Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Reexamination Certificate
2002-09-27
2004-07-20
Dote, Janis L. (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Post imaging process, finishing, or perfecting composition...
C430S110400, C430S111410, C430S122520
Reexamination Certificate
active
06764798
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a two-component developer used for the development of a latent image formed in electrophotography, electrostatic recording method, electrostatic printing method or the like.
2. Discussion of the Related Art
During durablity printing in a high-speed machine or durability printing in a low toner-consumptive mode, such as a long-term printing of fixed images in a low printing ratio, fixed images are likely to be deteriorated due to a decrease in image density and the like with the embedment of silica. Therefore, there has been proposed to use a toner in which an external additive having a large particle size is used (Japanese Patent Laid-Open No. Hei 6-332253), or to use a carrier having a low saturation magnetization. However, the decrease in image density, the background fogging, the toner scattering, the carrier sticking on photoconductor and the like may be caused.
An object of the present invention is to provide a two-component developer which can continuously give high-quality images, even in a high-speed machine, without causing the embedment of silica and the carrier sticking on photoconductor.
SUMMARY OF THE INVENTION
The present invention relates to a two-component developer comprising:
a toner onto which a hydrophobic silica having an average particle size of 25 nm or more is externally added, and
a carrier having a saturation magnetization of from 50 to 95 Am
2
/kg, wherein the carrier has a ratio of surface resistivity to volume resistivity of from 1×10
2
to 1×10
4
m
−1
at an electric field strength of 100 V/cm.
REFERENCES:
patent: 6214507 (2001-04-01), Sokol et al.
patent: 6294304 (2001-09-01), Sukovich et al.
patent: 62-042163 (1987-02-01), None
patent: 04-66958 (1992-03-01), None
Patent Abstracts of Japan English-Language Abstract Describing JP 62-042163, Copyright 1998, 2003.*
Patent Abstracts of Japan English-Language Abstract Describing JP 04-66958, Copyright 1998, 2003.*
Micro-PatentEnglish Abstract Describing JP-6-332253, 2002.
Akiyama Koji
Kameyama Koji
Yamazaki Masahito
Birch Stewart Kolasch & Birch
Dote Janis L.
Kao Corporation
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