(19) |
 |
|
(11) |
EP 0 306 330 A3 |
(12) |
EUROPEAN PATENT APPLICATION |
(88) |
Date of publication A3: |
|
09.08.1989 Bulletin 1989/32 |
(43) |
Date of publication A2: |
|
08.03.1989 Bulletin 1989/10 |
(22) |
Date of filing: 02.09.1988 |
|
(51) |
International Patent Classification (IPC)4: G03G 9/08 |
|
(84) |
Designated Contracting States: |
|
DE FR GB |
(30) |
Priority: |
02.09.1987 JP 221126/87
|
(71) |
Applicant: SOKEN CHEMICAL & ENGINEERING CO. LTD., |
|
Toshima-ku,
Tokyo 171 (JP) |
|
(72) |
Inventors: |
|
- Imai, Tatsuhiro
c/o Soken Chemical &
Sayami-shi
Saitama (JP)
- Kawase, Susumu
c/o Soken Chemical &
Sayami-shi
Saitama (JP)
|
(74) |
Representative: Pett, Christopher Phineas et al |
|
Frank B. Dehn & Co.,
European Patent Attorneys,
179 Queen Victoria Street London EC4V 4EL London EC4V 4EL (GB) |
|
|
|
(54) |
Toner and process for preparation thereof |
(57) Toner particles are described, each particle comprising a spheroidal resin core,
a pigment layer on the surface of said core and a layer of a static electrification
controlled resin on the surface of said pigment layer. The state of static electrification
of the toner is substantially determined by that of the outermost layer of the static
electrification controlled resin, and thus can be precisely controlled by simply
controlling the amount of static electrification of the resin particles used to form
the outermost layer. Since the state of static electrification of the toner can be
precisely controlled, the kind and concentration of the pigment used can be freely
selected. The presence of the outermost layer 3 prevents the pigment from breaking
away from the toner. Further, it is possible to improve the fluidity and anti-block
properties of the toner without any adverse effect. In addition, it is not necessary
to use an additional static electrification controlling agent such as silica which
might adversely affect the color shade of the toner.
