Toner for developing electrostatic image, method of producing toner, cartridge, image forming method, and image forming apparatus

1. A toner for developing an electrostatic image, comprising:

colored particles containing a colorant and a binder resin, and

two or more kinds of inorganic particles that are externally added to a surface of the colored particles,

wherein

the two or more kinds of inorganic particles contain titanium-containing particles and silica-containing particles,

an exposure ratio of the surface of the colored particles is about 25% or less,

a coverage of the silica-containing particles on the colored particles is from 20% to 45%, wherein a coverage of the titanium-containing particles on the colored particles is from about 90% to about 135%, and

a ratio of the silica-containing particles that are in contact with the colored particles is about 10% by number or less.

2. The toner for developing an electrostatic image according to claim 1 , wherein a total of a coverage of the titanium-containing particles and a coverage of the silica-containing particles on the colored particles is about 150% or less.

3. The toner for developing an electrostatic image according to claim 1 , wherein the exposure ratio of the surface of the colored particles is about 2% or more.

4. The toner for developing an electrostatic image according to claim 1 , wherein the silica-containing particles have a volume average particle diameter of from about 5 nm to about 40 nm.

5. The toner for developing an electrostatic image according to claim 1 , wherein the titanium-containing particles have a volume average particle diameter of from about 8 nm to about 50 nm.

6. The toner for developing an electrostatic image according to claim 1 , wherein a ratio of coverage of the titanium-containing particles to the silica-containing particles is from about 1/1 to about 1/10 based on the addition amounts.

7. A method of producing the toner for developing an electrostatic image according to claim 1 , comprising:

preparing colored particles containing a colorant and a binder resin;

adding titanium-containing particles to the colored particles in an aqueous medium, through wet external addition to provide colored particles having the titanium-containing particles added; and

adding silica-containing particles to the colored particles having the titanium-containing particles added, through dry external addition.

8. The method of producing the toner for developing an electrostatic image according to claim 7 , wherein a total of a coverage of the titanium-containing particles and a coverage of the silica-containing particles on the colored particles is about 150% or less.

9. The method of producing the toner for developing an electrostatic image according to claim 7 , wherein the exposure ratio of the surface of the colored particles is about 2% or more.

10. An image forming method comprising:

forming an electrostatic latent image on a surface of an image holding member;

developing the electrostatic latent image formed on the surface of the image holding member, with a toner, to form a toner image;

transferring the toner image to a surface of a transfer medium; and

fixing the toner image transferred to the surface of the transfer medium,

wherein the toner is the toner for developing an electrostatic image according to claim 1 .

11. The image forming method according to claim 10 , wherein a total of a coverage of the titanium-containing particles and a coverage of the silica-containing particles on the colored particles is about 150% or less.

12. The toner for developing an electrostatic image according to claim 1 , wherein the ratio of the silica-containing particles that are in contact with the colored particles is from about 4% to about 10% by number.