JPS62218966A - Substrate for electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain superior fundamental characteristics and high quality stability by using an alloy layer having resistance to oxidation, heat, and corrosion as an electrode and forming a resin layer having a folume intrinsic resistivity of 10<4>-10<13>OMEGA.cm on this layer. CONSTITUTION:The resin layer having a volume intrinsic resistivity of 10<4>-10<13>OMEGA.cm is formed on the surface of the electrode made of the alloy having resistances to oxidation, heat, and corrosion. As the material of the resin layer, an alcohol-soluble polyamide resin, such as copolymer nylon, casein, gelatin, cellulosic resins, polyvinyl alcohol, phenolic resins, nitrile rubber, butyral resin, alkyd resins, and the like are used considering adhesiveness, thus permitting the obtained photosensitive body to be enhanced in fundamental characteristics, such as electric and mechanical durability, and superior in image quality.

Description

[Detailed description of the invention] [Technical field] The present invention relates to improvements in supporting substrates for electrophotographic photoreceptors.

[Prior art] In an electrophotographic method generally called xerography, a photoconductive insulating layer (hereinafter referred to as a photosensitive layer) is provided on the surface of a support such as glass, plastic, or paper on which a conductive layer is provided with a metal, metal film, or conductive paint. A photoreceptor is used.

The material and form of the above-mentioned electrodes are appropriately selected depending on the characteristics of the photosensitive material and the manufacturing method.

When Se-based or 3i-based material is used as the photosensitive layer, A1 or A1
A drum-like member of the alloy itself is often used.

When the photosensitive layer is in the form of a solution or dispersion during coating, the support is often a plastic film coated with a metal layer by vapor deposition. In particular, a polyethylene terephthalate film with A1 metalized (metal coating) is widely used as a support substrate for an organic photoreceptor (hereinafter referred to as OPC).

The reason why A1 is widely used as a conductive material for electrodes is that it is relatively easy to form a film on a film, and it is easy to create a certain rectification property at the interface with the photosensitive layer.
This is because it is easy to obtain a high acceptance potential without impairing electrical properties, and it is also relatively inexpensive as a metal material.

A typical form of OPC is a so-called functionally separated type in which a charge generation layer is laminated on the electrode side and a charge transport layer is laminated thereon. That is, a configuration in which a polyethylene terephthalate film, an A1 layer, a charge generation layer, and a charge transport layer are laminated in this order is currently widely used as an OPC for electrophotography.

By the way, the charge transport layer is generally made of a polymer in which a hole transport substance such as triphenylamine or hydrazone is dissolved. Since no specific compound material that exhibits practically effective electron mobility has been found, a functionally separated electrophotographic photoreceptor using OPC is usually used with a negative charge.

However, the inventors have discovered that some metals have serious drawbacks, particularly as electrodes for photoreceptors used for negative charging. Moreover, they discovered that the most widely used AI has extremely significant shortcomings. Specifically, the charge passing through the electrode due to repeated charging exposures gradually oxidizes the metal of the electrode, and as a result, the passage of necessary charge is significantly inhibited. This reaction corresponds to anodic oxidation when used with a negative charge, and the electrode becomes an oxide, ultimately becoming an insulating thin film.

With the exception of expensive precious metals, most metals inevitably undergo oxidation reactions to varying degrees.

Prior to the present invention, the present inventors had already developed heat-resistant NiW alloys such as Hastelloy, Inconel, and Nimonic.
The patent application has shown that the material is good as an electrode material for PCs. The above-mentioned heat-resistant alloy hardly oxidizes even after repeated charging and exposure over a long period of time, and therefore the irrecoverable increase in residual potential is extremely small. To briefly add to the contents of the previous patent application, Fe-based and Co-based oxidation-resistant, heat-resistant, and corrosion-resistant alloys (hereinafter some are simply referred to as oxidation-resistant)
It also guarantees almost the same properties as Ni-based heat-resistant alloys.

However, it has become clear that these oxidation-resistant alloys have some limitations as materials for conductive layers when extremely high quality and high durability are desired for photoreceptors.

Firstly, since the heat-resistant alloy is a stable metallic material, when used as an electrode, the injection of charge into the photosensitive layer is relatively large.Especially in the case of a functionally separated type, depending on the combination of the charge generation layer and the charge transport layer, The decrease in acceptance potential and the increase in dark decay are unacceptably large. Generally, the easier it is to inject charges from the charge generation layer to the charge transport layer, the more susceptible the charge generation layer is to the interface between the charge generation layer and the charge generation layer.

The second reason is that all oxidation-resistant alloys, due to their composition, must rely on sputtering to form a thin film on a substrate. Another problem is that it is difficult to obtain a film with few surface defects.

The third problem is poor adhesion to the photosensitive layer. Although low adhesion is not a drawback specific to oxidation-resistant alloys, it is generally
Alloys with a high content of o tend to have low adhesion.

[Objective] The object of the present invention is to provide an IJ'r-standard support substrate for an electrophotographic photoreceptor, which guarantees excellent basic characteristics and high quality stability, and has excellent adhesion to a photosensitive layer.

[Structure] In order to achieve the above object, the present invention provides a supporting substrate for an electrophotographic photoreceptor, which has an oxidation-resistant, heat-resistant, and corrosion-resistant alloy layer as an electrode, and has a volume resistivity of 104 to 104. 101
It is characterized by having a resin layer in the range of 3Ω, cm. The resin layer corresponds in form to a photosensitive layer and an intermediate layer between the electrodes.

Oxidation-resistant, heat-resistant, and corrosion-resistant alloys are highly stable alloy materials used in chemical equipment, electron tube materials, jet engine parts, die-casting extrusion molds, etc., and are used in electrochemical applications such as anodization. High durability against chemical reactions. The properties of such materials effectively prevent the increase in residual potential caused by electrode oxidation.

Table 1 shows trade names or common names of representative examples of Ni-based, Fe-based, and Co-based heat-resistant alloys and their compositions.

The low-resistance resin layer on top of the alloy layer is made of oxidation-resistant alloy.
It suppresses a relatively high charge injection property, prevents a decrease in acceptance potential and an increase in dark decay, and also hides micro defects on the surface of the alloy layer formed by sputtering, and improves the adhesion between the photosensitive layer and the support. Contribute to the strengthening of

The resin layer material can be formed into a film and has a volume resistivity of 10
It is desirable to select from the range of 4 to 1013 Ω, cm.
Considering adhesiveness, alcohol-soluble polyamide resin (copolymerized nylon), casein, gelatin, cellulose resin, polyvinyl alcohol, phenolic resin,
Nitrile rubber, butyral resin, alkyd resin, etc. can be used.

The above-mentioned volume resistivity value does not uniquely determine the quality of the photoreceptor's characteristics. Not only does the resistance value of the resin layer vary depending on manufacturing conditions, drying conditions, and environmental conditions, but also the capacitance, which is another basic physical property value that forms the time constant that determines the speed of charge transfer along with the resistance value, depends on the film thickness and dielectric This is because the main factor is the rate, which can vary in various ways. Roughly speaking, the behavior of charge passing between different phases in a solid that deviates from Ohm's law is known as rectification. However, according to the inventors' study, the volume resistivity was 1013Ω.
, cm, even if the film thickness is about 0.2 .mu.m, the resins hinder the passage of charge to a large extent, and the increase in residual potential is practically unacceptable.

These include polystyrene (volume resistivity 1017~1
0190. cm), acrylonitrile-styrene copolymer (IQl5), acrylonitrile-butadiene copolymer (IQl5 or more), polycarbonate (IQIIi or more), methyl methacrylate (IQ15 or more),
5 or more). However, the above values are for the resin alone.

Incidentally, the volume resistivity of the desirable resin listed above is approximately within the following range. (Things (◯) listed in Examples are actually measured values after film formation.

O copolymerized nylon 109~10klΩ, cmQ casein 10v~1012 Gelatin 10"~102 Ethyl cellulose 1012.10μΩ, cm○ Polyvinyl alcohol 108~1QD // Phenol resin
10℃~IQOn nitrile rubber 109~1Q
11 //Butyral resin 109-1011
1 rt alkyd resin 1012~10u
(The range of resistance varies depending on the manufacturing method and raw materials.

Even with the above-mentioned resins, if the IQl is 1Ω, cm or more, it is not suitable for the use of the present invention.) It is generally impossible for the electrical resistance of the resin layer to be on the same level as that of a metal electrode. However, even if a resistance control agent (for example, an anionic, cationic, or ionic substance) is added to the resin layer to further lower the resistance, the resin layer must be placed under the metal underneath to avoid uneven charge passage. It is desirable that the electrodes also have a high resistance value.

In order to obtain stable performance, the specific resistance value of the resin must be 10.
It is sufficient if it is 4Ω, cm or more.

The supporting substrate provided by the present invention has high utility value especially when it is desired to make the supporting substrate transparent.

This is because the destruction of the electrode due to oxidation progresses more quickly and more thoroughly as the electrode layer becomes thinner. Therefore, metals that oxidize, that is, most of the total bending elements except for the total bending metal, cannot be used as optically transparent electrodes. In addition, even if an intermediate layer is interposed between the electrode and the photosensitive layer while using the metal material as it is, unless it is an insulating layer (in which case it will not function as a photosensitive layer), oxidation of the electrode is inevitable in principle.

By using an electrode made of an oxidation-resistant alloy provided by the present invention and a support base made of a low-resistance resin layer coated thereon, it is possible to achieve both excellent basic characteristics and high quality stability (durability). It is possible to make the substrate light-transmissive with several hundred layers without any adverse effects.

The details of the present invention will be specifically explained below with reference to Examples.

Example 1 A HaStelIOV C layer was placed on a 75 μm thick polyester film, and the average transmittance in the visible range (hereinafter simply referred to as transmittance) was 3.
0%.

On top of that, apply 4 layers of polyamide resin (ICM-8000).
It was applied as a wt% methyl alcohol solution to a thickness of 0.4 μm by blade coating.

On the substrate prepared by the above method, a charge generating layer (pigment/resin, weight ratio 2.5/1) consisting of a bisazo pigment represented by the following formula dispersed in a butyral resin was coated with a blade at a wavelength of 580 nm. Coating was performed so that the transmittance was 4%.

Thereon, a charge transport layer (styryl compound/resin, weight ratio 9/10) made by dissolving a styryl compound represented by the following formula (II>) in a polycarbonate resin was coated to a thickness of 20 μm using the same blade coating method. Sample No. 1 is taken as 1) This photoconductor was measured using a dynamic method using a paper analyzer manufactured by Kawaguchi Electric Seisakusho.The measurement conditions were a discharge current of -24 μA, a light beam of 4.511X, and a charge of -
Table (I
The characteristics shown in I) were obtained.

(All characteristics of Examples and Comparative Examples are shown in Table (n)) Vmax: Potential after 20 seconds of charging (V) [) [)
: Dark decay E (1/2) during 20 seconds: 8
Half-attenuation exposure fil (Lx-sec) from 00V ■R:
Potential after exposure (30SeC)
1uX, the discharge current during exposure was -9.6μA, and the charging and exposure were repeated for up to 5 hours (although some of them were interrupted for a short time), and after 1 and 5 hours, the basic characteristics were measured under the above measurement conditions. It was measured.

The various characteristics represented by acceptance potential, dark decay, residual potential, and sensitivity not only had excellent initial values, but also showed only slight deterioration over time, and the performance was extremely satisfactory. In addition, the adhesive property was extremely strong, and when images were produced using a Ricoh Co., Ltd.'s Mairicopy M-10 (modified) copying machine, excellent image quality with no defects was obtained.

Comparative Example 1 The rest was the same as Example 1 except that the polyamide layer was removed. (Sample No. 2) The acceptance potential decreased significantly as the dark decay increased, and the characteristics were unsatisfactory. Further, the photosensitive layer was easily peeled off with cellophane tape, and many white spots were observed in the evening part of the initial image.

Comparative Example 2 The other conditions were the same as in Example 1 except that the Hastelloy C layer was replaced with A1 having a transmittance of 30% formed by vapor deposition. (Lean pull No. 3) The increase in residual potential was large, and the result was unsatisfactory.

Example 2 The electrode of Example 1 was made of Discaloy (DiS) with a transmittance of 20%.
The resin layer was a 1 μm layer of casein coated as an aqueous ammonia solution.

Other preparation and measurement conditions were the same as in Example 1. (Sample No. 4) Almost the same excellent performance as in Example 1 was obtained.

Example 3 The electrode was a NiVCo layer with a transmittance of 20%, and the resin layer was a 1 μm layer of polyvinyl alcohol. Other preparation and measurement conditions were the same as in Example 1. (
Almost the same excellent performance as in Example 1 (referred to as sample No. 15) was obtained.

As is clear from the above Examples and Comparative Examples, the electrode layer is made of an oxidation-resistant, heat-resistant, and corrosion-resistant alloy such as Fe-based, Ni-based, Go-based, etc., and a supporting substrate is provided with a low-resistance resin layer thereon. By using the photoreceptor, it was possible to obtain a photoreceptor having excellent basic characteristics, electrical and mechanical durability, and excellent image quality.

In addition, the material, structure, and
The manufacturing method, evaluation means, etc. are not the essence of the present invention, and therefore do not limit the main technology of the present invention.

[Effects] According to the present invention, it is possible to obtain a photoreceptor having excellent basic properties, electrical and mechanical durability, and excellent image quality.

Claims (2)

[Claims] (1) The electrode surface is made of an oxidation-resistant, heat-resistant, and corrosion-resistant alloy with a volume resistivity of 10^4 to 10^1^3 Ω. c.
A support substrate for an electrophotographic photoreceptor, characterized by having a resin layer in the range of m. (2) The supporting substrate for an electrophotographic photoreceptor according to claim (1), wherein the alloy is one of Ni-based, iron-based, and Co-based.