JPH03288862A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To suppress a fluctuation to a low level even in terms of an environmental fluctuation and durability and to obtain always stable images of a high contrast by using a diamond-like thin film of an amorphous structure as an intermediate layer to be provided between the conductive base body and charge generating layer of the electrophotographic sensitive body. CONSTITUTION:This photosensitive body has the conductive base body 1, a conductive layer 2, the diamond-like thin film 3 of the amorphous structure to be used as UCL, the charge generating layer (CGL) 4 and a charge transfer layer (CTL) 5. The formation of a photosensitive layer 4 on a base is facilitated by using the amorphous diamond layer (diamond-like thin film 3 of the amorphous structure) as the intermediate layer 3 (UCL) to be provided between the conductive base 1 and photosensitive layer 4 of the electrophotographic sensitive body. Further, the easy control of the volumetric resistance to about 10<12>OMEGA.cm is possible and since the color is black, interference fringes is prevented in exposing using a laser beam. The ideal intermediate layer which is excellent in environmental stability is obtd. The electrophotographic sensitive body which has the excellent environmental stability and does not deteriorate the electrophotographic characteristics including the repetitive durability is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an electrophotographic photoreceptor, and particularly to an electrophotographic photoreceptor having a small residual potential, high contrast, and excellent durability stability.

[Prior Art] In recent years, many electrophotographic photoreceptors using organic compounds as photoconductors have been put into practical use.

In most cases, these photoreceptors are provided as devices by dissolving or dispersing a relatively low-molecular photoconductive substance in a resin and forming a film on a conductive substrate.

However, the photoconductive layer often does not have sufficient adhesion to the aluminum or vapor-deposited plastic film used as the conductive substrate inside the shell.

In addition, when the light guide ffi layer has a charge transport layer laminated on a charge generation layer, the charge generation layer is generally a thin layer of 1 μm or less, so it is easily affected by minute unevenness or unevenness of the substrate, and is uniform. It is difficult to form a thin film. Furthermore, charge injection from the substrate may significantly deteriorate the charging characteristics of the photoreceptor.

For the purpose of improving adhesion, improving film formability, and preventing charge injection as described above, an intermediate layer is provided between the photoconductive layer, especially the charge generating layer, and the substrate.

Thermoplastic resins used for the intermediate layer include Bossester resin, polycarbonate resin, cellulose resin, phenoxy resin, and butyral resin. The volume resistivity of these resins varies depending on the atmospheric environment, but is between 10" and 1.
The thickness of the intermediate layer is generally 1 μm or less.

The immersion method is often used as a distribution method, and the solvents used are methyl cellosolve, methanol xylene, toluene, M
EK etc. are used.

[Problems to be Solved by the Invention] However, the above problems were raised in the conventional example. The technique of providing an intermediate layer between the charge generation layer and the substrate has the following disadvantages. That is, the material used for the intermediate layer is required to be able to be uniformly formed on the substrate, and at the same time not to be easily dissolved in the solvents of the charge generation layer and charge transport layer when they are coated. In addition, it must have conductivity and barrier properties to prevent the injection of excess charge, so it is desirable to have a medium volume resistivity of 1011 to 1013 Ω. If the resistance value changes, for example in a high temperature and high humidity environment (32°C, 85% RH (II/+1)), the resistance will decrease and charges will be easily injected from the conductive substrate, causing the dark potential to increase. . In a system that performs reverse development, fogging occurs, and in a system that performs regular development, solid black and roughness occur. On the other hand, under a low temperature and low humidity environment (15'C, 1
At 0%RH (L/L, )), the resistance becomes high,
The residual potential vR is large, that is, the bright potential V does not drop completely,
A phenomenon completely opposite to the above occurs in each developing system.

Therefore, a first object of the present invention is to provide an electrophotographic photoreceptor with excellent environmental stability by providing an intermediate layer made of a specific material.

A second object of the present invention is to provide an electrophotographic photoreceptor that does not deteriorate electrophotographic properties including repeated durability by providing an intermediate layer made of a specific material.

[Means and effects for solving the problems] That is, the present invention provides an electrophotographic photoreceptor having a photosensitive layer containing an organic photoconductor on a conductive support. 5. An electrophotographic photoreceptor characterized by providing a layer, and a photosensitive layer containing an organic photoconductor on a conductive support, the photosensitive layer comprising a charge generation layer and a charge transport layer. According to the present invention, the electrophotographic photoreceptor is characterized in that an amorphous diamond layer is provided between the conductive support and the charge generation layer in the electrophotographic photoreceptor. By using an amorphous diamond layer (a diamond-like film with an amorphous structure) as an intermediate layer (UCL) provided between the photosensitive layer and the photosensitive layer, the photosensitive layer can be easily formed on the support. Further, the volume resistivity can be easily controlled to around 1012 Ω, and since the color is black, interference fringes are prevented even in exposure using laser light, and an ideal intermediate layer with excellent II boundary stability can be realized. Further, even when the photosensitive layer is composed of a charge generation layer and a charge transport layer, the intermediate layer of the amorphous diamond layer is never dissolved in the coating solvent when the charge generation layer and the charge transport layer are coated.

[Example] The present invention will be explained below with reference to Examples.

Example 1 FIG. 1 is a schematic cross-sectional view of an electrophotographic photoreceptor according to a first example of the present invention. In the figure, l is a conductive substrate, 2
3 is a diamond-like thin film with an amorphous structure used as a UCL in the present invention; 4 is a charge generation layer (CGL); 5 is a conductive layer;
is the charge transport layer (CTL).

Next, aspects of the electrophotographic photoreceptor will be specifically explained.

As the material of the conductive substrate 1, materials whose substrate itself is conductive can be used, such as aluminum, aluminum alloy, copper, zinc, stainless steel, vanadium molybdenum, chromium, titanium, nickel, indium, gold, platinum, etc. In addition, plastics have a layer formed by vacuum deposition of aluminum, aluminum alloy, indium oxide, tin oxide, indium oxide-tin oxide alloy, etc., substrates made of plastic or paper impregnated with conductive particles, and conductive polymers. It is possible to use plastics etc. that have In this example, an aluminum cylinder of φ30×250 m was used as the base.

Further, it is preferable to provide a conductive layer 2 between the substrate and the intermediate layer for the purpose of preventing irregularities and defects on the substrate and preventing interference fringes due to scattering when the image is to be imaged by laser light. This can be formed by dispersing conductive powder such as carbon black, metal particles, metal oxide, etc. in a binder resin. The thickness of the conductive layer 2 is 5 to 40 μm, preferably 1.0 to 30 μm.
μm is appropriate. In this example, titanium oxide is dispersed in phenolic resin and coated on an aluminum cylinder to a thickness of 20 μm.

A feature of the present invention is that a diamond-like thin film 3 having an amorphous structure is formed between the conductive layer 2 and the CGL 4. This thin film is formed by a plasma CVD (PI-CVD) method in which methane (CH4) gas is decomposed by glow discharge, and has an amorphous state intermediate between graphite and diamond.

FIG. 2 shows a schematic diagram of a PI-CVD apparatus for forming a diamond thin film on an aluminum cylinder. This device consists of a plasma generation 'IF52 and a film forming chamber 31.
It consists of The plasma generation tube 32 has a diameter of 60φ,
It is a glass tube with a length of 500 III 111, around which an excitation coil 33 is wound and a mesh type anode is arranged inside. The film forming chamber (■) is a cubic chamber with a side of 600 m, in which an aluminum cylinder 37, which is a sample, is placed.
It is exhausted to a certain extent. The aluminum cylinder 21 is supported by a motor 34, and can rotate and move up and down in accordance with the film forming speed.

A specific film forming method will be described below.

The gases used for film formation are Ar and CH4, and these gases are first introduced into the plasma generation etc. 32 from the gas inlet 35,
It is excited and ionized by the excitation coil 33 to which a high frequency is applied, and becomes a plasma state by glow discharge. The ions in this plasma state are connected to the anode in the plasma generating tube and a negative bias 36 is applied thereto. Aluminum·
It reaches and deposits on the aluminum cylinder due to the kinetic energy generated by the potential between the cylinders.

The volume resistance of the thin film produced in this way was 1018Ω・
Although the film is highly conductive, it is also sufficiently effective as a barrier to suppress the injection of excessive charges.In this example, the film thickness was set at 1 μm, but a sufficient effect can be obtained with a thickness of 0.3 μm.

On the other hand, if the film thickness exceeds 10 μm, the actual resistance of the film itself becomes high, making it easy to be affected by residual potential. Therefore, it is appropriate to select a preferable range of film thickness between 0.3 and 1011 m.

Electric charge is generated! (CGL) 4 is pyrylium, thiopyrillam dye, hydrazone dye, phthalocyanine pigment, anthoanthrone pigment, dibenzpyrenequinone pigment, pyranthrone pigment, trisazo pigment, disazo pigment, azo pigment, indigo pigment, quinacridone pigment, quinocyanine, etc. The charge generating material is dispersed in a suitable binder solution and a coating solution is applied onto the intermediate layer. The appropriate film thickness is 0.05 to 10 μm, preferably 0.1 to 10 μm.
It is 3 μm.

In this example, a hydrazone compound was applied to a thickness of 1 μm.

As charge transport materials, those with an oxidation potential of 0.7 e V or more are selected from common ones such as pyrazoline compounds, hydrazone compounds, stilbene compounds, triphenylamine compounds, benzidine compounds, and oxazole compounds. Select. A coating solution prepared by dissolving this in a suitable binder solution is applied onto the charge generation layer. Film thickness is 5-40
μm is suitable, preferably 10 to 30 μm.

In this example, a stilbene-based compound was used, and the film thickness was 20 μm.

As mentioned above. Charge generation layer (CGL) and the charge transport JFI
(CTL) can be applied by dipping method, spray method, beam method,
Although it is possible to use a known coating method such as a blade coating method or a spinner coating method, in this example, C
Both the GL and CTL layers were applied using a spray method.

The photoreceptor described above is processed at a process speed of 50 mm.
/s, A4 size 8-sheet laser printer, and a durability test of 10,000 sheets was conducted under various environments.

FIG. 3 is a schematic cross-sectional view of the engine section of the laser printer. In FIG. 2, a photoreceptor 21 rotating in the direction of the arrow comes into contact with the photoreceptor 21 during its rotation process, and is uniformly charged by a charging roller 23 connected to a power source 24. Then, in the device shown in the figure, an image is formed on this charging surface. The modulated laser beam 25 is projected to form an electrostatic latent image on the charged surface, and when the latent image reaches the position of the developing device 26 as the photoreceptor 21 rotates, toner is supplied from the developing device. The latent image is visualized and becomes a toner image.

When this toner image reaches a transfer site formed as a nip section where the photoreceptor 21 and the elastic transfer roller 22 formed of a conductive member come into contact with each other, the transfer material P is released from the conveyance path 27 at the same timing. At the same time, a transfer bias is applied to the transfer roller 22 from the power supply 24, and the toner image on the photoreceptor side is transferred to the transfer material. Thereafter, the transfer material leaves the transfer site and is conveyed to a fixing site (not shown), and the toner remaining on the photoreceptor is removed by a cleaner 28.
is cleaned and prepared for the first stage process.

The photoreceptor of the present invention is installed in the above laser printer, and Vo
was set to -600V. 10 in 3 environments: L/L, N/N (normal temperature and humidity environment; 23°C, 60% RH), and H/H.
Table 1 shows the results of a durability test of 000 sheets. The results in parentheses are similar experimental results for a photosensitive drum made using N-methylmethquinated nylon 6 for UCL. The intensity of image exposure by the semiconductor laser was fixed at 2.8 μJ/d at two positions from the light emitting surface, and L was set at -100V. Here, (8) is the residual potential.

As shown in Figure 1 above, by using an amorphous diamond thin film in the VCL, the decrease in the dark potential Vb due to environmental changes and durability, and the increase in the residual potential VR9 and the bright area potential VL are suppressed, and a stable high contrast is always maintained. An image is obtained.

Example 2 As a second example of the present invention, an example will be described in which polyethylene terephthalate (PET) on which aluminum is vapor-deposited is used as the conductive substrate 1 of an electrophotographic photoreceptor. The cross-sectional layer structure of the electrophotographic photoreceptor is the same as that shown in FIG. 1, so a description thereof will be omitted here.

In order to use PET as the substrate 1, in this example, the embodiment was made into a belt shape.

The embodiments of the belt photoreceptor will be specifically explained below.

The conductive substrate 1 has been described above. The surface of PET was coated with aluminum by vacuum evaporation. Therefore, the conductivity shown in FIG. Layer 2 will be vapor deposited aluminum in this example.

The thickness of the PET of the substrate 1 is 50 μm, the conductive layer 2 deposited
The thickness of the aluminum layer is approximately 0.05 to 0.07 μm.

An amorphous diamond thin film, which is a feature of the present invention, is formed on the conductive layer 2 in the same manner as in Example 1.

In this example, the film thickness was set to 1 to prevent the film from tearing and peeling without reducing the flexibility of the belt.
．． It was controlled to be 0 μm.

The reason why an amorphous diamond film is more suitable as an intermediate layer for a belt photoreceptor than a conventional thermoplastic resin is that it has much stronger adhesion to the substrate than conventional solvent-based coatings. Even higher hardness (Vickers hardness): 3
, 000 kg, 10 n2), so it is hard to get scratched, and there is no problem at all even if the base PET is made thinner than before and subjected to strong stress. Furthermore, it is durable, and its volume resistivity does not change significantly due to environmental changes, so it is characterized by high reliability.

Next, the formation of the charge generation layer (CGL) and charge transport layer (CTL) will be described. In this example, the phthalocyanine compound described in Example 1 was sprayed onto the intermediate layer of the amorphous diamond thin film as CGL.
．． It was applied to a thickness of 3 μm. Furthermore, the stilbene compound described in Example 1 was similarly applied as CTL to a thickness of 20 μm by spraying.

The OPC belt photoreceptor produced as described above was installed in a laser printer of A4 size 4 sheets at a process speed of 25 m1 sec, and a 10,000 sheet feeding durability test was conducted under each environment.

FIG. 4 is a schematic sectional view of the engine section of the laser printer.

In FIG. 4, an LED is used in the process in which a belt photoreceptor 40 supported by two pairs of support rollers 41, one of which is rotatable by a rotating device (not shown), rotates in the direction of the arrow in FIG. The surface is neutralized by the pre-exposure device 44 and then uniformly charged by the primary charger 43. This charged surface is irradiated with image-modulated laser light 45 to form an electrostatic latent image, and when the latent image reaches the position of the developing device 46 as the photoreceptor 40 rotates, toner is supplied to form the latent image. is visualized and becomes a toner image. When this toner image reaches a transfer area formed as a nip area where the photoreceptor 40 and the elastic transfer roller 42 formed of a conductive member come into contact, the transfer material is transferred from the resist roller 49 at the same timing. is supplied and brought to the transfer site through the conveyance path 47. At the same time, a transfer bias is applied to the transfer roller 42, and the toner image on the photoreceptor side is transferred to the transfer material. Thereafter, the transfer material leaves the transfer site, is conveyed to the fixing device 50, is cleaned by the toner 48 remaining on the photoreceptor, and is prepared for the next process.

Table 2 shows 10,000 in 3 environments: L/L, J/j, and H/H.
The results of a sheet-running durability test are shown. As in the first example, V n ''-600V, the image exposure intensity by the semiconductor laser was fixed at 2.8 μJ/a1 at a position 2a11 from the light emitting surface, and V was set to = 100V. Here, ■6 is the residual potential It is.

Table 2 Unit [V] As shown in Table 2 above, by using an amorphous diamond thin film for the VCL of the belt photoreceptor, it is easy to form the film at room temperature, so there is a wide range of materials to choose from for the substrate, and costs are reduced. can be achieved. Furthermore, as described in detail in Example 1, ■ after environmental changes and paper feeding durability. Down, VL, -
This suppresses the increase in VR and allows stable and high contrast to be obtained at all times.

[Effects of the Invention] As explained below, the intermediate layer (UCL) provided between the conductive substrate and the charge generation layer (CGL) of the electrophotographic photoreceptor
By using a diamond-like thin film with an amorphous structure, it is easy to form the film on the substrate, and since it is black, interference fringes are prevented during laser beam irradiation. Furthermore, since the charge generation layer (CGL) and the charge transport layer (CTL) are not dissolved in a solvent during coating, there is an advantage that a variety of solvents can be selected. In addition, since the film formation temperature is room temperature even when using horizontal resin as the base, the range of material selection is expanded and costs can be reduced. Furthermore, in terms of environmental changes and durability, dark potential ■
. , bright potential ■1, and residual potential vR are suppressed to an extremely low level, so you can always obtain stable, high-contrast images. Now you can get it.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of the electrophotographic photoreceptor of the present invention. FIG. 2 is a schematic cross-sectional view of an apparatus for forming a diamond-like thin film according to the present invention. FIG. 3 is a schematic sectional view of a laser printer equipped with the electrophotographic photoreceptor of the present invention. FIG. 4 is a schematic sectional view of a laser printer equipped with a belt photoreceptor according to a second embodiment of the present invention. 21: Photoconductor, 37: Aluminum cylinder, 40: Belt photoconductor.

Claims (1)

[Scope of Claims] 1. An electrophotographic photoreceptor having a photosensitive layer containing an organic photoconductor on a conductive support, characterized in that an amorphous diamond layer is provided on the conductive support. Photographic photoreceptor. 2. An electrophotographic photoreceptor having a photosensitive layer containing an organic photoconductor on a conductive support, the photosensitive layer comprising a charge generation layer and a charge transport layer, wherein the conductive support and the charge generation layer An electrophotographic photoreceptor characterized in that an amorphous diamond layer is provided between the layers.