EP0133469B1 - Electrophotographic recording materials with improved photosensitivity - Google Patents

Description

The invention relates to electrophotographic recording materials with electrically conductive supports, charge carrier-producing compounds or sensitizers, charge carrier transporting compounds and special additives.

Electrophotographic processes, materials required therefor and various variants for the construction of recording materials are known. Advantages for use in the reproduction sector are materials made of polymeric binders that can be adapted to the special requirements of the respective field of application, low molecular weight organic compounds that are soluble in the binders even in higher concentrations and are capable of transporting charge carriers of the electrical current, and compounds , in particular dyes or pigments, which generate charge carriers of the electrical current by absorption of the actinic light radiated imagewise and which can transfer them to the charge-transporting compounds with the aid of the electrical field impressed from the outside by the electrostatic surface charge. Depending on the field of application of the recording material, these charge carrier-producing compounds can be introduced as a separate layer within a composite structure (cf. DE-OS 22 20 408) or in the form of monodisperse dissolved dye molecules in the mixture of binder and charge carrier-carrying compounds (cf. PS 1 058836). The multilayer electrophotographic recording material described in DE-OS 2220408 consists of an electrically conductive carrier material, a first, dye-containing, about 0.005 to 2 gm thick, by exposure to actinic light charge carriers of the electric current generating layer of dark insulating organic materials with at least a charge transporting connection.

It is also known to use photoconductive organic compounds for the production of electrophotographic printing forms and in particular electrophotographic offset printing forms (cf. DE-PS 1 117 391 and 1 120 875, DE-AS 15 22 497 and 2726116).

The increased demands on reproduction systems require a variety of recording materials and systems in order to be able to find optimal solutions for special problems. Good resolution and good emphasis are desired. The often criticized inadequate emphasis, which indicates an unfavorable field strength differentiation between exposed and unexposed areas, is often due to an excessive dark conductivity of the recording material in the loaded state, so that there is an insufficient surface charge density before the actinic imagewise exposure.

High photosensitivity is particularly desirable in order to reduce the required process times. In the production of electrophotographic offset printing plates in particular, the necessary exposure time plays an important role. Here, however, the existing systems are frequently criticized.

The present invention was based on the task of developing electrophotographic recording materials, in particular for the production of electrophotographic printing forms, such as offset printing forms, which have improved photosensitivity, at the same time a low dark conductivity and good resolution.

enthalten, worin

• R' und R² einen substituierten oder unsubstituierten Alkylrest,
• R³ Wasserstoff oder einen substituierten oder unsubstituierten Alkylrest,
• M ein Element der Ordnungszahl 21 (Scandium), 39 (Yttrium) oder 57 bis 71 und
• n die Zahl 3 oder, falls M = Cerium (O.Z. 58) ist, auch die Zahl 4 bedeuten.

It has now been found that improved electrophotographic recording materials with electrically conductive supports, charge-generating compounds or sensitizers, charge-transporting compounds, binders and additives can be obtained if they are 0.5 to 30% by weight, but preferably 3 to 15, as additives % By weight, based on the proportion of binder in the layer containing charge transport compounds, of a metal-1,3-diketone complex of the formula (I)

included in what

• R 'and R ^{2 are} a substituted or unsubstituted alkyl radical,
• R ^{3 is} hydrogen or a substituted or unsubstituted alkyl radical,
• M is an element of atomic number 21 (scandium), 39 (yttrium) or 57 to 71 and
• n is the number 3 or, if M = cerium (OZ 58), the number 4.

• R³ Wasserstoff ist,
• M die Elemente Lanthan, Cerium, Praseodym, Neodym, Europium, Dysprosium, Holmium oder Ytterbium, und
• n die Zahl 3 bedeuten.

Preferred compounds of the formula (I) are those in which R 'and R ² , which may be the same or different, are a methyl, ethyl, isopropyl, tert-butyl, trifluoromethyl or heptafluoropropyl radical represent

• R ^{3 is} hydrogen,
• M the elements lanthanum, cerium, praseodymium, neodymium, europium, dysprosium, holmium or ytterbium, and
• n is the number 3.

• R³ Wasserstoff,
• M die Elemente Praseodym, Europium oder Holmium und
• N die Zahl 3 bedeuten.

Particular preference is given to those compounds of the formula (I) in which R 'and R ² , which may be the same or different, are methyl, heptafluoropropyl or tert. Butyl residue,

• R ^{3 is} hydrogen,
• M the elements praseodymium, europium or holmium and
• N is the number 3.

• 2,4-Pentandion, 1,1,1-Trifluor-2,4-pentadion, 1,1,1,5,5,5-Hexafluor-2,4-pentandion, 2,4-Hexandion, 5-Methyl-2,4-Hexandion, 5,5-Dimethyl-2,4-hexandion, 1,1,1-Trifluor-2,4-hexandion, 1,1,1-Trifluor-5-methyl-2,4-hexandion, 1,1,1-Trifluor-5,5-dimethyl-2,4-hexandion, 1,1,1,5,5,6,6,7,7,7-Decafluor-2,4-heptandion, 3,5-Heptandion, 2,2,6-Trimethyl-3,5-heptandion, 2,2,6,6-Tetramethyl-3,5-heptandion (Dipivalomethan), 1,1,1,2,2,3,3-Heptafluor-7,7-dimethyl-4,6-octandion, 2,4-Decandion oder 2,4-Heneicosandion. Von diesen sind 2,2,6,6-Tetramethyl-3,5-heptandion (Dipivalomethan) oder 1,1,1,2,2,3,3-Heptafluor-7,7-dimethyl-4,6-octandion ganz besonders bevorzugt.

The following compounds may be mentioned as 1,3-diketones which can form complexes of the formula (I) with the metals:

• 2,4-pentanedione, 1,1,1-trifluoro-2,4-pentadione, 1,1,1,5,5,5-hexafluoro-2,4-pentanedione, 2,4-hexanedione, 5-methyl 2,4-hexanedione, 5,5-dimethyl-2,4-hexanedione, 1,1,1-trifluoro-2,4-hexanedione, 1,1,1-trifluoro-5-methyl-2,4-hexanedione, 1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedione, 1,1,1,5,5,6,6,7,7,7-decafluoro-2,4-heptanedione, 3, 5-heptanedione, 2,2,6-trimethyl-3,5-heptanedione, 2,2,6,6-tetramethyl-3,5-heptanedione (dipivalomethane), 1,1,1,2,2,3,3 -Heptafluoro-7,7-dimethyl-4,6-octanedione, 2,4-decanedione or 2,4-heneicosanedione. Of these, 2,2,6,6-tetramethyl-3,5-heptanedione (dipivalomethane) or 1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octanedione are whole particularly preferred.

The compounds used according to the invention are known or can be prepared by known methods, for. B. according to the Gmelin Handbook of Inorganic Chemistry, Syst. No. 39 rare earths, vol. D3, 8th edition 1981, pp. 65 ff.

It is particularly surprising that the addition of the metal 1,3-diketone complexes according to the invention greatly improves the photosensitivity and at the same time also significantly increases the maximum potential acceptance of the electrophotographic recording materials without changing the dark properties, so that an improved differentiation in relation to the photosensitivity is also achieved occurs between exposed and unexposed areas of the loaded surface.

It is known to the person skilled in the art that metal halides - such as zinc chloride, magnesium bromide, aluminum chloride - and ketones - such as acetophenone, benzophenone, benzil - can also improve the photosensitivity of certain organic photo semiconductor layers in small amounts (e.g. US 3,037,861, US 3 553 009, U.S. 3,620,723). It has also been confirmed that additions of metal halides and ketones do not produce the effects according to the invention. The effect of the metal-1,3-diketone complexes achieved according to the invention cannot be derived from the known additives for the person skilled in the art.

The metal-1,3-diketone complexes which improve the photosensitivity and are used according to the invention can advantageously be used both in single-layer and in multi-layer recording systems applied to electroconductive supports.

Suitable single-layer systems preferably have a layer of (a) 45 to 75 parts by weight of a binder, (b) 30 to 60, in particular 35 to 50 parts by weight of a charge carrier transporting compound, (c) optionally 5 to 25 parts by weight of another on a conductive carrier material , essentially inactive binder, (d) 0.05 to 0.8 parts by weight of a compound which generates charge carriers upon actinic exposure, in particular a suitable dye, and (e) 0.5 to 30, in particular 3 to 15% by weight, based on the binder content, one or more of the metal 1,3-diketone complexes according to the invention. The layers are advantageously applied from an approx. 5% by weight solution in a suitable organic solvent to the cleaned conductive carrier material in such a way that after the solvent has been flashed off, a dry layer thickness of approx. 0.8 to 40 µm (depending on the intended use, in electrophotographic printing forms, in particular 0.8 to 6 μm) results.

Suitable multilayer systems advantageously have on an electroconductive carrier material (a) a layer with compounds generating charge carriers and (b) a further layer with (b1) at least one charge carrier transporting compound, (b2) at least one organic binder and (b3) optionally further, in particular additives which improve the mechanical properties of the layer, layer (b) 0.5 to 30 and preferably 3 to 15% by weight. based on the binder content, contains one or more of the metal 1,3-diketone complexes according to the invention. The layer (b) advantageously contains 30 to 60 parts by weight of (b1), 45 to 75 parts by weight of (b2) and, if appropriate, 5 to 25 parts by weight of the additives (b3).

The first layer is advantageously applied to the support material in a thickness of 0.005 to 5, in particular 0.1 to 0.9 μm from solution in a suitable solvent. After the application, the second layer is advantageously 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.

In principle, all conductive carrier materials can be used as electrically conductive carriers, insofar as they are suitable for the area of application. Depending on the field of application of the recording materials, aluminum, zinc, magnesium, copper or multi-metal plates, for. B. raw or pretreated, e.g. B. roughened and / or anodized aluminum sheets, aluminum foils, polymer films with metallized Surface such as aluminum-coated polyethylene terephthalate films or also electrically conductive special papers. Carriers for printing forms advantageously have a thickness of 0.08 to approximately 0.3 mm.

The type of suitable organic binders for the layers depends on the intended use of the recording materials. For the copy sector, z. B. 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. In their selection, their film-forming and electrical properties, their adhesive strength on the carrier material and their solubility properties play a special role. Particularly suitable for recording materials for the production of electrophotographic printing plates, and especially for those for offset printing, are those which are soluble in basic, aqueous or alcoholic solvents. These are mainly substances with alkali solubilizing. Groups such as anhydride, carboxyl, sulfonic acid, phenol or sulfonimide groups. Preference is given to 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 150,000 and in particular 1,200 and 80,000. Are suitable for. B. copolymers of methacrylic acid and methacrylic acid esters, especially copolymers of styrene and maleic anhydride and of styrene, methacrylic acid and methacrylic acid esters, insofar as they have the above solubility condition. Although binders with free carboxyl groups are known to undesirably increase the dark conductivity of the electrophotographic layers and thereby lead to poor stressing results, such binders can easily be adapted to the charge transport compounds used. 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 and in particular 10 to 30% by weight. -%, have satisfactory electrophotographic layers with sufficient dark conductivity. They have excellent solubility in washing-out agents consisting of 75% by weight of water, 23% by weight of isobutanol and 2% by weight of soda, but are insoluble in offset-typical cleaning water.

Suitable charge carrier-producing compounds or sensitizers are e.g. B. for single-layer systems, such as those used for the production of electrophotographic printing forms, dyes from the triarylmethane series, xanthene dyes and cyanine dyes. Very good results were obtained with rhodamine B (C.I. 45170), rhodamine 6 G (C.I. 45160), malachite green (C.I. 42000), methyl violet (C.I. 42535) and 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 particularly effective here. Good results are achieved with perylene-3,4: 9,10-tetracarboxylic acid diimide derivatives, as described in DE-OS 31 10 954 and 31 10 960.

Suitable charge carriers of the connections carrying electrical current are known to the person skilled in the art. Mention may be made of oxazole derivatives (DBP 11 20 875), oxdiazole derivatives (DBP 10 58 836), triazole derivatives (DBP 10 60 260), azomethines (US 3 041 165), pyrazoline derivatives (DBP 10 60 714) and imidazole derivatives (DBP 1106599). Benztriazole derivatives (German patent application P 32 15 968.4) and hydrazone derivatives (German patent application P 32 01 202.0) are preferred. These are usually low molecular weight compounds which are well compatible with the organic binders in the required amount. However, polymeric charge transport compounds can also be used, e.g. B. Poly (N-vinyl carbazole).

For the respective use, the electrophotographic recording material according to the invention may contain conventional additives, e.g. B. leveling agents and plasticizers in the photoconductive layer or adhesion promoter between carrier and layer.

The electrophotographic recording materials according to the invention are distinguished by a combination of very good properties, in particular a high photoconductivity with a very low dark conductivity, so that the layers are very suitable for copying technology.

They have clear advantages when used for the production of electrophotographic printing forms and meet high demands with regard to the resolution and the print run. The high sensitivity to light allows a significant reduction in the exposure time when processing in the repro camera compared to commercially available materials. A good resolution results from a very sharp image reproduction. Thanks to a high charge contrast, even fine halftone dots in the light tonal ranges can be reproduced well. Furthermore, the exposure of the layers leads to very low residual stresses and the images obtained during the concreting are characterized by good basic freedom in the non-image areas.

The production of electrophotographic offset printing forms takes place, as usual, 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, photo-semiconducting layer by means of a suitable washout solvent. The printing form thus obtained can still be prepared in a known manner for offset printing, e.g. B. by hydrophilization and gumming the water-bearing surface.

The following examples are intended to further illustrate the invention. The parts and percentages given relate to the weight.

The layers are evenly charged to a surface potential of -600 volts with a DC corona of -8.5 kV at a distance of 1 cm and then exposed to the white light of a high-pressure xenon lamp with an illuminance of 10 μW · cm ^―2 in the layer plane. The photo-induced potential drop during the exposure is tracked over time until the surface potential has fallen below 5% of the originally present value. Then the time is determined which elapses before the surface potential drops by half, corrected by the amount of the dark drop. The half-value photosensitivity as the product of half-life and illuminance in the plate plane is given in µJ · cm- ² . Furthermore, according to the xerographic method, the maximum potential acceptance in volts, the time until the recording materials are charged to ― 500 volts with a corona voltage of -8.5 kV at a distance of 10 mm, the potential drop in the dark in 20 seconds and the total photo-induced potential drop in% with an irradiated energy of 1 mJ. cm- ² determined.

example 1

55 parts of a copolymer of 70% styrene, 6% maleic anhydride and 24% acrylic acid with an average molecular weight M _w of about 2000, 45 parts of 2- (N, N-diethylphenyl) -6-methoxybenzotriazole-1,2,3, 0.6 part of methyl violet (CI 42535) and 5 parts of tris (dipivalomethanato) -Europium Eu (DPM ) ₃ (C ₃₃ H ₅₇ EuO ₆ ) are dissolved in a mixture of tetrahydrofuran and ethyl acetate, the solution is applied to an electrically conductive support made of an electrolytically roughened and then anodized aluminum sheet 0.15 mm thick so that after flashing off of the solvent and 30 minutes drying at 85 ° C results in a dry layer thickness of 4 microns. The xerographic test reveals a half-value photosensitivity of 20.7µJ · cm- ² .

Comparative Example 1

The procedure is as in Example 1, but the addition of tris (dipivalomethanato) -Europium is omitted. A half-value photosensitivity of 35.4 µJ · cm- ^{2 is} measured.

Comparative Example 2

The procedure is as in Example 1, but instead of the tris (dipivalomethanato) -Europium the same amount of pure dipivalomethane (C ₁₁ H ₂₀ O ₂ ) is used. The half-value photosensitivity is 29.5 µJ · cm- ² .

Comparative Example 3

The procedure is as in Example 1, but the tris (dipivalomethanato) europium is replaced by the same amount of europium perchlorate (Eu (C10 ₄ ) ₃ ) (pre-dissolved in a little water). A half-value photosensitivity of 34.7 µj · cm- ^{2 is} determined.

Examples 2 and 3

The procedure is as in Example 1, but the tris (dipivalomethanato) europium is replaced by tris [1,1,1,2,2,3,3-heptafluoro-7,7-dimethyloctandionato- (4,6)] holmium Ho (FOD) ₃ (C ₃₀ H ₃ () F ₂₁ H ₀ O ₆ ), example 2) or tris (dipivalomethanato) praseodymium Pr (DPM) ₃ (C ₃₃ H ₅₇ PrO ₆ ) example 3). The half-value photosensitivities are 21.6 (µj · cm-2 and 16.5 µJ · cm-2.

Example 4

60 parts of a copolymer of 80% styrene and 20% acrylic acid with an average molecular weight of 1600, 36 parts of p-diethylaminobenzaldehyde diphenylhydrazone, 1 part of rhodamine 6 G (CI 45160) and 8 parts of tris (dipivalomethanato) praseodymium are dissolved in tetrahydrofuran / methylglycol 1: 1 solved and applied in a dry layer thickness of 5.5 microns on a fine brushed aluminum sheet. A half-value photosensitivity of 10.8 µJ · cm ^{―2 is} determined on this electrophotographic recording material.

Comparative Example 4

The procedure is as in Example 4, but the tris (dipivalomethanato) praseodymium is omitted. The half-value photosensitivity is now 16.2µJ · cm-2.

Example 5

50 parts of a copolymer of 60% styrene and 40% of a maleic acid semi-esterified with methanol with an average molecular weight M _w of 10,000, 50 parts of 2- (4'-diethylaminophenyl) benzotriazole-1,2,3, 0.2 parts of crystal violet (CI 42555) and 4 parts of tris (dipivalomethanato) -europium are applied from a 5% solution in tetrahydrofuran to an electrolytically roughened and anodized aluminum foil of 0.15 mm thickness in a dry layer thickness of approximately 4 μm.

After a charge, this printing plate is exposed in a camera for 12 seconds using a high-voltage corona. It is then developed with a powder toner that is burned-in at 160 ° C and resistant to abrasion. The unconcrete layer is washed off with a mixture of 0.5% soda, 25% isopropanol and 74.5% water, which exposes the aluminum surface. The solutions are spread over the layer with a cotton ball. The differentiation into hydrophilic and oleophilic areas desired in offset printing is obtained, the carrier surface providing the hydrophilic areas.

After the treatment with the alkaline liquid, the printing plate is rinsed with water and the hydrophilicity of the support surface is further increased by wiping with dilute phosphoric acid solution. After inking with bold ink, it is used to print in a known manner in offset printing machines.

Example 6 and Comparative Example 5

• a) Zeit bis zur Aufladung auf -500 V (-8,5 kV, 10 mm) : 2,1 s (2,2s);
• b) maximale Potentialakzeptanz : 1 300 V (1 100 V) ;
• c) Dunkelabfall (20 s, - 600 V) : 11 % (16 %) ;
• d) photoinduzierter Potentialabfall (1 mJ - cm-²) : 88 % (79 %).

55 parts of a copolymer of 55% styrene, 30% acrylic acid and 15% maleic anhydride with an average molecular weight M _w of 35,000, 45 parts of 2- (N, N-diethylaminophenyl) benzotriazof-1,2,3, 0.6 parts Methyl violet (CI 42535) and 6 parts of tris (dipivalomethanato) praseodymium are dissolved in a mixture of tetrahydrofuran and methyl glycol acetate and applied as a layer with a dry layer thickness of 3.5 μm to a finely brushed aluminum sheet. The comparison layer 5 is produced as in Example 6 but without the tris (dipivalomethanato) praseodymium. The following characteristics are measured on the two layers (comparative example in brackets) using the xerographic method:

• a) Time to charge to -500 V (-8.5 kV, 10 mm): 2.1 s (2.2 s);
• b) maximum potential acceptance: 1 300 V (1 100 V);
• c) dark drop (20 s, - 600 V): 11% (16%);
• d) photo-induced potential drop (1 mJ - cm- ² ): 88% (79%).

Example 7 and Comparative Example 6

A layer of 60 parts of a chlorinated perylene-3,4: 9,10-tetracarboxylic acid diimide bisbenzimidazole with a chlorine content of about 38% and 50 parts of a commercially available copolymer of vinyl chloride is placed on a polyethylene terephthalate film with a vapor-deposited, conductive aluminum layer in a thickness of approximately 300 Å , Acrylic acid and a maleic acid diester applied in a thickness of about 0.55 microns as a charge carrier generating layer.

A charge transport layer consisting of 45 parts of a commercially available polycarbonate binder with a melting range of 220 to 230 ° C., 10 parts of a polyester with an acid number of approximately 40 and a molecular weight of approximately 4500, 40 is made from a solution in ethyl acetate onto this layer which generates charge carriers Parts of p-diethylaminobenzaldehyde diphenylhydrazone and 4 parts of tris (dipivalomethanato) praseodymium are applied in such a way that after drying off the solvent and drying for 30 minutes at 80 ° C., a dry layer thickness of 12 wm results.

A half-value photosensitivity of 2.35 μJ · cm- ^{2 is} determined on this layer. The same layer without tris (dipivalomethanato) praseodymium has a half-value photosensitivity of about 4.8 µJ · c _m -2 _.

If the layer of Example 7 is used as a copy film in a commercially available copier with dry toner, copies of good quality and in large numbers can be produced with it.

Claims (11)

1. An electrophotographic recording material comprising an electrically conductive base, a binder, a charge carrier-producing compound or sensitizer, a charge carrier-transporting compound and additives, characterized in that it contains, as an additive, from 0.5 to 30 % by weight, based on the amount of binder present in the layer containing the charge carrier-transporting compound, of a metal-1,3-diketone complex of the formula

where

R' and R² are each unsubstituted or substituted alkyl,

R³ is hydrogen or substituted or unsubstituted alkyl,

M is an element of atomic number 21, 39 or 57-71, and

n is 3 or, if M is cerium (atomic number 58), may also be 4.

2. An electrophotographic recording material as claimed in claim 1, characterized in that it contains from 3 to 15% by weight of the 1,3-diketone complex.

3. An electrophotographic recording material as claimed in claim 1 or 2, characterized in that it contains tris(dipivalomethanato)-europium as the 1,3-diketone complex.

4. An electrophotographic recording material as claimed in claim 1 or 2, characterized in that it contains tris(dipivalomethanato)-praseodymium as the 1,3-diketone complex.

5. An electrophotographic recording material as claimed in claim 1 or 2, characterized in that it contains tris [1,1,1,2,2,3,3-heptafluoro-7,7-dimethyloctane-4,6-dionato]-holmium as the 1,3-diketone complex.

6. An electrophotographic recording material as claimed in any of claims 1 to 5, characterized in that it comprises an electrically conductive base, a layer which contains a charge carrier-producing compound, and a further layer which contains a charge carrier-transporting compound and from 0.5 to 30 % by weight, based on the binder present in this layer, of a metal-1,3-diketone complex as claimed in claim 1.

7. A recording material for the production of electrophotographic printing plates, as claimed in any of claims 1 to 5, characterized in that it comprises, on a 0.08-0.6 mm thick base suitable for printing plates, a photosemiconducting layer containing.

a) at least one binder,

b) at least one charge carrier-transporting compound,

c) at least one dye as sensitizer, and

d) at least one metal-1,3-diketone complex as claimed in claim 1, with or without

e) further .additives.

8. A recording material as claimed in claim 7, characterized in that the binder is soluble in basic aqueous or aqueous-alcoholic solvents.

9. A recording material as claimed in claim 7 or 8, characterized in that the binder is a copolymer of styrene, maleic anhydride and acrylic and/or methacrylic acid, the copolymer containing from 5 to 50 % by weight of maleic anhydride groups as copolymerized units and from 5 to 35 % by weight of acrylic and/or methacrylic acid groups as copolymerized units.

10. The use of an electrophotographic recording material as claimed in claims 1 to 6 for reprographic purposes.

11. The use of an electrophotographic recording material as claimed in claims 1 to 6 or 7 to 9 for the production of electrophotographic printing plates, particularly offset printing plates.