Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Patent
1991-08-14
1993-07-27
McCamish, Marion E.
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Post imaging process, finishing, or perfecting composition...
430110, 430109, 430904, G03G 9087
Patent
active
052309789
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
This invention relates to an electrophotographic toner composition.
2. Background Art
In electrophotography, the copying speed has tended to increase in recent years to meet the ever increasing quantity of information to be dealt with. In a high-speed copying machine, the heat transmitted from a fixing hot roll is low compared with a medium-speed copying machine; as well, the surface temperature of the fixing hot roll falls appreciably because more heat absorbed by the paper than can be fully compensated for. Accordingly, there is a demand for a toner composition which can be fixed at low heat and does not cause an offset problem at this lower level of fixing temperature.
On the other hand, copying machines have become smaller, and the pressure and temperature of a fixing roll have lowered. In this field, the development and improvement of developers with good fixing properties and offset resistance even at low heat have also been conducted.
For example, there is known a process disclosed in Japanese Patent Publication No. 6895/1980 which provides a toner having good offset resistance using, as a resin for the developer, a resin having a weight-average molecular weight
umber-average molecular weight ratio of 3.5-40 and a number-average molecular weight of 2,000-30,000; and also a process disclosed in Japanese Patent Laid-Open No. 101031/1974 which widens the range of fixing temperature and provides a toner free from offset problems even at a comparatively high fixing temperature by using a crosslinked resin.
It has been found, however, that whereas the prior art as described above is effective for the conventional copying machine troubled with an offset problem, a sufficient effect cannot be obtained in the case of a copying machine which uses a lower heat for fixing. Namely, this is presumed to result from the improvements that have been made in order to increase the weight-average molecular weight of the resin to achieve an improvement in the strength of the toner and offset resistance.
The resins described above have such a high viscosity that they are not suitable in their conventional form for the lower-heat fixing copying machines. Viscosity reduction of the resin by lowering its weight-average molecular weight, however, tends to damage the offset resistance or the picture quality as the result of a long-term operation of the image.
DISCLOSURE OF THE INVENTION
An object of the present invention is to solve all the problems of the prior art and to provide a toner, which fixes at lower-heat levels and is excellent in strength, suitable for a recently-developed high-speed copying machine or lower-heat copying machine.
In accordance with the process of the present invention, an electrophotographic toner composition which always produces stable and good-quality pictures when fixed at lower heat levels is provided, which has not been actualized by the prior art. The resultant benefits of the present invention are that the lowest limit of the fixing temperature is low, non-offset range is wide and picture properties are remarkably good. It has, thus, excellent properties as an electrophotographic toner composition.
BEST MODE FOR CARRYING OUT THE INVENTION
Based on the finding that the problems described above can be eliminated by using a low-melt-viscosity and high-strength resin to produce a toner, the present inventors have completed the present invention.
Namely, the present invention provides an electrophotographic toner composition comprising as a principal component a polymer obtained by continuously adding dropwise or adding in portions, to 100 parts by weight (all designations of "part" indicate "part by weight" unless otherwise specifically indicated) of an ethylenically-unsaturated monomer or a solution composed of 100 parts of an ethylenically-unsaturated monomer and x parts of a solvent, a solution mixture composed of 0.01-30 parts of a divinyl compound, y parts of a solvent and 0.01-10 parts of a polymerization initiator, in which x plus y are at least 20
REFERENCES:
patent: 4626488 (1986-12-01), Inoue
Akiyama Hiromi
Hirayama Nobuhiro
Kawasaki Shoji
Sato Hisatomo
Uchiyama Kenji
Ashton Rosemary
McCamish Marion E.
Mitsui Toatsu Chemicals Incorporated
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