Hoechst Aktiengesellschaft

Erwin Lind

Franz Freimuth

Helmuth Haberhauer

Ilse Bader

Dieter Messner

An electrophotographic recording material is disclosed that comprises an electrically conducting layer support being in particular suitable for the production of printing plates or printed circuits, and a photoconductive layer comprising an organic photoconductor, a phenolic resin as the binder, a sensitizer and customary additives. The binder employed is an optionally substituted polyvinylphenol which has a molecular weight (weight average) of preferably between 1,500 and 60,000. The polyvinylphenol may be halogenated, preferably brominated. Furthermore, an o-quinonediazide may be contained in the photoconductive layer. The recording material is distinguished by a high charging capacity, good photosensitivity and excellent solubility properties. It is suitable for the reproduction of fine image elements.

Electrophotographic recording material

Disclosed is a developing apparatus and process for the liquid development of electrostatic charge images on an image carrier material. The developing apparatus includes a device for spraying a liquid developer onto the image carrier material to be developed, and a developing electrode connected to a direct-current voltage source. The developing electrode comprises an electrically conductive web positioned in operative relationship to the image carrier layer, the web is unwound from a supply roll and wound up on a take-up roll, the distance of the web-shaped developing electrode from the surface of the image carrier material being adjustable by means of at least one guide roll.

Developing apparatus for the liquid development of electrostatic charge

The invention describes an electrophotographic recording material composed of an electrically conductive support layer, which is suitable in particular for the production of printing forms or printed circuits, and of a photoconductive layer comprised of an organic photoconductor, a binder and a sensitizer. The photoconductive layer additionally contains a condensation product of benzophenone-2-carboxylic acid and a dialkyl aniline, for example, benzophenone-2-carboxylic acid and diethyl aniline or 4'-methylbenzophenone-2-carboxylic acid and diethyl aniline.

Electrophotographic recording material with condensation product

This invention relates to an improvement in the process for the preparation of printing forms and/or metallized images by electrostatic charging, exposing, and treating with a toner of a photoconductor layer applied to an electrically conductive support material, and removing the photoconductor layer in the non-image areas, the improvement which comprises effecting removal of the toner-free photoconductor layer by transferring it at a temperature in the range of about 50.degree. to 250.degree. C. to a receiving material which has a greater surface adhesion to the photoconductor layer than does the electrically conductive support material.

Process for the preparation of printing forms and/or metallized images

This invention relates to an improvement in the process for the manufacture of printing forms and printed circuits by coating an electrically conductive support with an organic photoconductor layer and by charging, exposing, and developing the electrostatic image by means of a finely particulate toner, fixing and dissolving the layer away from the non-image areas by means of a decoating medium and, if appropriate, etching of the bared support surface, the improvement which comprises, for the purpose of coating, transferring the organic photoconductor layer on a temporary support to the electrically conductive support with the aid of heat and pressure.

Electrophotographic process for the manufacture of printing forms or

This invention relates to an improvement in an electrophotographic recording material comprising an electrically conductive support, in particular a support adapted for the preparation of printing forms or printed circuits, and a panchromatically sensitized photoconductive layer which comprises an organic photoconductor, a binder, a sensitizing dye, and conventional additives, the improvement that the photoconductive layer contains, as the sensitizing dye, a mixture of a polymethine dye and a triarylmethane dye which absorb, respectively, between about 400 and 550 nm and between about 550 nm and 720 nm.

A process for patterned storage and reproduction of information in which a photoconductive recording material is altered by an electron beam in correspondence with the information, a free charge is applied to the photoconductive recording material and the flowing off of this charge is made visible differing in correspondence with the pattern.

Process for the storage and reproduction of information

This invention relates to an improvement in the process for the preparation of printing forms or metallic etchings from electrophotographic or electrographic reproduction materials composed of a support with a photoconductive or high-ohmic layer thereon, by charging and image-wise exposure, or by image-wise charging, development of the electrostatic image with a finely-divided toner, fixing, and removal of the layer in the image-free areas by means of a decoating solution, the improvement comprising developing the electrostatic image with a developer which reacts at least superficially with the image areas at room temperature, thereby simultaneously effecting development and resistance to the decoating solution, or developing the electrostatic image with a developer which reacts with the decoating solution and thereby deactivates it in the image areas.

Process for the preparation of printing forms

This invention relates to a material for electrophotographic reproduction, which comprises a conductive support having a sensitized photoconductive insulating layer thereon containing at least one photoconductor and containing, as a sensitizer, a polymethine dyestuff capable of absorbing radiation of a wavelength within the spectral range of 400 to 550 nm.

Material for electrophotographic reproduction

This invention relates to an electrophotographic process for the production of a printing form which comprises electrostatically charging a supported photoconductive and photopolymerizable layer, exposing the charged layer to light under a master, developing the resulting latent image with an electroscopic material, again exposing the layer to light, and removing the developed image areas from the support.

Process for the electrophotographic production of printing plates

A process for the production of a copy from an original which includes creating a charge image on a hydrophobic photoconductive material, pre-developing the charge image by the application thereto of a hydrophilic solid substance, meniscally contacting the pre-developed image with an aqueous liquid and transferring the image onto a copy receiving material. The hydrophobic photoconductive material may be a charge transfer complex of polyvinyl carbazole and trinitrofluorenone. The hydrophilic solid substance may be water-insoluble starch, silica, iron-III-oxide, zinc oxide, methylene blue, nigrosin or acid violet.

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Wiesbaden, Germany

Erwin Lind