Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Process of making developer composition
Reexamination Certificate
2000-10-06
2003-07-01
Rodee, Christopher (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Process of making developer composition
C430S137180, C430S110400, C241S019000, C241S023000, C241S029000
Reexamination Certificate
active
06586151
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to toner to be used in an image forming method such as an electrophotographic method, an electrostatic recording method, an electrostatic printing method, or a recording method of toner jet system, and to an image forming method as well as an apparatus unit using the above described toner, and the present invention relates to a toner manufacturing method to efficiently proceed with grinding and classification of toner with small particle size having bonding resin and to obtain toner having sharp particle density distribution efficiently.
2. Related Background Art
As electrophotographic method, a number of methods such as those described in U.S. Pat. No. 2,297,691 specification, Japanese Patent Publication No. 42-23910 specification and Japanese Patent Publication No. 42-24748 specification are known. In general, the above described method utilizes photoconductive substance to form electrostatic charge latent image onto a photosensitive body with a variety of means, and subsequently to develop the latent image with toner, to transfer a toner image onto a transferring material such as sheet paper in accordance with necessity, and afterward to undergo fixing by means of heating, pressing, heat-pressing or solvent steam so as to obtain a toner image.
In recently years, complying with multifunctionization of photocopiers and printers, high-fidelity of copied image, and moreover, high speeding, performance required to toner becomes severer and for instance a particle size of toner is micronized into a micro particle and as particle density distribution the one that does not contain coarse particles but provides with sharpness with less supermicro powders is required.
Among the above described steps, in the case of having transferred an toner image onto a transferring At material from the photosensitive body, there exists residual toner subject to transferring on the photosensitive body.
In order that continuous copying is implemented swiftly, the residual toner on this photosensitive body needs to be cleaned off. Moreover, the recovered residual toner is putted into a container installed inside the main body or into-a collection box, and afterwards is abandoned or is returned to a developing container again and used in a developing step for recycling.
As approach to ecological issues, a design on the main body in which a recycling system is installed inside the main body as waste tonerless system will be necessary.
However, in order to attain multifunctionization of photocopiers and printers, high-fidelity of copied image, and moreover, high speeding, a recycling system on a fairly large scale gets necessary inside a main body, resulting in that an image forming apparatus itself such as a photocopier as well as a printer will get large and will not cope with miniaturization from a point of view of space saving. Moreover, there are no differences in a system in which waste toner is contained in a container installed inside a main body or in a recovery box and a system in which a photosensitive body and the above described waste toner collecting portion are integrated.
In order to comply with them, it is necessary to improve a transferring ratio at the time when a toner image is transferred onto a transferring material from the photosensitive body so that the waste toner is reduced.
In Japanese Patent Application Laid-Open No. 9-26672 specification, such a method is disclosed for improving transferring efficiency by including a transferring efficiency improver having a mean particle size of 0.1 to 3 &mgr;m and hydrophobic silica micro powder in toner so that toner volumetric resistant is reduced and the transferring efficiency improver forms a thin film layer on a photosensitive body. However, because of particle density distribution in the toner manufactured by grinding method it is difficult to attain a uniform effect for all particles, and further improvement is needed.
As a method to improve transferring efficiency by providing spherical shape of toner particles, toner by means of manufacturing methods such as spray granulation method, solution dissolution method, polymerization method are disclosed in Japanese Patent Application Laid-Open No. 3-84558 specification, Japanese Patent Application Laid-Open No. 3-229268 specification, Japanese Patent Application Laid-Open No. 4-1766 specification, and Japanese Patent Application Laid-Open No. 4-102862 specification. However, these toner manufacturing methods not only require equipment on a fairly large scale, but also give rise to such a problem that toner particles, which have weak spherical shape, manage to pass through during a cleaning step, and therefore cannot be regarded as preferable method in the case where only transferability improvement is pursued.
As manufacturing means in general, binding resin for fixing it onto a material to be transferred to, various kinds of coloring agent for creating color taste of toner, and electrical charge control agent for giving particles charge are used as raw material, and in so-called mono-component developing as shown in Japanese Patent Application Laid-Open No. 54-42141 Specification and Japanese Patent Application Laid-Open No. 55-18656 Specification, in addition thereto various magnetic materials are used for giving toner itself carrying capacity, and moreover, if necessary, another additives, for example, mold release agent and flowability giving agent and the like are added and dry mixed, and then, there material are melt kneaded with a kneading apparatus for general use such as a roll mill and an extruder cooled and solidified, and thereafter the kneaded product is grinded with various grinding apparatus such as a jet stream mill and a mechanical impact mill or the like, and the obtained coarse ground product is introduced into various wind force classifiers for classification, thereby classified product falling within a particle size necessary as toner is obtained, and moreover, when as necessary, streamer or sliding agent, etc. is added from outside for dry mixing to get toner to be served for image forming. In the case of toner to be used for two component development, every kind of magnetic carrier is mixed with the above described toner, and thereafter is served for image forming.
As described above, in order to obtain toner particles being micro particles, a method shown in a flow chart in
FIG. 10
is generally adopted.
While toner coarse ground product is continuously or successively supplied to first dispersion means, coarse powder comprising a group of coarse particles as main component not smaller than dispersed regular grain size is conveyed to grinding means to undergo grinding and thereafter is circulated back to the first classification means again.
Toner pulverized product with particles within another regular grain size and particles not larger than regular grain size as main component is conveyed to second classification means and undergoes classification into medium size powder with a group of particles of regular grain size as main component and into fine powder with a group of particles not larger than the regular grain size as main component. However, the toner undergoing processing into micro particles intensifies electrostatic aggregation among particles, and since the toner that originally should have been conveyed to the second classification means is circulated to the first classification means again, fine powder as well as superfine powder having undergone over-grinding is brought about.
As grinding means, a variety of grinding apparatuses are used, but for grinding of toner coarse ground product with a binding resin as main substance, a jet stream mill using jet stream, in particular an impact airflow mill shown in
FIG. 13
is used.
An impact airflow mill shown using highly-pressured gas such as jet stream conveys a powder raw material with a jet stream, spray it from an outlet port of an acceleration duct so that the powder raw material is made to crash onto a crashing
Azuma Masami
Dojo Tadashi
Hasegawa Yusuke
Kasuya Takashige
Matsunaga Satoshi
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Rodee Christopher
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