Toner, image forming apparatus, image forming method, and process cartridge
A toner including toner base particles each including a binder resin and a colorant, and external additive, wherein the toner satisfies conditions (a), (b), and (c) below: (a) storage elastic modulus G′(50) of the toner at 50° C. and storage elastic modulus G′(90) of the toner at 90° C. satisfy Formula (1); G ′(50)/ G ′(90)≥6.0×10 2 Formula (1) (b) a BET specific surface area Bt(m 2 /g) of the toner and a coverage Ct (%) of the toner base particles covered with the external additive satisfy Formula (2); and Bt −0.03× Ct ≤1.60 Formula (2) (c) the external additive includes at least cohered particles, the cohered particles are non-spherical secondary particles each formed through cohesion of primary particles, and a number average secondary particle diameter of the cohered particles is 130 nm or greater.
1. A toner comprising:
toner base particles each including a binder resin and a colorant; and
external additive;
wherein the toner satisfies conditions (a), (b), and (c) below:
(a) storage elastic modulus G′(50) of the toner at 50° C. and storage elastic modulus G′(90) of the toner at 90° C. satisfy Formula (1):
G ′(50)/ G ′(90)≥6.0×10 2 Formula (1)
(b) a BET specific surface area Bt(m 2 /g) of the toner and a coverage Ct (%) of the toner base particles covered with the external additive satisfy Formula (2):
Bt− 0.03× Ct≤ 1.60 Formula (2)
(c) the external additive includes at least cohered particles,
the cohered particles are non-spherical secondary particles each formed through cohesion of primary particles, and
a number average secondary particle diameter of the cohered particles is 130 nm or greater.
2. The toner according to claim 1 ,
wherein an amount B (% by mass) of the external additive liberated from the toner satisfies Formula (4),
B> 0.8 Formula (4)
where the amount B of the liberated external additive is an amount of the external additive liberated from the toner when 3.75 g of the toner is dispersed in 50 mL of a 0.5% by mass polyoxyalkylene alkyl ether dispersion liquid in a 110 mL vial and applying ultrasonic wave vibrations for 1 minute at 20 kHz and 750 W.
3. An image forming apparatus comprising:
an electrostatic latent image bearing member;
an electrostatic latent image forming unit configured to form an electrostatic latent image on the electrostatic latent image bearing member;
a developing unit configured to develop the electrostatic latent image formed on the electrostatic latent image bearing member with a toner to form a toner image, where the developing unit stores therein the toner;
a transferring unit configured to transfer the toner image formed on the electrostatic latent image bearing member to a surface of a recording medium; and
a fixing unit configured to fix the toner image transferred onto the recording medium,
wherein the toner is the toner according to claim 1 .
4. The image forming apparatus according to claim 3 , further comprising a cleaning unit configured to remove the toner remained on the electrostatic latent image bearing member.
5. An image forming method comprising:
forming an electrostatic latent image on an electrostatic latent image bearing member;
developing the electrostatic latent image formed on the electrostatic latent image bearing member with a toner to form a toner image;
transferring the toner image formed on the electrostatic latent image bearing member to a surface of a recording medium; and
fixing the toner image transferred onto the surface of the recording medium,
wherein the toner is the toner according to claim 1 .
6. A process cartridge comprising:
an electrostatic latent image bearing member; and
a developing unit configured to develop an electrostatic latent image formed on the electrostatic latent image bearing member with the toner according to claim 1 to form a toner image, where the developing unit stores therein the toner.