatures and sometimes the effective times being varied.

With increasing temperature of the treatment bath, the alkali resistance of the oxide layer treated in this way increases. The electrochemical type of treatment usually improves the resistance to alkali compared to a pure immersion treatment under otherwise identical conditions. Oxide layers produced in H ₂ S0 ₄ solutions are attacked more strongly by silicate solutions at higher temperatures than oxide layers produced in H ₃ PO ₄ solutions, so that - without using the mixture according to the invention - the treatment times and temperatures are severely restricted.

Examples 16 and 17 and comparative examples V18 to V21

An aluminum foil is in dilute aqueous HCI or HN0 ₃ solution. electrochemically roughened with alternating current and anodized in dilute aqueous H ₂ SO ₄ solution. Which subsequent treatment with an aqueous solution of a content of 40 g / I of Na ₃ SiO ₃ · 5 H ₂ 0 and 20 g / I of KNa-tartrate (Examples 16 and 17) performed with foils without any post-treatment (V18 and V20) or with polyvinylphosphonic acid (PVPS) aftertreatment (V19 and V21). The test conditions and results can be found in the table below. The oxide layers aftertreated with aqueous polyvinylphosphonic acid solutions do show good hydrophilicity and a good reduction in the color fog sensitivity, but they are not yet satisfactory in all cases.

• 6,00 Gew.-TeileKresol-Formaldehyd-Novolak (Erweichungsbereich 105 bis 120°C nach DIN 53 181
• 1,10 Gew.-Teile4-(2-Phenyl-prop-2-yl)-phenylester der Naphthochinon-1,2)-diazid-(2)sulfonsäure-(4)
• 0,81 Gew.-TeilePolyvinylbutyral
• 0,75 Gew.-TeileNaphthochinon-(1,2)-diazid-(2)-sulfonsäurechlorid-(4)
• 0,08 Gew.-TeileKristallviolett
• 91,36 Gew.-TeileLösemittelgemisch aus 4 Vol.-Teilen Ethylenglykolmonomethylether, 5 Vol.-Teilen Tetrahydrofuran und 1 Vol.-Teil Butylacetat

An aluminum foil aftertreated according to Examples 16 and 17 is coated with the following positive-working light-sensitive mixture:

• 6.00 parts by weight of cresol-formaldehyde novolak (softening range 105 to 120 ° C according to DIN 53 181
• 1.10 parts by weight of 4- (2-phenyl-prop-2-yl) -phenyl ester of naphthoquinone-1,2) -diazide- (2) sulfonic acid- (4)
• 0.81 part by weight of polyvinyl butyral
• 0.75 part by weight of naphthoquinone- (1,2) -diazide- (2) -sulfonic acid chloride- (4)
• 0.08 part by weight of crystal violet
• 91.36 parts by weight of solvent mixture of 4 parts by volume of ethylene glycol monomethyl ether, 5 parts by volume of tetrahydrofuran and 1 part by volume of butyl acetate

After exposure and development, well over 100,000 prints of good quality can be produced from the offset printing plate thus produced.

Examples 18 to 61 and comparative examples V22 to V26

An aluminum foil is roughened in dilute aqueous HCI or HN0 ₃ solution with alternating electrochemically and in dilute aqueous H _z S0 ₄ solution anodically oxidized. The subsequent treatment is carried out with an aqueous solution of Na ₃ SiO ₃ .5 H ₂ O (comparative examples) or a mixture of silicate / organic carboxylic acid or carboxylic acid salt - as can be seen from the table. Hydroxycarbon or dicarboxylic acids are used as carboxylic acids, ie carboxylic acids with one or more carboxyl groups and at least one hydroxyl group or carboxylic acids with two carboxyl groups. When the free acids are used, the pH of the resulting aqueous solutions drops by about 1.5 to 2.5 values, which in some cases leads to a reduction in the alkali resistance (measured by the gravimetric method). This effect can be compensated for by increasing the temperature or extending the treatment time, including use the electrochemical process variant brings improvements. A significant improvement in the alkali resistance to pure silicate solutions can be achieved by adjusting the pH values of the aqueous solutions to values which are in the range of the pH value of pure silicate solutions. This setting can be brought about by the direct use of salts (alkali or ammonium salts) of the CaArbonic acids mentioned, or by adding bases such as aqueous NaOH solution to the aqueous silicate / acid mixtures. It is also possible to use alternating current instead of direct current in the electrochemical process variant.

Examples 62 to 72 and comparative examples V27 to V36

An aluminum foil is electrochemically roughened in a dilute aqueous HCl or HN0 ₃ solution with alternating current and anodically oxidized in a dilute aqueous H ₂ S0 ₄ solution. The subsequent treatment is no longer carried out with Na ₂ SiO _{3 '} 5 H ₂ 0 (sodium metasilicate) with a ratio of Na ₂ 0: Si0 ₂ such as 1: 1, which, without addition, has a relatively aggressive influence on the aluminum oxide layer, but with water glass DAB VI with a solids content of about 33%, ie usually a mixture of sodium tri- and tetrasilicates with an approximate ratio of Na ₂ O: Si0 ₂ such as 3: 1. In the examples according to the invention, KN tartrate is added as the second component.

Examples 73 to 76 and Comparative Examples V37 to V40 The procedure of the example groups 1 to 3 and V1 to V4 is followed, but with aluminum foil which is anodically oxidized in an aqueous electrolyte containing H ₂ S0 ₄ and H ₃ P0 ₄ (according to Teaching of DE-OS 28 36 803).

Claims (8)

1. Process for manufacturing materials in the form of sheets, foils or strips, based on chemically, mechanically and/or electrochemically roughened and anodically oxidized aluminum or an alloy thereof, the aluminum oxide layers of which are post-treated with an aqueous alkali metal silicate solution, wherein post-treating is carried out with an aqueous alkali metal silicate solution which additionally comprises at least one aliphatic monobasic, dibasic or tribasic hydroxycarboxylic acid, an aliphatic dicarboxylic acid or a water-soluble salt of these acids.

2. A process as claimed in claim 1, wherein the aqueous soluton used has a pH in the range from 11.5 to 13.5.

3. A process as claimed in claim 1 or claim 2, wherein the aqueous solution used has a pH in the range from 12.0 to 13.0.

4. A process as claimed in any of claims 1 to 3, wherein post-treating is carried out electrochemically, at a current density in the range from 0.1 to 10 A/dm².

5. A process as claimed in any of claims 1 to 4, wherein post-treating is carried out for a duration from 5 to 120 seconds and at a temperature from 15 to 80°C.

6. A process as claimed in any of claims 1 to 5, wherein the aqueous solution used comprises from 1 to 50 g/I of an alkali metal silicate and from 3 to 50 g/I of at least one carboxylic acid or a salt thereof.

7. A process as claimed in any of claims 1 to 6, wherein the materials are electrochemically roughened in an aqueous solution containing HCI and/or HN0₃ and anodically oxidized in an aqueous solution containing H₃PO₄.

8. Use of the process as claimed in any of claims 1 to 7, in the production of materials for use as supports for offset-printing plates.