Hoechst Aktiengesellschaft

Agfa-gevaert Ag

Silvia Lutz

Raimund J Faust

Engelbert Pliefke

Danuta Eva Allen

A graft copolymer of recurring units of (C.sub.6 -C.sub.18)alkyl (meth)acrylate (A), N-vinylpyrrolidone (B), glycidyl (meth)acrylate (C), and glycidyl (meth)acrylate units esterified with (meth)acrylic acid (D) onto which polymeric side chains of units of N-vinylpyrrolidone, (C.sub.1 -C.sub.3)alkyl acrylate and, if appropriate, (C.sub.1 -C.sub.3)alkyl methacrylate are grafted. The polymer is suitable as a binder for colorless, negatively chargeable liquid toners, in particular in combination with graft copolymers of (C.sub.1 -C.sub.6)alkyl (meth)acrylate, (C.sub.6 -C.sub.18)alkyl (meth)acrylate and units in which chains of N-vinyl-pyrrolidone units are grafted onto one of the units mentioned, as a charge control agent. After fixing of the electrophotographically produced toner image, the toners give colorless resist masks or printing screens with a high resistance toward etching agents and solvents.

Graft copolymers and colorless, transparent electrophotographic toners

A process for the production of a colored image by an electrophotographic route by electrostatic charging, imagewise exposure to light and toning of a photoconductor material with a colorless transparent toner which includes a colorless polymeric binder and a colorless polymeric charge control agent, and transfer of the toner image to a colored layer which is soluble in a solvent and is on a layer carrier, fixing of the toner image and removal of the areas of the colored layer not covered by the toner image by washing out with a solvent. The process utilizes the high photosensitivity of electrophotographic materials, without the possibility of color falsification due to colored toners. The procedure is simpler compared with known electrophotographic processes, since the same toner can be employed in all steps and does not have to be washed off.

Process for the production of colored images by an electrophotographic

The invention relates to a hydrophilic copolymer having the general structure:

Hydrophilic copolymers and their use in reprography

The invention relates to a hydrophilic copolymer having the general structure: ##STR1## in which R.sup.1 denotes H, CH.sub.3 or C.sub.2 H.sub.5,

The invention relates to a thermally crosslinkable hydrophilic copolymer have the general structure:

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Mainz, Germany

Silvia Lutz