Oce-van Der Grinten N.v.

Oce-van De Grinten N.v.

Adrianus M Hectors

Gerardus J Crommentuyn

Electrically conductive developer powder for developing electrostatic images by inductive attraction is provided, with avoidance of practical disadvantages of known 'one-component' developer powders, by incorporating finely divided water-insoluble quaternary ammonium salt into thermoplastic resin particles forming the powder, with or without other finely divided additives such as coloring material and/or magnetically attractable material. The specific resistance of the resin particles is lowered to between 10.sup.7 and 10.sup.11 ohm. cm by from 8 to 35% by weight of the quaternary ammonium salt, and can be lowered further by additions of fine conductive material such as carbon black. The resin particles remain sufficiently fusible even when they also contain enough magnetically attractable material, e.g. about 50% by weight, to render them transportable by a magnetic powder-applicator. A further important feature of the invention consists in preparing thermoplastic resin particles of suitable size with the quaternary ammonium salt already finely dispersed in them simply by coagulating an aqueous resin emulsion that contains one of the ions required for forming said salt, in a coagulant liquid containing the other of said ions. When so desired, the other additives can also be finely dispersed in these resin particles via the coagulant liquid.

Electrostatic image one-component electrically conductive thermoplastic

One-component developer powder and process for its preparation

In electrophotographic copying processes use is made of a reproduction element comprising on a conductive support a photoconductive layer containing dispersed in a binder a bisazo naphthol compound having a certain structure of substituents whereby the reproduction element exhibits relatively high light-sensitivity and is repeatedly exposable and developable imagewise so as to be useful for indirect electrophotographic copying. Special binder compositions enhance the light-sensitivity of the element and special layer constructions are provided to suit it for certain uses.

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Tegelen, Netherlands

Adrianus M Hectors