JPS62267755A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To increase the sensitivity of a sensitive body and to reduce the dark attenuation by forming a photosensitive layer contg. a specified squarylium pigment. CONSTITUTION:A squarylium pigment represented by the formula is used in the electrostatic charge generating layer of an electrophotographic sensitive body. In the formula, each of R1 and R2 is 1-6C straight chain alkyl, hydroxyl, 1-4C alkoxy, halogen, nitro, cyano, carboxyl or the like, each of R3 and R4 is H, hydroxyl, methyl, trifluoromethyl, halogen or carboxyl and each of R5 and R6 is 1-20C alkyl. Thus, a sensitive body having spectral sensitivity over the visible region and the near infrared region, high sensitivity and superior electrostatic chargeability can be obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrophotographic photoreceptor used in an electrophotographic process. More particularly, the present invention relates to electrophotographic photoreceptors containing square IJIJum pigments in the photoconductive layer.

[Conventional technology]

Conventionally, inorganic photosensitive materials such as amorphous selenium, selenium alloys, cadmium sulfide, and zinc oxide, and organic photosensitive materials typified by polyvinyl carbazole and polyvinyl carbazole derivatives are widely known 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. However, 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 excellent advantages in terms of transparency, film-forming properties, and flexibility, but polyvinylcarbazole itself has no sensitivity in the visible light range. It cannot be put to practical use as it is, so various sensitization methods have been devised.However, when polyvinylcarbazole is spectrally sensitized using a dye sensitizer, the spectral sensitivity range extends to the visible light range. Although it has been expanded, it still has the disadvantage of not being able to obtain sufficient sensitivity as an electrophotographic photoreceptor and causing severe photofatigue.Also, when chemically sensitized using an electron-accepting compound, the electrophotographic photoreceptor cannot be used as an electrophotographic photoreceptor. As a result, photoreceptors with sufficient sensitivity have been obtained, and some of them have been put into practical use. However, why is it that laminated photoreceptors with a charge generation layer and a charge transport layer have superior electrical properties compared to conventional ones? The charge-generating materials used in these photoreceptors include bisazos, trisazos, phthalocyanines, pyryliums, squarelyliums, etc. Phthalocyanines, trisazos, and squareyliums have been reported to have sensitivity to the outer region.

However, phthalocyanines have the disadvantage that their spectral sensitivity is biased toward long wavelengths and red color reproducibility is poor, and trisazo compounds do not have excellent electrical properties and sufficient sensitivity.

In addition, although the square IJ 17um compound shown in JP-A No. 49-105536 has relatively high sensitivity, it has drawbacks in chargeability, dark decay, etc., and it has not yet been possible to achieve both high sensitivity and low dark decay. .

[Problem that the invention seeks to solve]

An object of the present invention is to eliminate the above-mentioned drawbacks, and to provide an electrophotographic photoreceptor having spectral sensitivity over the visible and near infrared regions, high sensitivity, and excellent electrical properties.

[Means and effects for solving the problems] The objects of the present invention can be achieved by an electrophotographic photoreceptor using an asymmetric square lylium compound represented by the following general formula (1) as a photosensitive material.

Square+71J used in the electrophotographic photoreceptor of the present invention
The pigment is represented by the following general formula (1).

In the formula, R1 and R1 are independent of each other, and each represents a linear alkyl group having 1 to 6 carbon atoms, a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms, a nitrogen atom, a nitro group,
It represents a cyano group, a carboxyl group, an alkoxycarbonyl group having 1 to 4 carbon atoms, a trifluoromethyl group, and the benzene ring of the benzyl group to which R and R1 are bonded may be further substituted with other substituents. R3 and - are each independent, and each represents a hydrogen atom,
It represents a hydroxyl group, a methyl group, a trifluoromethyl group, a halogen atom, a carboxyl group, and the benzene ring to which Rm and R1 are bonded may be further substituted with other substituents, and RI B and The ``descendants'' and ``descendants'' are independent, and each represents an alkyl group having 1 to 20 carbon atoms.

Specific examples of the square IJium compound represented by the general formula (1) are shown below in terms of structural formulas. In the formula, M@ represents a methyl group, Et represents an ethyl group, Pτ represents a propyl group, and Bu represents a butyl group.

O- The square aryllium pigment represented by the general formula (1) 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, by providing a charge generation layer containing a square aryllium pigment and a known charge transport layer, it is possible to achieve high sensitivity and A photoreceptor with improved electrical properties such as chargeability and dark decay can be obtained.

As the charge transport layer, N-methyl-N-phenylhydrazino-3-methylidene-9-ethylcart<1-/L
/,p-')ethylaminobenzaldehyde-N,N
Hydrazones such as -diphenylhydrazone, p-diethylaminobenzaldehyde-N-α-naphthyl-N-phenylhydrazone, 1-phenyl-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, 1-[ Quinolyl (2) 3-3-(p-
Pyrazolines such as diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, oxazole compounds such as 2-(p-diethylaminosteryl)-6-dinithylaminopenzuoxazole, bis(4-diethylamino-2-methyl triarylmethane compounds such as phenyl)-phenylmethane, N,N'-dipheny/
L/ -N,N'-bis-(3-methylphenyl)-(
A binder resin containing a diamine compound such as 1,1'-biphenyl)-4,4'-diamine, or a photoconductive polymer such as poly-N-vinylcarbazole or polyvinylanthracene is used.

To explain the structure of the two-layered electrophotographic photoreceptor of the present invention, as shown in FIG. 1 and FIG.
A photosensitive layer 4 is provided, which is a laminate of a charge transport layer 3 containing charge transport wiit and a charge transport layer 3. The stacking order of the charge generation layer 2 and the charge transport layer 3 is arbitrary.

The charge generation layer may be formed by using the square lyllium pigment alone, but it can also be formed by using it in combination with a binder resin.

The ratio of pigment to binder resin is 10% by weight to 90%
Heavy! 1, preferably 10 to 50 weight.

Methods for forming a charge generation layer using square aryllium pigment alone without using a binder resin include solvent coating and vacuum evaporation.

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

When dispersing the pigment in the binder, the pigment is ground and used, and the grinding method is 5PEX MILL, ball mill, RE.
A known method such as D DEVIL (trade name) can be used.

The binder for the charge generation layer may be photoconductive or non-photoconductive. Examples of the photoconductive binder include polyvinylcarbazole, polyvinylcarbazole derivatives, polyvinylnaphthalene, Examples include photoconductive polymers such as polyvinylanthracene, polyvinylpyrene, or other organic matrix materials with charge transport capabilities.

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, polysulfone, 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.
It is possible to further improve the mechanical strength of the photoreceptor without deteriorating its sensitivity or electrical properties by adding up to 10% by weight.

A protective layer or a photosensitive layer 4 and a conductive support 1 are provided on the photosensitive layer 4.
An intermediate layer may be placed in between. The protective layer may be one in which a metal oxide is dispersed in a resin, or one in which an electron-accepting compound is added to a resin. Examples of the intermediate layer include metal oxides such as aluminum oxide, acrylic resins, phenolic resins, polyester resins, polyurethanes, and the like.

A binder in which square aryllium pigment is dispersed 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, a metal manuscript, 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 copying machines but also in semiconductor laser printers, copiers, and the like.

Next, the present invention will be explained by examples.

〔Example〕

Example 1 A compound represented by the structural formula 41 of the specific example Wltf part contains polyester wood (Dupont, Adhesif 49000)
1 part by weight and 10 parts by weight of Tetrahydro 7ran were added, pulverized in a ball mill for 4 hours, and the mixed dispersion was coated on a polyester film [Metal Me (registered trademark) manufactured by Toshi Co., Ltd.] on which aluminum was deposited using a bar coater. , 70
It was dried at °C for 5 hours to form a charge generation layer with a film thickness of 41μ.

On this charge generation layer ζ, N,N'-diphenyl-N.

Gobis-(3-methylphenyl)-(,1,1'-
biphenyl) -4,4'-diamine 1 part by weight, polycarbonate resin [Kanairi Co., Ltd., Panlite (registered trademark)] 1
A homogeneous solution consisting of 1 part by weight of 10 parts by weight of Tetrahydro 7ran was applied using an applicator and dried at 70° C. for 16 hours to form a charge transport layer with a thickness of 22 μm, thereby producing a photoreceptor.

Next, using an electrostatic copying paper testing device (manufactured by Kawaguchi Electric, Electrostatic Paper Analyzer 5P-428), a corona discharge of -6KV was applied to negatively charge the paper, and then the paper was negatively charged.
Leave it in the dark for 2 seconds, then use a tungsten lamp,
The photosensitive layer was irradiated with light so that the surface illuminance was 10 lux.

The exposure amount E1/2 at which the surface potential would be 172 of the surface potential vD after being left in a dark place was determined. The results are that the initial charging potential V0 = -1020V, and the potential Vp after being left in the dark for 2 seconds.
Dy=-980V, %E1/2=2.57L/7x·sec, and residual potential R,=OV.

In addition, the following measurements were performed to demonstrate that the material has extremely high sensitivity to long wavelength light. After the above photoreceptor was charged by corona discharge in a dark place, 1 μW/,
-, 1 monochromatic light was irradiated onto the photoreceptor. Then, the time required for the surface potential to decrease to 1/2 was measured, and the exposure amount was determined.

The result 12. It was Oerg/-.

Examples 2 to 10 In Example 1, instead of the square IJIJum pigment of the structural formula M1, as shown in Table 1, &2.3.5.16
．． 18.26.35.38.42 [Example 2~
A photoreceptor was prepared and evaluated in the same manner as in Example 1 except that the square aryllium pigment No. 10] was used. Table 1 shows the results of the evaluation.

〔Effect of the invention〕

The present invention provides an electrophotographic photoreceptor having a photosensitive layer containing a square aryllium compound having spectral sensitivity from the visible region to the near-infrared region and having high sensitivity and excellent electrical properties. It has excellent electrical properties such as dark decay, and can be widely used not only in copying machines but also in semiconductor laser printers.

[Brief explanation of drawings]

1 and 2 are cross-sectional views of examples 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)

[Claims] General formula ▲ Numerical formulas, chemical formulas, tables, etc.
represents an alkoxy group having 1 to 4 carbon atoms, a halogen atom, a nitro group, a cyano group, a carboxyl group, an alkoxycarbonyl group having 1 to 4 carbon atoms, a trifluoromethyl group,
3 and R_4 are each independent of each other, and each represents a hydrogen atom, a hydroxyl group, a methyl group, a trifluoromethyl group,
Represents a halogen atom or a carboxyl group, R_3 and R_6 are independent of each other, and each has a carbon number of 1
~20 alkyl groups. ] An electrophotographic photoreceptor characterized by having a photosensitive layer containing a squarerium pigment represented by the following.