Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Radiation-sensitive composition or product
Reexamination Certificate
2000-09-28
2003-12-02
Goodrow, John (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Radiation-sensitive composition or product
C430S108100, C430S124300
Reexamination Certificate
active
06656649
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a recording material for electrophotography and an image recording method. More specifically, the present invention relates to a recording material for electrophotography capable of forming a highly qualified image in which color reproducibility, recording density and smoothness of a recording surface are improved, and a degradation of image quality due to discoloration and bleeding is rarely occurred during storage.
2. Description of Related Art
An electrophotographic method is an image forming method applying a photoconductive effect and an electrostatic phenomenon, and the method is widely utilized in a variety of fields. The electrophotographic method has two kinds: one is to form an image on a semiconductor material itself such as zinc oxide paper; the other is to form an image by further transferring a toner image from the semiconductor material to a recording medium capable of receiving toner images. The latter, called a xerography method, is widely employed in copying machines for offices, and the image forming principle thereof is described below.
First, electrostatic charges are placed in the dark on a photosensitive plate having a photoconductor such as selenium by using corona charge or the like, and when the charged plate is exposed to an original image, charges are changed only in the irradiated parts to form a latent image. Charged toners, after mixed with carriers and introduced to the latent image, are adhered in an image-form. Then, the recording medium is applied thereon to transfer the toner to the recording medium, and then fixed the toner by heating or the like to form an image.
In recent years, color-copying machines are further widely used, and those color copying machines carry out the aforementioned method by utilizing color toners. Because the color copying machines are mostly used for copying images rather than letters, the images to be formed are sought to be clear and highly qualified. However, when color copying is intended to make on a plain paper, clear and highly qualified images cannot be achieved. Thus, it has been sought to improve recording materials.
The color toners used in such an electrophotographic method generally comprise particles prepared by dispersing a coloring matter such as a dye and a pigment into a thermoplastic resin; and the average diameter of the particles typically ranges from around 5 to 20 &mgr;m. A great variety of coloring matter is used in the toner; its stability in the toner-receiving layer after image forming is not always satisfactory. Thus, the image formed by the electrophotographic method has disadvantages in that a degradation of image quality due to discoloration and bleeding is worsened during storage.
Meanwhile, it has recently been sought to store a highly qualified image for a long period. Thus, it is sought to develop a technique that can store a highly qualified image close to a silver salt photograph without degradation.
SUMMARY OF THE INVENTION
It is an object of the invention to eliminate the aforementioned problems of the prior art. In other words, the invention provides, as an object to be accomplished, a recording material for electrophotography and an image recording method capable of forming a highly qualified image in which color reproducibility, recording density and smoothness of a recording surface are improved. The invention further provides, as another object to be accomplished, a recording material for electrophotography and an image recording method in which a degradation of image quality after a long period storage is reduced.
The inventors diligently studied to solve the above problems, and found that, when a coloring matter is fixed after forming an image, a highly qualified image can be retained for a long period, and therefore the invention has been reached.
This invention provides a recording material for electrophotography comprising a toner containing a coloring matter, and a recording medium for electrophotography wherein a toner-receiving layer which contains a resin capable of fixing the coloring matter contained in said toner is placed on a support, characterized in that said material contains a coloring matter-fixing agent capable of fixing the coloring matter in the toner and/or the toner-receiving layer. It is preferred that the coloring matter has a function of fixing the coloring matter by heating.
The preferred combinations of a coloring matter and a coloring matter-fixing agent used in this recording material for electrophotography can illustrate; those which said coloring matter-fixing agent can react with the coloring matter by the Diels-Alder reaction; those which said coloring matter-fixing agent is a metal ion or a compound capable of providing the metal ion, and said coloring matter is a compound which forms a chelate with the metal ion; those which said coloring matter-fixing agent is an acidic material or an acidic polymer, and said coloring matter is a basic compound or a compound having a basic group; those which said coloring matter-fixing agent is a basic material or a polymeric mordant having a basic group, and said coloring matter is a compound having an acidic dissociating group; those which said coloring matter-fixing agent is a high-molecular weight nucleophilic compound, and said coloring matter is a compound having an electrophilic center; those which said coloring matter is a compound in which an electrophilic group is coupled with in its molecule, and said coloring matter-fixing agent is a high-molecular weight amine compound which reacts with the compound; those which said coloring matter-fixing agent is a polymeric compound having an active hydrogen, and said coloring matter is a compound in which an electrophilic aziridine group and epoxy group is introduced; those which the coloring matter-fixing agent is a thermo-polymerization initiator, and the coloring matter is a compound having a polymerizable group in its molecule; and those which the coloring matter is a deprotonated cationic compound, and the coloring matter-fixing agent is a compound capable of re-protonating said deprotonated compound.
A resin used in the recording medium for electrophotography is preferably a thermoplastic resin having a temperature of flow beginning (Tfb) of 100° C. or less; and also it is preferred that the resin is comprised of the same polymer as a resin constituting the toner. It is preferred that the recording medium for electrophotography and the toner contain an anti-discoloring agent and/or an UV absorbent. Further, it is preferred that the toner is prepared by milling a resin containing a coloring matter at 0° C. or less, or by a polymerization method.
Alternatively, the present invention provides a toner for electrophotography characterized in that said toner contains a coloring matter and a coloring matter-fixing agent capable of fixing the coloring matter. Further, the present invention provides a recording medium for electrophotography wherein a toner-receiving layer, which contains a resin capable of fixing the coloring matter, is placed on a support, characterized in that said medium contains a coloring matter-fixing agent capable of fixing the coloring matter in the toner-receiving layer.
The present invention provides an image recording method comprising: forming a toner image containing a coloring matter that constitutes the same recording material for electrophotography on a recording medium for electrophotography that constitutes the recording material for electrophotography, and fixing the coloring matter by means of the coloring matter-fixing agent contained in the toner-receiving layer. It is preferred that a fixation is carried by heating.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In addition to a specific explanation of a constitution of a recording material for electrophotography of the invention, an image recording method of the invention will be explained in detail hereinafter.
The image recording material for electrophotography of the invention com
Kubodera Seiichi
Ohishi Yasushi
Satoh Kouzou
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