Magnetic toner for developing electrostatic images, process for producing it, image forming method and process cartridge
US6238834A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 28, 1998 |
| Grant date | May 29, 2001 |
| Priority date | — |
| Expiry date | May 28, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03G9/09725
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A magnetic toner for developing an electrostatic image is comprised of magnetic toner particles containing at least a binder resin, a magnetic fine powder and a wax. The magnetic toner particles have a weight-average particle diameter of from 3.5 to 6.5 .mu.m, and a dispersion prepared by dispersing 15 mg of the magnetic toner particles in 19 ml of an aqueous solution of ethyl alcohol and water in a volume ratio of 27:73 has an absorbance of from 0.2 to 0.7 at a wavelength of 600 nm. A process for producig such a magnetic toner is charcterized by, especially, the melt-kneading step carried out under the following conditions: EQU 2.2.times.10.sup.3.ltoreq.E/.epsilon..ltoreq.2.0.times.10.sup.4 EQU E=k.omega..sup.2 T, .epsilon.=F/(.pi.D.sup.2 L) wherein .omega. represents a screw rotational speed (m/min), T represents a preset temperature (K), F represents a feed rate (kg/min) of a mixture of a binder resin, a magnetic fine powder and a wax, D represents a cylinder inner diameter (m), L represents a screw effective length (m), .pi. represents the circular constant, and k represents (D.sub.0 /D).sup.2, where D.sub.0 is 0.1 m.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.