Patent ID: 8642239

Claim:
A toner for developing an electrostatic charge image comprising: a core layer including a first binder resin, a colorant and a releasing agent; and a shell layer coating the core layer and including a second binder resin, wherein the first binder resin of the core layer comprises a low molecular weight amorphous polyester resin having a weight-average molecular weight of about 6000 g/mol to about 20000 g/mol, a high molecular weight amorphous polyester resin having a weight-average molecular weight of about 25000 g/mol to about 100000 g/mol, and a crystalline polyester resin having a weight-average molecular weight of about 8000 g/mol to about 30000 g/mol, the second binder resin of the shell layer comprises the low and high molecular weight amorphous polyester resins, and the toner exhibits a rheological behavior satisfying the following equations (1), (2) and (3) according to a temperature change: 0.01 <Sκ <0.04,0.05 <Sλ< 0.2, and 2 <Sλ/Sκ <20, (1) where, Sκ=[log G′(40° C.)−log G′(50° C.)]/10 and Sλ=[log G′(50° C.)−log G′(60° C.)]/10, 0.1 <Sσ< 0.2 and 0.06 <Sτ <0.1, (2) where, Sσ=[log G′(60° C.)−log G′(70° C.)]/10 and Sτ=[log G′(70° C.)−log G′(80° C.)]/10, and 70° C.<Tp<80° C.,1×10 5 Pa< G′p< 5×10 5 Pa, (3) where, Tp denotes a temperature satisfying a condition (a p condition) of Sσ/Sτ>1, G′p denotes a shear storage modulus at a temperature satisfying the p condition, and G′(temperature) denotes a shear storage modulus (unit: Pa) measured under conditions including a measurement frequency of about 6.28 rad/s, a heating rate of about 2.0° C./min, an initial strain of about 0.3% and an indicated temperature; wherein the binder resins have a mixing ratio satisfying a condition of the following equation (4); 1<[α L ]/[α H ]<4 and 2<([α L ]+[α H ])/[β]<30 (4) where, [α L ] and [α] H denote weights of the high molecular weight amorphous polyester resin and the low molecular weight amorphous polyester resin in the toner, respectively, [β] denotes a weight of the crystalline polyester resin in the toner.