JPH0259759A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To prevent the flow and out of focus of images while maintaining high sensitivity in spite of repetitive use by incorporating a paraphenylene diamine compd. and one kind of a hindered amine compd. and hindered phenol compd. which are respectively specific into a photosensitive layer contg. a specific charge transfer material. CONSTITUTION:The styryl compd. expressed by the formula I is used as the charge transfer material and the paraphenylene diamine compd. and one kind of either of the hindered amine compd. having >=1 pieces of the formula II in one molecule and the hindered phenol compd. having >=1 pieces of the formula III in one molecule are incorporated into this compd. In the formulas I to III, Ar1 to Ar4 denote an aryl group which may have a substituent; n denotes 0 or 1; R denotes H or alkyl group. The oxidation deterioration is suppressed in this way and the prevention of the flow and out of focus (degraded resolution) of the images generated when the electrophotographic sensitive body are repetitively used and the high-speed light responsiveness (high sensitivity) are made compatible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a composite type electrophotographic photoreceptor, and particularly to an electrophotographic photoreceptor suitable for a laser beam printer.

[Conventional technology]

A large number of electrophotographic photoreceptors, both organic and inorganic, have been proposed.Among them, a two-layer photoreceptor consisting of a charge generation layer and a charge transport layer is a highly sensitive photoreceptor that is used in copiers and laser beams. It has been put into practical use as a photoreceptor for printers. As the charge generation substance for the charge generation layer, for example, Japanese Patent Application Laid-Open No. 1986-
Phthalocyanine pigments disclosed in Japanese Patent Application Laid-open No. 15253, disazo pigments disclosed in Japanese Patent Application Laid-Open No. 1983-16040, and the like are already known. On the other hand, the charge transporting material for the charge transporting layer is poly-N-vinylcarbazole as disclosed in JP-A-52-77730, and JP-A-49-1055.
Pyrazoline derivatives disclosed in Publication No. 37, JP-A-55-
A large number of compounds have been proposed, such as oxazole compounds and thiazole compounds shown in Japanese Patent Publication No. 35319, and hydrazone compounds shown in JP-A No. 54-59143.

Normally, an electrophotographic photoreceptor charges the surface of the photoreceptor with corona charging, forms an electrostatic latent image by exposure, converts this latent image into a visible image with toner, and transfers the toner to paper or the like. It is used repeatedly after going through a series of steps such as removing toner from the surface of the photoreceptor and eliminating static electricity. Therefore, electrophotographic photoreceptors are required to have good electrophotographic properties such as charging properties and sensitivity over a long period of time even after repeated use.

In general, when the above-mentioned two-layer photoreceptor is used as a photoreceptor in copiers, laser beam printers, etc., the deterioration factors include the strength and abrasion resistance of the coating film for printing durability, and the ozone generated during corona charging. Examples include oxidation with nitrogen oxides and nitrogen oxides. In particular, in the case of oxidative deterioration, the electrophotographic properties gradually deteriorate, and as the number of prints increases, the resulting images become blurred, blurred, etc., which is a major hindrance in the production of long-life electrophotographic photoreceptors. It became.

This oxidative deterioration is considered to be mainly due to the deterioration of the charge transport material used in the charge transport layer, which is the surface of the electrophotographic photoreceptor. Therefore, in order to obtain a long-life electrophotographic photoreceptor, there are two methods: 1. For example, a method of containing an antioxidant in the photosensitive layer as disclosed in JP-A No. 57-122444; A method of introducing a substituent having a chemical structure that is difficult to be oxidized by ozone and nitrogen oxides into a charge transporting substance as disclosed in the publication, JP-A-62-23416
A method of including a photodegradation inhibitor in a photosensitive layer as shown in Japanese Patent No. 4 has been proposed. Among these methods, the method of adding antioxidants has attracted particular attention, and is described in Japanese Patent Application Laid-Open No. 10515/1983.
No. 1, JP-A-63-18354, JP-A-63-183
No. 56, JP-A-63-50849, JP-A-63-50
No. 850, JP-A-63-50851, JP-A-63-5
No. 2150, etc. contain specific phenolic antioxidants, and JP-A-63-18355.

Japanese Patent Publication No. 63-50848, I4 Publication No. 63-52146
No. 63-58455 discloses a specific amine-based antioxidant.

Among them, as a fast response (high sensitivity) photoreceptor, JP-A-63
A method using a styryl compound as a charge transporting substance, as disclosed in Japanese Patent No. 30255, is attracting attention.

[Problem to be solved by the invention]

The resolution using the above-mentioned styryl compound also gradually decreased during repeated use, and it was insufficient from the viewpoint of high definition. As a method for preventing this decrease in resolution, it is known to add antioxidants to the photoreceptor as described above, but these antioxidants generally tend to cause a decrease in electrophotographic characteristics, that is, an increase in residual potential. Therefore, it has been difficult to achieve both high-speed response and high definition.

An object of the present invention is to provide an electrophotographic photoreceptor that can prevent image flow and blurring (deterioration in resolution) that occur when the electrophotographic photoreceptor is repeatedly used, and has high-speed photoresponsiveness (high sensitivity). be.

[Means to solve the problem]

The present invention provides an electrophotographic photoreceptor in which a photosensitive layer containing a charge-generating substance and a charge-transporting substance is provided on a conductive support, in which a styryl compound represented by the following structural formula (1) is used as a charge-transporting substance. Contains one or more of para-phenylenediamine compounds, hindered amine compounds having one or more of the following structural formulas (2) in one molecule, and hindered phenol compounds having one or more of the following structural formulas (3) in one molecule. It's about letting people know.

Structural formula (1) (In the formula, Ar1.Arz+ Ara and Ar4 represent an aryl group that may have a substituent, and n represents 0 or 1.) Structural formula (2) (In the formula, R is H or an alkyl group) Structural Formula (3) As a result of studies on improving oxidative deterioration caused by ozone or nitrogen oxides, the present inventors have developed a photosensitive layer containing a charge transporting substance represented by the above structural formula (1). It has been found that by containing at least one of a para-phenylene diamine compound, a hindered amine compound, and a hindered phenol compound, it is possible to prevent image bleeding and blurring while maintaining high sensitivity even after repeated use.

The amount of the antioxidant shown in the present invention varies depending on the type of charge transport substance and antioxidant used, but is usually 0.5 to 100% by weight, particularly preferably 1 to 50% by weight based on the charge transport substance.
Weight%. If the amount added is less than this range, the oxidation resistance will be poor, and images will likely fade or become blurred in a short period of time.

On the other hand, if the amount added is large, image smearing or blurring will not occur even if used repeatedly for a long time, but the photosensitivity will be poor and the residual potential will be large, making it impossible to put it to practical use.

The para-phenylenediamine compound, hindered amine compound (structural formula (1)), hindered phenol compound (structural formula (2)), etc. shown in the present invention are known as antioxidants, and commercially available products are easily available.

Representative compounds of the charge transport substance according to the present invention include, for example, aryl groups such as phenyl and naphthyl, and substituents such as alkyl, alkoxy, dialkylamino, benzyl, and dibenzylamino.

Examples include halogen.

Next, as a charge generating substance, for example, phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine, anthraquinone pigment, and indigo pigment.

Known materials such as quinacridone pigments, perylene pigments, polycyclic quinone pigments, moriazo and disazo pigments, squarine M, and derivatives can be used, and these pigments can be used alone or in combination of two or more.

Binding agent resin (binder) used in the photosensitive layer in the present invention
Although not particularly limited, in the case of a laminated type of charge generation layer and charge transport layer, a binder that is compatible with the charge transport substance is suitable for the charge transport layer.

The conductive support used in the present invention has a volume resistivity of 1010Ω
Those having four electric layers below the mark are preferable, such as aluminum, alloys of aluminum and other metals, iron, buttons, copper metal plates, metal compound plates such as tin oxide, indium oxide, copper iodide, and chromium oxide.

Conductive plastic plates and plastic and paper.

Glass or the like imparted with conductivity by vapor deposition, sputtering, etc. can be used, and these supports may be cylindrical or sheet-like, and are not limited in shape.

Next, a typical example of a method for forming a charge generation layer and a charge transport layer on a conductive support will be described.

First, for the charge generation layer, a charge generation substance is mixed with a binder resin and additives used as necessary, and an organic solvent is added thereto to disperse the charge generation material well to prepare a coating liquid. A conductive support is immersed in this liquid and pulled up, or this liquid is dropped onto the conductive support and coated using a bar coater, roll coater, applicator, casting method, etc., and then dried or dried by heat or light. Formed by crosslinking reaction.

As the binder resin, a known three-dimensional curing resin or thermoplastic resin can be used. Alternatively, a charge generation layer may be formed directly on the conductive support by vapor deposition of a charge generation substance. On the other hand, the charge transport layer is prepared by dissolving a charge transport substance and a known binder resin in a known organic solvent by mixing and stirring, adding the antioxidant shown in the present invention, and adding various kinds of additives as necessary. Add auxiliary agents to prepare coating liquid. A charge transport layer can be formed on the charge generation layer by using this coating liquid in the same manner as in the above coating method to obtain a two-layer type photoreceptor.

[Effect]

It is believed that the reason why image blurring and blurring phenomena can be prevented is that ozone or nitrogen oxide acts on the antioxidant of the present invention and protects the charge transporting material before the charge transporting material is degraded by oxidation. Further, the reason why high sensitivity can be maintained is that the charge transport material was formed and dried at 140°C. The thickness of the charge generation layer was 1 μm or less.

Table 1 shows that the deterioration of the bonding part is prevented and a stable charge density can be maintained, and that the deterioration of the dialkyl group is prevented and stable hole injection is performed efficiently. It is used in products such as rubber and rubber, and is thought to have good compatibility with binder resins.

〔Example〕

Examples of the present invention will be described in detail below.

Example 1 Using a dipping method with a coating liquid having the composition shown in Table 1 below, 100
Forming a charge generation layer on a μm aluminum plate, JP-A-62-30255 and JP-A-62-287257
Among the styryl compounds shown in Table 2 obtained by the synthesis method described in the publication, the compound of Nα1 was used as a charge transport substance, and a charge transport layer was applied using a dipping method with a coating liquid having the composition shown in Table 3. , and dried at 110'C to obtain an electrophotographic photoreceptor. The thickness of the charge transport layer was 15 μm.

Table 2 Table 3 The obtained photoreceptors were evaluated in terms of residual potential and resolution before and after the deterioration test. In the deterioration test, a sample is placed on a rotating drum at a circumferential speed of approximately 190 cm/min, and while the drum is rotating, a corona charger installed near the drum is charged with zero.
After being charged by applying a voltage of 5.2kV, the corona charger is 18o.

Tungsten lamp light installed in the direction (illuminance 501
The exposure step (1×) was repeated for 5 hours.

In addition, the residual potential was measured using an electrostatic recording paper evaluation device (manufactured by Kawaguchi Electric, S
P-428 type), when charged at 700 (-V),
The potential was expressed as the potential 0.2 seconds after irradiation with an illumination intensity of 50 Ux (tungsten lamp) for 0.2 seconds. Furthermore, the resolution is based on the electrophotographic society test chart (Nαl-R, 19
After contact exposure using the resolution pattern of 1975 edition), the images were developed and judged visually.

The electrophotographic photoreceptor manufactured in this example using the above evaluation method had an initial residual potential of 120 (-V), a resolution of 12.5 lines/n, and a residual potential of 125 (-V) after the deterioration test. ), the resolution remained almost unchanged at 12.5 lines/m.

Examples 2 to 6 and comparative example 1 A charge generation layer was produced in the same manner as in Example 1.

Next, a charge transport layer was prepared on this charge generation layer in the same manner as in Example 1 using a coating solution having the composition shown in Table 4 to obtain an electrophotographic photoreceptor. These photoreceptors were subjected to the same deterioration test as in Example 1, and changes in residual potential and resolution were investigated. The results are shown in Table 5.

As described above, as the amount of the hindered phenol compound (Irganox 1330) added increases, the residual potential tends to increase, and in particular, the increase in the residual potential after the deterioration test becomes remarkable. In addition, as the amount of the hindered phenol compound added increases, the decrease in resolution in the deterioration test decreases, so the amount of the hindered phenol compound added is in the range of 0.5 to 100 parts by weight based on the styryl compound. I found something good.

Examples 7 to 10 and Comparative Example 2 A charge transport layer was prepared in the same manner as in Example 1.

Next, a charge transport layer was formed on this charge generation layer in the same manner as in Example 1 using a coating solution having the composition shown in Table 6 to obtain an electrophotographic photoreceptor. These photoreceptors were subjected to the same deterioration test as in Example 1, and changes in residual potential and resolution were investigated. The results are shown in Table 7.

As in the previous examples, a hindered amine compound (
As the amount of Chimasorb 119FL) added increases, the residual potential tends to increase, but there is little decrease in resolution after the deterioration test.

〔Effect of the invention〕

The electrophotographic photoreceptor of the present invention is highly effective in preventing image deterioration caused by repeated use, such as image blurring and blurring, without deteriorating electrophotographic properties.

Claims (1)

[Scope of Claims] 1. In an electrophotographic photoreceptor in which a photosensitive layer containing a charge-generating substance and a charge-transporting substance is provided on a conductive support, a styryl compound represented by the following structural formula (1) is used for charge-transporting. As a substance, either a paraphenylenediamine compound, a hindered amine compound having one or more of the following structural formula (2) in one molecule, or a hindered phenol compound having one or more of the following structural formula (3) in one molecule. An electrophotographic photoreceptor characterized by containing one of the following. Structural formula (1) ▲ Numerical formulas, chemical formulas, tables, etc.
shows. ) Structural formula (2) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (R in the formula represents H or an alkyl group) Structural formula (3) ▲There are mathematical formulas, chemical formulas, tables, etc.▼