TONER POWDER CONTAINING AN EPOXY RESIN WITH EPOXY GROUPS MODIFIED BY REACTION WITH A MONOFUNCTIONAL CARBOXYLIC ACID AND/OR A MONOFUNCTIONAL PHENOL

摘要

ABSTRACT OF THE DISCLOSUREPositively chargeable toner powder comprising finely divided,coloured toner particles containing an insulating thermoplastic resin,colouring materials and a polarity control agent, the thermoplasticresin including at least 50% by weight of an epoxy resin having anepoxy molar mass of at least 10,000, said epoxy molar mass being achievedby modification of at least 5% of its epoxy groups with a monofunctionalcarboxylic acid and/or a monofunctional phenol which carry, except forthe carboxyl or hydroxyl group respectively, no substituents which arereactive towards the epoxy groups of the epoxy resin, under the conditionsof preparing the toner powder, and by modification of no more than 95%by intermolecular reaction or by cross-linking with the aid of a poly-functional epoxy hardener. The toner powder gives improved uniformchargeability, charge stability and permanence, reproducibility of thefusing properties, thermal stability and sensitivity to moisture.