JPH02253268A - Substrate for organic photosensitive body - Google Patents

Abstract

PURPOSE:To enhance adhesiveness between a substrate and a photosensitive layer, thin line reproducibility, image density, and gradation by adjusting the surface roughness of the coating surface of an organic photosensitive layer to a specified value. CONSTITUTION:The surface roughness Rmax of the substrate of this organic photosensitive body is set to about 0.5 - 2mum, and when its surface has such a roughness, the photosensitive layer formed by coating is prevented from peeling, and fine edge parts are formed on the surface of the photosensitive layer, when it is formed by coating, by a little roughening the surface of the substrate, thus permitting the toner to be liable to be caught, not to drop off, and to form an image uniform in density. Such a surface roughness can be sufficiently attained by working using an inexpensive sintered diamond cutting tool.

Description

DETAILED DESCRIPTION OF THE INVENTION (Al Industrial Application Field) This invention relates to improvements in conductive substrates for organic photoreceptors such as electrophotographic copying machines and laser printers.

(b) Prior Art Organic photoreceptors used in electrophotographic copying machines and the like are formed by coating a photoconductive material (photosensitive layer) on the surface of a photoreceptor base made of aluminum or the like. When forming such an organic photoreceptor, generally speaking, the smaller the surface roughness of the photoreceptor substrate (the smoother the surface), the better the surface precision of the photosensitive layer will be, and the higher the quality of the image obtained during image formation. It is assumed that For this reason, the surface of the photoreceptor substrate has conventionally been subjected to ultra-precision processing with extremely high precision, such as electrolytic polishing and surface cutting using a natural diamond bite.

(C1 Problem to be Solved by the Invention) However, in conventional organic photoreceptors, the coated photosensitive layer sometimes peels off, causing pinholes, uneven coating, etc., and reducing the yield of the photoreceptor.

In addition, as mentioned above, electrolytic polishing is used to process the surface of the photoreceptor substrate.
When performing ultra-precision machining such as cutting using a natural diamond bite, there is a problem in that the machining cost increases.

An object of the present invention is to provide an organic photoreceptor substrate whose surface precision is roughened within a permissible range, thereby preventing peeling of the photosensitive layer and reducing processing costs.

(Means for solving the d1 problem) When performing ultra-precision machining using conventional electrolytic polishing and a natural diamond bite, the surface roughness of the photoreceptor substrate Rma
x becomes a very flat state of about 0.05 to 0.1 μm. Conventionally, it has been thought that such high-precision processing is necessary to improve the surface precision of the photoreceptor itself (the photoreceptor as a product coated with a photosensitive layer). However, the inventors of the present invention focused on the possibility that this high-precision processing might actually cause the photoreceptor layer to peel off, etc., and conducted extensive studies.
The organic photoreceptor substrate of the present invention is characterized in that the surface roughness Raax of the organic photoreceptor N coated surface is approximately 0.5 to 2 μm.

(81 action) The organic photoreceptor substrate of this invention has a surface roughness Rmax of 0°5.
It is set to about ~2 μm, and if the substrate surface is this rough, the coated photosensitive layer will not peel off. Minute edges are formed on the surface,
This makes it easier to trap toner. Therefore, toner drop-off is eliminated and images with uniform density can be obtained.

In addition, if the surface roughness is at this level, processing using an inexpensive sintered diamond cutting tool can be sufficient.

(f) Example Electrophotographic copying machines generally have a cylindrical shape. , a human body is used, and in this embodiment, a cylindrical organic photoreceptor will be explained as an example. The surface of a cylindrical organic photoreceptor substrate (diameter 801 m, length 340 m) made of a conductive substrate such as aluminum is processed by lathe processing using a cutting tool. At this time, the surface roughness of the photoreceptor substrate changes by changing the rotational speed of the substrate, the feeding speed of the cutting tool, the type of cutting tool, etc. FIG. 1 is a diagram showing the correspondence between sample roughness and surface roughness RmaX of the formed photoreceptor substrate.

In the figure, sample Arashi 1 is a conventional photoreceptor substrate that has been processed with high precision using a natural diamond tool. Further, sample blocks 2 to 4 are photoreceptor substrates corresponding to this embodiment, and sample hole 5 is a photoreceptor substrate with rough surface precision, which is processed using an inexpensive sintered diamond cutting tool. At this time, the surface roughness can be changed as shown in Figures 1 to 5 by adjusting the rotational speed of the base, the feeding speed of the cutting tool, etc.

A photosensitive layer was applied to the surface of photoreceptor substrates 1 to 5 which had undergone such processing. The photosensitive layer generally consists of a charge generation layer and a charge transport layer. A photoreceptor substrate whose surface has been treated is immersed in a coating solution for the charge generation layer, then pulled up and dried, and then the photoreceptor substrate is charged. It is formed by immersing it in the coating liquid of the transport layer and pulling it out to dry it. The coating liquid for the charge generation layer and the coating liquid for the charge transport layer are as follows, for example.

Charge generation layer coating solution (1) 1 part by weight of polycarbonate resin is dissolved in 100 parts by weight of dicolethane, and 2 parts by weight of dibrom anthurone is added to the solution. This was milled in a ball mill.
Mix over time.

■ 1 part by weight of polyester resin, 5 parts by weight of tetrahydrofuran
2 parts by weight of half-type phthalocyanine was added to 0 parts by weight of the solution and mixed for 8 hours in a ball mill.

Coating liquid for charge transport layer: 1 part by weight of a hydrazone charge transport material (for example, "ABPH" manufactured by Anan Koryo) and 1 part by weight of a polycarbonate resin are dissolved in 8 parts by weight of dichloroethane.

To actually form a photosensitive layer using such a coating solution, for example, the photoreceptor substrate is immersed in the charge generation layer coating solution (2) to form a charge generation layer, then pulled out and dried at 80°C for 230 minutes. I do. The thickness of the charge generation layer depends on the immersion time. In this case II! The immersion treatment is performed so that the thickness becomes 0.45 μm (after drying).

After the charge generation layer is formed in this way, a charge transport layer is formed by immersing it in a charge transport M coating solution, and the film is pulled up and dried at 70° C. for 1 hour. Note that the dipping is performed so that the thickness of the charge transport layer after drying is 15 μm.

By dipping into such a coating layer, ll&lf~5
A photosensitive layer was formed on each of the photoreceptor substrates. As a result, for the photoreceptor substrates with roughened surface roughness of N12 and above, the adhesion of the photosensitive layer was improved, and there was almost no peeling off, and the yield of the photoreceptor could be increased. In addition, image forming experiments using these photoreceptors revealed that the N12 to N4 photoreceptors improved image quality by reducing fine line reproducibility and solid area density variation (density uniformity, two-tone gradation, There were effects such as improvement in This is thought to be because the surface of the photoreceptor substrate becomes slightly rough, resulting in the formation of minute edges on the surface of the photosensitive layer, which tend to trap toner. FIG. 2 shows the results of copying the electrophotographic society chart and measuring the image density of the solid portion of the formed image using a Macbeth densitometer. Note that the number of measurement points is 20. The surface roughness Rmax of the photoreceptor substrate is 0.5
Images formed with a photoreceptor in the range of ~2 μm (N12 to N4) yielded good results in both density and resolution.

Further, when a 0.51 degree halftone chart was copied using these photoreceptors, vertical stripes appeared in the positive 5 sample. This means that the surface roughness Rtaax is 2
It is believed that if it exceeds .mu.m, the edges of the surface of the photosensitive layer will become rough and the toner distribution in the latent image will become too pronounced due to the edge effect, and this is not suitable for practical use.

In addition, when using the charge generation layer coating liquid shown in (2), the layer thickness after drying is 0.4 μm, and drying is performed at 70° C. for 1 hour. Thereafter, the charge transport layer is laminated by immersing it in the charge transport layer coating solution in the same manner as in the above example. Even when this coating liquid is used, the surface roughness R of the photoreceptor substrate is
When the taax was in the range of approximately 0.5 to 2 pm, the yield of the photoreceptor could be increased, and the quality of the formed images was improved.

(g) Effects of the invention As described above, in this invention, by setting the surface roughness Rmax to approximately 0.5 to 2 μm, the adhesion between the substrate and the photosensitive layer is improved and the yield of the photoreceptor is increased. At the same time, the fine edge portions formed on the surface of the photosensitive layer make it easier to capture toner, resulting in the advantage of improved fine line reproducibility, two image areas, and one gradation. In addition, there is an advantage that processing costs can be reduced by roughening the processing accuracy of the photoreceptor substrate (see Figure 1).

[Brief explanation of drawings]

Figure 1 is a diagram showing the correspondence between the surface roughness of the photoreceptor base and sample ridges, and Figure 2 is an image evaluation when images are formed using photoreceptors formed from the photoreceptor base of each sample level. FIG.

Claims (1)

[Claims] (1) An organic photoreceptor substrate made of a conductive material and coated with an organic photosensitive layer on the surface, wherein the surface roughness Rmax of the surface coated with the organic photosensitive layer is approximately 0.5.
An organic photoreceptor substrate characterized in that it has a thickness of ~2 μm.