| 摘要 |
PURPOSE:To improve fixability and offset preventiveness by forming the developer of a positive chargeable toner which contains a specific polyester resin, etc., and a carrier which is formed by coating a core material with a resin and has a specific average grain size. CONSTITUTION:The polyester resin usable as a binder is basically constituted of polyvalent carboxylic acid or polyvalent carboxylate and polyhydric alcohol component. The polyester resin which has the glass transition point within a 50 to 70 deg.C range, the softening temp. within an 80 to 140 deg.C range, <=20mgKOH /g hydroxyl value, and <=1.7mgKOH/g acid value is incorporated into the binder. The developer is formed of the positive chargeable toner which contains this polyester resin, a colorless quaternary ammonium salt as a positive charge control agent and fine powder of positive chargeable silica and the carrier which is formed by coating the core material with the resin and has 50 to 300mum average grain size. The developer having the excellent fixability and offset preventiveness is obtd. in this way. |
