Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Reexamination Certificate
2002-08-16
2004-12-07
Goodrow, John L (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Post imaging process, finishing, or perfecting composition...
C430S110300, C430S111400, C430S126200
Reexamination Certificate
active
06828073
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a toner for developing an electrostatic image used for developing an electrostatic latent image formed by an electrophotographic process or an electrostatic recording process, a developer for an electrostatic image, and a process for forming an image.
2. Description of Related Art
A process for visualizing image information through an electrostatic image by an electrophotographic process has been utilized in various fields of art. In the electrophotographic process, an electrostatic image is formed on a photoreceptor by charging and exposing steps, and the electrostatic latent image is visualized by developing it with a developer containing a toner, followed by transferring and fixing steps. The developer used herein includes a two-component developer containing a toner and a carrier and a one-component developer formed solely with a magnetic toner or a non-magnetic toner. The toner is generally produced by a kneading and pulverizing process, in which a thermoplastic resin is melted and kneaded with a colorant, a charge controlling agent and a releasing agent, such as wax, and after cooling, the mixture is finely pulverized and classified. In order to improve the flowability and the cleaning property of the toner, inorganic or organic fine particles may be added to the surface of the toner particles, as required.
In recent years, duplicators and printers utilizing the color electrophotographic process and composite machine thereof with facsimile machines are quickly spread. In the case where moderate gloss upon reproduction of a color image and transparency for obtaining an excellent OHP image are to be realized, it is generally difficult to use a releasing agent, such as wax. Accordingly, a large amount of an oil is applied to a fixing roll for assisting release, but the oil causes sticky feeling of a duplicated image including an OHP image and difficulty in writing on the image with a pen, and uneven gloss feeling also sometimes occurs. Wax including polyethylene, polypropylene and paraffin, which is generally used for monochrome duplication, is more difficult to be used because it impairs the OHP transparency.
Even though the transparency is abandoned, it is difficult that exposure of the releasing agent to the toner surface is suppressed when the toner is produced by the conventional kneading and pulverizing process, and therefore, such problems as considerable deterioration of the flowability and filming on a developing unit and a photoreceptor are caused upon using as a developer.
As an ultimate solution for the problems, a process for producing a toner by such a polymerization process is proposed that an oily phase containing a monomer as a raw material of a resin and a colorant is dispersed in an aqueous phase, and the toner is directly polymerized to form a toner, whereby the wax is encompassed in the interior of the toner to control exposure thereof.
In addition to the above, as a method for enabling intentional control of the toner shape and the surface structure, production processes for a toner by a emulsion polymerization and aggregation process are proposed in Japanese Patent Laid-Open No. 282752/1988 and Japanese Patent Laid-Open No. 250439/1994. In these production processes, the following procedures are generally carried out. A resin dispersion is produced by emulsion polymerization, and separately, a colorant dispersion containing a colorant dispersed in a solvent is produced. They are mixed to form aggregates corresponding to the toner particle diameter, and then they are heated to coalesced, whereby a toner is produced.
These production processes not only realize internal inclusion of the wax, but also facilitate production of a toner of a small diameter, whereby clear image reproduction of high resolution is realized.
When these production processes are employed, the design of the characteristics of the resin becomes considerably important for attaining higher image quality. In order to realize a wide reproduction color gamut, it is necessary that not only the colorant is optimized, but also a gloss image of a certain level or higher is obtained by the melting characteristics of the resin. It is necessary therefore that the elasticity of the resin is decreased by decreasing the molecular weight to lower the melt viscosity thereof upon heating with a heat roll, whereby the resin is designed to increase the flowability thereof. However, when the elasticity is decreased, the adherability to the heat roll is increased, and thus release from the roll becomes difficult in the absence of a fixing oil even though a releasing agent, such as wax, is contained. Furthermore, hot offset at a high temperature due to the lowered molecular weight is liable to be a problem, and as a result, the toner often has a too narrow usable temperature range.
In this case, the fixing behavior becomes extremely sensitive to the temperature fall of a fixing heat roll and the temperature rise upon heating with a heater in continuous printing, and therefore, the temperature control becomes considerably difficult. In practice, influences of quality and thickness of paper on the temperature are to be also considered, whereby the control thereof becomes more complicated. Furthermore, when the molecular weight is decreased, the gloss is increased, but the fixed image becomes mechanically brittle to cause such a problem on durability of the image that the image is damaged upon folding the medium, such as paper.
As described in the foregoing, in order to provide a high quality image by the electrophotographic process and to maintain stable performance of a toner under various kinds of mechanical stress, it is necessary that the selection and the amount of the colorant and the releasing agent are optimized, and exposure of the releasing agent to the surface is suppressed, and also the following factors are extremely important, i.e., improvement of the gloss by optimization of the resin properties, and improvement of the releasing property and suppress of hot offset in the absence of a fixing oil. However, it is the current situation that further improvements are demanded.
SUMMARY OF THE INVENTION
Therefore, the invention has been developed to solve the problems associated with the conventional techniques to attain the following targets. The invention is to provide a toner for developing an electrostatic image that has a wide fixable temperature range, is excellent in development and transfer performance and excellent in releasing performance, realizes both glossiness and transparency, and is capable of providing an image (particularly a color image) of a wide color reproduction range having high quality and high durability, a developer for an electrostatic image, and a process for forming an image.
The invention relates to, as one aspect, a toner for developing an electrostatic image containing a binder resin, a colorant and an inorganic metallic salt. An amount of a toluene insoluble component (provided that the colorant, a releasing agent and inorganic and organic insoluble particles are excluded therefrom) is from 0.5 to 10% by weight.
The invention also relates to, as another aspect, a developer for an electrostatic image containing the toner and a carrier.
The invention also relates to, as a further aspect, a process for forming an image. The process contains the steps of: forming an electrostatic latent image on an electrostatic image holding member; developing the electrostatic latent image on a developer holding member with a developer for an electrostatic image containing a toner to form a toner image; transferring the toner image to a transfer material; and fixing the toner image with heat. The toner is the toner for developing an electrostatic image of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The invention will be described in detail.
The toner for developing an electrostatic image of the invention contains a binder resin, a colorant and an inorganic metallic salt, and an amount of
Fujii Takahisa
Matsumura Yasuo
Nakajima Tomohito
Yaguchi Hidekazu
Yoshida Satoshi
Fuji 'Xerox Co., Ltd.
Goodrow John L
Oliff & Berridg,e PLC
LandOfFree
Toner for developing electrostatic image, developer for... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Toner for developing electrostatic image, developer for..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Toner for developing electrostatic image, developer for... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3286369