JPH0473768A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To allow the execution of copying operations of many sheets as the film peeling and crazing from ends do not arise by providing a film thickness decremental part where the thickness of a photosensitive layer decreases from a central part side toward marginal ends on the outside of the image forming region of the photosensitive body. CONSTITUTION:The photosensitive layer 2 is provided via or with via an intermediate layer on a cylindrical conductive base body 1 and further a protective layer is provided at need thereon. The film thickness attenuating part where the thickness of the photosensitive layer 2 decreases from the central part side toward the marginal ends is provided on the outside of the image forming region of the photosensitive body. The film thickness attenuating rate of the photosensitive layer 2 is confined to <= 0.4%. This photosensitive body is formed by applying a photosensitive layer-forming liquid by spray coating onto the conductive base body 1 in the state of covering both ends of the base body with masking collars 3 having flares (skirts) toward one end, then by drying the coating. This photosensitive layer-forming means is applied to the formation of the intermediate layer and protective layer as well.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cylindrical electrophotographic photoreceptor, and more specifically, the film thickness of the photosensitive layer of a conductive substrate is adjusted to the extent that the thickness of the photosensitive layer on the outer edge of the image forming area (imaging area) is The present invention relates to an electrophotographic photoreceptor in which the attenuation is sloped toward the end.

[Conventional technology]

An electrophotographic photoreceptor (hereinafter sometimes abbreviated as "photoreceptor") is one in which a photosensitive layer is formed on a conductive substrate.
If necessary, an intermediate M (undercoat M) is provided between the conductive substrate and the photosensitive layer, and a protective layer is provided on the photosensitive layer, if necessary.

Incidentally, in commonly used organic photoreceptors, a photosensitive layer made of an organic photoconductive substance is formed on a conductive substrate. Conventionally, the methods for applying this organic photoconductive substance include the bead coating method (applied to sheets, seamless belts, etc.) and the dipping method (applied to drums, etc.). However, in recent years, a spray-only method has been used which allows for better adjustment of the thickness of the thin film. However, even with one spray method, the film thickness at the edges of sheets, belts, drums, etc. is either uniform or thicker than other coatings, and the coating is exposed at the edges. Cracks occur at the edges due to external force applied to the conductive substrate and expansion or contraction of the conductive substrate and coating film, and this also causes the photosensitive layer to peel or fall off from the conductive substrate intermediate layer. There are often disadvantages in that the life of the photoreceptor is significantly reduced.

However, in order to avoid these inconveniences, a 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. 1-51184). According to the photoreceptor prepared in this way, peeling of the film from the edges and occurrence of cracks can be considerably prevented, but there is a step between the photosensitive layer and the intermediate layer. Therefore, when the photoreceptor is used for a long time, it is unavoidable that the film will peel off or crack from this stepped portion.

[Problem to be solved by the invention]

The present invention prevents the above-mentioned film peeling even after long-term use.
An object of the present invention is to provide a cylindrical electrophotographic photoreceptor that does not cause problems such as cracks and has excellent printing durability.

[Means to solve the problem]

The present invention provides an electrophotographic photoreceptor in which a photosensitive layer is provided on a cylindrical conductive substrate with or without an intermediate layer, and a protective layer is further provided thereon as necessary. A thickness attenuation portion where the thickness of the photosensitive layer decreases from the center toward the edge is provided outside the image forming area of the photoreceptor, and the thickness attenuation rate of the photosensitive layer is 0.4% or less. It is characterized by the fact that

The "attenuation rate" here refers to the thickness of the photosensitive layer 2 in the image forming area as V (tile), as shown in FIG.
When the distance required to attenuate the thickness of the photosensitive layer in the non-imaging area (edge thickness attenuation distance) is 1° (ltm), V (thickness) x 100 (%) L (/J) It is calculated.

In addition, in the figure, 1 represents a conductive substrate.

To explain the present invention in more detail, the photoreceptor according to the present invention has a structure in which no steps are formed at both ends thereof, and the film thickness (1/) of the photosensitive layer and the attenuation distance of the photosensitive layer film thickness in the non-image forming area. H
Care has been taken to ensure that the ratio with (L) is within a certain range.

The film thickness (V) of the photosensitive layer in the image forming area C) naturally has electrophotographic characteristics, and is generally 10 to 40 μm, preferably 20 to 30 μm. The ratio (V/L) between the film thickness (V) and the end film thickness attenuation distance (L), that is, the film thickness attenuation rate, is 0.4% or less, preferably 0.133 to 0.4%, and Preferably it is about 0.2%. Film thickness (V) is 1
If the tones are less than 0 or more than 40, the characteristics of the electrophotographic photoreceptor will be significantly reduced, and if the film thickness attenuation rate is more than 0.4%, the effect on durability will be reduced. Film thickness attenuation rate is 0.1
If it is less than 33%, there will be unnecessary loss of non-image areas (non-image forming areas).

The conductive substrate 1 in the present invention is a sheet or drum made of a metal such as aluminum, nickel, or iron, or a paper or film-like plastic coated or vapor-deposited with a conductive substance.

The photosensitive layer 2 in the present invention is not particularly limited, but it is preferably organic based in order to form a thickness attenuating portion of the photosensitive layer near the end of the conductive substrate 1. The photoreceptor of the invention is advantageously of a functionally separated type in which the photosensitive layer 2 is composed of a charge generation layer and a charge transport layer.

As mentioned above, the photoreceptor of the present invention may be provided with an intermediate layer and/or a protective layer, if necessary. Even in such a type of photoreceptor, if the above-mentioned conditions are satisfied, it goes without saying that each layer existing in the non-image forming area on the conductive substrate is formed so as not to have a step difference.

In order to actually produce the photoreceptor of the present invention, as shown in FIG. Just spray it on and let it dry.

This photosensitive layer forming means is also applied to forming an intermediate layer and a protective layer.

〔Example〕

Next, examples and comparative examples will be shown.

Example 1 As shown in FIG. 2, a conductive substrate (an aluminum drum with a diameter of 80+ am and a length of 980 mm) 1 is supported horizontally, and a masking collar 3 is placed so that the tip of its skirt is connected to the conductive substrate 1. It was installed around the end of the conductive substrate 1 so that the distance (X) was Loam. In this state, conductive substrate 1
was rotated in the circumferential direction, and a spray gun (two-fluid automatic spray nozzle type; not shown) was set parallel to the axial direction of the conductive substrate 1 and scanned while spraying the photosensitive layer forming liquid.

The photosensitive layer thickness in the image forming area is about 30 pm, and the edge film thickness attenuation distance (1
7) to 10! Ill (film thickness attenuation rate: approx. 0.3%)
.

When the photoreceptor thus prepared was installed in a commercially available electrophotographic copying machine (Ricoh Co., Ltd., FV820) and its printing durability was examined, it was found that even after 50,000 sheets had been passed, there was no film peeling or cracking from the edges of the photoreceptor. was not seen.

Example 2 A photoreceptor was produced in the same manner as in Example 1, except that the distance (X) between the skirt tip of the masking collar and the conductive substrate was set to 38111111. In the obtained photoreceptor, the thickness of the photosensitive layer in the image forming area is about 30 tiles, and the end film thickness attenuation distance (I4) from about 30 pm to 0.7 m thick is about 40 fi.
lI11 (film thickness attenuation rate: approximately 0.079%).

The printing durability of this photoreceptor was examined in the same manner as in Example 1, and it was found to be good with no edge cracking even after 50,000 sheets were passed. However, since the film thickness attenuation portion does not contribute to image formation, it is not a good idea to make this portion long.

Comparative Example 1 A photoreceptor was produced in the same manner as in Example 1 except that no masking color was used. However, the thickness of the photosensitive layer in the image forming area is approximately 30
The end film thickness attenuation distance (L) from the film thickness of about 30 doors to the Opm thickness was about 3 mm (film thickness attenuation rate: about 1.0%).

When this comparative photoreceptor was tested for printing durability in the same manner as in Example 1, cracks were observed at the edges of the photoreceptor after 5,000 sheets were passed.

〔Effect of the invention〕

According to the electrophotographic photoreceptor of the present invention, since film peeling or cracking does not occur from the edges thereof, a large number of copies can be performed.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining the photoreceptor of the present invention. FIG. 2 shows a typical example of the means for producing the photoreceptor of the present invention, in which (a) is a sectional view thereof, and (b) is a perspective view thereof. 1... Conductive substrate 2... Photosensitive layer 3... Masking color patent applicant Rico Co., Ltd.

Claims (2)

[Claims] (1) An electrophotographic photoreceptor in which a photosensitive layer is provided on a cylindrical conductive substrate with or without an intermediate layer, and a protective layer is further provided thereon as necessary. A thickness attenuation portion where the thickness of the photosensitive layer decreases from the center toward the edge is provided outside the image forming area of the photoreceptor, and the thickness attenuation rate of the photosensitive layer is 0.4% or less. An electrophotographic photoreceptor characterized by: (2) The film thickness attenuation rate of the photosensitive layer outside the image forming area is 0
．． The electrophotographic photoreceptor according to claim 1, wherein the content is 133 to 0.4%.