Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Reexamination Certificate
2000-03-08
2001-03-20
Goodrow, John (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, C430S137170
Reexamination Certificate
active
06203959
ABSTRACT:
FIELD OF THE INVENTION AND RELATED ART
The present invention relates to a toner for use in electrophotography, electrostatic recording and toner jetting.
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 or fixation sheet, 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.
Various methods and devices have been developed for the step of fixing a toner image onto a sheet of paper, etc. For example, there are a pressure and heat fixing method using hot rollers, and a heat fixing method wherein a sheet carrying a toner image is pressed by a pressing member against a heating member via a film.
In such a hot roller fixing scheme and a heat fixing scheme using a film, a toner image surface carried on a fixation sheet is caused to pass in contact with the surface of a hot roller or film surfaced with a material exhibiting releasability with respect to the toner, thereby fixing the toner image onto the fixation sheet. In these methods, the hot roller or film surface contacts the toner image on the fixation sheet, it is possible to attain a very good heat efficiency for melt-attaching the toner image onto the fixation sheet, thus allowing quick fixation which is very advantageous in electrophotographic copying machines and printers. However, in the above-described methods wherein the hot roller or film surface contacts the toner image in a molten state, there can occur an undesirable offset phenomenon that a portion of the toner image is attached onto the fixing roller or film surface and then re-transferred to soil a subsequent fixation sheet. Accordingly, it is important to prevent the toner from being attached to the hot fixing roller or film surface in the heat-fixing scheme.
Hitherto, for the purpose of preventing toner attachment onto the fixing roller surface, it has been practiced to form the roller surface of a material showing good releasability to a toner, such as silicone rubber or fluorine-containing resin, and coating the roller surface with a film of liquid showing good releasability, such as silicone oil, for offset prevention and preventing the roller surface fatigue. This method is very effective for preventing toner offset but is accompanied with a difficulty that a device for supply offset-preventing liquid is required to complicate the fixing device.
This is a measure contrary to a current demand for a smaller-sized and light-weight apparatus. Moreover, the silicone oil can be vaporized on heating to soil the inside of the apparatus. Accordingly, based on a concept of supplying an offset prevention liquid from toner particles, it has been proposed to incorporate a release agent, such as low-molecular weight polyethylene or low-molecular weight polypropylene, within toner particles.
Further, toners containing two or more species of waxes for exhibiting better addition region to a high temperature region have been effects from a low temperature disclosed in Japanese Patent Publication (JP-B) 52-3305, Japanese Laid-Open Patent Application (JP-A) 58-215659, JP-A 62-100775, JP-A 4-124676, JP-A 4-299357, JP-A 4-358159, JP-A 4-362953, JP-A 6-130714 and JP-A 6-332244.
However, such toners have their own problems. For example, a toner exhibiting excellent anti-high-temperature offset characteristic may leave a room for improvement of low-temperature fixability. A toner exhibiting excellent anti-low-temperature offset characteristic and low-temperature fixability may exhibit somewhat inferior anti-blocking property and developing performance or fail to satisfy anti-offset property at both low temperatures and high temperatures.
Excellent toners having solved such problems have been disclosed in JP-A 8-278662, JP-A 8-334919, JP-A 8-334920, JP-A 10-104875 and JP-A 10-161347. These publications have proposed to use low melting point waxes for exhibiting excellent fixability. A low melting point wax can provide an improved fixability because of its plasticizing effect but is liable to adversely affect the flowability and anti-blocking property of the toner, and the use thereof has been restricted to some extent.
On the other hand, electrophotographic copying machines and printers in recent years are used systematically, and higher functionality and higher speed thereof are required. For complying with these demands, a toner is required of not only properties under melting but also powdery characteristics at normal temperature. For complying with a higher speed, a toner is required to exhibit better movement in the developing device and cleaner and improved anti-melt sticking onto the developing sleeve and photosensitive member, so that further improvements are desired.
SUMMARY OF THE INVENTION
A generic object of the present invention is to provide a toner having solved the above-mentioned problems.
A more specific object of the present invention is to provide a toner showing excellent fixability.
Another object of the present invention is to provide a toner exhibiting excellent storage stability and flowability yet free from toner plugging or cleaning failure.
Another object of the present invention is to provide a toner exhibiting excellent storage stability and flowability and allowing stable toner movement in the developing device and stable developing performance.
A further object of the present invention is to provide a toner excellent in anti-melt-sticking property, thus well suppressing the melt-sticking onto the developing sleeve and the photosensitive drum.
According to the present invention, there is provided a toner, comprising a resinous composition including a binder resin and a wax (A), wherein the wax (A) contains at least 92 wt. % thereof of n (normal)-paraffin comprising a plurality of n-paraffin species having different numbers of carbon atoms, and provides a DSC (differential scanning calorimetry)-heat-absorption curve exhibiting a maximum heat-absorption peak showing a peaktop temperature of 70-90° C. and a half-value width of at most 12° C.
These and other objects, features and advantages of the present invention will become more apparent upon a consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 2297691 (1942-10-01), Carlson
patent: 3666363 (1972-05-01), Tanaka et al.
patent: 4071361 (1978-01-01), Marushima
patent: 4921771 (1990-05-01), Tomono et al.
patent: 5225303 (1993-07-01), Tomita et al.
patent: 5292609 (1994-03-01), Yoshikawa et al.
patent: 5364722 (1994-11-01), Tanikawa et al.
patent: 5384224 (1995-01-01), Tanikawa et al.
patent: 5605778 (1997-02-01), Onuma et al.
patent: 5629122 (1997-05-01), Tanikawa et al.
patent: 6120961 (2000-09-01), Tanikawa et al.
patent: 0 743 563 (1996-11-01), None
patent: 0834775 (1998-04-01), None
patent: 58-215659 (1983-12-01), None
patent: 62-100775 (1987-05-01), None
patent: 4-124676 (1992-04-01), None
patent: 4-299357 (1992-10-01), None
patent: 4-362953 (1992-12-01), None
patent: 4-358159 (1992-12-01), None
patent: 6-130714 (1994-05-01), None
patent: 6-332244 (1994-12-01), None
patent: 8-278662 (1996-10-01), None
patent: 8-334920 (1996-12-01), None
patent: 8-334919 (1996-12-01), None
patent: 52-3305 (1997-01-01), None
patent: 10-104875 (1998-04-01), None
patent: 10-161347 (1998-06-01), None
Fujikawa Hiroyuki
Fujimoto Masami
Kobori Takakuni
Tanikawa Hirohide
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Goodrow John
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