Hoechst Aktiengesellschaft

Clariant Corporation

Rudiger Baur

Hans-Tobias Macholdt

Hans Joachim Metz

Wilfried Theiss

Hermann Fuchs

Jorg Gitzel

Dieter Baumgart

Pigment for electrophotographic toners and developers

The use of an azo pigment of the formula (1) ##STR1## as a colorant in electrophotographic toners, electrophotographic developers, powders and powder coatings, and electret materials, wherein said azo pigment is prepared in the presence of 20 to 50% by weight of an auxiliary selected from the group consisting of a rosin, a salt of a rosin, an abietic acid, and a salt of an abietic acid, wherein said weight is based on the overall weight of the azo pigment including said auxiliary, and wherein the azo pigment has a specific surface area of more than 70 m.sup.2 /g and the azo pigment particles comprising the azo pigment have a length-to-width ratio of on average less than 2.8:1 and a mean particle size d.sub.50 of less than 130 nm.

Electrophotographic, resin-containing, electret, or inkjet compositions

Cyclosaccharide-boron complexes consisting of 1 to 4 cyclodextrin units and one borate radical of the formula (I): ##STR1## have good charge control properties and lend themselves excellently to dispersion in toner, powder coating and electret binders.

Cyclooligosaccharide-boron complex

Azo pigment of the formula (1) ##STR1## which has a specific surface area of the pigment powder of more than 45 m.sup.2 /g. The azo pigment is particularly suitable as colorant in electrophotographic toners and developers, and in powder coatings and electret materials.

Inclusion compounds consisting of a host compound, which is a cyclically linked polysaccharide having 3 to 100 monomeric saccharide units and forming a cavity in its molecular framework, and of one or more chemical compounds which are included in this cavity as guest compound(s), are used as charge control agents and charging improvers in electrophotographic toners and developers, in triboelectrically or electrokinetically sprayable powders and powder coatings and in electret materials.

Use of inclusion compounds of cyclic polysaccharides as charge control

Tetraphenylborates are obtained in an industrially advantageous grade by spray drying an organic, aqueous or organic-aqueous extract of the tetraphenylborates obtainable in the tetraphenylborates synthesis. It is advantageous to treat the specified extract prior to spray drying with pH-controlling auxiliaries and adsorbents to remove byproducts or to limit their formation. The process gives tetraphenylborates in a homogeneous technical grade, i.e. in a narrow particle size distribution and in a particular particle shape, which improves the dispersibility in the medium to be used.

Process for isolating tetraphenylborates

Cyclic polysulfonyldiallylammonium salts which are obtainable by

Charge control with cyclic polysulfonyldially ammonium salts

Ionic monomeric diallylammonium compounds having a targeted combination of diallylammonium cations with selected anions have particularly high and constant charge control properties and very good heat stabilities and dispersibilities. The compounds according to the invention are outstandingly suitable for use as colorless charge control agents in toners and developers for electrophotographic recording processes and for use as charge-improving agents in powders and paints for surface coating, in particular in triboelectrically or electrokinetically sprayed powder paints.

Growing community of inventors

Eppstein, Germany

Rudiger Baur