GB1438110A - Developer powder composition - Google Patents

Abstract

1438110 Electrographic developer AGFA-GEVAERT 20 Sept 1973 [2 Oct 1972] 45376/72 Addition to 1359818 Heading G2H The developer comprises: carrier particles, toner particles, and 0.01-0.5 wt per cent of colloidal silica particles with respect to the weight of the toner particles; the toner particles having the composition of the toner material claimed in the parent Specification (see Division C3), i.e. a composition of which 5-15 wt per cent is a colouring material and 95-85 wt per cent is a resin mixture consisting of: (A) 40-60 wt per cent of a polymer comprising recurring units deriving from at least one styrene according to the formula: wherein: R is hydrogen or methyl, (B) 20-40 wt per cent of a polymer of the group consisting of homopolymers of butyl acrylate, homopolymers of butyl methacrylate, and copolymers of butyl acrylate or butyl methacrylate with methyl acrylate or methyl methacrylate containing up to 80 wt per cent of methyl acrylate or methacrylate, and (C) 5-20 wt per cent of a polymeric plasticizer of the group consisting of polyvinyl butyral, polyethylene and co (vinyl acetate/ethylene), the percentages of (A), (B) and (C) being calculated on the total weight of said resin mixture; the said particles having a diameter between 1 and 30 microns. The carrier particles may comprise resin coated or uncoated glass or steel beads.