JPH04110857A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To lower a residual potential and to enhance the efficiency of utilizing a toner as well as to lessen the toner splashing in a copying machine by covering the end of an intermediate layer with a charge generating layer. CONSTITUTION:This photosensitive body is formed by successively laminating the intermediate layer 12, the charge generating layer 131, a charge transfer layer 132 and if necessary, further a protective layer 14 on a conductive substrate 11. The end of the layer 12 is coated with the layer 131. Further, the end of the layer 132 is preferably positioned on the side inner than the end of the layer 12.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electrophotographic photoreceptor, and more specifically, the present invention relates to an electrophotographic photoreceptor, in particular, a method for specifying the end position of an intermediate layer (subbing layer) in relation to the end position of a photosensitive layer. Related to electrophotographic photoreceptors.

[Conventional technology]

An electrophotographic photoreceptor (hereinafter sometimes abbreviated as "photoreceptor") generally has a structure in which a photosensitive layer is formed on a conductive substrate with an intermediate layer interposed therebetween. A protective layer is generally provided on top.

Such a photoreceptor includes a conductive substrate 1 as shown in FIG.
1, an intermediate layer 12, a photosensitive layer 13' (consisting of a charge generation layer 131 and a charge transport layer 132), a protective layer 14, etc. are laminated on the layer 1, and in many cases, the end surfaces of these layers are aligned or almost aligned. is formed. In the production of such a photoreceptor, if the photosensitive layer 13' is organic, the bead coating method (sheet method, useful for coating on a conductive substrate such as a seamless belt) is used.
Conventionally, methods such as the coating method and the dipping method (useful for coating drum-shaped conductive substrates) have been used, but recently, the spray method, which allows for better control of the thickness of the thin film, has been increasingly used. It's coming.

However, no matter which coating method is used, the thickness of each layer at the edge of the conductive substrate may be uniform like the other layers, or may be thicker or thinner than the other layers, or the coating may be uneven at the edge. When exposed, cracks occur at the edges due to external forces applied to the edges, expansion and contraction of the conductive substrate and coating, and due to this, peeling or falling off of the photosensitive layer etc. from the conductive substrate is observed. However, there are disadvantages in that the life of the photoreceptor is significantly shortened.

However, in order to prevent such inconvenience from occurring, an electrophotographic photoreceptor has been proposed in which the end of the photosensitive layer is formed inside the end of the intermediate layer, and the end surface of the intermediate layer is exposed. (Special Publication No. 1-51184)
. However, even in electrophotographic photoreceptors employing such a structure, the photosensitive layer tends to peel off between the edges and the intermediate layer when a large number of copies are made, which eventually leads to cracking.
There is a concern that this may impede printing durability.

[Problem to be solved by the invention]

The present invention eliminates the above-mentioned inconveniences and concerns and provides an electrophotographic photoreceptor that provides excellent printing durability.

[Means for Solving the Problems] The present invention provides an intermediate layer, a charge generation layer (CGL) on a conductive substrate.
In an electrophotographic photoreceptor in which a charge transport layer (CTL) and a protective layer are sequentially laminated as necessary, the end surface of the intermediate layer is covered with the charge generation layer (in other words, the intermediate layer (all of which are covered with the charge generation layer).

As a result of various studies to achieve the above object, the inventors of the present invention focused on the significance of the existence of the middle class. That is, the intermediate layer is one of the resin layers, and this layer is intended to improve the charging property by preventing the opposite charge induced in the conductive substrate from being injected into the charge generation layer during electrification. be.

However, at low temperature and low humidity, if this intermediate layer is exposed at the edges, the residual potential will be high in the exposed areas, and the developer will adhere, resulting in background stains. Further, the efficiency of developer utilization is reduced, and furthermore, it becomes a cause for the developer to scatter. In addition, the residual potential of the intermediate portion (center portion of the photoreceptor) where the intermediate layer is covered with the charge generation layer and the charge transport layer is lower than that of the end portion where the intermediate layer is exposed. The reason for this is believed to be that the charge generation layer forming material permeates into the intermediate layer during formation of the charge generation layer.

These disadvantages can be avoided by covering the entire intermediate layer, including the edges, with a charge generation layer, thereby preventing the above-mentioned peeling and cracking.Furthermore, the residual potential at the edges of the photoreceptor can be kept low, resulting in a good You can now obtain images. The present invention has been made based on this knowledge.

The invention will be explained in more detail below with reference to the accompanying drawings.

1 and 2 are typical cross-sectional views of two sides of the electrophotographic photoreceptor according to the present invention. The leader line numbers attached here are the same as those in FIG. 3, and these conductive substrates 11,
Intermediate layer 12, photosensitive layer 13 (CGL131, CTL132
), and the material and thickness of the protection 814 are no different from those of conventionally known or used photoreceptors.

As is clear from FIGS. 1 and 2, in the photoreceptor of the present invention, the ends of the intermediate layer 12 are completely covered with the charge generation layer 131. Furthermore, preferably, the intermediate layer 1
The end of the charge transport M132 is located inside the end of the charge transport M132 (FIG. 1). By adopting such a structure (where the CGL 131 and CTL 132 overlap), a clear image forming area is created and a copying operation can be performed well.

〔Example〕

Parts here are by weight.

Example 1 The following intermediate layer coating solution was spray applied to the center of an AQ drum (conductive substrate) with an outer diameter of 80 mm outside the 10 mm of both ends of the drum, and dried by heating at 100° C. for 20 minutes to give a coating of about 0.5 mm.
Formed a middle layer with a thick voice.

(Intermediate layer coating solution) Alcohol-soluble nylon (manufactured by Toshi ■, CM-8000) 4
Part methanol 48 parts Butanol 48 parts Next, on the AQ drum on which the intermediate layer was formed, the charge generation layer coating solution shown below was spray applied to the center of the drum except for both ends of the drum, and dried by heating at 120°C for 20 minutes. A charge generation layer having a thickness of about 0.2 pm was formed.

(Charge generation layer coating solution) 5 parts of an azo pigment represented by the following structural formula and 160 parts of cyclohexanone were mixed in a ball mill for 72 hours to obtain a pigment dispersion, and then added to 100 parts of this pigment dispersion while stirring. 90 parts of cyclohexanol was additionally mixed to prepare a charge generation layer coating solution.

Subsequently, the following charge transport layer coating solution was spray-coated on the Afl drum on which the intermediate layer and the charge generation layer were formed, except for 13 mm from both ends of the drum, and dried by heating at 120°C for 1 hour to form a charge of approximately 25 mm. A transport layer was formed to obtain the electrophotographic photoreceptor of Example 1.

(Charge transport layer coating solution) Stilbene compound dibenzo 1 represented by the following structural formula
8 crowns 6 ether 0.03 parts tetrahydrofuran 46 parts cyclohexanone
46 parts Example 2 The electrophotographic photoreceptor of Example 2 was prepared in the same manner as in Example 1, except that the intermediate layer, charge generation layer, and charge transport layer were formed in the center at distances other than 14 mm, 10 mm, and 13 mm from both ends of the drum, respectively. did.

Comparative Example 1 The electrophotographic photoreceptor of Comparative Example 1 was prepared in the same manner as in Example 1, except that the intermediate layer, charge generation layer, and charge transport layer were formed in the center at a distance other than 10 mm, 12.5 mm, and 13 mm from both ends of the drum, respectively. did.

When these three types of electrophotographic photoreceptors (photoreceptor drums) were installed in a commercially available electrophotographic copying machine FT4820 (manufactured by Ricoh Co., Ltd.) filled with toner and copies were made, it was found that the photoreceptor drums of Examples 1 and 2 When using the photosensitive drum of Comparative Example 1, the image density was almost the same as the initial image even after 4,000 copies were made, but when the photosensitive drum of Comparative Example 1 was used, the image density began to decrease after about 3,500 copies. Further, when the photosensitive drum of Comparative Example 1 was used, toner scattering inside the copying machine was significant compared to when the photosensitive drums of Examples 1 and 2 were used.

〔Effect of the invention〕

(1) In the electrophotographic photoreceptor according to claim 1, the end of the intermediate layer is formed inside the end of the charge generation layer, and the intermediate layer is covered with a photoconductive charge generation layer. Therefore, the residual potential is small, and therefore the toner utilization efficiency is high and toner scattering within the copying machine is small.

(2) The electrophotographic photoreceptor described in claim 2 is the electrophotographic photoreceptor described in claim 1.
In addition to this effect, since the end of the charge transport layer is formed inside the end of the intermediate layer, the charge transport layer is less prone to peeling and cracking.

[Brief explanation of drawings]

1 and 2 are typical cross-sectional views of two sides of the electrophotographic photoreceptor according to the present invention. FIG. 3 is a sectional view of a comparative electrophotographic photoreceptor. 11... Conductive substrate 12... Intermediate layer 13... Photosensitive layer (131... Charge generation layer, 132... Charge transport layer)
14...Protective layer

Claims (2)

[Claims] (1) In an electrophotographic photoreceptor in which an intermediate layer, a charge generation layer, a charge transport layer, and a protective layer are sequentially laminated on a conductive substrate, the end surface of the intermediate layer is covered with the charge generation layer. An electrophotographic photoreceptor characterized by: (2) The electrophotographic photoreceptor according to claim 1, wherein the end portion of the charge transport layer is located inside the end portion of the intermediate layer.