JP2003215826A - Electrophotographic photoreceptor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent blade squaking under cleaning conditions under which the occurrence of a cleaning defect is averted even in the case the thickness of a conductive substrate is below 2.0 mm. <P>SOLUTION: The electrophotographic photoreceptor is formed by successively laminating a photoconductive layer 2, a first surface layer 3 which is regulated in dynamic indentation hardness to 220 to 400 kgf/mm<SP>2</SP>and a second surface layer 4 which is 0.95≤x<1.00 in an (x) value when an element ratio is expressed as composition formula a-Si<SB>1-</SB>XCX:H and is regulated in the dynamic indentation hardness on the free surface to 45 to 220 kgf/mm<SP>2</SP>on the conductive substrate 1 having a thickness of ≤2.0 mm. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member having a photoconductive layer and a surface layer made of hydrogenated amorphous silicon carbide laminated on a conductive substrate. . 2. Description of the Related Art An electrophotographic photosensitive member mounted on an image forming apparatus such as an electrophotographic copying machine or a printer has electrophotographic characteristics, that is, potential characteristics such as chargeability, photosensitivity, and residual potential. It has good image characteristics such as image density, resolution, contrast, gradation, etc., and also has excellent stability and durability such as abrasion resistance, printing durability, environmental resistance, and chemical resistance. Desired. In order to realize such excellent characteristics, the surface layer formed on the photoconductive layer plays a large role. Various materials and layer configurations have been proposed for the surface layer, and amorphous silicon-based materials, particularly hydrogenated amorphous silicon carbide containing carbon (C) (hereinafter referred to as hydrogenated amorphous silicon), have been proposed. The surface layer using silicon carbide (abbreviated as a-SiC: H) has excellent electrical characteristics, optical characteristics, image characteristics,
Attention has been paid to its durability and the like based on high hardness. Further, an a-SiC surface layer and an amorphous silicon-based photoconductive layer (hereinafter, amorphous silicon is referred to as a-Si
The electrophotographic photosensitive member in combination with the above has already been put to practical use. An electrophotographic photosensitive member having a-SiC: H is mounted on an electrophotographic apparatus, and particularly when printing is performed in a high humidity environment, an image defect often referred to as image deletion occurs. However, there is a problem in that a heater is used to heat the photoreceptor to disperse the moisture adsorbed on the surface layer, and that the carbon in the surface layer is disclosed in Japanese Patent Application Laid-Open No. 9-204056. By setting the atomic concentration, dynamic indentation hardness, surface roughness, etc. of silicon and silicon within predetermined ranges, a technology to prevent image deletion at low cost without using a heater has been proposed and put into practical use. I have. According to the electrophotographic photoreceptor disclosed in Japanese Patent Application Laid-Open No. 9-204056, the atomic concentration of carbon and silicon in the surface layer is determined.
The dynamic indentation hardness, surface roughness, and the like are set within a predetermined range, and the thickness of the conductive substrate used therein is 2.5 to 5.0 mm. [0006] However, the use of such a thickened substrate has increased the material cost, thereby increasing the cost of the photoreceptor itself. Further, in the a-Si type photoreceptor, the heat capacity of the photoreceptor using a thick substrate increases, and the dew condensation of the photoreceptor caused by the photoreceptor causes the surface of the photoreceptor to cause image deletion. This has also caused the opportunity for moisture adsorption to the surface. Therefore, in order to solve such a problem, for example, an electrophotographic photosensitive member having a substrate thickness reduced to 0.75 to 2.0 mm was manufactured and mounted on an electrophotographic apparatus. Friction between the cleaning blade and the photoreceptor surface resonates with the photoreceptor itself, and a phenomenon called blade squeal has occurred. This blade squeal occurs when the thickness of the conductive substrate is about 1.0 mm, and the coefficient of friction between the cleaning blade and the surface of the photoreceptor is large.
While generating an unpleasant sound when driving the electrophotographic device,
Very serious problems, such as poor cleaning or damage to the cleaning blade, may be induced. Therefore, in the conventional a-Si-based photoconductor, the thickness of the conductive substrate is set to about 2.5 mm or more. Accordingly, it is an object of the present invention to provide a low-cost and highly durable electrophotographic photoreceptor by reducing friction between a surface layer and a cleaning blade, thereby eliminating blade squeal. The electrophotographic photoreceptor of the present invention comprises a photoconductive layer and a surface layer made of hydrogenated amorphous silicon carbide which are sequentially laminated on a conductive substrate having a thickness of 2.0 mm or less. The surface layer was composed of a first surface layer having a dynamic indentation hardness of 220 to 400 kgf / mm ² and an element ratio represented by a composition formula a-Si _1-X C _X : H. Sometimes the x value is 0.95 ≦ x <1.00, and the dynamic indentation hardness of the free surface is 45-220 kgf /
It is characterized by being sequentially laminated with a second surface layer defined in mm ² . DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A typical layer structure of an electrophotographic photoreceptor of the present invention is shown in FIGS. In FIG. 1, 1 is a conductive substrate, 2 is a photoconductive layer, 3 is a first surface layer, and 4 is a second surface layer. In FIG. 2, a carrier injection blocking layer 5 made of an a-Si-based material is further formed on conductive substrate 1.
Is provided. According to the present invention, the thickness of the conductive substrate 1 is 2.0 mm or less. The thickness of the conductive substrate 1 is desirably 0.75 mm or more from the viewpoint of mechanical dimensional accuracy. However, an increase in the thickness of the substrate directly leads to an increase in cost, and a thinner substrate in terms of providing a heat capacity to prevent dew condensation. Is preferable, preferably 0.75 to 2.0 mm, and most preferably 1.0 to 2.0 mm.
It is good to be 1.5 mm. The conductive substrate 1 is made of aluminum (A).
l) or SUS ・ Zn ・ Cu ・ Fe ・ Ti ・ Ni ・
Any of the above-mentioned metals, ITO, and SnO on the surface of a conductive member such as a metal material such as Cr, Ta, Sn, Au, or Ag or an alloy material thereof, or an insulator such as a resin, glass, or ceramic.
A conductive film formed of a transparent conductive material such as ₂ by vapor deposition or the like and subjected to a conductive treatment is used. Above all, Al
When an alloy is used, the cost can be reduced and the weight can be reduced. In addition, when an a-Si-based material is used for the photoconductive layer 2 and a carrier injection blocking layer to be described later, the adhesion to those layers is increased. And the reliability is improved. The photoconductive layer 2 is made of a-Si or a
A-Se system, such as -Se or _{Se-Te · As 2 Se 3} , or Group II-VI compounds such as ZnO · CdS · CdSe, even more, they were granulated, it was dispersed resin, and, OPC A photoreceptor material such as a system can also be used. Above all, a-Si or a-SiC
When an a-Si material of an alloy to which N, O, etc. is added is used, excellent electrophotographic properties such as high photoconductive properties, high-speed response, repetition stability, heat resistance, and durability can be stably obtained. ,
Further, it is preferable in that it has excellent compatibility with the a-Si: H surface layers 3 and 4. Such a-Si-based materials include a-Si.a
-SiC.a-SiN.a-SiO.a-SiGe.a
-SiCN ・ a-SiNO ・ a-SiCO ・ a-SiC
NO and the like. These are formed by glow discharge decomposition method, various sputtering methods, various evaporation methods, ECR method, optical CVD method, catalytic CVD method, reactive evaporation method, and the like. Hydrogen (H) and a halogen element (F · Cl) are contained in the film in an amount of 1 to 40 atomic%. In addition, in order to obtain desired characteristics such as electrical properties such as dark conductivity and photoconductivity of each layer and optical band gaps, the periodic table II.
Group Ia elements (hereinafter abbreviated as IIIa elements) and Va group elements (hereinafter abbreviated as Va group elements), C.N.
The above properties are adjusted by adjusting the content of elements such as O. It is said that boron (B) and phosphorus (P), as the above-mentioned IIIa group element and Va group element, respectively, are excellent in covalent bondability and can change semiconductor characteristics sensitively, so that excellent photosensitivity can be obtained. Desirable in point. And C
When containing together with an element such as N.O, the group IIIa element is preferably 0.1 to 20,000 ppm, the group Va element is preferably 0.1 to 10,000 ppm, and C.N.O.
In the case where elements such as the above are not contained or are contained in trace amounts, it is preferred that the group IIIa element be contained in 0.01 to 200 ppm and the group Va element be contained in 0.01 to 100 ppm. These elements may be provided with a gradient in the thickness direction of the layer, in which case the average content of the entire layer may be within the above range. Further, the a-Si-based material may include microcrystalline silicon (μc-Si). When the a-Si-based material includes the μc-Si, the dark / photoconductivity can be increased. There is an advantage that the degree of freedom in designing the conductive layer 2 is increased.
Such μc-Si can be formed by employing the same forming method as described above and changing the film forming conditions. For example, in the glow discharge decomposition method, it can be formed by setting the substrate temperature and the high-frequency power to be higher and increasing the flow rate of hydrogen as a diluent gas. Further, even when μc-Si is contained, the same impurity element as described above may be added. The thickness of the photoconductive layer 2 is appropriately set according to the photoconductive material used and desired electrophotographic characteristics.
When an a-Si material is used, it is usually 5 to 100 μm.
m, preferably 10 to 80 μm. The first surface layer 3 is made of a-SiC: H and has a dynamic indentation hardness of 220 to 400 kgf.
/ Mm ^2, and the second surface layer 4 is also made of a-SiC: H. The dynamic indentation hardness of the first surface layer 3 is 2
20 to 400 kgf / mm ² , preferably 250 to 380
kgf / mm ² , optimally 300-350 kgf / mm ²
To The dynamic indentation hardness of the first surface layer 3 is 40
By setting the pressure to 0 kgf / mm ² or less, the frictional force between the surface of the photoconductor and the cleaning blade can be reduced, thereby preventing the friction between the blade and the surface of the photoconductor and a phenomenon called blade squealing in which the photoconductor itself resonates. On the other hand, by setting the dynamic indentation hardness of the first surface layer 3 to 220 kgf / mm ² or more, it is possible to prevent a remarkable decrease in the film forming rate on the first surface layer. The thickness of the first surface layer 3 is 0.5 to
Desirably, the thickness is 1.0 μm, whereby a high film strength is obtained. For example, it may be set to 0.8 μm. When the film thickness of the first surface layer 3 is less than 0.5 μm, the film strength is weakened, and film peeling may occur. When the film thickness exceeds 1.0 μm, a remarkable increase in the residual potential is caused. May be invited. However, in the present invention, the thickness of the first surface layer 3 is set to 0.5 to 1.
The thickness is not limited to 0 μm, and may be outside the range depending on other layer configurations. The second surface layer 4 has an x value of 0.95 when the element ratio is represented by a composition formula a-Si ₁ -x C _x : H.
≦ x <1.00, and the dynamic indentation hardness of the free surface is in 45~220kgf / mm ^2. With such a configuration, it is possible to provide an electrophotographic photoreceptor that does not cause image deletion even when printing is performed in a high-humidity environment under conditions in which the photoreceptor is not heated. The dynamic indentation hardness is such that the film thickness is 10 μm.
It is an effective hardness evaluation method for evaluating the following thin films,
A test weight is applied to the surface of the thin film with a triangular pyramid indenter,
The hardness is obtained by measuring the indentation depth of the indenter at that time and further calculating it. In the present invention, a micro hardness tester DUH-201 manufactured by Shimadzu Corporation was used. Thus, according to the electrophotographic photoreceptor of the present invention, a photoconductive layer 2 and a dynamic indentation hardness of 220 to 400 kgf / mm ² are formed on a conductive substrate 1 having a thickness of 2.0 mm or less.
The first surface layer 3 defined in the formula (1) and the element ratio are defined by a composition formula aS
i _1-X C _X : When expressed as H, the x value is 0.95 ≦ x <1.
00 and the dynamic indentation hardness of the free surface is 45-45.
By successively laminating the second surface layer 4 defined at 220 kgf / mm ² , friction with the cleaning blade was reduced, thereby eliminating blade squeal and further achieving low cost and high durability characteristics. Next, embodiments of the present invention will be described. (Example 1) The conductive substrate 1 is made of an aluminum alloy and has an outer diameter of 30 mm, a length of 254 mm, and a thickness of 1.
5 mm and 1.0 mm drawn pipes were prepared by mirror-finishing the outer peripheral surfaces of the drawn pipes, and were set in a glow discharge decomposition apparatus. The carrier injection blocking layer 5 and the photoconductive layer were deposited under the film forming conditions shown in Table 1. The layer 2, the first surface layer 3, and the second surface layer 4 are sequentially laminated to form a photoconductor A, as shown in FIG.
B and C were produced. These three types of photoconductors A, B and C are shown in Table 1.
As shown in the figure, the conditions for forming the first surface layer were changed. As comparative examples, as shown in Table 1, electrophotographic photosensitive members D (conductive substrate thickness 2.5 mm), E (conductive substrate thickness 1.5 mm), and F (conductive substrate thickness) 1.0
mm). [Table 1] Then, a sample of the first surface layer 3 was prepared for the photoconductors A, B, and D under the same conditions, and a part of the sample was cut into 5 mm squares, and each component was subjected to XPS analysis (X-ray photoelectron Analysis), and for each sample,
The dynamic indentation hardness is measured using a micro hardness tester (DU, manufactured by Shimadzu Corporation).
H-201), the results shown in Table 2 were obtained. [Table 2] Next, the photosensitive members A, B, C, D, E,
F was evaluated for the frictional force with the cleaning blade using a friction evaluation device, and the results shown in Table 3 were obtained. The friction evaluation apparatus used was an electrophotographic apparatus provided with only a photosensitive member and a cleaning blade. Specifically, an electrophotographic printer (FS-1 made by Kyocera)
750), in an apparatus excluding a primary charger, an exposure unit, a developing unit, a transfer unit, and a cleaning roller,
The drive motor of the photoreceptor (24V DC rated)
By applying a constant voltage of V and measuring the current flowing into the motor, the power required to drive the photoconductor, that is, the frictional force between the photoconductor and the cleaning blade was measured. [Table 3] Further, the photosensitive members A, B, C, D, E,
F was mounted on an electrophotographic printer (FS-1750 manufactured by Kyocera) to evaluate blade squeal. In this evaluation, when the pressing pressure of the blade is set to a value higher than that of the ordinary condition under the conventional condition,
The test was performed under three kinds of conditions in the case of weakness, and the influence on the electrophotographic apparatus side was also evaluated. Further, when the cleaning force was made weaker than usual by reducing the pressing pressure of the blade, a cleaning failure in which the toner on the drum could not be sufficiently cleaned occurred.
Shown in The criteria for blade squeal and cleaning properties were as follows. The evaluation criteria of blade squeal are classified into three stages.
The mark indicates that slight blade squealing occurred at the start and stop of driving, but was within an allowable range that would not hinder practical use, and the cross indicates that blade squealing occurred at the time of driving and hindered practically. The evaluation criteria for the cleaning performance are classified into two stages. The mark ○ indicates that no cleaning failure occurred, and the mark x indicates the case where cleaning failure occurred. [Table 4] As is apparent from the above results, by setting the dynamic indentation hardness of the first surface layer 3 to 400 kgf / mm ² or less, the frictional force between the photosensitive member surface and the cleaning blade can be reduced. The thickness of the conductive substrate is set to 1.
Even when the thickness is 5 mm or 1.0 mm, the blade squeal phenomenon can be prevented under the cleaning condition in which the cleaning failure does not occur as in the case of the thickness of 2.5 mm. (Example 2) In the same manner as in (Example 1), when producing the electrophotographic photosensitive member of the present invention, the thickness of the conductive substrate 1 was set to 1.5 mm, and the film thickness of the first surface layer 3 was changed. ,
As shown in Table 5, the H ₂ gas flow rate was changed in various ways,
While diluting the gas, changing the flow rates of SiH ₄ and CH ₄ , photoconductors G, H,
I, J, K, and L were prepared, and each photoconductor G was prepared in the same manner as in (Example 1).
When the frictional force between L and the cleaning blade was evaluated, the results in Table 5 were obtained. The evaluation of blade squeal cleaning properties was performed in the same manner as in (Example 1). The results shown in Table 6 were obtained. [Table 5] [Table 6] As is apparent from the above results, by setting the dynamic indentation hardness of the first surface layer 3 to 400 kgf / mm ² or less, the frictional force between the photosensitive member surface and the cleaning blade can be reduced. In addition, the blade squeal phenomenon could be prevented under cleaning conditions that do not cause cleaning failure. As described above, according to the present invention, by setting the dynamic indentation hardness of the first surface layer to 400 kgf / mm ² or less, the frictional force between the surface of the photosensitive member and the cleaning blade is reduced. Can be reduced, and the thickness of the conductive substrate can be reduced.
Even under the condition of 0 mm or less, the blade squealing phenomenon can be prevented under the cleaning condition that does not cause the cleaning failure, and the electrophotographic photoreceptor having low cost and high durability can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view showing a layer structure of an electrophotographic photosensitive member of the present invention. FIG. 2 is a cross-sectional view illustrating another layer configuration of the electrophotographic photosensitive member of the present invention. [Description of Signs] 1 conductive substrate 2 photoconductive layer 3 first surface layer 4 second surface layer 5 carrier injection blocking layer

Claims (1)

1. An electrophotographic photoreceptor comprising a photoconductive layer and a surface layer made of hydrogenated amorphous silicon carbide sequentially laminated on a conductive substrate having a thickness of 2.0 mm or less,
The surface layer has a dynamic indentation hardness of 220 to 400 kg.
When the first surface layer defined as f / mm ² and the element ratio are represented by the composition formula a-Si _1-x C _x : H, the x value is 0.95 ≦
An electrophotographic photoreceptor comprising: x <1.00; and a second surface layer having a free surface having a dynamic indentation hardness of 45 to 220 kgf / mm ² , which is sequentially laminated.