EP0468313B1 - Plate-, foil- and web-shaped support material for offset printing plates, process for its production and use thereof - Google Patents

Description

The invention relates to plate, film or tape-shaped carrier material for offset printing plates, consisting of pretreated aluminum or one of its alloys, which has a hydrophilic coating of a polymer containing acid side groups on at least one side, a process for producing a carrier material and the use of a carrier material .

Backing materials for offset printing plates are provided either by the consumer directly or by the manufacturer of precoated printing plates on one or both sides with a light-sensitive layer (copying layer), with the aid of which a printing image is generated photomechanically. After the printing image has been produced, the layer support carries the printing image areas and at the same time forms the hydrophilic image background for the lithographic printing process in the non-image areas (non-image areas).

• Die nach der Belichtung relativ löslicheren Teile der lichtempfindlichen Schicht müssen durch eine Entwicklung leicht zur Erzeugung der hydrophilen Nichtbildstellen rückstandsfrei vom Träger zu entfernen sein.
• Der an 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 druckende Teil der Schicht nach der Belichtung muß in einem ausreichenden Maß gegeben sein, um eine hohe Druckauflage zu garantieren.

The following requirements must therefore be placed on a layer support for light-sensitive material for the production of lithographic plates:

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

Aluminum, steel, copper, brass or zinc, but also plastic films or paper can be used as the base material for such layer supports. These raw materials are processed through suitable processing measures, e.g. Grain, matt chrome plating, surface oxidation and / or application of an intermediate layer, transferred into layer supports 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 such as dry brushing, wet brushing, sandblasting, chemical and / or electrochemical treatment or a combination thereof. 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 practice, the carrier materials, in particular anodically oxidized carrier materials based on aluminum, are often used to improve the layer adhesion, to increase the hydrophilicity and / or to facilitate the developability of the undergo a further treatment step before applying a photosensitive layer, these include, for example, the following methods:
In DE-C 907 147 (= US-A 2,714,066), DE-B 14 71 707 (= US-A 3,181,461 and US-A 3,280,734) or DE-A 25 32 769 (= US-A 3,902,976) Process for the hydrophilization of printing plate support materials based on optionally anodized aluminum, in which these materials are treated with aqueous sodium silicate solution without or with the use of electric current.

From DE-A 11 34 093 (= US-A 3,276,868) and DE-C 16 21 478 (= US-A 4,153,461) it is known to use polyvinylphosphonic acid or copolymers based on vinylphosphonic acid, acrylic acid and vinyl acetate for the hydrophilization of printing plate support materials to be used on the basis of optionally anodized aluminum. The use of salts of these compounds is also mentioned, but is not specified in detail.

The use of complex fluorides of titanium, zircon or hafnium according to DE-B 13 00 415 (= US-A 3,440,050) also leads to additional hydrophilization of aluminum oxide layers on printing plate support materials.

In addition to these particularly well-known hydrophilization methods, there is also, for example Use of the following polymers has been described in this area of application:
DE-B 10 56 931 describes the use of water-soluble, linear copolymers based on alkyl vinyl ethers and maleic anhydrides in light-sensitive layers for printing plates. Of these copolymers, those in which the maleic anhydride component has not been reacted with, or more or less completely, with ammonia, an alkali metal hydroxide or an alcohol are particularly hydrophilic.

DE-B 10 91 433 discloses the hydrophilization of printing plate support materials based on metals with film-forming organic polymers, such as polymethacrylic acid or sodium carboxymethyl cellulose or hydroxyethyl cellulose in the case of aluminum supports or a mixed polymer of methyl vinyl ether and maleic anhydride in the case of magnesium supports.

For the hydrophilization of printing plate support materials made of metals according to DE-B 11 73 917 (= GB-A 907.718), water-soluble polyfunctional amino-urea-aldehyde synthetic resins or sulfonated urea-aldehyde synthetic resins which are cured in a water-insoluble state on the metal support are first used become.

To produce a hydrophilic layer on printing plate support materials, according to DE-B 12 00 847 (= US Pat. No. 3,232,783), a) an aqueous dispersion of a modified one is first of all carried out on the support Urea-formaldehyde resin, an alkylated methylol-melamine resin or a melamine-formaldehyde-polyalkylene polyamine resin applied, b) an aqueous dispersion of a polyhydroxy or polycarboxy compound, such as sodium carboxymethyl cellulose, and finally the thus coated base c) with a treated aqueous solution of a Zr, Hf, Ti or Th salt.

DE-B 12 57 170 (= US Pat. No. 2,991,204) describes a copolymer as a hydrophilizing agent for printing plate support materials which, in addition to acrylic acid, acrylate, acrylamide or methacrylamide units, also contains Si-trisubstituted vinylsilane units.

From DE-A 14 71 706 (= US-A 3,298,852) the use of polyacrylic acid as a hydrophilizing agent for printing plate support materials made of aluminum, copper or zinc is known.

The hydrophilic layer on a printing plate support material according to DE-C 21 07 901 (= US-A 3,733,200) is formed from a water-insoluble hydrophilic acrylate or methacrylate homopolymer or copolymer with a water absorption of at least 20% by weight.

DE-B 23 05 231 (= GB-A 1,414,575) describes a hydrophilization of printing plate support materials in which a solution or dispersion of a mixture of an aldehyde and a synthetic polyacrylamide is applied to the support.

DE-A 23 08 196 (= US-A 3,861,917) describes the hydrophilization of roughened and anodically oxidized aluminum printing plate supports with ethylene or methyl vinyl ether / maleic anhydride copolymers, polyacrylic acid, carboxymethyl cellulose, sodium poly (vinylbenzene-2,4- disulfonic acid) or polyacrylamide.

DE-B 23 64 177 (= US-A 3,860,426) describes a hydrophilic adhesive layer for aluminum offset printing plates, which is arranged between the anodized surface of the printing plate support and the light-sensitive layer and, in addition to a cellulose ether, a water-soluble Zn-, Ca -, Mg, Ba, Sr, Co or Mn salt contains. The layer weight of the hydrophilic adhesive layer on cellulose ether is 0.2 to 1.1 mg / dm², and the same layer weight is also given for the water-soluble salts. The mixture of cellulose ether and salt is applied to the support in aqueous solution, optionally with the addition of an organic solvent and / or a surfactant.

To seal anodically oxidized aluminum surfaces according to US Pat. No. 3,672,966, aqueous solutions of acrylic acid, polyacrylic acid, polymethacrylic acid, polymaleic acid or copolymers of maleic acid with ethylene or vinyl alcohol are used after their sealing to avoid seal deposits.

Contain the hydrophilizing agent for printing plate support materials according to US-A 4,049,746 salt-like reaction products from water-soluble polyacrylic resins with carboxyl groups and polyalkyleneimine-urea-aldehyde resins.

GB-A 1,246,696 describes hydrophilic colloids such as hydroxyethyl cellulose, polyacrylamide, polyethylene oxide, polyvinyl pyrrolidone, starch or gum arabic as hydrophilizing agents for anodized aluminum printing plate supports.

EP-B 0 149 490 describes compounds for hydrophilization which, in addition to amino groups, additionally contain carboxyl or carboxylate groups, sulfo groups or hydroxyl groups, is based on monomers and describes a molecular weight of 1000 as the upper limit.

• Komplexionen aus zwei- oder mehrwertigen Metallkationen und Liganden, wie Ammoniak, Wasser, Ethylendiamin, Stickstoffoxid, Harnstoff oder Ethylendiamintetraacetat nach der DE-A 28 07 396 (= US-A 4,208,212),
• Eisencyanid-Komplexe wie K₄(Fe(CN)₆) oder Na₃(Fe(CN)₆) in Anwesenheit von Heteropolysäuren, wie Phosphormolybdänsäure oder ihren Salzen und von Phosphaten nach der US-A 3,769,043 oder und US-A 4,420,549 oder
• Eisencyanid-Komplexe in Anwesenheit von Phosphaten und Komplexbildnern wie Ethylendiamintetraessigsäure für elektrophotographische Druckplatten mit Zinkoxidoberfläche nach der US-A 3,672,885.

The use of such metal complexes for the hydrophilization of printing plate support materials which have low molecular weight ligands has also become known from the prior art, for example:

• Complex ions of divalent or polyvalent metal cations and ligands, such as ammonia, water, ethylenediamine, nitrogen oxide, urea or ethylenediaminetetraacetate according to DE-A 28 07 396 (= US-A 4,208,212),
• Iron cyanide complexes such as K₄ (Fe (CN) ₆) or Na₃ (Fe (CN) ₆) in the presence of heteropolyacids, such as phosphoromolybdic acid or its salts and of phosphates according to US Pat. No. 3,769,043 or and US Pat. No. 4,420,549 or
• Iron cyanide complexes in the presence of phosphates and complexing agents such as ethylenediaminetetraacetic acid for electrophotographic printing plates with a zinc oxide surface according to US Pat. No. 3,672,885.

EP-A 0 069 320 (= US-A 4,427,765) describes a process in which salts of polyvinylphosphonic acids, polyvinylsulfonic acids, polyvinylmethylphosphinic acids and other polyvinyl compounds are used as aftertreatment agents.

DE-A 26 15 075 (= GB-A 1,495,895) uses a method for treating image-bearing offset printing plates with polyacrylamide or a mixture of polyacrylamide and polyacrylic acid.

SU-A 647 142 uses a copolymer of acrylamide and vinyl monomers for the hydrophilization of offset printing plates.

DE-C 10 91 433 describes a process for the aftertreatment of offset printing plate supports with polymers of methacrylic acid, methyl vinyl ether and maleic anhydride.

Acrylamide for the treatment of printing plate supports is also mentioned in DE-A 25 40 561.

For the same purpose, in particular to improve the shelf life of printing plates, DE-A 29 47 708 describes u.a. Ni salt solutions of acrylamide and acrylic acid as well as acrylamide and vinyl pyrrolidone.

• So muß nach der Behandlung mit Alkalisilikaten, die zu guter Entwickelbarkeit und Hydrophilie führen, eine gewisse Verschlechterung der Lagerfähigkeit von darauf aufgebrachten lichtempfindlichen Schichten hingenommen werden, und die Auflage einer so nachbehandelten Druckplatte sinkt drastisch.
• Die Komplexe der Übergangsmetalle begünstigen zwar prinzipiell die Hydrophilie von anodisch oxidierten Aluminiumoberflächen, sie haben jedoch den Nachteil, sehr leicht in Wasser löslich zu sein, so daß sie beim Entwickeln der Schicht mit wäßrigen Entwicklersystemen, die neuerdings in zunehmendem Maße Tenside und/oder Chelatbildner enthalten, die eine große Affinität zu diesen Metallen besitzen, leicht entfernt werden können. Dadurch wird die Konzentration der Übergangsmetallkomplexe auf der Oberfläche mehr oder weniger stark reduziert, was zu einer Abschwächung der hydrophilen Wirkung führen kann.
• Bei der Behandlung von Trägern mit wasserlöslichen Polymeren ohne Verankerungsmöglichkeiten führt deren gute Löslichkeit besonders in wäßrig-alkalischen Entwicklern, wie sie überwiegend zum Entwickeln von positiv arbeitenden lichtempfindlichen Schichten verwendet werden, ebenfalls zur deutlichen Abschwächung der hydrophilierenden Wirkung.
• Monomere, hydrophile Verbindungen, wie z.B. in der EP-B 149 490 beschrieben, haben ganz allgemein den Nachteil, daß sie während des Entwicklungs- bzw. Druckprozesses relativ schnell von der freigelegten Nichtbildstellenoberfläche weggewaschen werden und ihre hydrophile Wirkung verlieren, da nicht genügend Verankerungsstellen in der Oberfläche gegeben sind.
• Auch die Kombination eines Gemisches aus einem wasserlöslichen Polymeren, wie einem Celluloseether, und einem wasserlöslichen Metallsalz führt, da die Schichtgewichte und damit die Schichtstärke relativ hoch gewählt werden (siehe DE-B 23 64 177), zu einer verminderten Kopierschichthaftung, die sich beispielsweise darin äußern kann, daß beim Entwickeln Teile der Entwicklerflüssigkeit Bildstellen unterwandern.

However, all of the methods described above have more or less major disadvantages, so that the carrier materials produced in this way often no longer meet the current requirements of offset printing with regard to developer strength, water flow, free-running behavior and contact resistance:

• After the treatment with alkali silicates, which lead to good developability and hydrophilicity, a certain deterioration in the shelf life of photosensitive layers applied thereon has to be accepted, and the number of such a post-treated printing plate drops drastically.
• The complexes of the transition metals favor the hydrophilicity of anodically oxidized aluminum surfaces in principle, but they have the disadvantage of being very easily soluble in water, so that when the layer is developed, it contains aqueous developer systems, which now increasingly contain surfactants and / or chelating agents which have a great affinity for these metals can be easily removed. As a result, the concentration of the transition metal complexes on the surface is reduced to a greater or lesser extent, which can lead to a weakening of the hydrophilic effect.
• When treating carriers with water-soluble polymers without anchoring options, their good solubility, particularly in aqueous alkaline developers, as are mainly used for developing positive-working light-sensitive layers, also leads to a marked weakening of the hydrophilizing effect.
• Monomeric, hydrophilic compounds, as described, for example, in EP-B 149 490, have the general disadvantage that they are washed away from the exposed non-image area surface relatively quickly during the development or printing process and lose their hydrophilic effect since insufficient anchorage points in the surface are given.
• The combination of a mixture of a water-soluble polymer, such as a cellulose ether, and a water-soluble metal salt also leads, since the layer weights and thus the layer thickness are chosen to be relatively high (see DE-B 23 64 177), to a reduced copying layer adhesion, which can be found therein, for example can express that parts of the developer liquid infiltrate image areas during development.

From JP-A-63-112193 a carrier material for offset printing plates is known, the surface of which is hydrophilized with a high molecular weight, cationic polymer containing numerous amino groups, which additionally improves esterified (non-acidic) carboxy groups, hydroxy groups to improve the hydrophilic properties. or may contain amino groups.

The object of the invention is therefore to produce support materials for offset printing plates with good hydrophilization properties, which are suitable as supports for positive, negative or electrophotographic light-sensitive layers, without reducing their shelf life, reactions between the hydrophilizing agent and the photosensitive layer or reducing the layer adhesion.

The invention is based on a plate, film or tape-shaped carrier material for offset printing plates, consisting of mechanically, chemically or electrochemically roughened and optionally anodized aluminum or one of its alloys, which has a hydrophilic coating of a polymer containing acid side groups on at least one side has an average molecular weight of at least 1000.

The solution to the problem is that the hydrophilic polymer with repeating units also contains basic groups capable of protonation in addition to the acid side groups.

The further development of the carrier material results from the features of claims 2 to 19.

The mixed polymer consists of at least 2 mol% of units with a basic side group, optionally nonionic units, and at least 2 mol% of units with an acidic side group capable of salt formation - preferably with a divalent or higher-valent metal cation.

Suitable monomer units with basic side groups are compounds which contain aliphatic or aromatic amino groups, in particular tertiary amino groups, for example dimethylaminoethyl acrylate, Dimethylaminoethyl methacrylate and vinyl pyridine.

Vinyl compounds can be used as non-ionic components, e.g. Acrylic acid esters, such as ethyl, propyl, butyl, hexyl and decyl acrylate as well as the corresponding methacrylic acid esters and styrene, isoprene and butadiene.

The acidic components include Carboxylic, sulfonic and phosphonic acids, e.g. Acrylic, methacrylic, vinylphosphonic, vinylsulfonic, maleic, itaconic, vinylbenzoic, vinylnaphthoeic, vinylphenylsulfonic, vinylphenylphosphonic and cinnamic acids.

The ratio of the monomer units can be varied within a wide range. For example, the molar ratios of the acidic to the basic monomer units can be varied from 2:98 to 98: 2. However, a ratio of about 1: 1 (equimolar) is particularly preferred. For this purpose, non-ionic, neutral groups can still be used in the copolymer to adjust solubility.

The acidic groups ensure good adhesion to the (anodized) aluminum substrate; The basic groups effect an additional hydrophilization of the non-image areas and an improvement in adhesion through interaction with layer components in the image areas in the acidic wash water. Because the groups are anchored to a polymer backbone, there are numerous anchoring points to the layer and to the support, and the risk of loss of effectiveness during the printing process is reduced very strong. The average molecular weight is at least 1,000, preferably between 5,000 and 50,000, but polymers with an even higher average molecular weight than 50,000 can also be used with technical advantage. The copolymers are preferably dissolved in water with the addition of acids or alkalis so that a pH between 1 and 13, preferably between 3 and 10, is set. The compounds described can also be used in the form of their metal or ammonium salts, the salts of divalent and higher-valent metals being particularly preferred.

To prepare metal salts of the copolymers, the metal cations are generally used in the form of their salts with mineral acid anions or as acetates; the divalent, trivalent or tetravalent, in particular the divalent, are preferred. The cations of the coating are in particular V⁵⁺-, Bi³⁺-, Al³⁺-, Fe³⁺-, Zr⁴⁺-, Sn⁴⁺-, Ca²⁺-, Ba²⁺-, Sr²⁺-, Ti³⁺-, Co²⁺-, Fe²⁺, Mn²⁺, Ni²⁺, Cu²⁺, Ce⁴⁺, Zn²⁺ or Mg²⁺ ions.

These reaction products can be prepared in a simple manner in aqueous solution at temperatures from 20 to 100 ° C., preferably at 25 to 40 ° C. The metal salt, dissolved in water or, if necessary, dissolved in dilute mineral acid, is slowly added dropwise to the aqueous polymer solution. This leads to the immediate conversion of the reaction components to the previously described products. The rapid onset of reaction can - depending on the metal cation used - in show immediately occurring color change of the solution or through precipitation.

For purification, the products can be precipitated by neutralizing the reaction solution with dilute alkali hydroxide or ammonia solutions, the unreacted starting products remaining in the solution. The yields of these reactions are over 90%. It is also possible to use the salt forms with a monovalent cation, such as sodium or ammonium salt, instead of the acid forms of the polymers described.

For the treatment of the aluminum surface for the production of the carrier materials for offset printing plates according to the invention, the aqueous solutions of the copolymers are used in concentrations of 0.001 to 10%, preferably in concentrations of 0.1 to 1%.

The treatment of these substrates with the solutions is expediently carried out by dipping formats or by passing the substrate tape through a bath of these solutions. Temperatures from 20 to 95 ° C., preferably from 40 to 80 ° C., and residence times from 1 s to 10 min, preferably from 2 s to 1 min, are found to be the most favorable for practical use. An increase in the bath temperature accelerates the chemisorption of the copolymers and the polymer-metal complexes on the substrate. This makes it possible to reduce the dwell times considerably, particularly in the case of continuous strip treatment. The immersion treatment is then advantageously followed by a rinsing step with water. The substrate treated in this way is then expediently dried at temperatures of 110 to 130.degree. The pH is adjusted between 1 to 13, preferably to a pH of 3 to 10, and in particular to a value of 4 to 8.

The treatment of the aluminum substrate with the salts of the copolymers can also be carried out as a two-stage process. In the first step, the substrate is immersed, for example, in a 0.01 to 10%, preferably 0.1 to 5%, aqueous solution of the starting polymer. The substrate can then be transferred to a second bath without prior rinsing or drying, which contains a 0.1% to saturated, preferably 0.5 to 10%, aqueous salt solution with the polyvalent metal ions listed above. The rinsing and drying is carried out as in the one-step process. In the two-step treatment, the reaction products described above are formed on the substrate during the treatment. This variant of the process can also be used to apply the reaction products of trivalent metal ions, which are sparingly soluble in strongly acidic media, to the substrate.

Determining the weight of the applied hydrophilic coating is problematic since even small amounts of the applied product have clear effects and are anchored relatively strongly in and on the surface of the carrier material. However, it can be assumed that the amount applied is clearly below 1 mg / dm², in particular below 0.8 mg / dm².

The support materials according to the invention thus produced can then be coated with various light-sensitive layers for the production of offset printing plates.

• "Reinaluminium" (DIN-Werkstoff Nr. 3.0255), d.h. bestehend aus ≧ 99,5 % Al 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
• "Al-Legierung 3003" (vergleichbar mit DIN-Werkstoff Nr. 3.0515), d.h. bestehend aus ≧ 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, 0,02 % Zn, 0,1 % Cu und 0,15 % Sonstigem.

Suitable substrates for the production of the carrier materials according to the invention include those made of aluminum or one of its alloys. These include, for example:

• "Pure aluminum" (DIN material no. 3.0255), ie consisting of ≧ 99.5% Al 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
• "Al alloy 3003" (comparable to DIN material no. 3.0515), ie consisting of ≧ 98.5% Al, the alloy components 0 to 0.3% Mg and 0.8 to 1.5% Mn and the following permissible Additions of 0.5% Si, 0.5% Fe, 0.2% Ti, 0.02% Zn, 0.1% Cu and 0.15% other.

However, the method according to the invention can also be applied to other aluminum alloys.

The aluminum support materials for printing plates, which are very common in practice, are generally 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 HCl or HNO₃ solutions) roughened. For the present invention especially aluminum printing plates with electrochemical roughening used.

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 / l, the current density between 15 and 130 A / dm², the residence time between 10 and 100 s and the electrolyte flow rate on the surface of the workpiece to be treated between 5 and 100 cm / s; 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 mean roughness depth R _{z of} the roughened surface is in the range from about 1 to 15 »m, in particular in the range from 2 to 7» m.

The roughness depth is determined in accordance with DIN 4768 (as of October 1970), the roughness depth R _z is then the arithmetic mean of the individual roughness depths of five adjacent individual measuring sections. The individual roughness depth is defined as the distance between two parallels to the middle line, which touch the roughness profile at the highest or lowest point within the individual measurement sections. The individual measuring section is the fifth part of the length of the part of the roughness profile which is used directly for evaluation and is projected perpendicularly onto the middle line. The middle line is the line parallel to the general direction of the roughness profile from the shape of the geometrically ideal profile, which divides the roughness profile so that the sum of the material-filled areas above it and the material-free areas below it are the same.

• Das Gleichstrom-Schwefelsäure-Verfahren, bei dem in einem wäßrigen Elektrolyten aus üblicherweise ca. 230 g H₂SO₄ pro 1 Liter Lösung bei 10 bis 22 °C und einer Stromdichte von 0,5 bis 2,5 A/dm² während 10 bis 60 min anodisch oxidiert wird. Die Schwefelsäurekonzentration in der wäßrigen Elektrolytlösung kann dabei auch bis auf 8 bis 10 Gew.-% H₂SO₄ (ca. 100 g/l H₂SO₄) verringert oder auch auf 30 Gew.-% (365 g/l H₂SO₄) und mehr erhöht werden.
• Die "Hartanodisierung" wird mit einem wäßrigen H₂SO₄ enthaltenden Elektrolyten einer Konzentration von 166 g/l H₂SO₄ (oder ca. 230 g/l 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, which may be used, in order to improve, for example, the abrasion and adhesion properties of the surface of the carrier material. The usual electrolytes, such as H₂SO₄, H₃PO₄, H₂C₂O₄, amidosulfonic acid, sulfosuccinic acid, sulfosalicylic acid or mixtures thereof, can be used for anodic oxidation. For example, reference is made to the following standard methods for the use of aqueous electrolytes containing H₂SO₄ for the anodic oxidation of aluminum (see, for example, M. Schenk, material aluminum and its anodic oxidation, Francke Verlag - Bern, 1948, page 760; practical electroplating technology, 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 approximately 230 g H₂SO₄ per 1 liter of solution at 10 to 22 ° C and a current density of 0.5 to 2.5 A / dm² for anodic for 10 to 60 min is oxidized. The sulfuric acid concentration in the aqueous electrolyte solution can also up to 8 to 10 wt .-% H₂SO₄ (about 100 g / l H₂SO₄) reduced or increased to 30 wt .-% (365 g / l H₂SO₄) and more.
• The "hard anodizing" is carried out with an aqueous electrolyte containing H₂SO₄ with a concentration of 166 g / l H₂SO₄ (or approx. 230 g / l H₂SO₄) at an operating temperature of 0 to 5 ° C, with a current density of 2 to 3 A / dm², 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 the anodic oxidation of printing plate support materials already mentioned in the previous paragraph, the following processes can also be used, for example: the anodic oxidation of aluminum in an aqueous electrolyte containing H₂SO₄, the Al³⁺ ion content of which is more than 12 g / l is set (according to DE-A 28 11 396 = US-A 4,211,619), in an aqueous electrolyte containing H₂SO₄ and H₃PO₄ (according to DE-A 27 07 810 = US-A 4,049,504) or in an aqueous H₂SO₄ and Al³ Electrolytes containing ⁺ ions (according to DE-A 28 36 803 = US-A 4,229,226).

Direct current is preferably used for the anodic oxidation, however alternating current or a combination of these types of current (for example direct current with superimposed alternating current) can also be used. The layer weights of aluminum oxide range from 1 to 10 g / m², corresponding to a layer thickness of approximately 0.3 to 3.0 »m.

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 applied either by the manufacturer of presensitized printing plates or directly by the consumer on one of the usual carrier materials.

In addition to the layers containing silver halides used in many fields, various others are also known, as are described, for example, in "Light-Sensitive Systems" by Jaromir Kosar, John Wiley & Sons Verlag, New York 1965: the colloid layers containing chromates and dichromates (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-diazoquinones, such as naphthoquinonediazides, p-diazoquinones 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 contain other constituents, such as resins, dyes or plasticizers. In particular, the following photosensitive compositions or compounds can be used in the coating of the Carrier materials produced by the process according to the invention are used:
positive working, o-quinonediazide, preferably o-naphthoquinonediazide compounds, which are described, for example, in DE-C 854 890, 865 109, 879 203, 894 959, 938 233, 1 109 521, 1 144 705, 1 118 606, 1 120 273 and 1 124 817;
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-C 596 731, 1 138 399, 1 138 400, 1 138 401, 1 142 871, 1 154 123 US-A 2,679,498 and 3,050,502 and GB-A 712 606;
Negative working, mixed condensation products of aromatic diazonium compounds, for example according to DE-A 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 which is present in an acidic medium on at least one Position of the molecule is capable of condensation with an active carbonyl compound;
positive working layers which contain a compound which releases acid upon irradiation, a compound which has at least one COC group which can be removed by acid (for example an orthocarboxylic acid ester group, a carboxamide amide acetal group or an acetal group) and optionally 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 di-isocyanates with partial esters of polyhydric alcohols, as described, for example, in US Pat. Nos. 2,670,863 and 3,060,023 and DE-A 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 large number of soluble organic polymers can be used as binders, for example polyamides, polyesters, alkyd resins, polyvinyl alcohol, polyvinylpyrrolidone, polyethylene oxide, gelatin or cellulose ether;
Negative working layers according to DE-A 30 36 077, which as a photosensitive compound is a diazonium salt polycondensation product or an organic azido compound and as a binder a high molecular weight polymer with pendant alkenylsulfonyl or Contain cycloalkenylsulfonyl urethane groups.

It is also possible to use photo-semiconducting layers such as e.g. in DE-C 11 17 391, 15 22 497, 15 72 312, 23 22 046 and 23 22 047 are described, to which carrier materials are applied, which results in highly light-sensitive, electrophotographic layers.

The coated offset printing plates obtained from the carrier materials according to the invention are converted into the desired printing form in a known manner by imagewise exposure or irradiation and washing out of the non-image areas with a developer, preferably an aqueous developer solution. Surprisingly, offset printing plates, the base carrier materials of which have been treated according to the invention, show a significantly lower color haze and improved hydrophilicity compared to plates which have been treated with high polymer acrylic acid, with polymeric vinylphosphonic acid or only with hot water. The adhesion of the light-sensitive layer to the surface of the support was also better in the samples treated according to the invention than in the comparison samples.

Examples for the production of a roughened and anodized printing plate carrier

A1:

A bright rolled aluminum strip (DIN material no. 3.0255) with a thickness of 0.3 mm is treated with an aqueous alkaline 2% pickling solution at elevated temperature degreased from about 50 to 70 ° C. The electrochemical roughening of the aluminum surface is carried out with alternating current and in an electrolyte containing HNO₃; a surface roughness with an R _z value of 6 »m is obtained. The subsequent anodic oxidation is carried out in an electrolyte containing sulfuric acid in accordance with the process described in DE-A 28 11 396; the oxide weight is about 3.0 g / m².
A carrier produced in this way is designated by the number 1 in Tables 2 and 3.
The aluminum strip prepared in this way is then passed through a bath at 60 ° C. from a 0.5% solution, which is one of the polymers according to the invention or one of the comparison substances (A to C), which is brought to pH 5 with H 3 PO 4 or NaOH until 6 has been set. The compositions of these solutions are listed in Table 1. The dwell time in the bath is 30 s. The excess solution is then removed with tap water in a rinsing step and the strip is dried with hot air at temperatures between 100 and 130 ° C.

A2:

A bright rolled aluminum strip (DIN material no. 3.0515) with a thickness of 0.3 mm is degreased with an aqueous alkaline 2% pickling solution at an elevated temperature of around 50 to 70 ° C. The electrochemical roughening of the aluminum surface is done with alternating current and in one Electrolytes containing hydrochloric acid; a surface roughness with an R _z value of 6 »m is obtained. The subsequent anodic oxidation is carried out in an electrolyte containing sulfuric acid in accordance with the process described in DE-A 28 11 396; the oxide weight is about 3.0 g / m².
A carrier produced in this way is designated with the number 2 in Tables 2 and 3.
The aluminum strip prepared in this way is then passed through a 50 ° C. warm bath from a 0.5% solution, which is one of the polymers according to the invention or one of the comparison substances (A to C), which is brought to a pH value between 5 with H 3 PO 4 or NaOH and 6 have been set. The compositions of these solutions are listed in Table 1.

A3:

A bright rolled aluminum strip (DIN material no. 3.0255) with a thickness of 0.2 mm is degreased with an aqueous alkaline 2% pickling solution at an elevated temperature of around 50 to 70 ° C. Then the carrier is brushed using cutting granules. A surface roughness with an R _z value of 4 »m is obtained. The subsequent anodic oxidation takes place according to the process described in DE-C 16 71 614 (= US-A 3,511,661) in an electrolyte containing phosphoric acid. The oxide weight is 0.9 g / m². The aluminum strip processed in this way is cut into sheets measuring 50 x 45 cm.

A carrier produced in this way is designated in Table 2 with the number 3.

The thus prepared carriers are immersed in a 60 ° C warm bath of an aqueous solution of 0.4% of one of the aftertreatment agents listed in Table 1 under A to N, which was adjusted to a pH between 5 and 6 with H₃PO₄ or NaOH . The dwell time in the bath is 60 s. The excess solution is then removed with deionized water in a rinsing step and the carrier is air-dried.

The carrier materials described under A1 to A3, each of which was treated with 13 different solutions, gave a total of 39 post-treated carriers. They are listed in Table 2 together with the measurement results explained below.

Instead of the immersion treatment described under A1 to A3, some carriers were subjected to an electrochemical aftertreatment, which is described below.

Electrochemical treatment

Carriers from Example A2 are immersed in a 0.2% solution of preparations A to N (Table 1) at 40 ° C. The carriers are switched as an anode and treated with 10 volt direct current for 20 s. The excess solution is then removed with deionized water in a rinsing step, and the carriers are on air dried. Table 3 shows the supports thus produced and the results of the measurements described below.

The following measurements were carried out on each of the carrier materials obtained according to the examples:

Testing the alkali resistance of the surface

The rate of dissolution of the layer in an alkaline zincate solution in seconds is 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 H₂O, 480 g of KOH and 80 g of zinc oxide is brought to the surface to be examined and the period of time until the appearance of metallic zinc is determined, which can be recognized by a blackening of the examination site. This "zinc certificate" is mentioned in column 4 of Table 2. This method is described, for example, in US Pat. No. 3,940,321, columns 3 and 4, lines 29 to 68 and lines 1 to 8.

Testing the hydrophilicity of the carrier materials

The test is carried out using wetting angle measurements against a drop of water. The angle is determined between the carrier surface under the drop and a tangent placed through the point of contact of the drop; it is generally between 0 ° and 90 °. The smaller the angle, the better the wetting.

The information in column 5 of Table 2 relates to these contact angle measurements.

Coating the supports with light-sensitive materials:

D1:

A piece of each of the supports described in support examples A1 to A3 is coated with the following solution:

6.6 parts by weight

Cresol-formaldehyde novolak (with a softening range of 105 to 120 ° C according to DIN 53 181),

1.1 parts by weight

the 4- (2-phenyl-prop-2-yl) phenyl ester of naphthoquinone (1,2) diazide (2) sulfonic acid (4),

0.6 parts by weight

2,2'-bis (naphthoquinone- (1,2) -diazide- (2) -sulfonyloxy- (5)) - dinaphthyl- (1,1 ') - methane,

0.24 parts by weight

Naphthoquinone- (1,2) -diazide- (2) -sulfochloride- (4),

0.08 parts by weight

Crystal violet,

91.36 parts by weight

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.

5,3 Gew.-Teile

Natriummetasilikat x 9 H₂O

3,4 Gew.-Teile

Trinatriumphosphat x 12 H₂O

0,3 Gew.-Teile

Natriumdihydrogenphosphat (wasserfrei)

91,0 Gew.-Teile

Wasser.

The coated substrates are dried in the dryer at temperatures up to 120 ° C. The printing plates thus produced are exposed under a positive template and developed with a developer of the following composition:

5.3 parts by weight

Sodium metasilicate x 9 H₂O

3.4 parts by weight

Trisodium phosphate x 12 H₂O

0.3 parts by weight

Sodium dihydrogen phosphate (anhydrous)

91.0 parts by weight

Water.

D2:

Ein Stück eines jeden der in den Träger-Beispielen A1 bis A3 beschriebenen Träger wird mit der folgenden negativ arbeitenden lichtempfindlichen Schicht versehen:

16,75 Gew.-Teile

einer 8%igen Losung des Umsetzungsproduktes eines Polyvinylbutyrals mit einem Molekulargewicht von 70 000 bis 80 000, bestehend aus 71 Gew.-% Vinylbutyral-, 2 Gew.-% Vinylacetat- und 27 Gew.-% Vinylalkohol-Einheiten, mit Propenylsulfonylisocyanat.

2,14 Gew.-Teile

2,6-Bis-(4-azido-benzal)-4-methylcyclohexanon,

0,23 Gew.-Teile

^(R)Rhodamin 6 GDN extra und

0,21 Gew.-Teile

2-Benzoylmethylen-1-methyl-β-naphthothiazolin in

100 Vol.-Teile

Ethylenglykolmonomethylether und

50 Vol.-Teile

Tetrahydrofuran

The printing forms obtained are assessed optically with regard to any dye residues (blue fog) still present in the non-image areas. The result is shown in column 6 of table 2.

D2:

A piece of each of the supports described in support examples A1 to A3 is provided with the following negative-working photosensitive layer:

16.75 parts by weight

an 8% solution of the reaction product of a polyvinyl butyral with a molecular weight of 70,000 to 80,000, consisting of 71% by weight of vinylbutyral, 2% by weight of vinyl acetate and 27% by weight of vinyl alcohol units, with propenylsulfonyl isocyanate.

2.14 parts by weight

2,6-bis- (4-azido-benzal) -4-methylcyclohexanone,

0.23 parts by weight

^(R) Rhodamine 6 GDN extra and

0.21 part by weight

2-benzoylmethylene-1-methyl-β-naphthothiazoline in

100 parts by volume

Ethylene glycol monomethyl ether and

50 parts by volume

Tetrahydrofuran

The carriers are dried as described under point D1.

The dry layer weight is 0.75 g / m². The reproduction layer is exposed under a negative original for 35 s with a metal halide lamp with a power of 5 kW. The exposed layer is covered with a plush pad with a developer solution of the following composition
5 parts by weight of sodium lauryl sulfate
1 part by weight of sodium metasilicate x 5 H₂O
94 parts by volume of water
developed.

The non-image areas of the printing forms obtained are assessed optically with regard to any remaining layers. The result of this assessment in comparison to the prior art (A) is shown in column 7 of table 2.

-

schlechter als der Stand der Technik gemäß dem Vergleichsbeispiel der Lösung A

o

gleich gut wie der Stand der Technik gemäß dem Vergleichsbeispiel der Lösung A

+

besser als der Stand der Technik gemäß dem Vergleichsbeispiel der Lösung A.

D3:

Ein gemäß Beispiel 15 der Tabelle 2 hergestellter, anodisch oxidierter Träger wird zur Herstellung einer elektrophotographisch arbeitenden Offsetdruckplatte mit folgender Lösung beschichtet:

10 Gew.-Teile

2,5-Bis-(4'-diethylaminophenyl)-1,3,4-oxadiazol,

10 Gew.-Teile

eines Mischpolymerisats aus Styrol und Maleinsäureanhydrid mit einem Erweichungspunkt von 210 °C,

0,02 Gew.-Teile

^(R)Rhodamin FB (C.I.45 170),

300 Gew.-Teile

Ethylenglykolmonomethylether

The characters in Table 2 mean

-

worse than the prior art according to the comparative example of solution A.

O

as good as the prior art according to the comparative example of solution A.

+

better than the prior art according to the comparative example of solution A.

D3:

An anodized support prepared according to Example 15 in Table 2 becomes for the production of an electrophotographic offset printing plate coated with the following solution:

10 parts by weight

2,5-bis- (4'-diethylaminophenyl) -1,3,4-oxadiazole,

10 parts by weight

a copolymer of styrene and maleic anhydride with a softening point of 210 ° C,

0.02 parts by weight

^(R) Rhodamine FB (CI45 170),

300 parts by weight

Ethylene glycol monomethyl ether

The carriers are dried as described under point D1.

35 Gew.-Teilen

Natriummetasilikat x 9 H₂O,

140 Gew.-Teilen

Glycerin,

550 Vol.-Teilen

Ethylenglykol und

140 Vol.-Teilen

Ethanol

getaucht. Die Platte wird dann mit einem kräftigen Wasserstrahl abgespült, wobei die nicht mit Toner bedeckten Stellen der Photoleiterschicht entfernt werden. Die Platte ist dann druckfertig. Die Nichtbildstellen der Platte zeigen eine gute Hydrophilie und lassen auch nach der Einwirkung alkalischer Lösungen keine Zeichen eines Angriffs erkennen. Es lassen sich mit der Druckform mehrere zehntausend Drucke erzielen.

The layer is negatively charged to about 400 V in the dark by means of a corona. The charged plate is exposed imagewise in a repro camera and then developed with an electrophotographic suspension developer which also contains a dispersion of 3.0 parts by weight of magnesium sulfate in a solution of 7.5 parts by weight of pentaerythritol resin ester in 1200 parts by volume of an isoparaffin mixture represents a boiling range of 185 to 210 ° C. After removing the excess developer liquid, the developer is fixed and the plate is poured out into a solution for 60 s

35 parts by weight

Sodium metasilicate x 9 H₂O,

140 parts by weight

Glycerin,

550 parts by volume

Ethylene glycol and

140 parts by volume

Ethanol

submerged. The plate is then rinsed off with a powerful jet of water, removing the areas of the photoconductor layer not covered with toner. The plate is then ready for printing. The non-image areas of the plate show good hydrophilicity and show no signs of attack even after exposure to alkaline solutions. Several tens of thousands of prints can be achieved with the printing form.

Table 2 shows that the products according to the invention are better than the prior art in many properties, but none worse than this in none. Table 3 Example No. carrier Post-treatment agent Zincate test time (s) Contact angle Color veil 1) * Layer remnants 2) * 40 2nd D + + + + 41 2nd F + + + + 42 2nd E + O + + 43 2nd G + O + + 44 2nd L + O + + 45 2nd H + O + O 46 2nd K + O + + 47 2nd M + O + + 48 2nd I. + O + + 49 2nd N + O + O 50 2nd B - - + - 51 2nd A O O O O 1 *) for positive layers 2 *) for negative layers

Table 3 shows that the electrochemically aftertreated supports give correspondingly good values as in Table 2, the values for the zincate test in particular being still improved.

In addition to the tests described above, which were carried out on all supports, supports which had been prepared according to Examples 1 to 3 of Table 2, as described in Example D1, were coated with a positive-working photosensitive layer and printing plates were produced by exposure and development. With this, printing attempts were undertaken which delivered flawless prints up to a print run of 210,000. A printing form which was produced in an analogous manner with a support of Comparative Example A (Table 2) showed poorer freewheeling behavior. After 170,000 prints, fine halftone dots were no longer reproduced correctly.

Claims (18)

1. Support material for offset-printing plates in the form of a sheet, a foil or a tape, which comprises mechanically, chemically or electrochemically roughened and optionally anodized aluminum or an alloy thereof and is coated on at least one side with a hydrophilic coating formed of a polymer containing acidic side groups having a mean molecular weight of at least 1,000, wherein the hydrophilic polymer comprises at least 2 mol% of units having acidic side groups and, in addition to the acidic side groups, at least 2 mol% of units having basic groups which are capable of being protonated.
2. The support material as claimed in claim 1, wherein the hydrophilic polymer is a copolymer comprising a monomer unit with basic groups and a monomer unit carrying acidic groups.
3. The support material as claimed in claim 2, wherein the monomer carrying basic groups contains an amino group.
4. The support material as claimed in claim 3, wherein the amino group contains at least one alkyl or aryl group.
5. The support material as claimed in claim 2, wherein the monomer carrying acidic groups contains a carboxyl group.
6. The support material as claimed in claim 2, wherein the monomer carrying acidic groups contains a sulfonic acid group.
7. The support material as claimed in claim 2, wherein the monomer carrying acidic groups contains a phosphonic acid group.
8. The support material as claimed in claim 1, wherein the copolymer contains, in addition to the acidic and basic side groups, also units which are non-acidic and non-basic.
9. The support material as claimed in claim 1, wherein the copolymer has a mean molecular weight of 5,000 to 50,000.
10. The support material as claimed in claim 1, wherein the copolymer has a molecular weight of more than 50,000.
11. The support material as claimed in claim 1, wherein the monomer ratio of the basic monomer units present in the copolymer to the acidic monomer units varies in the range from 2 : 98 to 98 : 2.
12. The support material as claimed in claim 11, wherein the molar ratio of the basic monomer units to the acidic monomer units is equimolar.
13. The support material as claimed in claim 12, wherein the molar ratio of the ionic monomer units to the non-ionic monomer units ranges from 4 : 96 to 100 : 0.
14. The support material as claimed in claim 1, wherein the acidic side groups are present in the form of metal salts with metal cations.
15. The support material as claimed in claim 14, wherein the metal cation of the coating is a V⁵⁺, Bi³⁺, Al³⁺, Fe³⁺, Zr⁴⁺, Sn⁴⁺, Ca²⁺, Ba²⁺, Sr²⁺, Ti³⁺, Co²⁺, Fe²⁺, Ce⁴⁺, Mn²⁺, Ni²⁺, Cu²⁺, Zn²⁺ or Mg²⁺ ion.
16. Process for the production of a support material for offset-printing plates as claimed in any of claims 1 to 15, wherein the aluminum or an alloy thereof is coated with the dissolved copolymers, in a concentration of 0.02 to 5.0 % by weight in an aqueous, optionally acidic solution, by immersion treatment or electrochemical treatment and the layer obtained is then dried.
17. Process for the production of a support material as claimed in claim 16, wherein the aluminum or an alloy thereof is first treated with an 0.01 to 10.0 % strength solution of the polymers according to the invention and then with a 1.0 % strength to saturated, preferably aqueous solution of a salt having the cations V⁵⁺, Bi³⁺, Al³⁺, Fe³⁺, Zr⁴⁺, Sn⁴⁺, Ca²⁺, Ba²⁺, Sr²⁺, Ti³⁺, Co²⁺, Fe²⁺, Ce⁴⁺, Mn²⁺, Ni²⁺, Cu²⁺, Zn²⁺ or Mg²⁺ and the layer produced from the reaction products is dried.
18. Use of a support material as claimed in any of claims 1 to 15 for coating with photosensitive substances.