Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Patent
1988-09-23
1991-02-26
McCamish, Marion C.
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Post imaging process, finishing, or perfecting composition...
430137, 430111, G03G 900, G03G 500
Patent
active
049961276
DESCRIPTION:
BRIEF SUMMARY
TECHNOLOGICAL FIELD
This invention relates to a toner for developing an electrostatically charged image in electrophotography, electrostatic recording, electrostatic printing, etc., and a process for its production.
BACKGROUND TECHNOLOGY
Toners generally used widely heretofore are produced by dry-blending a styrene/acrylate-type co-polymer powder obtained by suspension polymerization with a coloring agent such as carbon black and optionally a charge controlling agent and/or a magnetic material, melt-kneading the mixture by an extruder or the like, and then pulverizing and classifying the kneaded mixture (see Japanese Laid-Open Patent Publication No. 23354/1976).
With the conventional toners obtained by the above melt-kneading/pulverizing method, controlling of the particle diameter of the toners is limited, and it is substantially difficult to produce toners having an average particle diameter of not more than 10 microns, especially not more than 8 microns, above all not more than 5 microns, in good yields. Moreover, it is difficult to avoid the defect that developers prepared from the toners have a low resolution and poor chargeability and fogging occurs.
It has also been proposed to produce a toner by copolymerizing monomers in the presence of a coloring agent. The product, however, still has the defect that it has insufficient chargeability and fogging occurs.
OBJECT OF THE INVENTION
It is an object of this invention to greatly eliminate the above defects of toners heretofore used widely, and to provide a toner at a lower price than the conventional toners by using a novel process for production.
DISCLOSURE OF THE INVENTION
The toner for developing an electrostatically charged image in accordance with this invention is a toner for developing an electrostatically charged image, composed of associated particles of secondary particles comprising primary particles of a polymer having an acidic or basic polar group (to be referred to as the "polymer having a polar group"), preferably a polymer having an acidic polar group, and particles of a coloring agent and optionally a charge controlling agent.
The primary particles of the polymer having a polar group as used in this invention are particles of a thermoplastic polymer having an average particle diameter of 0.05 to 0.5 micron, preferably 0.1 to 0.3 micron, and are preferably obtained by an emulsion polymerization method in general. The secondary particles constituting the associated particles which are the toner of the invention are particles resulting from aggregation of primary particles of the coloring agent having an average particle diameter of 0.01 to 0.5, preferably 0.03 to 0.1 micrometer, and the primary particles of the polymer having a polar group by bonding forces such as forces of an ionic bonding, a hydrogen bonding, a metal coordination bonding and a weak-acid weak base bonding, or Van der Waals force. Generally, the seconday particles have an average particle diameter of 0.5 to 5 microns, preferably 1 to 4 microns. FIG. 1 is a scanning electron micrograph (magnification 1,000X) showing one example of secondary particles formed in the toner producing process in the present invention.
The associated particles are irregularly-shaped particles formed by aggregation of the secondary particles. The associated particles have an average particle diameter of generally 3 to 25 microns, preferably 5 to 15 microns, most preferably 5 to 13 microns. FIG. 2 is a scanning electron micrograph (magnification 1000X) showing one example of the associated particles which are the toner of the invention.
In a preferred embodiment of the invention, there are used associated particles in which the contacting portions among the secondary particles constituting the associated particles are at least partly, preferably mostly, melt-adhered by film formation. FIG. 3 is a scanning electron micrograph (magnification 1000X) of associated particles of this invention in which at least a part of the contacting portions among the secondary particles are melt-adhered b
REFERENCES:
patent: 4659506 (1987-04-01), Nakamura et al.
Hasegawa Yukinobu
Maruyama Masatoshi
Murai Koichi
Shimomura Hiroyoshi
Tange Toyokichi
Crossan Stephen C.
McCamish Marion C.
Nippon Carbide Kogyo Kabushiki Kaisha
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