JPH02230256A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To provide the photosensitive body which has good electrostatic chargeability, low residual potential and good durability and can retain a high sensitivity even in a near IR region by providing a charge generating layer essentially consisting of a specific titanyl phthalocyanine compd. and a charge transfer layer essentially consisting of a specific hydrazone compd. on a conductive substrate. CONSTITUTION:The charge generating layer 2 essentially consisting of the titanyl phthalocyanine compd. which is expressed by formula I and has such an X-ray analysis diagram as to exhibit peaks at 7.6 deg., 10.2 deg., 12.3 deg., 16.5 deg., 28.6 deg. Bragg angles (2theta+ or -0.2 deg.) and to have 0.2 to 0.6 ratio P1/P2 between the peak intensity P1 of 28.6 deg. and the peak intensity P2 of 7.6 deg. and the charge transfer layer 1 essentially consisting of the hydrazone compd. expressed by formula II are provided on the conductive substrate 4. In the formulas I, II, Y denotes oxygen, halogen, n denotes 0 to 2 integer; Bu denotes a butyl group. The high sensitivity even in the long wavelength region yet the excellent durability, the good electrostatic chargeability and the low residual potential are obtd. in this way.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to an electrophotographic photoreceptor used in copying machines, optical printers, etc. The present invention relates to a laminated electrophotographic photoreceptor that is provided with a protective layer and has high sensitivity up to the near-infrared region.

(Prior Art) Conventionally, electrophotographic photoreceptors include those whose photosensitive layer is a vapor-deposited film of an alloy of selenium and arsenic, and those whose photosensitive layer is made of α-Si (amorphous silicon) formed by plasma CVD and sputtering.
Well-known examples include those in which a film is used as a photosensitive layer, and those in which a layer formed by coating CdS-ZnO dispersed in a binder resin are used as a photosensitive layer. The photosensitive layer in this electrophotographic photoreceptor is used as an image support for electrophotography to form an electrostatic image according to the image of a document, and as a main component of the electrophotographic process. The forms of these photoreceptors include a sheet, a belt, a drum, and the like. In recent years, research on organic photoconductive layers used in organic photosensitive layers has been active, and their performance has improved in terms of sensitivity, durability, etc., and they are being applied to copiers and optical printers, and are rapidly becoming popular.

In recent years, there has been active development of laser beam printers that use laser light as a light source instead of conventional white light and have the advantages of high speed, high image quality, and compact size, and there is a desire to develop photoreceptors that can meet these demands. . The wavelength of semiconductor and laser light sources, which have made remarkable progress in recent years, is 780 to 830 nm.
Therefore, it is strongly desired to realize a photoreceptor having characteristics of high sensitivity to long wavelength light of around 800 nm.

Conventionally, methine squaric acid dyes, indoline dyes, cyanine dyes, naphthoquinone dyes, and phthalocyanine dyes are known as charge-generating materials that meet this requirement.

Naphthoquinone dyes, methine squaric acid dyes, indoline dyes, and cyanine dyes can have longer wavelengths, but they have problems with stability and sensitivity, and there are many challenges to their practical application. Among the cyanine-based dyes, metal phthalocyanine compounds can shift the sensitivity peak to a longer wavelength region by selecting the central metal.

(Problems to be Solved by the Invention) Practical organic electronic photoreceptors that have low sensitivity, high residual potential, and durability problems even if they are organic photoconductive materials that have a sensitivity peak in a long wavelength range. However, there are few that have sufficient performance.

The present inventors have studied and arrived at the present invention in order to obtain an organic electrophotographic photoreceptor that has good charging properties, low residual potential, good durability, and high sensitivity even in the near-infrared region. It was.

(Means for Solving the Problems) The present invention provides a structure that is expressed by the structural formula (1) on a conductive support, and has a Black angle (2θ±0.2') of 7.6°10.2'.
, 12.3', 18.5' and 28.8', and the ratio P I/ P 2 of the peak intensity P at 28.8' and the peak intensity P2 at 7.6° is 0.2. It is characterized by providing a charge generation layer mainly composed of a titanyl phthalocyanine compound having an X-ray analysis diagram of ~0.6, and a charge transport layer mainly composed of a hydrazone compound represented by structural formula (2). This is a laminated type electrophotographic photoreceptor.

(Y represents oxygen or halogen, n represents an integer of 0 to 2) (Bu represents a butyl group) The charge generation layer of the present invention contains a titanyl phthalocyanine compound represented by structural formula (1) together with a binder polymer. A layer is formed by coating a polymer dispersed in a solvent or medium, and examples of the binder polymer include polyvinyl butyral, polymethyl methacrylate, polycarbonate, polystyrene, polyurethane, epoxy resin, and polyester. The amount of binder polymer used is 0 relative to the titanyl phthalocyanine compound.
．． The amount is in the range of 1 to 5.0 times by weight, preferably 0.2 to 2 times by weight. Further, it is preferable that the titanyl phthalocyanine compound is dispersed in the binder in the form of fine particles of 1 or less, and it is effective to perform particle crushing and dispersion using a device such as a ball mill for mixing and dispersing.

The charge generation layer of the present invention may have a thickness of 0.1 to 0.0 tu, preferably 0.2 to 0.5 tu. The solvents and medium used include ethers such as tetrahydrofuran, 1-4 dioxane, methyltetrahydrofuran,
Ketones such as methyl ethyl ketone and cyclohexane, aromatic hydrocarbons such as toluene and xylene, methanol,
Examples include alcohols such as ethanol and isobrobyl alcohol, and chlorinated hydrocarbons such as methylene chloride, dichloroethane, and chloroform. These media may be used alone or in combination of two or more.

As the conductive support on which the charge generation layer is coated, any of those used in well-known electrophotographic photoreceptors can be used, but specifically aluminum drums,
There are plastic sheets 1, plastic films, and plastic cylinders in which a conductive material is provided as a thin film by vapor deposition or sputtering.

As a means for forming a charge generation layer on these conductive supports, a dip coating method is used in the case of a drum-shaped support, and a roll coating method is used in the case of a sheet-like support.

The charge transport layer (charge transport layer) has the function of transporting the charges generated in the charge generation layer, and therefore has efficient charge injection at the charge generation layer interface and high charge transfer speed in the transport layer. It takes.

Therefore, it is necessary to strictly select a charge transport material suitable for the charge generating material used, and it is also necessary to select coating liquid formulation conditions and coating drying conditions for each layer.

The charge transport layer of the present invention is a layer formed by coating a hydrazone compound represented by the structural formula (2) and a binder polymer dispersed in a solvent or medium. ■
Bu in the formula represents a butyl group, preferably an n-butyl group.

The hydrazone compound in the charge transport layer is 0.1 to 2.0, preferably 0.3 to 1.5, relative to the binder polymer.
Use within twice the weight. The binder polymer, solvent, or medium used in forming the charge transport layer may be the same as that used in forming the charge generation layer. The thickness of the charge transport layer is 10 to 30 pJIx, preferably 15 to 20 pJIx.
It is IJJ.

The charge transport layer may be provided on the charge generation layer or between the conductive support and the charge generation layer.

In the present invention, the charge generation layer or the charge transport layer may be provided directly on the conductive support, but preferably, an undercoat layer is provided on the conductive support, and the charge generation layer or charge transport layer is provided on the undercoat layer.
It is better to provide a charge transport layer. Furthermore, in the present invention, an intermediate layer or a transparent surface protective layer may be provided between the charge generation layer and the charge transport layer.

(Example) [Example 1. ] Ammonia aqueous solution of casein (10% casein, 1 g of ammonia water, 200 cc of water) was dried on a solvent-cleaned AQ plate (surface polishing level 0.IS) using a spin coat to a film thickness of 0.5 u. The undercoat layer was applied in the same manner.

Next, the Black angle (2θ±0.2°) of structural formula (1) is 7.8 @ 10.2°. 12.3'18.5'. It shows a peak at 28.6°, and P 1
/ Titanyl phthalocyanine (Y=O, n=1) exhibiting an X-ray diffraction pattern with P2 of 0.3 and polyvinyl butyral resin (Denka 2000-L) were mixed in tetrahydrofuran at a ratio of 3/l by weight. Milling was carried out using a ball mill for about 5 hours, and the resulting dispersion coating solution was used in a spin coater to form a charge generation layer such that the dry coating film was 0.3 mm.

A charge transport layer was further formed on this in the following manner. In the hydrazone compound represented by the above structural formula (2), B
A charge transport layer was formed using a spin coater using dichloroethane as a solvent and a dry coating film having a thickness of 20 IJR using dichloromethane as a solvent and a polycarbonate resin in a weight ratio of 1.

The spectral sensitivity characteristics of the spectrophotometer of the photoreceptor obtained in this way are
This is shown by curve a in the figure.

The sensitivity of the photoreceptor is expressed by the number of exposure doses required to reduce the initial surface potential to 1/2, assuming an initial surface potential of -600V.

(Effect of the invention) By selecting and using the specific titanyl phthalocyanine of the present invention as a charge generating material and a specific hydrazone compound as a charge transporting material, high sensitivity in the long wavelength region and excellent durability can be achieved. It was found that this material can be used as a practical electrophotographic photoreceptor.

[Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing the structure of the electrophotographic photoreceptor of the present invention, and FIG. 2 is a diagram showing the spectral sensitivity characteristics of the photoreceptor in Example 1. Patent developer Toyobo Co., Ltd. 2: Charge generation layer

Claims (1)

[Claims] (1) Expressed by the structural formula (1) on a conductive support, the Black angle (2θ ± 0.2°) is 7.6°, 10.2°, 1
It shows peaks at 2.3°, 16.5°, 28, and 6°, and the ratio P_1/P_2 of the peak intensity P_1 at 28.6° and the peak intensity P_2 at 7.6° is 0.2-0. A laminated electrophotographic photoreceptor comprising a charge generation layer containing a titanyl phthalocyanine compound as a main component, and a charge transport layer containing a hydrazone compound represented by Structural Formula (2) as a main component. . ▲There are mathematical formulas, chemical formulas, tables, etc.▼(1) (Y: oxygen, halogen, n represents an integer from 0 to 2) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(2) (Bu: represents a butyl group )