Magnetic carrier particles
US5268249A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 29, 1992 |
| Grant date | Dec 7, 1993 |
| Priority date | — |
| Expiry date | Oct 29, 2012 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03G9/1085
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Carrier particles suitable for magnetic brush development comprising hard magnetic ferrite material having a single phase, W-type hexagonal crystalline structure represented by the formula MFe.sub.16 Me.sub.2 O.sub.27 where M is strontium or barium and Me is a divalent transition metal selected from the group consisting of nickel, cobalt, copper, zinc, manganese, magnesium, iron and mixtures thereof, exhibiting a coercivity of approximately 100 to 300 Oersteds when magnetically saturated and an induced magnetic moment of at least 60 EMU/g when in an applied magnetic field of 1000 Oersteds are disclosed. Also disclosed are electrostatic two-component dry developer compositions comprising charged toner particles mixed with oppositely charged carrier particles comprising the magnetically hard ferrite material described above and a method of developing an electrostatic charge pattern by contacting the charge pattern with a two-component dry developer composition described above. The carrier particles provide high development efficiencies and improved image density.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.