Novel Hydrazone Based Hole Transport Materials for Electrophotography

Abstract

Monomeric, dimeric and polymeric hydrazone based hole transporting materials (TM) with the following structures were developed and evaluated for electrophotography.The general synthesis for all of these derivatives involves the reaction of the suitable aldehydes, having heterocyclic or aromatic chromophores (Ar), with the phenylhydrazine, followed by the reaction with epichlorohydrin. The dimeric and polymeric structures require an additional reaction step involving structures a-e (denoted as X above) to bind the hydrazone units into the dimeric structure or polymeric chain. The final products were purified several times and their structures were confirmed by H-NMR, C-NMR, and UV and IR spectra. The ionization potential (Ip) and hole mobility (using xerographic time of flight technique) were measured for all the compounds. The presence of oxiranyl or hydroxyl groups improves adhesion and compatibility not only with traditional polycarbonate (PC) binder material but also with polyvinylbutyral (PVB). Meanwhile, such dimeric or polymeric hole TM can be chemically cross-linked in the layer, for example, by reaction of the hydroxyl groups with polyisocyanates. Monomers with two oxiranyl groups can be cross-linked with polythiols. These TM properties increase the layer stability to bending, stretching and abrasion, as well as the effects of abrasion. The synthesized TM and compositions with binder exhibit good hole transporting properties and high mobility making them useful for preparation of high sensitivity electro-photographic photoconductors. They also can be used for preparation of bipolar transporting compositions and single layer photoreceptors.