| 摘要 |
A positively chargeable heat- fixable toner powder suitable for use in a high volume copying apparatus with a contact fixing device comprises finely divided toner particles comprising a thermoplastic resin, colouring material and a charge regulator (which is other than an epoxy amine), the thermoplastic resin constituent being mainly composed of resin having an epoxy molar mass of approximately 2000 to 7500, the resin being either (i) a derivative of an epoxy resin having a molecular weight of at most approximately 1000 and an epoxy molar mass of at most approximately 700 in which approximately 25 to 95% of the epoxy groups have been blocked by reaction with a monofunctional carboxylic acid, phenol or diarylsulphonamide and approximately 5 to 75% have been blocked by intermolecular reaction with hydroxyl groups on the epoxy resin and/or by reaction with a bi- or poly-functional reagent; or (ii) a mixture comprising at least 20 parts by weight of a resin as defined under (i) and at most 80 parts by weight of a phenoxy resin or of a resin which is a derivative of an epoxy resin having a molecular weight of at least approximately 1500 and an epoxy molar mass of at least approximately 900 in which at least 5% of the epoxy groups have been blocked by intermolecular reaction and/or reaction with a bi- or polyfunctional reagent. p |
