Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Reexamination Certificate
2002-03-15
2004-01-13
Goodrow, John (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Post imaging process, finishing, or perfecting composition...
C430S110100
Reexamination Certificate
active
06677097
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a toner for developing a static image to be used for a copying machine or a printer, a method producing the toner, and an image forming method using the toner.
BACKGROUND OF THE INVENTION
Recently, a digital image formation system become to the main current in image forming method by electron-microscopic photography. The image forming method by the digital system is based on the technique to make appear a small dot image of pixel having a size such as 1200 dpi, number of dot per inch, so a high quality image technique to reproduce the small dot with a high fidelity is required. The minimization of the toner particle diameter is proceeded from such the viewpoint.
A polymerized toner produced by a suspension polymerization or an emulsion polymerization has been noticed as a means for making small the toner particle diameter and for unifying the size distribution and the shape of the toner particles. Japanese Patent Publication Open to Public Inspection, hereinafter referred to as JP O.P.I., No. 2000-214629 discloses that the toner produced by the polymerization method can be controlled in the shape, roundness and the size distribution thereof.
A heat-roller fixing method is widely applied as a method for fixing a toner image formed on an image forming support such a sheet of paper by which the image forming support on which a toner image is formed is passed between a heating roller and a pressure roller to fix the toner image. The heat-roller method has a drawback such that an image contamination tends to be occurred by an off-set phenomenon which is caused by adhesion of the melted toner onto the heating roller.
It has been known as a means for prevent the occurrence of the off-set phenomenon that the heating roller of the fixing device is coated with silicone oil to give a mold-releasing ability to the roller. This method is advantageous since there is no limitation on the kind of the toner. However, the method is not suitable for business use because writing by a ball-point pen on the support paper is made difficult by adhesion of the silicone oil on the paper. In the market, the copied document is directly used as a business document and the writing on the document is usually required. Accordingly, the method of silicone coating is becoming one not satisfying the requirement at the present time.
For responding to such the requirement, a technique is applied by which a mold-releasing agent such as a wax is added into the toner itself for providing the mold-releasing ability. JP O.P.I. No. 3-296067 discloses a toner in which polypropylene as the mold-releasing agent is dispersed in the binder polymer to form a domain-matrix structure at the cross section of the toner, and the largest length of the domain of the polypropylene in the major axis direction and the average distance of the space between the domains are specified. JP O.P.I. No. 10-161338 discloses one having the domain-matrix structure in which the domain diameter of the mold-releasing agent before the heat fixation is specified and the domain-matrix structure is disappeared after the fixation.
However, a cleaning mechanism is necessary even when the mold-releasing agent is introduced in the reason of that an off-set phenomenon so called as a invisible off-set is caused by accumulation of the toner onto the fixing roller after a lot of image forming operations such as a number of ten thousands to twenty thousands even though the off-set is not occurred when several copies are made. The cleaning member of the fixing device should be changed every several ten thousands times of copying.
Besides, a high speed machine capable of outputting 50 or more sheets per minute is appeared on the market accompanied with rising of the processing ability of the image forming machine. In such the machine, the mold-releasing agent contained in the toner cannot sufficiently functions since the fixing process is finished before sufficient penetration of the mold-releasing agent to the toner surface. Thus the invisible off-set is easily occurred and the off-set occurred at a stage after a little number of copying.
Moreover, the toners disclosed in the above publications are produced by a crushing method with a kneading process, and the domain of the mold-releasing agent is oriented in one direction, so called orientation, in the toner particle in the course of the kneading process. When the mold-releasing agent is oriented in the toner, the effect of the mold-releasing agent between the fixing roller and the image receiving paper is difficultly appeared since the penetration of the mold-releasing agent in all directions cannot be occurred because the penetrating direction of the mold-releasing agent is decided according to the oriented direction thereof. As mentioned above, any toner usable in the high speed machine can not be obtained by the crushing method.
The effort to make smaller the toner diameter is proceeded from the view point of the rising of image quality, and the improvement of the compound for mold-releasing agent and a technique for increasing the adding amount of the mold-releasing agent into the toner have been studied as is shown in JP O.P.I. No. 8-41468. However, problems such as the mold-releasing agent released from the toner causes degradation of the developer, lowering of the fluidity of the toner and occurrence of the filming by the reason of the structure of the toner that the toner particle is composed of a resin particle and a mold-releasing agent particle.
JP O.P.I. No. 5-88409 discloses a toner particle having a specified structure. The disclosed toner is a polymerized toner having a large spherical domain of the mold-releasing agent in a binder resin. However, a particle containing no domain of the mold-releasing agent is found in such the toner since the problem of the partial distribution of the amount of the mold-releasing agent in each of the individual particle is not solved. Moreover, degradation of the toner such as lowering of the charging ability is caused by the mold-releasing agent released from the toner particle because the contacting area between the mold-releasing agent and the resin is decreased since the shape of the mold-releasing agent in the toner particle has a spherical shape.
The toners described in the above publications have a problem that the layer of the mold-releasing agent between the fixing roller and the toner cannot be sufficiently formed since a time is necessary for penetrating out the mold-releasing agent until the toner surface because only one or two large domains of the mold-releasing agent is existed near the center of the toner particle. As above-mentioned, development of a toner suitably used in the high speed image forming machine is desired.
SUMMARY OF THE INVENTION
The first object of the invention is to provide a toner for developing a static image, which is excellent in the resistivity against the invisible off-set and forms no image contamination even when the total number of the processed image is increased accompanied with the prolongation of the using period.
The second object of the invention is to provide a toner for developing a static image excellent in the fusibility and the fluidity, in which the penetration of the mold-releasing agent to the toner surface is effectively performed so that the wind-jamming in the fixing process caused by the shortage of the mold-releasing agent is not occurred.
The third object of the invention is to provide a toner for developing a static image having a high durability in which the mold-releasing agent is not released from the toner.
The fourth object of the invention is to provide a toner for developing a static image usable for a high speed image forming apparatus having a fixing process without oiling/cleaning.
The fifth object of the invention is to provide an image forming method using the foregoing toner.
The inventors noticed on the structure of the polymerized toner having the domain-matrix structure obtained by association of a resin particle according to the in
Hirano Shiro
Matsushima Asao
Nishimori Yoshiki
Ohmura Ken
Yamada Hiroyuki
Goodrow John
Konica Corporation
Muserlian Lucas and Mercanti
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