Toner, developer, and image forming apparatus
A toner includes a base particle comprising a crystalline polyester resin; and an external additive which is a group of silica particles having a number-average particle diameter of from 0.01 μm to 0.11 μm on the surface of the toner. A number ratio of the silica particles having a circularity not less than 0.8 is 20% or more in the total number of the silica particles.
1. A toner, comprising:
a base particle comprising a crystalline polyester resin; and
an external additive which is a group of silica particles having a number-average particle diameter of from 0.01 μm to 0.11 μm on the surface of the toner,
wherein a number ratio of the silica particles having a circularity not less than 0.8 is from 20% to 49% in the total number of the silica particles.
2. The toner of claim 1 , wherein the toner has a glass transition temperature at a first temperature rising (Tg1st) of from 20° C. to 50° C. in differential scanning calorimetry (DSC), and wherein a storage modulus of a tetrahydrofuran-insoluble matter of the toner at 100° C. [G′ (100) (tetrahydrofuran-insoluble)] is from 1.0×10 5 Pa to 1.0×10 7 Pa, and a ratio [G′ (40) (tetrahydrofuran-insoluble)]/[G′ (100) (tetrahydrofuran-insoluble)] of a storage modulus of a tetrahydrofuran-insoluble matter of the toner at 40° C. [G′ (40) (tetrahydrofuran-insoluble)] to the tetrahydrofuran-insoluble matter of the toner at 100° C. [G′ (100) (tetrahydrofuran-insoluble)] is not greater than 3.5×10.
3. The toner of claim 1 , wherein the base particle comprises an amorphous polyester resin.
4. The toner of claim 3 , wherein the amorphous polyester resin comprises an amorphous resin having at least one of a urethane bond and a urea bond.
5. The toner of claim 3 , wherein the amorphous polyester resin comprises an amorphous resin having neither a urethane bond nor a urea bond.
6. A developer comprising the toner according to claim 1 .
7. The toner of claim 1 , wherein a number ratio of the silica particles having a circularity not less than 0.8 is from 20% to 42% in the total number of the silica particles.
8. The toner of claim 1 , wherein a number ratio of the silica particles having a circularity not less than 0.8 is from 20% to 41% in the total number of the silica particles.
9. The toner of claim 1 , wherein a number ratio of the silica particles having a circularity not less than 0.8 is from 20% to 40% in the total number of the silica particles.