JPS60258551A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain an org. photosensitive body having high sensitivity and flat spectral sensitivity from a visible region to a near IR region and excellent mechanical strength such as wear resistance by providing a photosensitive layer contg. a specific squarium pigment to said body. CONSTITUTION:The squarium pigment expressed by the formula (R is a chain alkyl of 2-6C) is coated on a conductive base by using a solvent and is dried or is formed thereon by vacuum deposition. Said pigment is otherwise dispersed in a binder resin to form an electrostatic charge generating layer 2. An electrostatic charge transfer layer 3 consisting of a photoconductive polymer such as polyvinyl carbazole or triallyl pyrazoline incorporated into a binder resin is laminated on the layer 2 to form the photosensitive layer 4. The long-life electrophotographic sensitive body having the high sensitivity and flat spectral sensitivity from the visible region to the near IR region, the low wearing property and the excellent mechanical strength is thus obtd. The layers 2, 3 may be provided on the base in reverse order.

Description

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

Prior Art 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 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 using zinc oxide,
Zinc oxide is used as a dispersed photosensitive material in which it 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, so it cannot be used as is. Therefore, various sensitization methods have been devised. However, when polyvinylcarbazole is spectrally sensitized using a dye sensitizer, the spectral sensitivity is extended to the visible light range, but it still does not have sufficient sensitivity as a photoreceptor for electrophotography and suffers from severe optical fatigue. It has the disadvantage of being 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, but mechanical strength still remains. However, there are still problems in terms of lifespan, etc.

Although active research has been conducted on organic dispersion photosensitive materials and there have been numerous reports, a photoreceptor with excellent electrical properties and sufficient sensitivity for use as an electrophotographic photoreceptor has not yet been obtained. Currently, there are reports that phthalocyanine exhibits excellent electrophotographic properties as a dispersed light-sensitive material, but it has the disadvantage that its spectral sensitivity is biased toward the long wavelength region, and therefore its red color reproducibility is poor.

Purpose of the Invention The purpose 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. be.

Another object of the present invention is to have flexibility that inorganic photosensitive materials do not have, to improve low abrasion resistance and insufficient mechanical strength, which are defects of polyvinylcarbazole-trinitrofluorenone organic photosensitive materials, and to improve visible It is an object of the present invention to provide an electrophotographic photoreceptor that is highly sensitive and has substantially 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.

Structure of the Invention The present inventors have developed conventional inorganic photosensitive materials, organic photosensitive materials,
We are working diligently to improve the various drawbacks of organic dispersion photosensitive materials, to create photoconductive materials that have both excellent electrophotographic properties and flexibility, and 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 represented by the following general formula (I).

0θ [In the formula, R represents a chain alkyl group having 2 to 6 carbon atoms.

] This squareium pigment is a 3,4-dihydroxy-3-cyclobutene-
1,2-dione and formula (■) [In the formula, 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 (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 a squareium pigment and a known charge transport layer,
For example, photoconductive polymers such as polyvinyldibenzothiophene, polyvinylpyrene, polyvinylanthracene, polyvinylcarbazole, or triallylpyrazoline, triphenylmethane, oxadiazole, tetraphenylbenzidine, trinitrofluorocarbon, etc. in the binder resin. By forming a layer made of a material containing , it is possible to improve the charging property 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 conductive support 1, a charge generation layer 2 containing a squareium pigment, and a charge transport 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 pigment to binder resin is from 10% by weight to 90% by weight, preferably from 10% by weight to 50% by weight.

Methods for forming a charge generation layer using a squareium pigment alone without using a binder resin 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, and the grinding method is 5PEX MILL, ball mill, RE.
A known method such as D DEVIL (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 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, polyvinyl acetate, 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.
By adding 10% by weight, it is possible to further improve the mechanical strength of the photoreceptor without deteriorating its sensitivity or electrical properties.

A binder in which a squareium pigment is dispersed is coated on a conductive support. Coating methods include a dipping method, a spray method, a bar coater method, and an applicator method, and a good-looking 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 (I) in which R represents CqHe (
1) is ground with methylene chloride and steel balls for 12 hours. After crushing, add 3 to polyester resin (trade name, Byron 200).
Add 0% by weight and mix. The mixture was applied onto an aluminum plate using an applicator to form a charge generation layer so that the film thickness after drying was about 0.5 μm. On top of this, 1
-phenyl-3-[p-diethylaminostyryl]-5
A charge transport layer containing 50% by weight of p-diethylaminophenyl cupirazoline mixed in a polycarbonate resin (trade name, Panlite) was coated 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.
Measure o, then measure the illuminance lOlux of tungsten.
The photosensitive layer is irradiated with a halogen lamp, and its surface potential is V.

Calculate the time (seconds) it takes to reach l and calculate the half-life exposure amount Es/2
I met. As a result, v. =820v1F, /2=3.2
It was a look second.

Examples 2 to 4 In formula (I), R=n-C, H, (2), R=n C4H
A photoreceptor was prepared in the same manner as in Example 1, except that the squareium pigment of No. 11(3), R=1-C4H, (4) was used, and its electrical properties were measured. The results are shown in Table 1.

Examples 5 to 8 In the photoreceptor of this example, the order of the charge generation layer and the charge transport layer was reversed. That is, photoreceptors were prepared under the same conditions as the squareium pigments (1) to (4) used in Examples 1 to 4, except that the order of the charge generation layer and the charge transport layer was reversed.
Table 2 shows the results of measuring the electrical properties.

Table 2 Effect of the invention The present invention relates to general formula (I) (In the formula, R represents a chain alkyl group having 2 to 6 carbon atoms.

) provides an electrophotographic photoreceptor having a photosensitive layer containing a squareium pigment, which has low abrasion resistance, which is a drawback of conventional inorganic photosensitive materials, organic photosensitive materials, and organic dispersion photosensitive materials. It has improved flexibility and mechanical strength, has excellent electrophotographic properties and flexibility, and has high sensitivity over a wide range from the visible region to the near-infrared region.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views of an example of the structure 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. First page

Claims (1)

[Scope of Claims] An electrophotographic photoreceptor comprising a photosensitive layer containing a squareium pigment represented by the following formula: (wherein R represents a chain alkyl group having 2 to 6 carbon atoms.)