Image forming method and electrostatic image developing toner

Details Image forming method and electrostatic image developing toner Image forming method and electrostatic image developing toner

2002-04-19

2004-02-10

Chapman, Mark A. (Department: 1756)

Radiation imagery chemistry: process, composition, or product th

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

To produce color reproduction

C430S110400

Reexamination Certificate

active

06689522

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to an image forming method in which a latent image, formed on a photoreceptor, is visualized employing a developer, comprising an electrostatic image developing toner.
BACKGROUND OF THE INVENTION
An electrostatic latent image developing method, mainly based on the electrophotographic system, which has been employed in copiers and printers, is employed in the image forming apparatus, which is required for high speed as well as high quality images. Listed as additional reasons, other than the advantages described above, is the fact that high image quality is consistently obtained during use over an extended period of time, and it is also possible to form color images.
Many electrostatic latent image developing methods (hereinafter occasionally referred to as an electrophotographic method, since most of them depend upon the electrophotographic system) have been developed to achieve specific purposes, and exhibit specific features of each. While taking advantage of said features, an optimal method is selected and applied to each use. Of these, common requirements are further improvement of image quality as well as durability, and saving of resources, non-pollution, and lowered cost.
Of electrostatic latent image developing methods, a one-component non-magnetic developing method is preferred as a simple and convenient method due to fact that no density adjusting mechanism is required, and is often employed in image forming apparatus such as relatively small-sized printers as well as facsimile machines.
On the other hand, a two-component magnetic developing method is a system in which a carrier and a toner are blended, and overall dimensions of the resultant apparatus tend to increase somewhat. However, images are stably formed due to the function-separating structure of the charge application, and currently, it is the one most widely employed.
In any of these, in order to achieve higher image quality, it is effective to decrease the diameter of toner particles. In the recent trend of digitization, importance of toner comprised of particles having a small diameter (hereinafter referred also as the small-diameter toner) is increasingly elevated to form high quality images. Further, from the viewpoint of saving of resources, non-environmental pollution, and a decrease in image forming cost, a recycling system is useful in which toner, which has been recovered from a photoreceptor by cleaning, is reused.
However, when toner comprised of particles having a decreased diameter is employed in the conventional image forming systems described above, said toner particles tend to be affected by such as mechanical stress in the development unit. During development employing a single non-magnetic component developer, the toner particles are subjected to stress during formation of a thin layer in the toner conveying system, as well as stress such as shearing stress during cleaning in the toner recycling system and its conveying system. On the other hand, when a double component developer is employed, the contained carrier is stained. As a result, when the small-diameter toner is employed over an extended period of time, it has been extremely difficult to achieve consistent development due to occurrence of various image problems.
In addition, when the small-diameter toner is employed, cleaning properties tend to be degraded. Further, when color toner is employed, problems have been noted in which the color difference between the initial image and images after a long production run tend to increase.
SUMMARY OF THE INVENTION
An object of the invention is to provide an image forming method, which results in high quality copies, and exhibits excellent cleaning properties as well as minimal color difference between the initial image and images after a long production run.
The aforesaid object of the invention was achieved by following Structures.
[Structure 1]
An image forming method, comprising the steps of:
forming a latent image on a photoreceptor having an electrically conductive support having thereon a charge generating layer and a charge transporting layer;
developing the latent image with a developer containing a toner so as to form a toner image on the photoreceptor; and
transferring the toner image from the photoreceptor onto an image receiving member,
wherein the ratio (Dv50/Dp50) of 50% volume particle diameter of the toner (Dv50) to 50% number particle diameter of the toner (Dp50) is within the range of 1.0 to 1.15, the ratio (Dv75/Dp75) of the cumulative 75% volume particle diameter from the largest particle diameter of the toner (Dv75) to the cumulative 75% number particle diameter from the largest particle diameter of the toner (Dp75) is within the range of 1.0 to 1.20 and the number of toner particles having a particle diameter of not larger than 0.7×Dp50 in the toner is at most 10% of the number of all the toner particles in the toner.
[Structure 2]
An image forming method comprising the steps of:
forming a latent image on a photoreceptor having an electrically conductive support having thereon a charge generating layer and a charge transporting layer;
developing the latent image with a developer containing toner so as to form a toner image on the photoreceptor;
transferring the toner image from the photoreceptor onto an intermediate image receiving member; and
transferring the toner image from the intermadiate image receiving member onto an image receiving member,
wherein the ratio (Dv50/Dp50) of 50% volume particle diameter of the toner (Dv50) to 50% number particle diameter of the toner (Dp50) is within the range of 1.0 to 1.15, the ratio (Dv75/Dp75) of the cumulative 75% volume particle diameter from the largest particle diameter of the toner (Dv75) to the cumulative 75% number particle diameter from the largest particle diameter (Dp75) is within the range of 1.0 to 1.20 and the number of toner particles having a particle diameter of not more than 0.7×Dp50 in the toner is at most 10% of the number of all the toner particles in the toner.
[Structure 3]
A color image forming method, comprising the steps of:
forming plural latent images separately on plural photoreceptors, each of which comprises an electrically conductive support having thereon a charge generating layer and a charge transporting layer;
developing the plural latent images with plural different color developers so as to form plural toner images on the plural photoreceptors, the plural different color developers containing plural different color toners from each other;
superimposing the plural different color toner images by transferring the plural different color toner images one after on other from the plural photoreceptors onto an intermediate image receiving member so that a color image is formed on the intermediate image receiving member; and
transferring the color image is formed from the intermediate image receiving member onto an image receiving member,
wherein the following relations are satisfied in at least one of the color toners: the ratio (Dv50/Dp50) of 50% volume particle diameter of the toner (Dv50) to 50% number particle diameter of at least one of the toners (Dp50) is within the range of 1.0 to 1.15, the ratio (Dv75/Dp75) of the cumulative 75% volume particle diameter from the largest particle diameter (Dv75) to the cumulative 75% number particle diameter from the largest particle diameter (Dp75) is within the range of 1.0 to 1.20 and the number of toner particles having a particle diameter of not larger than 0.7×Dp50 in the toner is at most 10% of the number of all the toner particles in the toner.
[Structure 4]
An electrostatic image developing toner,
wherein the ratio (Dv50/Dp50) of 50% volume particle diameter of the toner (Dv50), to 50% number particle diameter of the toner (Dp50), is within the range of 1.0 to 1.15, the ratio (Dv75/Dp75) of the cumulative 75% volume particle diameter from the largest particle diameter of the toner (Dv75) to the cumulative 75% number particle diameter from the

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