JPH06130687A - Electrophotographic sensitive body having sensitivity for both of positive and negative polarity - Google Patents

Abstract

PURPOSE:To obtain a photosensitive body having good sensitivity for both of positive and negative charges and excellent mechanical strength by using a specified nitro- styrylnaphthalene compd. as a charge transfer material. CONSTITUTION:This electrophotographic sensitive body contains a charge producing material and a charge transfer material on a conductive supporting body. As for the charge transfer material, 4'-nitro-styrylnaphthalene compd. expressed by formula I is used. In formula, R is an amino group, dialkylamino group, alkoxy group, alkyl group, or phenyl group, and n is 1 or 2. The photosensitive body may be a monolayer photosensitive body having a photosensitive layer containing the charge producing material and the transfer material expressed by formula in a single layer formed on a substrate. Also it may be a laminar photosensitive body obtd. by successively forming a charge producing layer containing the charge producing material and a charge transfer layer containing the charge transfer material expressed by formula on the substrate. Thereby, the same layer structure can be formed as that of a conventional one, and the charge producing material can be selected from a wider range for the photosensitive body. Thus, the obtd. photosensitive body can be used for various electrophotographic processes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member used in a copying machine, a printer, etc., and more particularly to an electrophotographic photosensitive member containing a charge transfer substance having a specific structural formula and having sensitivity to both positive and negative polarities. It relates to a photoconductor.

[0002]

2. Description of the Related Art Conventionally, as electrophotographic photoreceptors, selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide,
Inorganic photoconductive materials such as zinc oxide have been widely used.
On the other hand, in recent years, research on organic photoconductive materials has progressed,
Electrophotographic photoreceptors (hereinafter referred to as OPCs) that use organic photoconductive materials are used in many copiers, printers, etc. because they are advantageous over inorganic photoconductive materials in terms of safety and panchromaticity. It has been overwhelmed by inorganic photoconductors.

The OPC is generally composed of a charge-generating substance which generates conductive carriers by light absorption and a photosensitive layer which mainly contains a charge-transfer substance which moves conductive carriers by the action of an electric field. A charge generation layer containing a charge generation material as a main component on a conductive layer made of a conductive material,
A laminated type in which a charge transfer layer containing a charge transfer material as a main component is sequentially stacked (the reverse configuration is also possible) and a single layer type in which a charge generation substance is dispersed or dissolved in a layer containing a charge transfer material as a main component. There are two types.

Generally, the charge polarity when using OPC is determined depending on whether the charge transfer substance is a hole transfer type or an electron transfer type and cannot be arbitrarily selected.

Holes and electrons can be moved,
That is, as the electrophotographic photosensitive member having both positive and negative charging and photosensitivity, the only pyrylium salt dye, bisphenol A-
There is an example of a eutectic complex composed of a polycarbonate and a triphenylmethane low molecular weight donor (Japanese Examined Patent Publication No. 50-38430, J. Appl. Phys. 49 5543). However, the eutectic complex in this example is in a state where polycarbonate is aggregated, has low mechanical strength, is easily worn, and has a narrow selection range of materials forming the eutectic complex, and thus has poor panchromaticity. There are drawbacks.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electrophotographic photoreceptor which exhibits good sensitivity to both positive and negative charges by using a specific charge transfer substance and has excellent mechanical strength. It is in.

[0007]

Means for Solving the Problems The present inventors have conducted extensive studies and found a compound having a function of moving both holes and electrons, and completed the present invention.

That is, according to the present invention, in an electrophotographic photoreceptor comprising a charge generating substance and a charge transfer substance on a conductive support, the charge transfer substance is represented by the following formula (I).
An electrophotographic photoreceptor using the 4'-nitro-styrylnaphthalene compound represented by

[0009]

[Chemical 1] ... (I) (In the formula, R represents an amino group, a dialkylamino group, an alkoxy group, an alkyl group, or a phenyl group, and n is an integer of 1 or 2.)

The electrophotographic photoreceptor of the present invention is a single-layer type photoreceptor in which a photosensitive layer in which a charge generating substance and a charge transfer substance represented by the formula (I) are present in a single layer is provided on a substrate. Alternatively, it may be a so-called laminated type photoreceptor in which a charge generation layer containing a charge generation substance and a charge transfer layer containing a charge transfer substance represented by the formula (I) of the present invention are sequentially provided on a substrate. .

4'-used as the charge transfer material of the present invention
Since the nitro-styrylnaphthalene compound has an electron-withdrawing and electron-donating substituent in the molecule, it seems that holes and electrons can be transferred, but the details are unknown.

Next, the structure of the photoconductor of the present invention will be described with reference to the drawings. As the photoconductor, for example, as shown in FIG. 1, a layer containing a charge generating substance and optionally a binder resin on a support 1 (a conductive support or a sheet on which a conductive layer is provided) (charge generating layer). ) 2 as a lower layer, and a photosensitive layer 4 having a laminated structure in which a layer (charge transfer layer) 3 containing a charge transfer substance and optionally a binder resin as an upper layer is provided, and as shown in FIG. Protective layer 5 on photoreceptor layer 4
And a photosensitive layer 6 having a single-layer structure containing a charge generating substance, a charge transfer substance and, if necessary, a binder resin on a support as shown in FIG. 3, a protective layer may be provided on the upper layer of the photoreceptor layer 6 having a single layer structure, and an intermediate layer may be provided between the support and the photoreceptor layer.

As the charge generating substance used in the present invention,
Either an inorganic substance or an organic substance can be used as long as it absorbs light and generates a conductive carrier.
For example, amorphous selenium, trigonal selenium, selenium-arsenic alloy, selenium-tellurium alloy, cadmium sulfide, cadmium selenide, cadmium sulfide selenide, mercury sulfide, lead oxide, lead sulfide, inorganic substances such as amorphous silicon, or Bisazo dyes, polyazo dyes, triarylmethane dyes, thiazine dyes, oxazine dyes, xanthene dyes, cyanine dyes, styryl dyes, pyrylium dyes, quinacridone dyes, indigo dyes, perylene dyes, Examples thereof include polycyclic quinone dyes, bisbenzimidazole dyes, indanthrone dyes, squarylium dyes, anthraquinone dyes, and phthalocyanine dyes.

Examples of the binder resin usable in the photosensitive layer in the present invention include polyethylene, polypropylene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, epoxy resin, polyurethane resin, phenol resin, polyester resin and alkyd. Resin, polycarbonate resin, silicone resin, addition polymerization type resin such as melamine resin, polyaddition type resin, polycondensation type resin,
And an insulating resin such as a copolymer resin containing two or more of repeating units of these resins, for example, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer resin, Examples include polymer organic semiconductors such as poly-N-vinylcarbazole.

As the conductive support for supporting the photosensitive layer, a metal plate such as aluminum or nickel, a metal drum or a metal foil, a plastic film deposited with aluminum, tin oxide or indium oxide, or a conductive substance is used. A coated paper, a film such as plastic, or a drum can be used.

When the photoreceptor according to the present invention is formed with a laminated structure of a charge generation layer and a charge transfer layer, that is, in the case of FIGS. 1 and 2, the charge transfer material of the present invention is used alone or in a suitable solvent. It is provided by a method in which a material dissolved or dispersed with an appropriate binder resin is applied and dried. Examples of the solvent used for the charge transport layer include N, N-dimethylformamide, toluene, xylene,
Monochlorobenzene, 1,2-dichloroethane, dichloromethane, 1,1,1-trichloroethane, 1,1,
2-Trichloroethylene, tetrahydrofuran, methyl ethyl ketone, cyclohexanone, ethyl acetate, butyl acetate and the like can be mentioned. In this charge transport layer, the proportion of the charge transport material contained in the binder resin is 20 to 100 parts by weight of the binder resin.
It is set to 200 parts by weight. At this time, the thickness of the charge transport layer is
It is preferably 5 to 50 μm, particularly preferably 5 to 30 μm.

The charge generating layer is formed by vacuum deposition on the charge generating substance and a conductive support, or by coating or dissolving a suitable solvent alone or dissolved or dispersed with a suitable binder resin, and drying to form a charge transport layer. It can be similarly formed.

When the charge generating layer is formed by dispersing the above charge generating substance, it is preferable that the charge generating substance is a granular material having an average particle diameter of 2 μm or less, preferably 1 μm or less. That is, when the particle size is too large, the dispersion in the layer becomes poor, and the particles partially project on the surface to deteriorate the smoothness of the surface. Particles are likely to adhere to the toner filming development. However, if the above particle size is too small, it tends to agglomerate, the resistance of the layer increases, the crystal defects increase and the sensitivity and repeatability deteriorate, or there is a limit on miniaturization, so the average particle The lower limit of the diameter is preferably 0.01 μm.

The charge generating material layer can be provided by the following method. That is, the charge generating substance is made into fine particles in a dispersion medium by a ball mill, a homomixer, etc.,
It is a method of applying a dispersion liquid obtained by adding a binder resin and mixing and dispersing. In this method, if the particles are dispersed under the action of ultrasonic waves, uniform dispersion is possible. In the charge generation layer, the ratio of the charge generation material to be contained in the binder resin is 20 parts with respect to 100 parts by weight of the binder resin.
Up to 200 parts by weight. The thickness of the charge generation layer formed as described above is preferably 0.1 to 10 μm, particularly preferably 0.5 to 5 μm.

When the following photoreceptor of the present invention is formed in a single layer structure, that is, in the case of FIG. 3, the ratio of the charge generating substance and the charge transporting substance contained in the binder resin is 100 parts by weight of the binder resin. 20 to 2 generated substances
00 parts by weight, and the charge transport material is 20 to 200 parts by weight. The film thickness of the photoreceptor having this single-layer structure is 7 to 50 μm, and more preferably 10 to 30 μm. The intermediate layer functions as an adhesive layer or a barrier layer, and in addition to the above binder resin, for example, polyvinyl alcohol, ethyl cellulose, carboxymethyl cellulose,
Resins such as vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, casein, N-alkoxymethyl nylon and the like as they are, or those in which tin oxide or indium is dispersed, aluminum oxide, A deposited film of zinc oxide, silicon oxide, or the like is used. The thickness of the intermediate layer is preferably 1 μm or less.

As the material used for the protective layer, it is suitable to use the above resin as it is or to disperse a low resistance substance such as tin oxide or indium oxide. Also, organic plasma polymerized film can be used,
The organic plasma-polymerized film may optionally contain oxygen, nitrogen, halogen, and Group III and Group V atoms of the periodic table.

[0022]

EXAMPLES The present invention will be described below with reference to examples, but the embodiments of the present invention are not limited thereby.

Specific synthetic examples of the 4'-nitro-styrylnaphthalene compound used in the present invention are given below. [Synthesis Example] [Synthesis method of N, N-dimethylamino-4- (4'-nitro-styryl) naphthalene] (N, N-dimethylamino) naphthylaldehyde 4.00 g (0.02 mol) and diethoxy (p-nitrobenzyl) ) 5.47 g (0.02 mol) of phosphonate is dissolved in 200 ml of N, N-dimethylformamide, 5.79 g (0.03 mol) of sodium methylate is added dropwise little by little, and the mixture is reacted at room temperature for 3 hours. After completion of the reaction, 200 ml of ice water and 200 ml of toluene were added to this and well stirred, and the separated toluene layer was thoroughly washed with water until neutral and dried over anhydrous magnesium sulfate. Toluene was distilled off, the residue was subjected to silica gel column chromatography using toluene as a developing solvent, and the obtained crude target substance was recrystallized from ethanol to obtain 5.17 g of a pure target substance.

[Example 1] 75 deposited with aluminum
A charge generation layer-forming liquid having the following formulation was applied on a polyester film having a thickness of μm by a doctor blade to form a charge generation layer having a thickness of 0.5 μm after drying.

[Formulation of Charge Generation Layer Forming Liquid] 1 part by weight of trisazo pigment of the following formula (II)

[Chemical 2] ………… (II) Polyvinyl butyral resin (S-REC BL-2; manufactured by Sekisui Chemical Co., Ltd.) 0.5 parts by weight Cyclohexanone 30 parts by weight Tetrahydrofuran 68.5 parts by weight

Next, a charge transfer layer-forming liquid prepared by the following formulation is applied onto the charge generation layer by a doctor blade to form a charge transfer layer having a thickness of 15 μm after drying. A photoconductor was prepared.

[Formulation of Charge Transfer Layer Forming Liquid] (N, N-Dimethylamino) -4- (4′-nitro-styryl) naphthalene 4.5 parts by weight Polycarbonate Z (manufactured by Teijin Chemicals Ltd.) 5 parts by weight Methylphenyl Silicone 0.001 parts by weight (KF50 100 CPS; manufactured by Shin-Etsu Chemical Co., Ltd.) Tetrahydrofuran 40.5 parts by weight

The electrophotographic photosensitive member thus obtained was subjected to an electrostatic copying paper test apparatus (Kawaguchi Denki Seisakusho; SP428).
Type), a corona discharge of +6 kV was first performed for 20 seconds to charge it, then dark decay was performed for 20 seconds, the surface potential V ₀ (volt) at that time was measured, and then the surface illuminance was 20 Lux by a tungsten lamp. To be 30
Exposure for 2 seconds, the decay of surface potential and time at that time are recorded by a recorder, and the exposure amount required for V ₀ to decay to 1/2 and 1/5, respectively, E1 / 2 (lux seconds), E1 / 5 ( looks·
Second) and the surface potential V ₃₀ after 30 seconds of exposure were measured. Next, using the same electrophotographic photosensitive member sample, -6 kV corona discharge is performed for 20 seconds, and the same measurement as in the case of positive charging is performed to measure V ₀ , E1 / 2, E1 / 5, and V ₃₀ . did. The measurement results are shown in Table 1 below.

[0029]

[Table 1] It can be seen that both positive and negative charging show good sensitivity.

Next, the same sample was used to charge to +800 V and -800 V with a spectral sensitivity measuring apparatus manufactured by the inventors, and monochromatic light having an illuminance of 1 μW / cm ² was irradiated at 20 nm intervals, and the respective charges were applied. When the spectral sensitivity was measured with polarity,
Spectral sensitivity corresponding to the absorption spectrum of the charge generation layer is obtained for both positive charging and negative charging, and the 4'-nitro-styrylnaphthane compound used in the examples has a function of transferring electrons and holes. Backed up.

[0031]

The electrophotographic photoreceptor according to the present invention has good sensitivity to both positive and negative charging, can have the same layer structure as conventional OPC, is excellent in mechanical strength, and is excellent in charge generation property. It has a wide selection range and can be applied to various electrophotographic processes.

[0032]

[Brief description of drawings]

FIG. 1 is a schematic view of a laminated electrophotographic photosensitive member in which a charge generation layer and a charge transfer layer are sequentially provided on a support. FIG. 2 is a schematic cross-sectional view of an electrophotographic photoconductor in which a protective layer is provided on the photoconductor of FIG. FIG. 3 is a schematic cross-sectional view of an electrophotographic photosensitive member in which a single photosensitive layer is provided on a support.

[0033]

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Support body 2 ... Charge generation layer 3 ... Charge transport layer 4 ... Photoconductor layer (laminated structure) 5 ... Protective layer

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Akio Kojima 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd. (72) Inventor Masao Yoshikawa 1-3-6 Nakamagome, Ota-ku, Tokyo Stocks Company Ricoh

Claims (3)

[Claims] 1. An electrophotographic photoreceptor comprising a 4'-nitro-styrylnaphthalene compound represented by the following formula (I) as a charge transfer material. ... (I) (In the formula, R represents an amino group, a dialkylamino group, an alkoxy group, an alkyl group, or a phenyl group, and n is an integer of 1 or 2.) 2. A charge generation layer containing a charge generation substance that generates a conduction carrier by light absorption as a main component is provided on a conductive substrate, and the conduction carrier is injected and moved on the charge generation layer by the action of an electric field. The positive-negative sign according to claim 1, wherein the charge transfer layer contains a 4'-nitro-styrylnaphthalene compound of the formula (I) in the laminated electrophotographic photoreceptor provided with the charge transfer layer. An electrophotographic photoreceptor having photosensitivity in both polarities. 3. A single-layer type electrophotographic apparatus, which comprises a photosensitive layer containing, as a main component, a charge-generating substance that generates conductive carriers by absorbing light and a charge-transporting substance that moves conductive carriers by the action of an electric field, on a conductive substrate. 2. The electrophotographic photosensitive material having both positive and negative polarities and photosensitivity according to claim 1, wherein the charge transfer material contains a 4′-nitro-styrylnaphthalene compound of the formula (I) in the photosensitive material. body.