EP0256255A2 - Manufacturing process of electrophotographical-recording elements - Google Patents

Abstract

The invention relates to a method for producing an electrophotographic recording element from an aluminum carrier which has been pretreated mechanically, chemically and / or electrochemically in the usual way and a photoconductive layer which is applied to this carrier, a thin hydrophilizing layer composed of a hydrolyzate or between the carrier and the photoconductive layer Condensate of a silane is applied. These recording elements are particularly suitable for electrophotographic offset printing.

Description

The invention relates to a process for the production of electrophotographic recording elements from pretreated aluminum supports and photoconductive layers, an intermediate layer being applied between the support and the photoconductive layer, and to the use of these electrophotographic recording elements for electrophotographic offset printing, in particular those using aqueous, alcoholic or aqueous / alkaline solutions can be developed.

• A) einem für dem Offsetdruck geeigneten elektrisch leitfähigen Aluminiumträgerblech in einer Dicke von 0,1 bis 0,6 mm mit z.B. einer elektrolytisch aufgerauhten oder anodisierten Oberfläche, und
• B) der elektrophotographischen Schicht aus
  • B1) mindestens einem mit allen in der Rezeptur vorhandenen Komponenten verträglichen Bindemittel, das in offsettypischen Auswaschmedien löslich ist,
  • B2) einer niedermolekularen Ladungstransportverbindung,
  • B3) mindestens einem Sensibilisator für den gewünschten aktinischen Bereich und
  • B4) weiteren Zusätzen, die die allgemeinen Schichteigenschaften verbessern.

The use of homogeneously sensitized photoconductor layers for the production of electrophotographic printing forms, in particular electrophotographic offset printing forms, is known. Such layers and the associated processes are described, for example, in DE-PS 11 17 391 and in DE-OS 23 22 047 and 25 26 720. Such electrophotographic offset printing forms essentially consist of

• A) an electrically conductive aluminum carrier sheet suitable for offset printing in a thickness of 0.1 to 0.6 mm with, for example, an electrolytically roughened or anodized surface, and
• B) the electrophotographic layer
  • B1) at least one binder which is compatible with all of the components present in the formulation and which is soluble in offset-typical washout media,
  • B2) a low-molecular charge transport compound,
  • B3) at least one sensitizer for the desired actinic range and
  • B4) further additives which improve the general layer properties.

In a conventional embodiment of these photoconductor layers and printing forms, the photoconductor layer applied to the electrically conductive substrate is charged, exposed imagewise, developed with liquid or dry toner to form an image, the toner image is fixed by heating, and the printing plate is removed by removing the unstressed one Developed photoconductor layer. The offset printing form obtained takes on ink at the toner image areas and water at the exposed areas of the carrier surface.

A substrate which is to be suitable for light-sensitive material for the production of a printing plate has to satisfy two criteria. On the one hand, the printing image areas developed from the copying layer of the material must adhere very firmly to it, on the other hand, the support must represent a sufficiently hydrophilic image background so that it retains its repellent effect against oleophilic printing inks under the diverse requirements of the printing process. The latter is brought about by a porous surface structure, so that the surface of the support retains enough water to be sufficiently repellent to oleophilic printing inks.

Aluminum and aluminum alloys are mainly used for offset printing plates, which are modified by a series of pretreatment steps in order to ensure good adhesion of the radiation-sensitive layer and thus long print runs.

For example, aluminum is roughened mechanically, chemically and / or electrochemically, if necessary pickled and anodized. The standard pretreatment methods include electrochemical roughening in HCl and / or HNO₃ and anodic oxidation in H₂SO₄ and / or H₃PO₄.

According to the prior art, it is customary to subject such anodized support materials to a further treatment step in order to improve the layer adhesion, to increase the hydrophilicity or to facilitate the developability of the light-sensitive copying layers. The patent literature includes methods such as silicating (see, for example, DE-OS 25 32 769 or US Pat. No. 3,902,976), treatment with complex fluorides (see, for example, DE-AS 13 00 415 or US Pat. No. 3 440 050) or with polyvinylphosphonic acid (cf. for example DE-PS 11 34 093 or US-PS 3 276 868, DE-PS 16 21 478 or US-PS 4 153 461.

However, the methods described above have more or less major disadvantages. For example, treatment with alkali silicates has to accept a certain deterioration in shelf life.

The use of polyvinylphosphonic acid (= PVPS) for the aftertreatment of the carrier leads to good printing properties of the printing plates, the deposition of the PVPS on the support material can however, lead to production-related difficulties, such as the formation of an extremely sparingly soluble precipitate by reaction with Al³⁺ ions, which results in wetting disorders or layer breakouts during development or printing.

Carrier materials treated with PVPS also tend to show signs of aging when stored uncoated. These manifest themselves in decreasing hydrophilicity as well as in the reduced developability of negatively working light-sensitive layers, which are coated only a long time after the carrier has been produced.

The object of the invention was to provide a class of compound which, as an intermediate layer between the support and the photoconductive layer, increases the hydrophilicity of the non-image areas without negatively influencing the adhesion of the radiation-sensitive layer to the support material, and thus avoids the aforementioned disadvantages of known treatment agents.

It is known to use silanes as adhesion-promoting or coupling compounds, especially when it comes to ensuring the adhesion of a plastic to glass surfaces or glass fibers (cf. e.g. Lieng-Huang Lee, Adhesive Chemistry, Vol. 29, p. 139ff.). But silanes are also used as adhesion promoters in so-called dry offset printing plates. The "dry" planographic printing plate is based on the principle of ensuring a differentiation between printing and non-printing parts by means of an ink-accepting, light-sensitive polymer layer and an oleophobic, oily ink-repellent and thus non-printing silicone rubber layer. For this purpose e.g. a photosensitive polymer layer is applied to a silicone rubber layer on a metal support, imagewise exposed and developed, so that e.g. in the case of a negative-working plate, the silicone rubber layer is exposed at the unexposed areas, while the polymer layer which is hardened by actinic radiation and is insoluble in the developer is formed on the exposed areas. Since a silicone rubber with high color repellency does not have good adhesion to other materials due to its special properties, a silane coupling agent is used which acts as an adhesive contact between the carrier and the silicone rubber (see e.g. DE-PS 23 57 871 and DE-PS 23 23 453).

It was therefore surprising that the aftertreatment according to the invention of aluminum supports pretreated according to the prior art with an aqueous or alcoholic solution of silane hydrolyzate or condensate formed by hydrolysis of silanes improves the hydrophilic properties of the support so strongly that the non-image areas of the image exposed Plate after aqueous / alkaline development and application of an oily paint showed no color acceptance, since it was not to be expected from the prior art that silane hydrolyzates can be used to improve the hydrophilicity. In the case of an aqueous / alkaline developable photosensitive planographic printing plate, the non-aftertreated support also assumed color at the non-image areas.

The invention relates to a method for producing an electrophotographic recording element from a mechanically, chemically and / or electrochemically pretreated and anodically oxidized aluminum support and a photoconductive layer which is applied to this support, which is characterized in that between the support and the photoconductive Layer is applied a thin hydrophilizing layer of a hydrolyzate or condensate of at least one silane.

steht, wobei R³ für Wasserstoff, einen Alkylrest mit 1 bis 9 Kohlenstoffatomen, einen Carbonsäurerest mit 1 bis 9 Kohlenstoffatomen oder einen aus diesem Carbonsäurerest und dem an R³ gebundenen

        HO―

―

H―Rest
gebildeten Carbonsäureanhydridring steht, R⁴ und R⁵ untereinander gleich oder verschieden sind und für einen Alkylrest mit 1 bis 9 Kohlenstoffatomen oder einen Arylrest mit 6 bis 12 Kohlenstoffatomen stehen,
R⁶ für Wasserstoff, einen Alkylrest mit 1 bis 9 Kohlenstoffatomen oder einen Arylrest mit 6 bis 12 Kohlenstoffatomen,
Ar für einen Arylenrest mit 6 bis 12 Kohlenstoffatomen,
Z für Wasserstoff oder ein Alkalimetall,
Hal für Chlor oder Brom,
y für eine ganze Zahl von 1 bis 4 und
n = 0, 1 oder 2
stehen.Particularly suitable as the silanes to be used in hydrolyzed or condensed form for the process according to the invention are silanes of the general formula (I)
X- (CH₂) _y -Si (R¹) _n (OR²) _3-n (I)
wherein R¹ and R² are the same or different from each other and represent alkyl radicals having 1 to 9 carbon atoms or aryl radicals having 6 to 12 carbon atoms and
X for one of the residues

stands for R³ for hydrogen, an alkyl radical with 1 to 9 carbon atoms, a carboxylic acid radical with 1 to 9 carbon atoms or one of this carboxylic acid radical and that bound to R³

HO―

-

H ― rest
formed carboxylic acid anhydride ring, R⁴ and R⁵ are identical or different from one another and represent an alkyl radical with 1 to 9 carbon atoms or an aryl radical with 6 to 12 carbon atoms,
R⁶ represents hydrogen, an alkyl radical with 1 to 9 carbon atoms or an aryl radical with 6 to 12 carbon atoms,
Ar is an arylene radical with 6 to 12 carbon atoms,
Z represents hydrogen or an alkali metal,
Hal for chlorine or bromine,
y for an integer from 1 to 4 and
n = 0, 1 or 2
stand.

The silanes of the formulas given above are used in hydrolyzed or condensed form.

In the process according to the invention, the hydrolyzate or condensate of the silane is generally applied in the form of its solution to the pretreated aluminum support by customary application methods, such as spraying or dipping, any excess is removed and the coated support is dried at 50 to 120 ° C.

The present invention also relates to electrophotographic recording elements which have been produced by the process according to the invention and to their use for the electrophotographic production of offset printing plates.

The hydrolyzate or condensate of the silane is expediently used in an aqueous or alcoholic solution.

These solutions generally contain the hydrolyzate or condensate of the silane in amounts of 0.05 to 30, preferably 0.1 to 10, in particular 0.5 to 3% by weight. They can be prepared in an unusual manner by, if appropriate acid-catalyzed, hydrolysis from the underlying silanes of the general formula (I). The application of these solutions to the mechanically, chemically and / or electrochemically pretreated aluminum support in a thin layer can be carried out by customary application methods, preferably by spraying or in particular by immersing the support in the aqueous solution at temperatures between 15 and 85 ° C, preferably at 25 to 60 ° C, for example during a period of 0.5 to 120, preferably 10 to 60 seconds.

Excess solution can then be removed by rinsing or rinsing with water or alcohol, and the supports treated in this way can be dried at temperatures between 20 and 120 ° C., preferably 50 and 110 ° C.

steht, wobei R³ für Wasserstoff, einen Alkylrest mit 1 bis 9 Kohlenstoffatomen, vorzugsweise 1 bis 4 Kohlenstoffatomen, z.B. Methyl-, Ethyl-, Propyl-, Butylreste, einen Carbonsäurerest mit 1 bis 9, vorzugsweise 1 bis 4 Kohlenstoffatomen, z.B. -COOH, -CH₂COOH, -C₂H₄COOH, -C₃H₆COOH oder für einen aus diesem Carbonsäurerest und dem an R³ gebundenen

        HO―

―

H-Rest
gebildeten Carbonsäureanhydridring, z.B. einen Bernsteinsäureanhydridring, steht,
R⁴ und R⁵ untereinander gleich oder verschieden sind und für einen Alkylrest mit 1 bis 9, vorzugsweise 1 bis 4 Kohlenstoffatomen, z.B. Methyl-, Ethyl-, Propyl-, Butylreste oder einen Arylrest mit 6 bis 12 Kohlenstoffatomen, z.B. Phenyl-, Benzyl-, Methylphenylrest stehen,
R⁶ für Wasserstoff, einen Alkylrest mit 1 bis 9, vorzugsweise 1 bis 4 Kohlenstoffatomen, z.B. Methyl-, Ethyl-, Propyl-, Butylreste oder einen Arylrest mit 6 bis 12 Kohlenstoffatomen, z.B. einen Phenyl-, Benzyl-, Methylphenylrest,
Ar für einen Arylenrest mit 6 bis 12 Kohlenstoffatomen, vorzugsweise einen Phenylenrest,
Z für Wasserstoff oder ein Alkalimetall, wie Li, Na, K oder auch NH₄,
Hal für Chlor oder Brom, vorzugsweise Chlor,
y für eine ganze Zahl von 1 bis 4, insbesondere 3,
n = 0, 1 oder 2
stehen.As already stated above, silanes of the general formula (I) are particularly suitable for the process according to the invention
X- (CH₂) _y -Si (R¹) _n (OR²) _3-n (I)
in which R 1 and R 2 are identical or different from one another and for alkyl radicals having 1 to 9, preferably 1 to 4 carbon atoms, such as, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl radicals or for aryl radicals having 6 to 12 carbon atoms, such as phenyl, benzyl or methylphenyl and
X for one of the residues

R³ is hydrogen, an alkyl radical with 1 to 9 carbon atoms, preferably 1 to 4 carbon atoms, for example methyl, ethyl, propyl or butyl radicals, a carboxylic acid radical with 1 to 9, preferably 1 to 4 carbon atoms, for example -COOH, -CH₂COOH, -C₂H₄COOH, -C₃H₆COOH or for one of this carboxylic acid residue and that bound to R³

HO―

-

H rest
carboxylic acid anhydride ring formed, for example a succinic anhydride ring,
R⁴ and R⁵ are identical or different from one another and for an alkyl radical having 1 to 9, preferably 1 to 4 carbon atoms, for example methyl, ethyl, propyl or butyl radicals or an aryl radical with 6 to 12 carbon atoms, for example phenyl, benzyl, Methylphenyl radical,
R⁶ represents hydrogen, an alkyl radical with 1 to 9, preferably 1 to 4 carbon atoms, for example methyl, ethyl, propyl, butyl radicals or an aryl radical with 6 to 12 carbon atoms, for example a phenyl, benzyl, methylphenyl radical,
Ar is an arylene radical having 6 to 12 carbon atoms, preferably a phenylene radical,
Z for hydrogen or an alkali metal, such as Li, Na, K or also NH₄,
Hal for chlorine or bromine, preferably chlorine,
y for an integer from 1 to 4, in particular 3,
n = 0, 1 or 2
stand.

Examples of preferred silanes are (2-tripropoxysilylethyl) carboxylic acid, (3-trimethoxysilylpropyl) carboxylic acid, (4-trimethoxysilylbutyl) carboxylic acid and its methyl, ethyl, propyl and butyl esters, (3-triethoxysilylpropyl) succinic anhydride), (3-triethoxy) maleic anhydride, (2-trimethoxysilylethyl) phosphonic acid dimethylester, (3-triethoxysilylpropyl) phosphonic acid dimethyl ester and -phosphonic acid diethyl ester, (2-trimethoxysilylmethyl) phosphonic acid dichloride, (3-trimethoxysilylpropyl) phosphylulfonic acid (2) - (4-Sulfonylphenyl) ethyltrimethoxysilane, (3-trimethoxysilylpropyl) sulfonic acid chloride and (3-trimethoxysilylpropyl) sulfonic acid.

The hydrolysis of such silanes can be carried out in the usual way in water or aqueous solutions of alcohols, if appropriate in the presence of acids. To a certain extent, condensates can also form during hydrolysis. Both hydrolyzates and condensates as well as mixtures of hydrolyzates and condensates of the abovementioned silanes are suitable for the process according to the invention, as long as it is ensured that the hydrolysates or condensates are completely dissolved in the aqueous or alcoholic solution.

The aluminum supports to be used for the method according to the invention are pretreated mechanically, chemically and / or electrochemically in the usual way and anodically oxidized. Such pretreatment methods are described for example in Wernick, Pinner, Zurbrugg, Weiner, "The surface treatment of aluminum", Eugen G. Leuze Verlag, 1977.

After the treatment of the pretreated aluminum support according to the invention with the solution of the hydrolyzate or condensate of the silane and drying of the thin layer, the post-treated aluminum support is provided in the usual way with the photoconductive layer. This photoconductive layer can be constructed from a single-layer or from a two-layer system.

Suitable single-layer systems preferably have a layer (B) of (a) 65 to 35% by weight of at least one organic binder, (b) 30 to 60, in particular 38 to 46% by weight, of a conductive support material (A) treated with silane hydrolyzate according to the invention Mixture of the compounds which transport charge carriers and (c) 0.02 to 2.5% by weight of a compound which generates charge carriers upon actinic exposure, in particular a suitable dye. The layers are advantageously applied from an approximately 6% by weight solution in a suitable organic solvent to the carrier material treated according to the invention in such a way that, after the solvent has been flashed off, a dry layer thickness of approximately 0.8 to 40 μm, depending on the intended use electrophotographic printing forms, in particular 0.8 to 6 microns, results.

Suitable multilayer systems have, for example, on the conductive carrier material (A) treated according to the invention with silane hydrolyzate, e.g. (α) a charge carrier-generating layer and (β) a charge transport layer composed of 30 to 60% by weight of the mixture of the compounds which transport the charge carriers, 65 to 35% by weight of an organic binder and optionally up to 15% by weight of further the mechanical properties of the Layer-improving additives. The first layer is advantageously applied to the carrier material in a thickness of 0.005 to 5 μm, in particular 0.1 to 0.9 μm, as a solution in a suitable solvent. After the application, the second layer is applied in a thickness that results in a layer thickness of 5 to 25, in particular 7 to 15 μm, after drying the composite structure.

The type of suitable organic binders (a) for the layers depends on the intended use of the recording materials. Cellulose ethers, polyester resins, polyvinyl chlorides, polycarbonates, copolymers such as styrene-maleic anhydride copolymers or vinyl chloride-maleic anhydride copolymers or mixtures of such binders are suitable for the copying sector. In their selection, their film-forming and electrical play Properties, their adhesive strength on the carrier material and their solubility properties play a special role. Particularly in the case of recording materials for the production of electrophotographic printing plates and particularly in those for offset printing, those which are soluble in basic, aqueous or alcoholic solvents are particularly suitable. These are mainly substances with alkali-solubilizing groups such as anhydride, carboxyl, sulfonic acid, phenol or sulfonimide groups. Preferred are binders, especially those with high acid numbers, which are readily soluble in basic aqueous-alcoholic solvent systems and have an average molecular weight (weight average) of 800 to 80,000 and in particular 1,500 to 50,000. Suitable are, for example, copolymers of methacrylic acid and methacrylic acid esters, particularly copolymers of styrene and maleic anhydride and of styrene, methacrylic acid and methacrylic acid esters, provided they have the above solubility conditions. It has been shown that copolymers of styrene, maleic anhydride and acrylic or methacrylic acid, which have a copolymerized maleic anhydride content of 5 to 50% by weight and a copolymerized acrylic or methacrylic acid content of 5 to 35, in particular 10 to 30,%. % have satisfactory electrophotographic layers with sufficiently low dark conductivity. They have excellent solubility in detergents made from 75% by weight of water, 23% by weight of isobutanol and 2% by weight of soda, but are insoluble in offset-typical wiping water.

Suitable charge carrier transporting compounds (b) which are contained in this layer are compounds which do not impair transparency for visible light, such as low molecular weight compounds, in particular heterocyclic compounds such as pyrazoline derivatives, oxazoles, oxadiazoles, phenylhydrazones, imidazoles, triphenylamine derivatives, carbazole derivatives, Pyrene derivatives and other condensed aromatics, as well as compounds such as those mentioned in EP application no. 86105253.8, as well as polymeric materials such as polyvinylpyrene, poly (N-vinylcarbazole), copolymers of carbazole and styrene, or vinyl acetate and / or Vinyl chloride. Of the polymeric type, poly- (N-vinylcarbazole) is particularly suitable.

Suitable compounds which generate charge carriers under actinic exposure, (c) or sensitizers are e.g. for systems applied in one layer, such as those used for the production of electrophotographic printing forms, dyes from the triarylmethane series, xanthene dyes and cyanine dyes. Very good results have been e.g. with rhodamine B (C.I. 45170), rhodamine 6 G (C.I. 45160), malachite green (C.I. Basic Green 4; C.I. 4200), methyl violet (C.I. 42535) or crystal violet (C.I: 42555). In systems applied in multiple layers, the dye or pigment is present in a separate layer which generates charge carriers. Azo dyes, phthalocyanines, isoindoline dyes and perylene tetracarboxylic acid derivatives are effective here. Particularly good results are achieved with perylene-3,4: 9,10-tetracarbonic acid diimide derivatives, as described in DE-OS 31 10 954 and DE-OS 31 10 960.

For the particular use, the electrophotographic recording material can contain conventional additives, e.g. Leveling agent and plasticizer in the photoconductive layer or adhesion promoter between carrier and layer.

As usual, electrophotographic offset printing forms are produced by electrostatically charging the electrophotographic recording material using a high-voltage corona, immediately following image-wise exposure, developing the electrostatic latent charge image present using a dry or liquid toner, fixing the toner by means of a subsequent melting process and removing it the unstressed, photoconductive layer by means of a suitable washout solvent. The printing form thus obtained can also be prepared for offset printing in a known manner, e.g. through a rubber coating on the water-bearing surface.

The parts and percentages given in the examples and comparative examples relate to the weight, unless stated otherwise.

Suitability test for offset printing:

• A = ließ sich vollkommen sauber Abspülen, keine Farbannahme auf Nichtbildstellen, für schwierige Anwendungen beim Offsetdruck geeignet;
• B = leicht getont bzw. gesprenkelt, geringfügige Farbannahme (noch für Offsetdruck geeignet);
• C = stark getont, für Offsetdruck nicht geeignet

The plates produced in each case were examined by wiping the finished printing form with a bold printing ink which is customary in printing technology, the evaluations during the inking test having the following meaning:

• A = could be rinsed off completely clean, no ink acceptance on non-image areas, suitable for difficult applications in offset printing;
• B = slightly toned or speckled, slight ink acceptance (still suitable for offset printing);
• C = heavily toned, not suitable for offset printing

The ratings refer to the non-printing areas of the printing form.

Comparative Example 1

An electrochemically roughened by AC treatment in aqueous HCl and HNO₃ solution and anodized in sulfuric acid oxidized aluminum sheet is coated with a 10% solution of an electrophotographic recording material in tetrahydrofuran so that the layer weight after drying (30 minutes at 80 ° C) 4 g / m².

The electrophotographic recording material used for this has the following composition:
54.6% of a copolymer of styrene and methacrylic acid (weight ratio 2: 1)
45% 2,5-bis (4ʹ-diethylaminophenyl) oxadiazole-1,3,4
0.4% CI Basis Red 1; CI No. 45160

The layer is then loaded with a corona at a distance of 10 mm and an associated high-voltage source of 6.75 kV to a surface potential of -850 V and exposed in a repro camera with 4 halogen lamps of 1000 W each for 15 seconds using a test template.

After the accentuation of the latent charge image created by the exposure with a commercially available toner, an image of the original is obtained, which is fixed by the action of heat.

To convert it into a printing form, the aluminum foil with the concrete-coated photoconductor layer is placed in a cuvette and developed with the aid of a commercially available aqueous-alkaline developer.

The printing plate thus produced is colored with printing ink.

Test result:
Evaluation: C

Comparative Example 2

An electrochemically roughened by alternating current treatment in aqueous HCl and HNO₃ solution and anodically oxidized in phosphoric acid serves as a support for a printing plate produced according to Comparative Example 1.

Test result:
Evaluation: C

example 1

A 3% aqueous solution of the corresponding silane hydrolyzate is prepared by hydrolysis of (3-triethoxysilylpropyl) succinic anhydride in water.

An aluminum sheet which had been electrochemically pretreated and anodized in sulfuric acid as in Comparative Example 1 is immersed in this solution at 60 ° C. for 60 seconds, then rinsed thoroughly with water and dried at 80 ° C.

Then the plate aftertreated in this way is coated in accordance with Comparative Example 1, exposed imagewise, developed and colored.

Test result:
Evaluation: B

Example 2

A printing plate aftertreated and coated in accordance with Example 1 is stored at 50 ° C. for 30 days and then processed in the usual manner.

Result:
Evaluation: B

Example 3

The procedure is as described in Example 1, with the change that, as described in Comparative Example 2, it is an aluminum sheet anodized in phosphoric acid.

Result:
Evaluation: B

Example 4

A printing plate aftertreated and coated in accordance with Example 1 is stored at 50 ° C. for 30 days and then processed in the usual manner.

Test result:
Evaluation: B

Example 5

An aluminum sheet anodized in sulfuric acid as described in Comparative Example 1 is processed according to Example 1 with the difference that the temperature of the 3% silane hydrolyzate solution is 25 ° C.

Test result:
Evaluation: A

Example 6

A printing plate produced according to Example 5 is first stored at 50 ° C. for 30 days and then processed in the usual way.

Test result:
Evaluation: A

Example 7

An aluminum sheet anodized in phosphoric acid as described in Comparative Example 2 is processed according to Example 1 with the difference that the temperature of the 3% silane hydrolyzate solution is 25 ° C.

Test result:
Evaluation: A

Example 8

A printing plate produced according to Example 7 is first stored at 50 ° C. for 30 days and then processed in the usual way.

Test result:
Evaluation: A

Example 9

An aluminum sheet anodized in sulfuric acid as described in Comparative Example 1 is processed in accordance with Example 1 with the difference that the aftertreatment takes place by immersion in a 1% silane hydrolyzate solution at 25 ° C.

Test result:
Evaluation: A

The printing plate produced in this way delivered 100,000 flawless prints on a newspaper rotary printing press (COLORMAN) despite several interruptions and drying of the printing plate.

Example 10

A printing plate produced according to Example 9 is first stored at 50 ° C. for 30 days and then processed in the usual way.

Test result:
Evaluation: A

Example 11

An aluminum sheet anodized in phosphoric acid as described in Comparative Example 2 is processed according to Example 1 with the difference that the aftertreatment is carried out by immersion in a 1% silane hydrolyzate solution at 25 ° C.

Test result:
Evaluation: A

Example 12

A printing plate produced according to Example 10 is first stored at 50 ° C. for 30 days and then processed in the usual way.

Test result:
Evaluation: A

Claims (6)

1. A process for producing an electrophotographic recording element from a mechanically, chemically and / or electrochemically pretreated and anodically oxidized aluminum support and a photoconductive layer which is applied to this support, characterized in that a thin hydrophilizing layer between the support and the photoconductive layer is applied from a hydrolyzate or condensate of at least one silane. 2. The method according to claim 1, characterized in that at least one compound of the general formula (I) as the silane
X- (CH₂) _y -Si (R¹) _n (OR²) _3-n (I)
wherein R¹ and R² are the same or different from each other and represent alkyl radicals having 1 to 9 carbon atoms or aryl radicals having 6 to 12 carbon atoms and
X for one of the residues

stands for R³ for hydrogen, an alkyl radical with 1 to 9 carbon atoms, a carboxylic acid radical with 1 to 9 carbon atoms or one of this carboxylic acid radical and that bound to R³

HO―

-

H ― rest
formed carboxylic acid anhydride ring,
R⁴ and R⁵ are the same or different from each other and represent an alkyl radical with 1 to 9 carbon atoms or an aryl radical with 6 to 12 carbon atoms,
R⁶ represents hydrogen, an alkyl radical with 1 to 9 carbon atoms or an aryl radical with 6 to 12 carbon atoms,
Ar is an arylene radical with 6 to 12 carbon atoms,
Hal for chlorine or bromine,
Z represents hydrogen or an alkali metal,
y for an integer from 1 to 4 and
n = 0, 1 or 2
stand,
is used in hydrolyzed and / or condensed form. 3. The method according to any one of the preceding claims, characterized in that the hydrolyzate or condensate of the silane in the form of its solution by conventional application methods, such as spraying or dipping, applied to the pretreated aluminum support, an excess optionally removed and the coated support at 50 to 120 ° C is dried. 4. The method according to claim 3, characterized in that the hydrolyzate or condensate of the silane is used in 0.05 to 30% by weight aqueous or alcoholic solution and the application at 15 to 85 ° C within 0.5 to 120 seconds he follows. 5. Electrophotographic recording element produced by a method according to any one of the preceding claims. 6. Use of the electrophotographic recording elements for electrophotographic offset printing plates produced by a method according to one of claims 1 to 4.