Patent ID: 6025107
Filing Date: 2000-02-15
Classification: G03G

Abstract:
A negatively chargeable toner for developing electrostatic latent images comprising:negatively chargeable toner particles including a binder resin having an acid value of 5 to 50 KOHmg/g, a colorant, and a boron compound represented by a structural formula (A); ##STR4## wherein R.sub.1 and R.sub.3 respectively represent substituted or non-substituted aryl group, R.sub.2 and R.sub.4 respectively represent hydrogen atom, alkyl group, substituted or non-substituted aryl group, X represents a cation, and n is an integer of either 1 or 2; andexterior additive particles adhered to the surface of the toner particle, said exterior additive particles comprising hydrophobic silica particles having a specific surface area of 100 to 250 m.sup.2 /g and metal titanate particles having a specific surface area of 3 to 15 m.sup.2 /g, wherein the additive weight ratio of said hydrophobic silica particles and metal titanate particles is within a range of 5:1 to 1:1.2, a total specific surface area S of the exterior additive particles is 40 to 120 expressed by the equation (1):S=Ss.times.Vs+St.times.Vt (1)wherein Ss is the specific surface area of the hydrophobic silica particles (m.sup.2 /g) , Vs is an additive amount of hydrophobic silica particles relative to the toner particles (percent-by-weight), St is the specific surface area of the metal titanate particles (m.sup.2 /g), and Vt is an additive amount of metal titanate particles relative to the toner particles (percent-by-weight).