| 摘要 |
PURPOSE:To prevent offset without coating an offset preventive liquid in a heat roller fixing system and to permit fixing at a power fixing temp. by using a specific polyester resin as an essential component for a binder resin. CONSTITUTION:The polyester resin obtd. by the co-condensation polymn. of A) a diol component expressed by the formula, B) divalent carboxylic acid or the acid anhydride thereof or the lower alkyl ester thereof, and C) trivalent or higher polyvalent carboxylic acid or the acid anhydride thereof or the lower alkyl ester thereof or trihydric or higher polyhydric alcohol is used as the essential component of the binder resin of a developer compsn. contg. the binder resin and coloring agent as well as other additives at need. The value of the hydroxyl value/acid value of the polyester resin is specified to >=1.2. The lowest fixing temp. is high and fluidity is poor if the value is <1.2. The binder resin is adjusted to have 106-160 deg.C softening point and 50-80 deg.C glass transition temp. in order to obtain a non-offset region, to obviate the increase in the lowest fixing temp. and to giving no ill effect on the shelf stability and fixability. |
