Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Patent
1989-02-24
1992-01-28
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...
430904, G03G 900
Patent
active
050843680
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to an electrophotographic toner for use in the development of an electrostatic image in electrophotography, electrostatic recording, electrostatic printing and the like.
BACKGROUND OF THE TECHNIC
Still more increasing tendency of duplication speed has recently been found in the electrophotography due to the increase of information to be treated.
Consequently, the heat quantity transferred from hot fixing rolls to toner is less at high duplication speed than at low duplication speed. A remarkable decrease in the surface temperature of fixing rolls is also caused by the heat removal to copying papers. Therefore the toner is required to be fixed at lower temperatures and also to be free from offset phenomenon at these fixing temperatures. In order to obtain a sharp image, improvement of resin has been conducted with respect to hot melt properties such as fixing ability at lower temperatures and offset resistance, as well as electrostatic characteristics of the toner.
For example, several patents have been known. Japanese Patent Publication No. 6895/1980 discloses a method for providing a toner having a good offset resistance by using a resin having a weightaverage molecular weight
umber average molecular weight ratio of 3.5-40 and a number average molecular weight of 2,000-30,000. Japanese Patent Laid-open No. 144,446/1975 describes a method for improving the fixing ability by adding a small amount of plasticizers such as phthalic acid diester into a toner having a good blocking and offset resistance. Japanese Patent Laid-open No. 101,031/1974 discloses a method for extending the range of fixing temperatures by using a crosslinked resin and for employing a toner which is offset resistant even at relatively high fixing temperatures. Besides patents are known as a countermeasure for providing the high electrostatic charge characteristics for the toner. For example, Japanese Patent Publication 40,183/1983 discloses a method for using aliphatic unsaturated carboxylic acids such as methacrylic acid as a component of the resin. Japanese Patent Laid-open No. 93,457/1984 discloses a method for providing charge stability together with the high electrostatic charge characteristics by adding a charge control agent composed of metal containing dyestuff as a toner ingredient.
Furthermore, Japanese Patent Laid-open No. 16,144/1981 relevant to U.S. Pat. No. 4,499,168 describes a method for providing a magnetic toner which is excellent in the fixing ability and impact resistance by employing the resin having the maximum value of molecular weight in a specific molecular weight region.
As above mentioned, the heat quantity provided from the hot fixing rolls is less at the high duplication speed than at the low-duplication speed. A marked decrease in the surface temperature of fixing rolls is also caused by the heat removal to the copying papers. Therefore it is necessary fixing with a smaller quantity of heat. Smaller molecules having lower glass transition temperature (hereinafter abbreviated as Tg) are required for melting with low calory. Excess lowering of Tg, however, causes blocking and there is naturally a lower limit for the Tg. The smaller molecules are assumed to reduce their melt viscosity more rapidly, enhance flowability of the resin at lower temperatures, and improve the fixing ability. Too small molecules, however, lead to lowering of Tg and occurrence of blocking problems.
On the other hand, as a result of increase in the duplication speed and numbers of copying papers, the duplicated images are expected to have the same quality from the 1 st to the dozens of thousandth sheet in addition to have a sharp image and perfect fixation of the toner to the paper.
Conventional methods for the improvement of offset resistance and low temperature fixation are related to the problems occurring after adhesion of the toner to the paper. These methods are important and yet not considered upon the requirement for adhering the toner in advance on each copying paper unif
REFERENCES:
patent: 4499168 (1985-02-01), Mitsuhashi
patent: 4626488 (1986-12-01), Inoue
patent: 4702986 (1987-10-01), Imai et al.
patent: 4917984 (1990-04-01), Saito
Fred W. Billmeyer, Jr., Textbook of Polymer Science, 1984, John Wiley & Sons, pp. 127 & 138.
Fujiwara Akio
Hirayama Nobuhiro
Kawasaki Shoji
Misawa Akira
Shin Masaaki
Crossan S.
McCamish Marion E.
Mitsui Toatsu Chemicals Incorporated
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