Electrostatic image developing carrier, electrostatic image developer, process cartridge, image forming method and image forming apparatus
View Patent ↗An electrostatic image developing carrier includes a ferrite particle and a resin layer that coats the ferrite particle, wherein a magnesium element content of the ferrite particle is from about 3.0% by weight to about 20.0% by weight; wherein a manganese element content of the ferrite particle is from about 0.2% by weight to about 0.8% by weight; and wherein a content of toluene is more than about 100 ppm and not more than about 2,000 ppm.
1. An electrostatic image developer, comprising:
an electrostatic image developing carrier, comprising a ferrite particle, and a resin layer that coats the ferrite particle; and
an electrostatic image developing toner,
wherein:
an average value of the shape factor SF1 (average shape factor) of the electrostatic image developing toner is 115 to 130;
a magnesium element content of the ferrite particle is from about 3.0% by weight to about 20.0% by weight;
a manganese element content of the ferrite particle is from about 0.2% by weight to about 0.8% by weight; and
a content of toluene is more than about 100 ppm and not more than about 2,000 ppm.
2. The electrostatic image developer according to claim 1 , wherein the resin layer of the electrostatic image developing carrier comprises a resin and a content of the resin in the carrier is from about 0.2% by weight to about 5.0% by weight, based on the total weight of the carrier.
3. The electrostatic image developer according to claim 1 , wherein a volume average particle size of the ferrite particle of the electrostatic image developing carrier is from about 10 μm to about 500 μm.
4. The electrostatic image developer according to claim 1 , wherein the resin layer of the electrostatic image developing carrier comprises a conductive powder.
5. The electrostatic image developer according to claim 4 , wherein the conductive power is a carbon black particle.
6. The electrostatic image developer according to claim 5 , wherein the carbon black particle has a dibutyl phthalate (DBP) oil absorption of from about 50 mL/100 g to about 250 mL/100 g.
7. The electrostatic image developer according to claim 4 , wherein a volume average particle size of the conductive powder is from about 0.05 μm to about 0.5 μm.
8. The electrostatic image developer according to claim 4 , wherein a volume electric resistance of the conductive powder is from about 10 1 Ω·cm to about 10 11 Ω·cm.
9. The electrostatic image developer according to claim 4 , wherein a content of the conductive powder is from about 1% by volume to about 50% by volume, based on the whole of the resin layer.
10. The electrostatic image developer according to claim 1 , wherein the resin layer comprises a resin particle.
11. The electrostatic image developer according to claim 10 , wherein a volume average particle size of the resin particle is from about 0.1 μm to about 2.0 μm.
12. The electrostatic image developer according to claim 1 , having a volume average particle size of from about 10 μm to about 500 μm.
13. The electrostatic image developer according to claim 1 , wherein a volume average particle size of the electrostatic image developing toner is from about 2 μm to about 8 μm.
14. The electrostatic image developer according to claim 1 , wherein the electrostatic image developing toner comprises an inorganic oxide having a primary particle size of from about 7 nm to about 40 nm in terms of an average particle size.
15. The electrostatic image developer according to claim 14 , wherein the inorganic oxide is titanium oxide having a volume average particle size of from about 15 nm to about 40 nm.
16. The electrostatic image developer according to claim 1 , wherein the electrostatic image developing toner is an emulsion aggregation toner.
17. A process cartridge comprising:
a development unit that accommodates the electrostatic image developer according to claim 1 therein and develops an electrostatic latent image formed on a surface of an image holding member by the electrostatic image developer to form a toner image; and
at least one member selected from the group consisting of the image holding member; a charge unit that charges the surface of the image holding member; and a cleaning unit that removes the toner remaining on the surface of the image holding member.
18. 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 by a developer comprising a toner to form a toner image;
transferring the toner image formed on the surface of the image holding member onto a surface of a transfer-receiving material; and
fixing the toner image transferred onto the surface of the transfer-receiving material,
wherein the developer is the electrostatic image developer according to claim 1 .
19. An image forming apparatus comprising:
an image holding member;
a charge unit that charges the image holding member;
an exposure unit that exposes the charged image holding member to form an electrostatic latent image on a surface of the image holding member;
a development unit that develops the electrostatic latent image by a developer that comprises a toner to form a toner image;
a transfer unit that transfers the toner image onto a surface of a transfer-receiving material from the image holding member; and
a fixing unit that fixes the transferred toner image on the surface of the transfer-receiving material,
wherein the developer is the electrostatic image developer according to claim 1 .
20. The electrostatic image developer according to claim 1 , wherein the average value of the shape factor SF1 of the electrostatic image developing toner is about 120.
21. The electrostatic image developer according to claim 1 , wherein the magnesium element content of the ferrite particle is from about 3.0% by weight to about 8.0% by weight.