JPS60128454A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain a photoconductive material having high spectral sensitivity from the visible region to the near IR region by forming a photosensitive layer contg. a squarium pigment represented by a specified general formula on a conductive substrate. CONSTITUTION:A photosensitive layer 4 is obtained by laminating an electrostatic charge generating layer 2 contg. a squarium pigment represented by the formula shown here alone or together with a binder resin in a pigment/binder ratio of 10-90wt%, and a charge transfer layer 3 contg. a charge transfer material on a conductive substrate 1. In the formula, X is H or 1-4 C alkyl, and Y is H, 1-4 C alkyl or such alkoxy, or OH.

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, and organic photosensitive materials such as polyvinyl carbazole and polyvinyl carbazole derivatives have been widely used as electrophotographic photoreceptors. .

It is well known that amorphous selenium or selenium alloys have extremely excellent properties as electrophotographic photoreceptors 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 range, it cannot be put to practical use as it is, and therefore various sensitization methods have been devised. However, when polyvinylcarbazole is spectrally sensitized using a dye sensitizer, the 1 spectral sensitivity range is extended to the visible light range.

However, as an electrophotographic process, it has the disadvantage that sufficient sensitivity cannot be obtained and optical fatigue is severe. In addition, when chemically sensitized using a photosensitive compound, a photoreceptor with sufficient sensitivity as an electrophotographic photoreceptor can be obtained, and although some of the photoreceptors have been put into practical use, it is still difficult to make one machine. Problems remain in terms of strength, lifespan, etc.

Although active research has been carried out on organic dispersion photosensitive materials and there have been numerous reports, a photoreceptor having excellent electrical properties and sufficient sensitivity as an electrophotographic photoreceptor has not yet been obtained.

Currently, there are reports that 7-thalocyanine exhibits excellent electrophotographic properties as a dispersed photosensitive material.

Its spectral sensitivity is biased towards the long wavelength range, 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, lack of mechanical strength, and other defects of polyvinylcarbazole-tristrofluorenone based organic photosensitive materials. The object of the present invention is to provide an electrophotographic photoreceptor that is highly sensitive and has a flat spectral sensitivity over a wide range from the near-infrared region to the near-infrared region, and has excellent mechanical strength such as abrasion 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 properties 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, it was discovered that a specific squareium pigment has extremely excellent properties, and the present invention was completed.The squareium pigment used in the present invention is.

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

(In the formula, xt'z represents hydrogen or an alkyl group having 1 to 4 carbon atoms, and Y represents hydrogen, an alkyl group having 1 to 4 carbon atoms, a hydroxyl group, or an alkoxyl group having 1 to 4 carbon atoms.) This squareium The pigment is represented by formula (II) 3,
It is obtained by reacting 4-dihydroquicou-3-cyclobutene-1,2-dione with an aniline derivative represented by the general formula (wherein X and Y have the same meanings as above).

The squareium pigment represented by the general formula (I) can be used in an electrophotographic photoreceptor having a multilayer structure. That is, in an electrophotographic photoreceptor including a photosensitive layer with a two-layer structure consisting of a charge generation layer and a charge transport layer, a charge generation layer containing Squarium M#+ and a known charge transport layer such as polyvinyldibenzothiophene or polyvinylpyrene are used. , poly, vinylanthracene, photoconductive polymers such as polyvinylcarbasol, or triallylpyrazoline, triphenylmethane.

Oxadiazole, Tetraphenylbe/Gidi/.

By forming a layer containing trinide-fluorenone or the like contained in the binder/der resin, it is possible to improve the chargeability of the photoreceptor, reduce the residual potential, and further improve the mechanical strength.

To explain the structure of the two-layered electrophotographic photoreceptor of the present invention, as shown in FIGS. 1 and 2, a charge generation layer 2 containing a squareium pigment and a charge transport material are formed on a conductive support 1. A photosensitive layer 4 made of a laminate with a charge transport layer 3 containing .

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 is 10% to 90% by weight, preferably 10% to 50% by weight. Solvent coating is a method for forming a charge generation layer using the squareium pigment alone without using a binder resin. and vacuum evaporation method.

The thickness of the charge generation layer should be 0.1 to 3μ, preferably 0.2 to 3μ.
The pigment is pulverized and used when dispersing it in the binder, but the pulverization method is 5PEX MILL, ball mill,
A known method such as RED Dgvrt (trade 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 polyvinylbire, and other organic matrix materials having charge transport ability.

Further, as a binder, a known insulating resin having no photoconductivity can also be used.

Known insulating resins include polystyrene, polyester, polyvinyltoluene, polyvinylanisole, HolJ
Chlorostyrene, folipinylbutyral, polyvinyl acetate, polyvinyl butyl methacrylate, cobolystere/-butadiene, polyfluorone, 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 piphenyl, phosphate plasticizer, phthalate plasticizer, etc. can be used.
By adding 0% by weight, it is possible to further improve the mechanical strength of the photoreceptor without deteriorating its sensitivity or electrical properties.

The Squarium Face 4!1 dispersed binder 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.

In addition, as a conductive support, metal or conductive treated paper,
A polymer film or glass having a conductive layer 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, etc. Next, the present invention will be explained with reference to examples.

Example 1 Squareium pigment (1)' in formula (I) where X is H and Y is H'l1! l'Methylene chloride, milled with steel balls for 12 hours. After pulverization, 30% by weight of polyester resin (trade name, Tsukiron 200) is added and mixed, and the L0 mixture is applied onto an aluminum plate using an applicator so that the film thickness after drying is approximately 0.5μ to form a charge generation layer. did. On top of this, 1-7znyl-3-(P-diethylaminost IJ/ShiE = 5-CP-diethylaminophenyl)-pyrazoline was added to a polycarbonate resin (trade name,
・A charge transport layer mixed with 50% by weight of Kunlite) was applied with an applicator to a film thickness of approximately 15 μm.Next, a charge transport layer of 16 KY was applied to the photosensitive layer surface of this photoreceptor using an electrostatic copying paper tester manufactured by Kawaguchi Electric. After performing corona emission TFT for 2 seconds to make it negatively charged, it was left in a dark place for 2 seconds, and the surface potential V at that time. The photosensitive layer is then irradiated with a tungsten halogen lamp with an illumination intensity of 10 lux, and its surface potential is
. Take the time (seconds) it takes to reduce to 1/2 of the amount of exposure E.
Achieved 0/2. As a result, V, = 750 V,
El/2 = 2.2 units, seconds.Examples 2 and 3 In formula (1), X is H and Y is CH3'a? A photoreceptor was prepared in the same manner as in Example 1, except that the squareium pigment represented by (2) and the squareium pigment (3) in which Y represents 0H were used, and the electrical properties were measured.The results are shown in Table 1. .

Examples 4 to 6 In formula (1), X is CH3, and Y is H and CH3°O, respectively.
Squarium pigments of H ((4), (5), (6) respectively)
) A photoreceptor was prepared in the same manner as in Example 1, except that the photoreceptor was used, and the electrical properties were measured. Table 2 shows the results.

Examples 7 to 12 In the photoreceptors of the present examples, the order of the charge generation layer and the charge transport layer was reversed. That is, the squareium pigments (1) to (6) used in Examples 1 to 6.

A photoreceptor was created under the same conditions except that the order of the charge generation layer and charge transport layer was reversed, and the electrical properties were determined. It was measured. Table 3 shows the results.
Shown below.

Table 3

[Brief explanation of the drawing]

FIGS. 1 and 2 are cross-sectional views of an example of the construction of an electrophotographic photoreceptor according to the present invention. Symbols in the figure: 1... conductive support; 2... charge generation layer; 3.-
- Charge transport layer; 4... photosensitive layer. (3 others) - No. 111J

Claims (1)

[Scope of Claims] General formula (where xt'z represents hydrogen or an alkyl group having 1 to 4 carbon atoms, and Y represents hydrogen, an alkyl group having 1 to 4 carbon atoms, a hydroxyl group, or an alkoxy group having 1 to 4 carbon atoms) A photoreceptor for electrophotography, characterized in that it has a photosensitive layer containing a squareium pigment represented by the following formula.