Patent ID: 6969574

Claim:
A method of preparing a toner, comprising: mixing toner particles, each comprising a black metal oxide colorant having a number average particle diameter d of 0.02Ã—10 âˆ’6 to 0.100Ã—10 âˆ’6 in m and a binder resin, with fine metal oxide powder using a Henschel mixer for a period of time of T in seconds, said mixer comprising an inside wall defining a mixing chamber, and a rotating blade having a tip portion and being disposed in said mixing chamber so that a clearance C in m is defined between said tip portion and said inside wall, said mixer being operated so that said tip portion of said rotating blade moves at a peripheral speed of V in m/sec, wherein said number average particle diameter d, clearance C, peripheral speed V and mixing time T satisfy the following condition: ( CÃ—d )/( VÃ—T )â‰¦5Ã—10 âˆ’13 ; and wherein said black colorant comprises said metal oxide in an amount of 10 to 40% by weight based on a total weight of said toner particles.