(19)
(11) EP 1 424 606 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
19.01.2005 Bulletin 2005/03

(43) Date of publication A2:
02.06.2004 Bulletin 2004/23

(21) Application number: 03026952.6

(22) Date of filing: 25.11.2003
(51) International Patent Classification (IPC)7: G03G 9/087, G03G 9/08
(84) Designated Contracting States:
AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IT LI LU MC NL PT RO SE SI SK TR
Designated Extension States:
AL LT LV MK

(30) Priority: 28.11.2002 JP 2002345636
09.10.2003 JP 2003350356

(71) Applicant: Fuji Electric Imaging Device Co., Ltd.
Matsumoto-shi, Nagano 390-0821 (JP)

(72) Inventors:
  • Sawada, Manabu
    4-18-1 Tsukama Matsumoto Nagano 390-0821 (JP)
  • Yamaguchi, Kei
    4-18-1 Tsukama Matsumoto Nagano 390-0821 (JP)
  • Nishimaki, Shinichiro
    4-18-1 Tsukama Matsumoto Nagano 390-0821 (JP)
  • Emori, Hiroshi
    4-18-1 Tsukama Matsumoto Nagano 390-0821 (JP)

(74) Representative: Liesegang, Roland, Dr.-Ing. 
FORRESTER & BOEHMERT Pettenkoferstrasse 20-22
80336 München
80336 München (DE)

   


(54) Electrophotographic positively charged toner and manufacturing method thereof


(57) [Problem] To provide an electrophotographic positively charged toner and a manufacturing method thereof, according to which even if after kneading, pulverization and classification the toner is made spherical by melting the surfaces of the particles in a hot air current, the charge control agent is not coated and hence the charging ability thereof is not reduced, and thus the toner has sufficient tribo-charging ability for good image formation, excellent transfer efficiency, and excellent charge build-up performance and excellent charge stability upon continuous printing.
[Means of Solution] In the case of an electrophotographic positively charged toner comprising a core toner that has a binder resin, a wax, a colorant and a charge control agent as principal component materials thereof and has been spherified through heat treatment, and at least fine silica particles as an external additive, the charge control agent is made to contain a resin having a quaternary ammonium salt group as a functional group and a nigrosine dye.






Search report