Hoechst Aktiengesellschaft

Reinhold Arneth

Werner Frass

Guenter Jung

Jurgen Neumann

Rudi Schwandt

Eberhard Hehl

Hartmut Schmidt

The invention describes a solvent mixture for photohardenable compositions, which includes

Negative-working photosensitive coating solution containing

A process and apparatus for developing a latent electrostatic image on an electrophotographic copying material by means of a toner dispersion. An infeed roller applies the toner dispersion to the copying material, and, downstream thereof, a distribution roller acts on the surface of the copying material. To solve the problem of reproducing fine white indicia, such as thin white lines, on a black background, a voltage, having the same polarity as the surface charge of the latent electrostatic image on the copying material, is applied to the distribution roller. Squeegee rollers downstream of the distribution roller effect removal of unused toner. Toner, which adheres to the distribution roller during application of voltage to the distribution roller, is sprayed off and recovered for recycling, the spraying agent being toner dispersion.

Apparatus for developing a latent electrostatic image on an

Disclosed is a process and apparatus for separating aspherical particles from spherical particles in an admixture thereof, preferably in the preparation of a particulate carrier material for two-component developer systems for electrostatic copy devices. The process comprises directing the mixture of particles onto a surface which is inclined with respect to the horizontal; producing a relative velocity between the inclined surface and the mixture of particles, the velocity having a directional component transverse to the steepest inclination gradient of the inclined surface; and collecting a portion of the mixture of particles in a zone of the inclined surface wherein predominantly spherical particles have accummulated as a result of their greater tendency to roll in response to the relative velocity than the aspherical particles.

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Budenheim, Germany

Reinhold Arneth