Coloured toner for electrostatic recording avoiding image density redn. - comprises positively chargeable cpd. fixed to particles of binder resins, colourant and charge controller for uniform charge e.g. for electrostatic or electrophotographic copiers

摘要

The toner (I) comprises (a) a positively chargeable cpd. (II) and (b) coloured particles (III) based on a binder resin (IV), a colourant (V) and a charge controller (VI). The 0.1-10.0 (wt.) % is fixed to the surface of (III). Pref. (II) comprises Al203 particles with a CO2 absorption of max. 4.0 mol/n3 and BET specific surface area of min. 80 m2/g, treated with a silane coupling agent (VII) pref. methyl trimethoxysilane (3-aminopropyl)tri(m)ethoxysilane, (3-(2-aminoethoxy amino)propyl tri(m)ethoxysilane or esp. dimethylsilicone (VIIA) and C8F17SO2NC2H5(CH2)3Si(OMe)3 (VIIB); or (II) comprises thermoplastic resin particles with an average size of 0.05-2.0 microns pref. with specific melt viscosity characteristics (3 x 10 power 5 Pa.s at 85 and 170 deg.C and 5 x 10 power 3 Pa.s at 120 and 205 deg.C). USE/ADVANTAGE - (I) is useful in electrostatic processes, e.g. electrophotography and electrostatic recording. It may give large numbers of copiers without the problem of uneven positive charging property, e.g. redn. in image density, rise in fog density and spraying.