JPH05323645A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain a stable potential without defects in picture images by satisfying a specified relation between the surface roughness of a conductive base body and the thickness of a base coating layer. CONSTITUTION:This photosensitive body has a conductive base body 1, base coating layer 2, and photosensitive layer 3. The base coating layer 2 and photosensitive layer 3 are successively formed on the conductive base body 1. The surface roughness Rmax of the conductive base body 1 and the thickness L of the base coating layer satisfy the relation of Rmax/L<=4. The base coating layer 2 consists of a resin essentially consisting of copolymer polyamide or a resin consisting of copolymer polyamide and methoxymethylated nylon with the weight ratio ranging from 2:8 to 4:6 of the copolymer polyamide to methoxymethylated nylon. Thereby, by satisfying the relation of Rmax/L<4, image defect can be prevented and high stability of the potential is obtd. By forming the base coating layer 2 of the resin essentially consisting of copolymer polyamide or copolymer polyamide and methoxymethylated nylon, the obtd. photosensitive body has higher stability against environmental changes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoreceptor, and more particularly to a conductive substrate and an undercoat layer for an electrophotographic photoreceptor.

[0002]

2. Description of the Related Art In electrophotography according to the invention of Carlson, a photoreceptor using an inorganic photoconductive substance such as selenium, zinc oxide, and cadmium sulfide has been used. However, recently, a photoreceptor using an organic photoconductive substance has been attracting attention and being actively developed from the viewpoints of flexibility, lightness, productivity, and the like. Among them, the multi-layer organic electrophotographic photoreceptor having the function-separated charge generating layer for generating charges and the charge transporting layer for transferring charges can significantly improve the sensitivity.
It is expected that it will become the mainstream of future development of electrophotographic photoconductors because it is possible to select materials with various spectral sensitivities depending on the wavelength of the light source. These photoconductors are used in various devices such as copiers, laser beam printers, light emitting diode printers, and facsimiles.

The charge generation layer of a multi-layer type organic electrophotographic photoreceptor is generally formed to have an extremely thin film thickness and is provided on a conductive substrate. Therefore, if the conductive substrate has stains, scratches, irregularities, etc., these cause uneven film thickness of the charge generation layer and coating unevenness, resulting in image defects such as white spots, black spots, and density unevenness of the photoreceptor. In order to remove such surface defects on the conductive substrate, improvement of cleaning conditions and improvement of surface polishing have been carried out.

However, in a laser printer using laser light as a light source, interference fringes are generated due to the coherence of the laser light. Roughening of the surface of the conductive substrate is effective for preventing interference fringes, and it is known that the laser light that has passed through the charge generation layer and reaches the surface of the conductive substrate is diffusely reflected to prevent interference of the laser light. ing. However, such a method of intentionally forming irregularities on the surface of the conductive substrate is likely to cause many image defects such as white spots and black spots on the photoconductor for the laser printer, and is one of the major causes of the decrease in yield in the photoconductor production. It has become one.

Therefore, the surface of the conductive substrate having dirt, scratches, irregularities or the like, or the surface of the conductive substrate which has been roughened in advance such as a laser printer is covered with a transparent undercoating layer to hide defects on the surface of the conductive substrate. Attempts are being made. For the undercoat layer, a resin having a relatively low electric resistance such as polyamide, nylon or polyether is used.

[0006]

However, in the photoconductor using the conventional undercoat layer as described above, the thickness of the undercoat layer is not controlled to the optimum value with respect to the surface roughness of the conductive substrate, and thus the image is not formed. There is a problem that defects are generated and a more stable potential cannot be held. Furthermore, in the conventionally used undercoat layer resin, the resistance changes with changes in temperature and humidity, so there is also the problem that stable photoreceptor performance cannot be maintained against a wide range of environmental condition changes from low temperature low humidity to high temperature high humidity. there were.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and an object thereof is to provide an electrophotographic photoreceptor for which a stable potential can be obtained without image defects by improving the undercoat layer. Another object of the present invention is to provide an electrophotographic photosensitive member which is capable of obtaining a stable potential without image defects even with environmental changes by improving the undercoat layer.

[0008]

According to the present invention, the above object has a conductive substrate, an undercoat layer and a photosensitive layer, and the undercoat layer and the photosensitive layer are sequentially laminated on the conductive substrate. The conductive substrate has a surface roughness Rmax, and the undercoat layer has a thickness L. At this time, Rmax and L satisfy the following equation Rmax / L≤4.

The undercoat layer is a resin mainly composed of copolyamide, or is composed of copolyamide and methoxymethylated nylon, and the weight ratio of the two is 2/8 to 4/6 of copolyamide / methoxymethylated nylon. Resins in the range are used.

[0010]

When the relationship of Rmax / L≤4 is established, image defects are eliminated and the potential stability is improved. Further, the undercoat layer is a resin mainly composed of copolyamide, or composed of copolyamide and methoxymethylated nylon, and a weight ratio of the both,
2/8 of copolyamide / methoxymethylated nylon
If it is made of a resin in the range of 4/6, the stability of the photoreceptor against environmental changes is increased.

[0011]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a sectional view showing an electrophotographic photoreceptor according to an embodiment of the present invention. An undercoat layer 2, a charge generation layer 3, and a charge transport layer 4 are sequentially laminated on a conductive substrate 1. The surface roughness Rmax of the conductive substrate 1 is set in the range of 0.5 μm to 1,2 μm by cutting and finishing the surface of a cylindrical aluminum substrate.

The undercoat layer comprises 5 parts by weight of copolyamide or 5 parts by weight of a resin having a copolyamide / methoxymethylated nylon weight ratio in the range of 1/4 to 2/3, 66 parts by weight of methanol and n-butanol. It is dissolved in 29 parts by weight and applied onto the above conductive substrate. The charge generation layer 3 is made of polyester resin in dichloromethane at a ratio of 1:10.
It was prepared by applying a coating liquid in which X-type metal-free phthalocyanine was mixed and dispersed to a mixture of 0 weight ratio.

The charge transport layer 4 comprises 1 part by weight of a hydrazone derivative, 1 part by weight of a polycarbonate resin, and 9 parts of dichloromethane.
A coating solution prepared by mixing and dispersing parts by weight was used and prepared by coating on the charge generation layer. Table 1 shows the characteristics of the electrophotographic photoreceptor using the copolyamide resin as the undercoat layer. R
When the relationship of max / L ≦ 4 is established, image defects disappear,
It can be seen that the stability of the potential is increased. The above relationship corresponds to the case where the film thickness L of the undercoat layer is 0.3 μm or more.

Tables 2 and 3 show the characteristics of electrophotographic photoreceptors using a mixed resin of copolymerized polyamide and methoxymethylated nylon as the undercoat layer. A resin in which the relationship of Rmax / L≤4 is satisfied and the copolyamide / methoxymethylated nylon is in the range of 2/8 to 4/6 is used for the undercoat layer. It can be seen that a stable electric potential and a good image are brought about.

[0015]

[Table 1] The Rmax (μm) was measured using a surface roughness meter, and the thickness of the undercoat layer was measured using a reflected light analyzer.

[0016]

[Table 2]

[0017]

[Table 3] Environmental tests were conducted with the photoconductor at 5 ° C and relative humidity of 30% or 35%.
It was left for 24 hours in an environment of ° C and relative humidity of 85%, and then the potential was measured and the image was evaluated to examine the variation from the initial value. For the potential measurement, a potential probe was used to measure the dark potential and the bright potential.

[0018]

According to the present invention, a conductive substrate, an undercoat layer and a photosensitive layer are provided, and an undercoat layer and a photosensitive layer are sequentially laminated on the conductive substrate, and the conductive substrate has its surface. Roughness is Rma
x, and the undercoat layer has a thickness L, where R
Since max and L satisfy the following formula Rmax / L ≦ 4, an electrophotographic photoreceptor having no image defect and excellent potential stability can be obtained. The undercoat layer is composed of a resin mainly composed of copolyamide, or is composed of copolyamide and methoxymethylated nylon, and the weight ratio of both is within the range of 2/8 to 4/6 for copolyamide / methoxymethylated nylon. When a certain resin is used, an electrophotographic photoreceptor having excellent stability against environmental changes can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing an electrophotographic photoreceptor according to an embodiment of the present invention.

[Explanation of symbols]

 1 Conductive Substrate 2 Undercoat Layer 3 Charge Generation Layer 4 Charge Transport Layer

Claims (3)

[Claims] 1. A conductive substrate, an undercoat layer, and a photosensitive layer, wherein an undercoat layer and a photosensitive layer are sequentially laminated on the conductive substrate, and the conductive substrate has a surface roughness Rmax. The undercoat layer has a thickness of L, and at this time, Rmax and L satisfy the following formula: Rmax / L ≦ 4. 2. The electrophotographic photosensitive member according to claim 1, wherein the undercoat layer is mainly composed of a copolyamide. 3. The electrophotographic photosensitive member according to claim 1, wherein the undercoat layer comprises a copolyamide and methoxymethylated nylon, and the weight ratio of the two is: copolyamide /
A photoreceptor for electrophotography, characterized in that methoxymethylated nylon is in the range of 2/8 to 4/6.