Toner for developing electrostatic charge image, and apparatus and method for forming image using the same

A method for forming an image, the method comprising:

• attaching a toner to an electrostatic latent image formed on a photoreceptor to form a visible image;
• and
• transferring the visible image to a transfer member,
• wherein the toner comprises:
• a toner particle comprising a binder resin, a colorant, and a releasing agent;
• and
• an external additive disposed on the surface of the toner particle, the external additive comprising:
• sol-gel silica particles having an average sphericity value in a range of from about 0.8 to about 0.97, a Braunauer-Emmett-Teller (BET) specific surface area of about 30 m2/g to about 70 m2/g, and an average primary particle diameter in a range of from about 10 nm to less than 80 nm, wherein the sphericity value is a ratio between a shortest diameter and a longest diameter of each of the sol-gel particles and a ratio of the number of sol-gel silica particles having a sphericity value of less than about 0.97 to the total number of the sol-gel silica particles is at least about 50%;
• hydrophobically surface-treated fumed silica particles having average primary particle diameters in a range of from about 7 nm to about 50 nm;
• and
• hydrophobically surface-treated titanium dioxide particles having average primary particle diameters in a range of from about 10 nm to about 50 nm,
• wherein a (D84v/D16v)1/2 value of the sol-gel silica particles is in a range of from about 1.7 to about 2.3,
• in which D16v is a particle diameter at which a cumulative percentage of 16% is attained, and D84v is a particle diameter at which a cumulative percentage of 84% is attained, in a cumulative volume distribution of the sol-gel silica particles as measured by the Coulter method.

A toner for developing an electrostatic charge image, the toner comprising:

• a toner particle;
• sol-gel silica particles disposed on the toner particle and having an average sphericity value in a range of from about 0.8 to about 0.97, a Braunauer-Emmett-Teller (BET) specific surface area of about 30 m2/g to about 70 m2/g, and an average primary particle diameter in a range of from about 10 nm to less than 80 nm, wherein the sphericity value is a ratio between a shortest diameter and a longest diameter of each of the sol-gel particles and a ratio of the number of sol-gel silica particles having a sphericity value of less than about 0.97 to the total number of the sol-gel silica particles is at least about 50%;
• hydrophobically surface-treated fumed silica particles having average primary particle diameters in a range of from about 7 nm to about 50 nm disposed on the toner particle and in gaps between the sol-gel particles;
• and
• hydrophobically surface-treated titanium dioxide particles having average primary particle diameters in a range of from about 10 nm to about 50 nm disposed on the toner particle,
• wherein a (D84v/D16v)1/2 value of the sol-gel silica particles is in a range of from about 1.7 to about 2.3,
• in which D16v is a particle diameter at which a cumulative percentage of 16% is attained, and D84v is a particle diameter at which a cumulative percentage of 84% is attained,
• in a cumulative volume distribution of the sol-gel silica particles as measured by the Coulter method.