JPS60258554A - 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 body contg. a specific squarium pigment to said body. CONSTITUTION:The squarium pigment expressed by the formula (R is -NHCO CH3 or -NHSO2CH3) is formed by vacuum deposition on a conductive substrate 1 or is dispersed into a biner resin to form an electrostatic charge generating layer 2. An electrostatic charge transfer layer 3 in which a charge transfer material, for example 1-phenyl-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)- pyrazoline, etc. is mixed with a polycarbonate resin is formed on the layer 2. The layer 2 and 3 may be formed in reverse order on the substrate 1. The long- life electrophotographic sensitive body having the high sensitivity from the visible light region to the near IR region is thus obtd.

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 a 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. Another object of the present invention is to have flexibility not found in inorganic photosensitive materials, improve low abrasion resistance and insufficient mechanical strength, which are defects of polyvinylcarbazole trinitronefluorenone organic photosensitive materials, and further The object of the present invention is to provide a photoreceptor for electrophotography which has high sensitivity and has a fairly uniform spectral sensitivity in a wide range from the visible 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,
Intensive research aimed at improving the various drawbacks of organic dispersion photosensitive materials and creating 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, they discovered that a specific squareium pigment has extremely excellent properties, and completed the present invention.

The squareium pigment used in the present invention has the following general formula (
I).

e (“wherein R is -NHCOCHs or -NH902C
It is H3. ) This squareium pigment is represented by formula (II) 3,
It is obtained by reacting 4-dihydroxy-3-cyclobutene-1,2-dione with an aniline derivative represented by the formula (I[) (wherein R has the same meaning as above).

A squareium pigment represented by the general formula (υ) can be used in an electrophotographic photoreceptor having a multilayer structure. In other words, an electrophotographic photoreceptor rich in a photosensitive layer with a two-layer structure consisting of a charge generation layer and a charge transport layer. A charge generating layer containing a squareium pigment as well as a known charge transport layer, such as a photoconductive polymer such as polyvinyldipenzotheophene, polyvinylpyrene, polyvinylanthracene, polyvinylcarbazole, or triallylpyrazoline, triphenylmethane. , oxadiazole, tet:7 phenylbenzidine, trinitrofluorenone, etc. in the binder resin improves the chargeability of the photoreceptor, reduces residual potential, and improves mechanical strength. etc. can be achieved.

The structure of the electrophotographic photoreceptor having a two-layer structure according to the present invention will be described. As shown in FIGS. 1 and 2, a charge generation layer 2 containing a squareium pigment on a conductive support 1
and a charge transport layer 3 containing a charge transport substance.

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% to 90% by weight, preferably from 10% 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 in a binder, the pigment is ground and used, and the grinding method is SPF, X MILL, ball mill, R
A known method such as ED 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, polyvinylanisole, polychlorostyrene, polyvinyl acetate, 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 biphenyl, 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 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 N) of the formula (I) in which R represents an acetylamino group is ground with methylene chloride and a steel ball for 12 hours. After grinding, polyester resin (trade name: Vylon 200)
) and mix by 30% by weight. 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-(p-diethylaminophenylcupirazoline) was added to polycarbonate resin (trade name Pan 2ite) for 50 minutes.
The charge transport layer added and mixed in weight percent was applied with an applicator to a thickness of about 15 μm.

Next, the surface of the photosensitive layer of this photoreceptor was negatively charged by applying a 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.
0, then irradiate the photosensitive layer with a tungsten chloride lamp of 10 lux, and measure the time (seconds) until the surface potential becomes 1/2 of vo to determine the half-reduction exposure amount E1/2. I met. As a result, v0=720, V*Kt
/2 = 4.3 lux° seconds.

Example 2 A photoreceptor was prepared in the same manner as in Example 1, except that a squareium pigment of the formula (I) in which R was a methylsulfonamino group was used, and its electrical properties were measured. As a result, v0=
680vXEIA=5.1 Lux·sec.

Examples 3 to 4 In the photoreceptor of this example, the order of the charge generation layer and the charge transport layer was reversed. That is, as for the squareium pigment used in Examples 1 and 2, a photoreceptor was prepared under the same conditions except that the order of the charge generation layer and the charge transport layer was reversed, and the electrical properties were measured. In case v
.

= 700 V, E172 = 4.5 lux seconds, when R is a methylsul7one amino group, Vo=
660V.

El/I = 4.9 lux e seconds.

Effects of the Invention The present invention provides general formula (1) general formula (wherein R is -NHCOCH, or -NISO, CH
, is. ) The present invention provides an electrophotographic photoreceptor having a photosensitive layer containing a squareium pigment represented by It has improved 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: l... Conductive support -2... Charge generation layer; 3...
Charge transport layer: 4...Photosensitive layer. Figure 1

Claims (1)

[Claims] General formula (wherein R is -NHCOCH, or -NH5O, CH
, is. ) An electrophotographic photoreceptor comprising a photosensitive layer containing a squareium pigment.