Non-magnetic toner for developing electrostatic latent image

Details Non-magnetic toner for developing electrostatic latent image Non-magnetic toner for developing electrostatic latent image

2000-04-11

2001-01-16

Martin, Roland (Department: 1753)

Radiation imagery chemistry: process, composition, or product th

Electric or magnetic imagery, e.g., xerography,...

Process of making developer composition

Reexamination Certificate

active

06174641

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a toner used for developing electrostatic latent images in electrophotography, electrostatic printing, etc., and more specifically concerns a non-magnetic toner used for developing electrostatic latent images in the non-magnetic developing system.
2. Description of the Related Art
Recently, there have been increasing demands for full-color image-forming apparatuses as image-forming apparatuses such as copying machines, printers, etc. In the full-color image-forming apparatus, a system has been well-known in which toner images of respective colors, formed on a photosensitive member, are successively transferred on an intermediate transfer member and temporarily held thereon, and then again transferred on a sheet of copy paper at one time.
Moreover, in recent years, various attempts have been made so as to achieve high-quality images in the field of electrophotography, and it has been recognized that down-sizing of toner particle size and toner conglobation are very effective for this purpose. However, as the toner particle size is made small, the transferring properties tend to decrease, resulting in poor image quality. On the other hand, it has been known that toner conglobation makes it possible to improve the toner transferring properties (see Japanese Patent Application Laid-Open No. 9-258474).
Under these circumstances, there are also demands for high-speed image-formation in the field of color copying machines and color printers.
Therefore, attempts have been made so as to achieve high speeds while providing high-quality images by using spherical toner. When an attempt is made to provide high speeds in an apparatus using the above-mentioned system, it is necessary to shorten the time required for copy paper to pass through the transferring section; therefore, it is necessary to increase the transferring pressure when an attempt is made to obtain the same transferring capability as conventionally obtained. However, when the transferring pressure is increased, toner tends to aggregate due to the pressure upon transferring, failing to carry out a preferable transferring process and causing an image loss during an image-formation.
SUMMARY OF THE INVENTION
The present invention is to provide a non-magnetic toner used for developing electrostatic latent images which has a superior transferring properties so that desired images can be obtained not only in a low-speed area, but also in a high-speed area.
The present invention relates to a non-magnetic toner for developing electrostatic latent images, having;
an average degree of roundness of not less than 0.960,
a standard deviation of degree of roundness of not more than 0.040,
a value of D/d
50
of not less than 0.40, in which D=6/(&rgr;·S) (&rgr; is a true density of toner (g/cm
3
), and S is a BET specific surface area of toner (m
2
/g)); d
50
is an average weight particle size of toner, and
an adhesive stress of 6 g/cm
2
or less under a compression of 1 kg/cm
2
.


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