Toner for development of electrostatic image and production process thereof
AssigneeNippon Zeon Co., Ltd.
InventorsKazuhiro Sato, Takeo Fujino
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Abstract
A toner for development of electrostatic images which has a residual polymerizable monomer content lower than 70 ppm and is substantially spherical as demonstrated by the flowability of at least 55%, and a process for producing a toner reduced in residual polymerizable monomer content by subjecting a slurry containing polymer particles obtained by polymerization to a stripping treatment under reduced pressure.
Claims22
A toner for development of electrostatic images, comprising at least a binder resin and a colorant, wherein
- (A) the content of residual polymerizable monomers in the toner is lower than 70 ppm,
- (B) the toner is substantially spherical wherein the spheroidicity of the toner is 1.0 to 1.3, and
- (C) the flowability of the toner is at least 55%.
A process for producing a toner for development of electrostatic images, comprising the step of subjecting a polymerizable monomer composition containing at least a colorant and a polymerizable monomer to suspension polymerization in an aqueous dispersion medium containing a dispersion stabilizer, the process comprising the steps of:
- (1) forming polymer particles by suspension polymerization, thereby obtaining a slurry containing the polymer particles,
- (2) subjecting the slurry to a stripping treatment under conditions of reduced pressure to distill off volatile components including the aqueous dispersion medium and the polymerizable monomer, and
- (3) recovering the polymer particles from the remaining slurry,
- wherein in the recovery step (3), polymer particles, which have a residual polymerizable monomer content lower than 70 ppm and flowability of at least 55% and which are substantially spherical, wherein the spheroidicity of the particles is 1.0 to 1.3, are recovered after dewatering, washing and driving.
Dependencies are inferred from the claim text.