Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Patent
1997-12-19
2000-10-31
Rodee, Christopher D.
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Post imaging process, finishing, or perfecting composition...
5263184, G03G 9087
Patent
active
061400025
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a binder resin for toners which are used for electrophotography, electrostatic printing, etc. and to a toner which employs the resin. More specifically, the present invention relates to a binder resin for toners which has a wide molecular weight distribution of high molecular polymer components and gives excellent toner fixation and anti-offset property, as well as to a toner which employs the resin.
BACKGROUND ART
Typical image forming processes involving electrophotography and electrostatic printing include a developing step in which a photo conductive insulating layer is uniformly electrified, an electrical latent image is formed by dissipating the charge on the exposed sections once the dielectric layer has been exposed to light and a fine powder toner carrying a charge is adhered to the latent image to render it visible, a transfer step in which the resulting visible image is transferred to a transfer material such as transfer paper, and a fixing step for permanently fixing it by heat or pressure.
The toners and toner binder resins used in electrophotography and electrostatic printing must have a number of different properties for each of these steps. For example, in order to adhere the toner to the electrical latent image in the developing step, the toner and toner binder resin must maintain an amount of charge suitable for copying machines without being affected by the temperature or humidity of the surrounding environment. Also, in the fixation step using a heated roller fixing system, they must have an anti-offset property so as not to stick to heated rollers, while having satisfactory fixability onto the paper. Blocking resistance is also required so that the toner does not undergo blocking during storage in the copying machine.
Styrene-acrylic resins have been widely used as toner resins in the past, and especially linear resins and crosslinked resins. In the case of linear resins, a high molecular weight polymer is blended with a low molecular weight polymer to improve the toner fixing property and anti-offset property. However, with toners which employ such resins, for instance when the fixing property is improved, the melt viscosity of the resin decreases and the anti-offset property of the toner is lowered, and it is therefore difficult to obtain toner with an adequate balance between the two. Attempts have therefore been made to improve the balance between fixing property and anti-offset property by widening the molecular weight distribution of the resin.
For example, in Japanese Examined Patent Publication No. 63-32182, No.63-32183, No.63-32382 and 3-48506 there are proposed methods for improving the balance between fixing property and anti-offset property by widening the molecular weight distribution of the resin, by means of a blend of high molecular weight polymers and low molecular weight polymers with specific molecular weight distributions. However, it has still not been possible to fully satisfy demands for both the fixing property and anti-offset property by simple blending of high molecular weight polymers and low molecular weight polymers.
DISCLOSURE OF THE INVENTION
It is therefore an object of the present invention to provide a binder resin for toners which contains high molecular weight polymer components and low molecular weight polymer components in a wider molecular weight distribution to achieve a satisfactory balance between the toner fixing property and anti-offset property, as well as a toner which employs the resin.
In light of the circumstances described above, the present inventors have carried out diligent research in regard to molecular weight distributions of high molecular weight polymer components of toner binder resins and, as a result, have completed the present invention based upon the finding that toner binder resins which have a satisfactory balance between both toner fixing property and anti-offset property can be provided by using high molecular weight polymer components with specific molecular weigh
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Patent Abstracts of Japan, vol. 11, No. 331 (P-630), Oct. 29, 1987, JP 62-115170, May 26, 1987.
Harada Yoko
Inagaki Motoshi
Shimizu Koji
Tajiri Noriyuki
Mitsubishi Rayon Co. Ltd.
Rodee Christopher D.
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