JPS62151853A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To improve sensitivity to the light of a near IR region by incorporating a specific bisazo compd. into a photosensitive layer. CONSTITUTION:The bisazo pigment expressed by the formula I is incorporated as a carrier generating layer in the photosensitive layer. In the formula I, Ar1, Ar2 respectively denote an (un)substd. phenyl or naphthyl and Ar3 denotes an (un)substd. arom. heterocyclic ring or arom. carbon ring. The substituents of Ar1-Ar3 include a halogen and lower alkyl and the embodiment of the formula I includes the compd. expressed by the formula II. The photosensitive body having the good electrostatic charge characteristic and photosensitivity and the high sensitivity particularly to the light of the near IR region is obtd. if the bisazo compd. expressed by the formula I is incorporated into the photosensitive layer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to an electrophotographic photoreceptor having a photosensitive layer containing as an active ingredient a bisazo compound using a coupler having a 9-carbazolyl group.

[Prior art and its problems]

A photoreceptor for electrophotography is required to be able to be charged to a required potential by corona discharge in a dark place, to have little leakage of charge, and to have the ability to quickly discharge charges when irradiated with light. Conventionally, inorganic materials such as shaped selenium, amorphous silicon, selenium-tellurium alloy, cadmium sulfide, and zinc oxide have been used as materials for photoconductors with such performance, but In recent years, materials for organic photoreceptors that can be easily formed into films with excellent flexibility and impact resistance, such as indigo pigments and phthalocyanine pigments, have been developed using azo compounds. A photoreceptor having a base material (O) has been attracting attention (for example, Japanese Patent Publication No. 44-16474, Japanese Patent Application Laid-Open No. 47-37543, and Japanese Patent Application Laid-Open No. 52-4241).

For image formation by electrophotography using these photoreceptors, for example, the force to Luzon system is applied.

Image formation in this method involves charging the surface of the photoconductor in a dark place by corona discharge, and forming an electrostatic latent image of text or pictures on the document by light reflected by the document onto the surface of the charged photoconductor. , the formed electrostatic latent image is developed with toner, the developed toner image is transferred to a support such as paper, and the toner image is fixed to the support such as paper, and the photoreceptor after the toner image is transferred. After static electricity removal, residual toner removal, and optical static electricity removal,
Subject to reuse.

When copying an original, it is desirable to obtain a copy that faithfully reproduces the image density of the original, but in order to achieve this, the light sensitivity of the photoreceptor used in the copying machine must exceed the color density of the human eye over the entire visible light range. It was necessary to match the visibility with respect to

Unlike conventional copying machines, demand has increased in recent years for printers that convert a document into an electrical image signal and then convert it into the original image signal to form an electrostatic latent image on the surface of a photoreceptor. Lasers and LEDs are used as light sources for these printers, but since the light sources have only a specific wavelength, the photoreceptor must be highly sensitive at that wavelength.

However, conventional photoconductors for copying machines have a peak sensitivity of around 550 nm in order to match the visibility of the human eye, so they are highly sensitive to the near-infrared region of the oscillation wavelength of the light source for printers. It had the disadvantage of not having

As a result of further research, the present inventor discovered that by using a bisazo compound using a coupler having a 9-carbazolyl group as a carrier-generating substance, it has a high resistance to the near-infrared region of a light source for printers such as a laser beam. It was discovered that a sensitive electrophotographic photoreceptor can be obtained, leading to the present invention.

[Purpose of the invention]

An object of the present invention is to provide an electrophotographic photoreceptor using a bisazo compound that exhibits excellent photoconductive performance in the near-infrared region.

[Key points of the invention]

An object of the present invention is to use a bisazo compound having a 9-carbazolyl group as a carrier generating substance in an electrophotographic photoreceptor equipped with a photosensitive layer containing a bisfuji compound as a carrier generating substance, and to utilize its unique aggregation state. This is achieved by

Therefore, the present invention has the following structural formula (where Ar and Arz each represent a substituted or unsubstituted phenyl or naphthyl group, and Ar3 represents a substituted or unsubstituted aromatic carbocycle or an aromatic carbocycle). The present invention relates to an electrophotographic photoreceptor comprising a photosensitive layer containing a bisazo compound represented by the following formula.

Examples of substituents for Ar+, Ar2 and Ar3 include halogen atoms and lower alkyl groups.

The bisazo compound of the present invention can be effectively used as a carrier-generating substance in a carrier-generating layer in an electrophotographic photoreceptor, thereby making it possible to obtain a photoreceptor that exhibits excellent photoconductive performance in the near-infrared region. .

Examples of the present invention will be described below, in particular, a photoreceptor using the above-mentioned bisazo compound as a carrier generating substance.

This will be described in detail in connection with the production of a so-called functionally separated photoreceptor.

Of course, the present invention is not limited to such photoreceptors.

[Embodiments of the invention]

Generally, as mentioned above, in a functionally separated photoreceptor, a carrier generation layer is provided on a conductive substrate, and a carrier transport layer is further provided on top of the carrier generation layer, or a carrier transport layer is provided first and then a carrier generation layer is provided. Consisted of.

As the tetraelectric substrate, a metal plate or sheet made of aluminum, copper, zinc, etc., a plastic sheet or film made of polyester, etc., on which the above metals are vapor-deposited, etc. are used.

The carrier generation layer is prepared by uniformly mixing the bisazo compound of the present invention as a carrier generation substance with a suitable resin binder, solvent, etc. to prepare a coating solution, and coating this on a conductive substrate.
Formed by drying. As binders, known resins used for this type of purpose, such as polyesters, (meth)acrylics, polyamides, polyurethanes,
It may be epoxy polycarbonate, N°J cone resin, or the like. The solvent may be alcohol, ether, aromatic hydrocarbon, or the like. As a coating method, an applicator method, a bar coater method, etc. can be used.

The carrier transport layer can be formed by uniformly mixing a carrier transport substance with the same binder and solvent as described above to form a coating solution, and applying the same in the same manner.

Examples of carrier transport substances include known ones, such as aromatic tertiary amino (and diamino and triamino) compounds, polyvinylcarbazole compounds, birapurine derivatives, triazine derivatives, quinazoline derivatives, and oxadiazole derivatives.

-S, the carrier generation layer has a thickness of 0.005 to 10 μm
The thickness of the carrier transport layer may be 5 to 100 μm.

A bisazo compound having Example 1 was ground into particles of 1 μm or less using a ball mill. 1 part by weight of the fine particles of the pulverized bisazo compound and a polar organic solvent. Thirty weight portions of N,N-dimethylformamide (EMF) were subjected to ultrasonic dispersion treatment for 2 hours using an ultrasonic homogenizer to prepare a suspension in which fine particles of a bisazo compound were uniformly dispersed in a polar solvent.

This suspension polymethyl methacrylate (P M M , A
) and 6 parts by weight of toluene were added and mixed well with a magnetic stirrer to prepare a uniform coating solution.

This coating solution was dried with a wire bar on a 75 μm thick aluminum vapor-deposited polyester film substrate until the film thickness was 0.
．． It was applied to a thickness of 2 μm and dried to form a carrier generation layer. On top of this, 1 part by weight of N,,N-diethylaminobenzaltehyde-1,l-diphenylhydrazone and 1 part by weight of polyester resin were layered with tetrahydrofuran. A carrier transport layer was formed by coating and drying.

The electrophotographic properties of the thus prepared photoreceptor were evaluated using a Kawaguchi Electric Seisakusho Model 5P-428 electrostatic paper tester. Corona discharge was performed for 10 seconds at a voltage of -6, OKV to negatively charge the photoreceptor, and the charged potential V on the surface of the photoreceptor at that time was measured.

After that, the charged potential V when discharging for 2 seconds in a dark place.

Then, the surface of the photoreceptor was irradiated with monochromatic light of 800 nm, and the light energy until ① was reduced by half was determined, and the half-reduction exposure 1ttE'/2 was determined. As a result, a value of vA = -800V E'/2 = 1411 J/cat was obtained, indicating that the photoreceptor had excellent characteristics even in the near-infrared region.

Comparative Example 1 A photoreceptor was prepared according to the following structural formula 1 in place of the bisazo compound of Example 1, and its electrophotographic properties were evaluated. As a result, the value was Va = 800V E° 8 to l sOμJ /CIl+, and it was found that even the bisazo structure does not impart photosensitivity to the near-red region of the bisazo compound.

tJL-1 A photoreceptor was prepared in the same manner as in Example 1, except that a bisazo compound having the following structural formula was used in place of the compound in Example 1, and its electrophotographic properties were evaluated. the result,.

■A value of 900V E'/z = 2001JJ/cot was obtained.

It is known that the bisazo compound having the above structural formula provides a photoreceptor with excellent properties in the visible light region, but it has been found that even the bisazo structure does not provide photosensitive properties in the near-infrared region.

Effects of the Invention According to the present invention, a photoreceptor having a photoreceptor layer containing a bisazo compound using a coupler having a 9-carbazolyl group as a carrier generating substance of a functionally separated photoreceptor has good charging characteristics and photosensitivity. In particular, it has high sensitivity to the near-infrared region of the oscillation wavelength of a light source for a printer.

Claims (1)

[Claims] 1) The following structural formula ▲ Numerical formula, chemical formula, table, etc. ▼ 1. A photoreceptor for electrophotography, comprising a photosensitive layer containing a bisazo compound represented by an aromatic heterocycle or an aromatic carbon ring.