JPS59125735A - Photosensitive body for electrophotography - Google Patents

Abstract

PURPOSE:To obtain a photoconductive material having very high sensitivity and spectral sensitivity from the visible region to the near infrared region by incorporating a specified squarelium pigment into a photoconductive layer. CONSTITUTION:A squarelium pigment represented by formula I (where R is 2- 6C linear alkyl, cyclic alkyl, phenyl or substituted phenyl) is incorporated into the photosensitive layer 4 of a photosensitive body for electrophotography having a two-layered structure consisting of a charge generating layer 2 and a charge transferring layer 3. The squarelium pigment is prepd. by reacting 3,4-dihydroxy- 3-cyclo-butene-1,2-dione represented by formula II with an aniline deriv. represented by formula III.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic photoreceptor used in an electrophotographic process. More specifically, the present invention relates to an electrophotographic photoreceptor containing a squareium pigment in a photoconductive layer.

Conventionally, inorganic photosensitive materials such as amorphous selenium, selenium alloys, cadmium sulfide, and zinc oxide, as well as organic photosensitive materials such as polyvinylcarbachy/L4 and polyvinylcarbazole derivatives, have been widely used as electrophotographic photoreceptors. It is being

It is well known that amorphous selenium or selenium alloy ts'H electrophotographic photoreceptors have extremely excellent properties and are used in practical applications. but.

Its production requires a complicated step of vapor deposition, and the produced vapor-deposited film has the drawback of not being flexible. When zinc oxide is used, it is used as a dispersed photosensitive material in which zinc oxide is dispersed in a resin, but such a photosensitive material has a drawback in mechanical strength and cannot withstand repeated use as it is.

Polyvinylcarbazole, which is widely known as an organic photoconductive material, has advantages such as transparency, film-forming properties, and flexibility.

Since polyvinylcarbazole itself has no sensitivity in the visible light region, it cannot be put to practical use as K as it is, and therefore various sensitization methods have been devised. However, when polyvinylcarbazole is spectrally sensitized using a dye sensitizer, the spectral sensitivity can be extended to the visible light range, but sufficient sensitivity cannot be obtained as a photoreceptor for electrophotography, and photofatigue may occur. It has a serious drawback. In addition, when chemically sensitized using an electron-accepting compound, a photoreceptor with sufficient sensitivity as an electrophotographic photoreceptor can be obtained, and some of them have been put into practical use. Problems remain with respect to strength, life, etc.

Although active research has been carried out on organic dispersion photosensitive materials and there have been numerous reports, a photoreceptor with excellent electrical properties and sufficient sensitivity as an electrophotographic photoreceptor has not yet been obtained. There is no work.

Currently, there are reports that phthalocyanine can be used as a dispersed photosensitive material in an excellent electrophotographic process.

Its spectral sensitivity is biased towards the long wavelength region, and therefore it has the disadvantage of poor red reproducibility.

An object of the present invention is to provide an extremely sensitive photoconductive material that can be used in any existing electrophotographic process and has spectral sensitivity from the visible region to the near-infrared region.

Another object of the present invention is to have flexibility that is not found in inorganic photosensitive materials, improve low abrasion resistance and lack of mechanical strength, which are defects of polyvinylcarbaso-root sonylotrofluorenone organic photosensitive materials, and further It is an object of the present invention to provide a photoreceptor for electrophotography which is highly sensitive and has substantially flat spectral sensitivity in a wide range from the optical range to the near-infrared region, and has excellent mechanical strength such as wear resistance.

The present inventors have developed conventional inorganic photosensitive materials, organic photosensitive materials,
We aim to improve the various drawbacks of organic dispersion photosensitive materials and to obtain photoconductive materials that have both excellent electrophotographic customization and flexibility, and also have high sensitivity over a wide range from the visible region to the near-infrared region. As a result of research, the inventors discovered that a specific squareium pigment has extremely excellent properties and completed the present invention.

The squareium pigment used in the present invention is:

It is represented by the following general formula (I).

θ [In the formula, 11 represents a chain alkyl group having 2 to 6 carbon atoms, a cyclic alkyl group, a substituted phenyl group, or a non-@-substituted phenyl group. ] This squareium pigment is composed of 3,4-dihydro-7-3-'/ri-butene-1,2-dione represented by formula (II)H [wherein R represents the same meaning as above]. ] can be obtained by reacting with the aniline derivative shown below.

The squareium pigment represented by the general formula (1) can be used in an electrophotographic photoreceptor having a multilayer structure. That is, in an electrophotographic photoreceptor having a two-layer structure consisting of a charge generation layer and a charge transport layer, a charge generation layer containing a squareium pigment and a known charge transport layer 1 are used.
Photoconductive hepolymers such as, for example, polyvinyldibenzothiophene, polyvinylpyrene, polyvinyla/traceno, polyvinylcarbazole, or triallylpyrazoline, triphenylmethane.

By forming a layer containing substances such as oxadiazole, tetraphenylbenzidine, trinitroflurofluoride, etc. in the binder resin, the banding properties of the photoreceptor can be improved, the residual potential can be reduced, and the mechanical strength can be improved. can be achieved.

To explain the structure of the two-layer structure electrophotographic photoreceptor of the present invention, as shown in FIG. 1 and FIG. A photosensitive layer 4 made of a laminate with a charge transport layer 3 containing a substance is provided.

The charge generation layer may be formed by using the squareium pigment alone, but it can also be formed by using it in combination with a binder resin. The ratio of the pigment to the binder resin ranges from 10% by weight to 90% by weight, preferably from 10% by weight to 50% by weight.

Charge generation layer using squareium pigment alone without using binder resin? Forming methods include solvent coating and vacuum evaporation.

The thickness of the charge generation layer is 0.1 to 3 μm, preferably 0.2 to 1 μm.
μ.

When dispersing the pigment in the binder, the pigment is ground and used, but grinding method 1:! 5PEX MILL ball mill,
Known methods such as RED DEVIL (product name)! Can be used.

The binder of the charge generation layer may or may not itself have photoconductivity. Examples of the photoconductive binder include photoconductive polymers such as polyvinylcarbazole, polyvinylcarbazole derivatives, polyvinylnaphthalene/polyvinylanthracene, and polyvinylpyrene, and other organic matrix materials having charge transport ability.

Furthermore, known insulating resins that do not have photoconductivity can also be used as the binder. Known insulating resins include polystyrene/, polyester, polyvinyltoluene, polyvinylanisole, polychlorostyrene, polyvinyl butyral, polyvinyl acetate, polyvinyl butyl methacrylate, copolystyrene-butadiene, polypurphono, copolystyrene/-methyl methacrylate,
Polycarbonate etc. can be used.

At this time, in order to further improve the mechanical strength of the resulting photoreceptor, a plasticizer can be used in the same manner as in general polymeric materials. As the plasticizer, for example, chlorinated paraffin, chlorinated biphenyl, phosphate plasticizer, phthalate plasticizer, etc. can be used.
Added 10% by weight, reducing the sensitivity and electrical properties of the photoreceptor 2
It is possible to further improve its mechanical strength without having to do so.

A binder with a dispersed squareium pigment is applied onto a conductive support. Coating methods include a dipping method, a spray method, a bar coater method, and an applicator method, and a good photosensitive layer can be formed by any of these methods.

Further, as the conductive support, metal, paper treated with conductivity, a polymer film having a conductive layer, glass, etc. can be used.

The electrophotographic photoreceptor of the present invention can be widely used not only in ordinary copying machines but also in semiconductor laser printers, intelligent copiers, and the like.

Next, the present invention will be explained by examples.

Example 1 A squareium pigment (1) of the formula (I) in which R represents C2H5'g is ground with methylene chloride/hard spheres for 12 hours.

After crushing, add 3 to polyester resin (product name Byron 200).
0 weight ratio addition and mixing. The mixture was applied onto an aluminum grate using an applicator to form a charge generating layer so that the film thickness after drying was approximately 0.5 μm. On top of this
1-phenyl-3-(p-diethylaminostyryl)-
A charge transport layer was prepared by adding and mixing 5-Cp-diethylaminophenyl cupirazoline into a polycarbonate resin (trade name, Panlite) and applying it with an applicator to a thickness of about 15 μm.

Next, the photosensitive layer surface of this photoreceptor was negatively charged by applying corona discharge of 16 KV for 2 seconds using an electrostatic copying paper tester manufactured by Kawaguchi Electric, and then left in a dark place for 2 seconds, and the surface potential at that time was V.
. tungsten with an illumination intensity of 10 lux.
The photosensitive layer is irradiated with a halogen lamp, and its surface potential is V.

Calculate the time (seconds) it takes to reduce to 1/2 of the halved exposure amount E.
l/2 was calculated. As a result, Vo=760 V-El
, 72 = 1.6 lux·sec.

Examples 2 to 6 In formula (1), R=n C3H7(2), R-n-C
4Hg (3), R=iC3H7 (4), R=C6Hs
A photoreceptor was prepared in the same manner as in Example 1, except that the squareium pigment of (5)-R""CaHto (6) was used, and its electrical properties were measured. The results are shown in Table 1.

Table 1 Examples 7 to 12 The photoreceptor of this example was modified by reversing the order of the charge generation layer and charge transport layer. That is, the squareium pigments (1), (2), and (3) used in Examples 1 to 6.

In (4), (5), and (6), photoreceptors were prepared under the same conditions except that the order of the charge-generating layer and the charge transport layer was reversed.

Table 2 shows the results of measuring the electrical properties.

Table 2

[Brief explanation of drawings]

FIGS. 1 and 2 are cross-sectional views of examples of groove bottoms of the electrophotographic photoreceptor of the present invention. Symbols in the figure: 1... Conductive support; 2... Charge generation layer; 3...
Charge transport layer; 4... Photosensitive layer.

Claims (1)

[Scope of Claims] A photosensitive material containing a squareium pigment represented by the general formula (wherein R represents a chain alkyl group having 2 to 6 carbon atoms, a cyclic alkyl group, a phenyl group or a substituted phenyl group) An electrophotographic photoreceptor characterized by having a layer.