Toner, method for preparing the toner, and image forming method using the toner
The toner includes a binder resin; a colorant; and a release agent. The first inter-particle force Fp(A) of the toner, which is measured under an environmental condition of 23° C. and 60% RH after the toner is pressed for 1 minute at 25° C. under a compression stress of 15 kg/cm 2 , is from 1.0×10 −9 (N) to 1.0×10 −6 (N). The difference (Fp(B)−Fp(A)) between the second inter-particle force Fp(B) of the toner, which is measured under the environmental condition of 23° C. and 60% RH after the toner is pressed for 1 minute at 50° C. under a compression stress of 15 kg/cm 2 , and the first inter-particle force Fp(A) is 0 (N) to 1.0×10 −7 (N).
1. A toner comprising:
a binder resin;
a colorant; and
a release agent,
wherein the toner satisfies the following relationships (1) and (2):
1.0×10 −9 ( N )≦ Fp ( A )<1.0×10 −6 ( N ) (1)
0( N )< Fp ( B )− Fp ( A )≦1.0×10 −7 ( N ) (2)
wherein
Fp(A) represents a first inter-particle force of the toner, which is measured under an environmental condition of 23° C. and 60% RH after the toner is pressed for 1 minute at 25° C. under a compression stress of 15 kg/cm 2 , and
Fp(B) represents a second inter-particle force of the toner, which is measured under the environmental condition of 23° C. and 60% RH after the toner is pressed for 1 minute at 50° C. under a compression stress of 15 kg/cm 2 .
2. The toner according to claim 1 , further comprising:
a modified layered inorganic material in which at least part of metal cations is replaced with an organic cation.
3. The toner according to claim 1 , further comprising:
a particulate inorganic material having a BET specific surface area of from 50 m 2 /g to 400 m 2 /g.
4. The toner according to claim 1 , wherein the toner has an average circularity of from 0.94 to 0.99.
5. The toner according to claim 1 , wherein the toner has a volume average particle diameter (Dv) of from 3 μm to 8 μm, and a ratio (Dv/Dn) of the volume average particle diameter (Dv) of the toner to a number average particle diameter (Dn) of the toner is from 1.00 to 1.30.
6. The toner according to claim 1 , wherein the toner includes particles having a particle diameter of not greater than 2 μm in an amount of from 1% by number to 10% by number.
7. A method for preparing the toner according to claim 1 , comprising:
dissolving or dispersing toner constituents including at least a polyester resin serving as the binder resin, the colorant and the release agent in an organic solvent to prepare a first liquid;
mixing an anionic surfactant, and a particulate anionic resin, which has a volume average particle diameter of from 5 nm to 50 nm, with an aqueous medium to prepare an aqueous liquid;
emulsifying the first liquid in the aqueous liquid to prepare a second liquid;
adding a particulate resin having a volume average particle diameter of from 50 nm to 500 nm to the aqueous liquid or the second liquid; and
then removing the organic solvent from the second liquid.
8. The method according to claim 7 , wherein the polyester resin includes a polyester prepolymer having a functional group capable of reacting with an active hydrogen atom, and wherein the method further comprising:
adding a compound having an active hydrogen atom to the first liquid, the aqueous liquid or the second liquid; and
reacting the polyester prepolymer with the compound having a hydrogen atom in the second liquid.
9. The method according to claim 7 , wherein the toner constituents further include:
a modified layered inorganic material in which at least part of metal cations is replaced with an organic cation, and
wherein the first liquid has a Casson yield value of from 1 Pa to 100 Pa at 25° C.
10. The method according to claim 9 , wherein the modified layered inorganic material is included in the first liquid in an amount of from 0.05% by weight to 10% by weight based on solid components included in the first liquid.
11. An image forming method comprising:
forming an electrostatic latent image on an image bearing member;
developing the electrostatic latent image with a developer including the toner according to claim 1 to prepare a toner image on the image bearing member;
transferring the toner image onto a receiving material; and
fixing the toner image to the receiving material.
12. The toner according to claim 1 , wherein 0 (N)≦Fp(B)−Fp(A)≦1.0×10 −8 (N).
13. The toner according to claim 1 , wherein Fp(B)−Fp(A) is 0 (N).
14. The toner according to claim 1 , wherein the binder resin comprises a polyester resin.
15. The toner according to claim 1 , wherein the binder resin comprises a urea-modified polyester resin and an unmodified polyester resin.
16. The toner according to claim 1 , wherein the binder resin has a glass transition temperature of from 30 to 70° C.
17. The toner according to claim 1 , which further comprises a release agent.