Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Reexamination Certificate
1998-12-28
2001-01-23
Dote, Janis L. (Department: 1753)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Post imaging process, finishing, or perfecting composition...
C430S109500, C430S110100, C430S111400, C430S124300, C430S125320
Reexamination Certificate
active
06177223
ABSTRACT:
FIELD OF THE INVENTION AND RELATED ART
The present invention relates to a toner for use in a recording method or image forming method, such as electrophotography, electrostatic recording, magnetic recording or toner jetting, and an image forming method using the toner. More specifically, the present invention relates to a toner for use in an image recording apparatus applicable to a copying machine, a printer, a facsimile apparatus, a plotter, etc., and an image forming method using the toner.
Hitherto, a large number of electrophotographic processes have been known, inclusive of those disclosed in U.S. Pat. Nos. 2,297,691; 3,666,363; and 4,071,361. In these processes, in general, an electrostatic latent image is formed on a photosensitive member comprising a photoconductive material by various means, then the latent image is developed with a toner, and the resultant toner image is transferred via or without via an intermediate transfer member onto a transfer(-receiving) material such as paper etc., as desired, fixed by heating, pressing, or heating and pressing, or with solvent vapor to obtain a copy or print carrying a fixed toner image. A portion of the toner remaining on the photosensitive member without being transferred is cleaned by various means, and the above mentioned steps are repeated for a subsequent cycle of image formation.
An example of ordinary full-color image forming process will now be described. A photosensitive member (electrostatic image-bearing member) in the form of a drum is uniformly charged by a primary charger and then subjected to imagewise exposure with laser light modulated by a magenta image signal obtained from an original to form an electrostatic image on the photosensitive drum, which is then developed with a magenta toner contained in a magenta developing device to form a magenta toner image. Then, the magenta toner image formed on the photosensitive drum is transferred directly or indirectly onto a transfer material under the action of a transfer charger.
The photosensitive drum after the above-mentioned developing of an electrostatic image is charge-removed by a charge-removing charger and cleaned by a cleaning means so as to be prepared for a subsequent cyan-image forming cycle including charging again by the primary charger, a cyan toner image formation and a transfer of the cyan toner image onto the transfer material carrying the magenta toner image already transferred thereto, followed further by a yellow-image forming cycle and a black image forming cycle to provide the transfer material with four-color toner images thereon. Then, the transfer material carrying the four-color toner images is subjected to fixation under application of heat and pressure, thereby forming a full-color image.
In recent years, an image-forming apparatus performing an image forming method as described above not only is used as a business copier for simply reproducing an original but also has been used as a printer, typically a laser beam printer (LBP), for computer output, and a personal copier (PC) for individual users.
In addition to such uses as representatively satisfied by a laser beam printer, the application of the basic image forming mechanism to a plain paper facsimile apparatus is also popular.
For such uses, the image forming apparatus has been required to be smaller in size and weight and satisfy higher speed, higher quality and higher reliability. Accordingly, the apparatus has been composed of simpler elements in various respects. As a result, the toner used therefor is required to show higher performances. Further, in accordance with various needs for copying and printing, a greater demand is urged for color image formation, and a higher image quality and a higher resolution are required for faithfully reproducing an original color image. There is also an increasing demand for an image forming system allowing the formation of an image sheet having images on both sides from an original sheet having images on both sides.
In order to comply with the demands for a toner used in such a color image forming process, each color toner is required to exhibit excellent meltability and color-mixing characteristic on heating under application of a pressure. For this purpose, it is preferred to use a toner having a low softening point and a melt-viscosity which sharply decreases down to a low value below a prescribed temperature (i.e., having a high degree of sharp melting characteristic). By using such a toner, it is possible to provide a color copy satisfying a broader range of color reproducibility and faithful to the original image.
However, such a color toner having a high degree of sharp meltability generally has a high affinity to a fixing roller and is liable to cause offsetting onto the fixing roller at the time of fixation.
Particularly, in the case of a fixing device for a color image forming apparatus, a plurality of toner layers including those of magenta toner, cyan toner, yellow toner and black toner, are formed on a transfer-receiving material, so that the offset is liable to be caused as a result of an increased toner layer thickness.
Hitherto, in order to prevent the attachment of a toner onto a fixing roller surface, it has been practiced to compose the roller surface of a material, such as a silicone rubber or a fluorine-containing resin, showing excellent releasability against a toner, and coat the roller surface with a film of a liquid showing a high releasability, such as silicone oil or a fluorine-containing oil, for the purpose of preventing offset and deterioration of the roller surface. However, such a measure, though very effective for preventing toner offset, requires an equipment for supplying the offset-preventing liquid and complicates the fixing device. Further, the oil application is liable to promote a peeling between layers constituting the fixing roller, thus causing a shorter life of the fixing roller.
Accordingly, based on a concept of not using such a silicone oil-supplying device but supplying an offset-preventing liquid from toner particles on heating under pressure, it has been proposed to incorporate a release agent, such as low-molecular weight polyethylene or low-molecular weight polypropylene within toner particles.
For example, the incorporation of a wax in toner particles has been disclosed in Japanese Patent Publication (JP-B) 52-3304, JP-B 52-3305 and Japanese Laid-Open Patent Application (JP-A) 57-52574.
Further, the incorporation of a wax in toner particles is also disclosed in JP-A 3-50559, JP-A 2-79860, JP-A 1-109359, JP-A 62-14166, JP-A 61-273554, JP-A 61-94062, JP-A 61-138259, JP-A 60-252361, JP-A 60-252360 and JP-A 60-217366.
Wax has been used in order to provide improved anti-offset characteristic of the toner at low or high temperatures, and also an improved fixability at low temperatures. On the other hand, the resultant toner is liable to have a lower anti-blocking property or inferior developing performance due to migration of the wax to the surface of toner particles when exposed to heat due to a temperature increase in a copying machine or due to a long term of standing of the toner.
For such problems, a great expectation has been imparted to development of a novel toner.
For complying with such an expectation, a toner obtained through a suspension polymerization process has been proposed (JP-B 36-10231). In the suspension polymerization process, a monomer composition is prepared by uniformly mixing (i.e., dissolving or dispersing) a polymerizable monomer and a colorant, and optionally a polymerization initiator, a crosslinking agent, a charge control agent, and other additives, and the monomer composition is dispersed in an aqueous medium containing a dispersion stabilizer under the action of an appropriate stirrer, and subjected to polymerization, thereby providing toner particles having a desired particle size.
In the suspension polymerization process, the monomer composition is dispersed into liquid droplets in a dispersion medium, such as water, having a large polarity. Accordingly, a c
Ayaki Yasukazu
Handa Satoshi
Hashimoto Akira
Komoto Keiji
Ohno Manabu
Canon Kabushiki Kaisha
Dote Janis L.
Fitzpatrick ,Cella, Harper & Scinto
LandOfFree
Toner and image forming method using the toner 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 and image forming method using the toner, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Toner and image forming method using the toner will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2502852