JP2833017B2 - Electrophotographic photoreceptor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electrophotographic photoreceptor. More specifically, the present invention relates to an electrophotographic photoreceptor excellent in ozone resistance, stability and durability.

(Prior Art) Conventionally, inorganic photoconductive materials such as selenium, selenium-tellurium alloy, arsenic selenide, and cadmium sulfide have been widely used for electrophotographic photoreceptors.

In recent years, research on the use of organic photoconductive materials for the photosensitive layer has become active, and since it is suitable for mass production and has the potential to be highly safe, charge carriers are generated particularly by absorbing light. A photoreceptor having a charge generation layer and a charge transfer layer, which separates the function of transferring a generated charge carrier from the function of transferring the generated charge carriers, has been devised and has become the mainstream of research. The laminated photoreceptor has been put to practical use by obtaining a highly sensitive photoreceptor by combining an organic compound having a highly efficient charge generating action and a high charge transfer action.
In such a laminated electrophotographic photoreceptor, the charge transfer layer is stacked on the charge generation layer, and since the charge transfer layer usually has only a hole transfer function, the sensitivity is increased only when negatively charged. And used under negative charging.

On the other hand, in the electrophotographic method, the charging of the photoreceptor is usually performed by corona discharge, but the negative corona discharge is more difficult to make a uniform discharge in the wire direction than the positive corona discharge, and thus obtains uniform charging. It is difficult to do this, and the selenium-based photoreceptor, which was the center of the conventional technology, was positively charged.We want to use the conventional technology for the developer and other peripheral processes used in this system. An organic photoreceptor that can be used in a photoconductor is also being studied. For example, a so-called reverse two-layer type photoreceptor in which a charge transfer layer and a charge generation layer are laminated in this order on a support, and a dispersion type photoreceptor in which particles of a charge generation substance are dispersed in a charge transfer medium have been proposed and studied. ing. In the case of a reverse two-layer, dispersion type photoreceptor, incident light is absorbed on the surface, and the region where carriers are generated becomes near the surface and is used with positive charge.

As described above, photoconductors having several configurations have been proposed and studied, and photoconductors having excellent chargeability and sensitivity have been developed. However, the electrophotographic photoreceptor is used repeatedly in the system, and the electrophotographic photoreceptor is always required to have constant and stable electrophotographic characteristics in such a system. However, at present, enough things have not yet been obtained. That is, as the device is used repeatedly, a decrease in potential, a rise in residual potential, a change in sensitivity, and the like occur. Not all of the causes of these deteriorations are known, but there are several possible causes. In particular, it has been found that oxidizing gases such as ozone and nitrogen oxides emitted from a corona discharge charger significantly damage the photosensitive layer. These oxidizing gases chemically change the material in the photosensitive layer and cause various changes in characteristics. For example, a decrease in charging potential, an increase in residual potential, a decrease in resolution due to a decrease in surface resistance, and the like are observed. As a result, image quality is significantly reduced, and the life of the photoconductor is shortened. For this,
Efforts have been made to efficiently exhaust and replace the gas around the corona charger to avoid affecting the photoreceptor, and it has been proposed to add an antioxidant and stabilizer to the photosensitive layer to prevent deterioration. . For example, the addition of an antioxidant having a triazine ring and a hindered phenol skeleton in the molecule disclosed in JP-A-62-105151 and the addition of a specific hindered amine are described in JP-A-63-18355. .

(Problems to be Solved by the Invention) However, even with these conventional techniques, a sufficient ozone resistance effect has not yet been obtained, or electrophotographic characteristics such as sensitivity and residual potential have been reduced by the addition of such an antioxidant. At present, only insufficient effects for practical use, such as worsening, were obtained.

(Means for Solving the Problems) The present inventors have conducted intensive studies on the improvement of the ozone resistance of an organic photoreceptor having a charge generating substance and a charge transfer substance, and as a result, added a specific amine compound to the photosensitive layer. As a result, the present inventors have found that a photoreceptor having significantly improved ozone resistance and excellent electrical properties can be obtained, thereby completing the present invention.

That is, the gist of the present invention is an electrophotographic photoreceptor having a photosensitive layer containing at least a charge generating substance, a charge transfer substance and an amine compound represented by the following general formula (I) on a conductive support, The electrophotographic photoreceptor is characterized in that the binder resin of the layer containing the charge transfer material is a polycarbonate resin containing bisphenol C as a bisphenol component.

(Where A, B, and C represent a hydrogen atom or a monovalent organic residue, and R ¹ , R ² , R ³ and R ⁴ represent a hydrogen atom or an alkyl group which may have a substituent. Wherein R ⁵ and R ⁶ each represent a hydrogen atom, a halogen atom, a hydroxyl group or an alkyl group which may have a substituent.) (Action) The present invention will be described in detail below.

The photosensitive layer according to the invention contains at least a charge generating substance and a charge transporting substance. More specifically, a laminated photoconductor in which a charge generation layer mainly containing a charge generation substance, a charge transfer layer mainly containing a charge transfer substance and a binder resin are stacked on a conductive support in this order.

An inverted two-layer photoreceptor in which a charge transfer layer mainly containing a charge transfer material and a binder resin and a charge generation layer mainly containing a charge generation material are laminated in this order on a conductive support;

A dispersion type photoconductor in which a charge generation substance is dispersed in a layer containing a charge transfer substance and a binder resin on a conductive support.

Such a configuration is given as an example of a basic form.

These photosensitive layers are formed on a conductive support by a known method such as roll coating, bar coating, dip coating, spray coating and the like. If necessary, polyamide between the conductive substrate and the photosensitive layer,
A barrier layer such as polyurethane or aluminum oxide may be provided. Further, a protective layer made of polyamide, thermosetting silicone resin, crosslinked acrylic resin, or the like may be provided on the surface of the photosensitive layer as needed.

Various known conductive supports can be used.
For example, a metal drum of aluminum, copper, nickel, stainless steel, etc .; a metal foil laminated, a metal, a conductive oxide, etc. deposited or sputtered,
Alternatively, a plastic film, a plastic drum, a glass drum, paper, or the like, which has been subjected to a conductive treatment such as applying a conductive material such as metal powder, carbon black, copper iodide, or tin oxide together with a binder resin as necessary, may be used. .

As the charge generating substance used in the present invention, various kinds of inorganic and organic charge generating substances can be used. For example, as an inorganic charge generating substance, various alloy materials mainly containing selenium such as amorphous selenium, selenium-tellurium alloy, trigonal selenium, arsenic triselenide; II-VI such as cadmium sulfide and cadmium selenide; Group compound semiconductor materials; amorphous silicon,
A known material such as silicon hydride is used in the form of fine particles. Further, phthalocyanine pigments, perylene pigments, polycyclic quinones, quinacridone pigments as organic charge generating substances,
Indigo pigments, squarylium salts, azo pigments and the like can be used.

Among them, phthalocyanine pigments and azo pigments can be used as more preferable materials. As phthalocyanine pigments,
The following general formula can be exemplified.

M is Cu, Fe, Mg, Si, Ge, Sn, Pb, InCl, Ga
Examples include phthalocyanines containing metal atoms such as Cl, AlCl, and TiO, and metal-free phthalocyanines to which two hydrogen atoms have been added. X includes a hydrogen atom, a lower alkyl group, a lower alkoxy group, a nitro group, a cyano group, a halogen atom and the like, and m represents an integer of 0 to 4.

The azo pigment includes various types, and more preferable materials include monoazo pigments, bisazo pigments, trisazo pigments and other polyazo pigments having at least one coupler component represented by the following general formula.

However, A in the formula represents a divalent group of an aromatic hydrocarbon or a divalent group of a heterocyclic ring containing a nitrogen atom in the ring.

The charge generating substance is used as a main component of the charge generating layer in the case of a laminated structure, for example, may be used as a uniform layer formed by a method such as evaporation or sputtering,
It may be used in the form of particles dispersed in a binder resin. In this case, as the binder resin, polyvinyl acetate, polyacrylate, methacrylate resin, polyester resin, polycarbonate resin, polyvinyl butyral, polyvinyl acetal resin such as polyvinyl formal, phenoxy resin, cellulose ester, cellulose ether, urethane resin, epoxy resin, etc. Various binder resins can be used. The composition ratio of the charge generating substance to the binder resin is usually preferably in the range of 100: 10 to 5: 100 by weight, and a charge transfer substance may be mixed in this layer. The thickness of the charge generation layer is usually
Preferably it is used at 0.1 to 10 μm. In the case of the dispersion type photosensitive layer as described above, the charge generating substance is dispersed in the form of fine particles in a matrix having a charge transporting substance and a binder resin.

Examples of the charge transport material used in the present invention include various known materials used for an electrophotographic photoreceptor. Carbazole, indole, imidazole, thiazole,
Compounds having a heterocyclic ring such as oxadiazole, pyrazole and pyrazoline; phenylamine, diphenylamine,
An electron donating substance such as an aniline derivative such as triphenylamine; a hydrazone derivative; a stilbene derivative; or a polymer having a group consisting of these compounds in a main chain or a side chain.

Particularly preferred substances include hydrazone derivatives, aniline derivatives, and stilbene derivatives.

As the binder resin used together with the charge transport material, a polycarbonate resin containing bisphenol C or bisphenol Z as a bisphenol component is used.

The mixing ratio of the charge transfer material and the binder resin is
For example, 20 to 200 parts by weight, preferably 40 to 200 parts by weight with respect to 0 parts by weight.
It is blended in the range of 150 parts by weight. In the case of a laminated photoreceptor, a charge transfer layer is formed mainly of the above components, and the thickness of the charge transfer layer is usually 5 to 50 μm, preferably 10 to 50 μm.
Used at 4040 μm.

In the case of a dispersion type photoreceptor, the charge generation substance is dispersed in fine particles in a matrix mainly composed of the charge transfer substance and the binder resin having the above-described compounding ratio, but the particle diameter needs to be sufficiently small. , Preferably 1 μm or less,
It is more preferably used at 0.5 μm or less. If the amount of the charge generating substance dispersed in the photosensitive layer is too small, sufficient sensitivity cannot be obtained. If the amount is too large, adverse effects such as a decrease in chargeability and a decrease in sensitivity occur. For example, preferably 0.5 to 50% by weight And more preferably in the range of 1 to 20% by weight. The thickness of the photosensitive layer is usually 5 to 50 μm, more preferably 10 to 50 μm.
Used at 4040 μm.

The amine compound used in the present invention is a compound represented by the following general formula (I) as described above.

However, in the formula, A, B, and C represent a hydrogen atom or a monovalent organic residue, and in the case of an organic residue, may be aliphatic or aromatic, for example, an alkyl group or an aryl group which may be substituted with a hydroxyl group or an acetoxy group. Groups, an aralkyl group, an acyl group, a carbamoyl group and the like. Among them, B is preferably a hydrogen atom. R ¹ , R ² , R ³ , R ⁴ are selected from a hydrogen atom and an alkyl group which may have a substituent, and two or more of R ^{1 to} R ⁴ are preferably an alkyl group, particularly R ^{1 to} R 4 ⁴ It is preferable that all are methyl groups. R ⁵ and R ^{6 each} represent a hydrogen atom, a halogen atom, a hydroxyl group or an alkyl group which may have a substituent, and generally preferably a hydrogen atom.

Table 1 below shows specific examples of the compound represented by such a general formula.

These amine compounds are added to all or part of the photosensitive layer. Since the deterioration proceeds from the surface, it is preferable that it is added to at least the surface layer. When a protective layer or a blocking layer is provided, it is added to these layers as needed. The amount of the amine compound to be added is usually 0.1 to 20% by weight, more preferably 1 to 1% by weight in the layer.
6% by weight is added.

Further, the photosensitive layer of the present invention has a known plasticizer for improving film formability, flexibility, mechanical strength, etc., an additive for suppressing accumulation of residual potential, and a dispersion for improving dispersion stability. An auxiliary agent and a leveling agent for improving applicability, for example, silicone oil and other additives may be added.

(Effect of the Invention) The electrophotographic photoreceptor of the present invention has excellent electrophotographic properties, is hardly affected by ozone and nitrogen oxides generated from the system, and has stable properties and image quality even when used repeatedly. It has the advantage of being a photoreceptor with extremely high durability.

The photoreceptor of the present invention can be used in a wide range of electrophotographic applications, such as electrophotographic copying machines and various printers.

(Examples) Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist.

 In the examples, "parts" means parts by weight.

Example 1 180 parts of cyclohexanone was added to 5 parts of a bisazo compound having the following structure, and preliminarily dispersed by a sand grinding mill.

Meanwhile, 380 parts of cyclohexanone and 50 parts of a polycarbonate resin having the following repeating structural unit 50 parts of a hydrazone compound having the following structure and 1.5 parts of the amine compound represented by (5) in Table 1 described above were dissolved, and the above preliminary dispersion was further added. This was subjected to a main dispersion treatment with a homogenizer to obtain a coating liquid.

This coating solution was applied on a polyester film on which aluminum was deposited so as to have a thickness of 20 μm after drying.

When the electrophotographic characteristics of this sample were measured, the initial charged voltage was +552 V, the surface potential was from 500 V to 100 V, the exposure amount E1 / 5 2.7 luxsec required for attenuation, and the residual potential was +2 V after 10 seconds of exposure. .

Next, in order to examine the ozone resistance of the photoconductor, the sample was left in a corona discharge atmosphere. A corona charger was placed in the box, a voltage of -7 kV was applied, and air was circulated by a fan provided in the box to create a uniform atmosphere. The ozone concentration at this time was 25 ppm. After exposure to this atmosphere for 5 hours, the characteristics of these photoreceptors were examined.
The charging voltage, which was 2V, decreased only slightly to + 514V.

Comparative Example 1 A comparative sample 1A was prepared in the same manner as in Example 1 except that the amine compound was omitted for comparison. Next, except that the following amine compounds (1) and (2), which are known to be added to an organic electrophotographic photoreceptor as an amine compound, were added, except that the following amine compounds (1) and (2) were added, Comparative Sample 1B,
1C was created.

Next, a comparative sample 1D was prepared in exactly the same manner except that di-t-butyl and hydroxytoluene, which are known antioxidants, were similarly added to the photosensitive layer instead of the amine compound. Created.

These samples were evaluated for electrophotographic properties and ozone resistance in the same manner as in Example 1. The results are shown in Table 2 below. As can be seen, the photosensitive layers of the examples have excellent sensitivity, and also have excellent ozone resistance, but without addition of the amine compound of the present invention, a marked decrease in charged voltage due to ozone exposure is observed, Comparative Sample 1B It can be seen that addition of a known amine compound such as 1C improves the change in potential due to exposure to ozone, but significantly lowers the initial sensitivity. It is also found that the effect of a known phenol-based antioxidant is insufficient (Comparative Example 1D).

Continuation of the front page (56) References JP-A-2-1466051 (JP, A) JP-A-2-210457 (JP, A) JP-A-2-144545 (JP, A) (58) Fields investigated (Int) .Cl. ⁶ , DB name) G03G 5/05

Claims (1)

(57) [Claims] 1. An electrophotographic photosensitive member having a photosensitive layer containing at least a charge generating substance, a charge transfer substance, and an amine compound represented by the following general formula (I) on a conductive support, An electrophotographic photoreceptor, wherein the binder resin of the layer containing the substance is a polycarbonate resin containing bisphenol C as a bisphenol component. (Wherein, A, B and C each represent a hydrogen atom or a monovalent organic residue, and R ¹ , R ² , R ³ and R ⁴ each represent a hydrogen atom or an alkyl which may have a substituent. R ⁵ and R ⁶ represent a hydrogen atom, a halogen atom,
It represents a hydroxyl group or an alkyl group which may have a substituent. )