JPH0659474A - Electrophotographic sensitive body having sensitivity to both positive and negative polarities - Google Patents

Abstract

PURPOSE:To provide an electrophotographic sensitive body having satisfactory sensitivity in both positive electrification and negative electrification and excellent in mechanical strength. CONSTITUTION:This electrophotographic sensitive body is a monolayer or laminate type electrophotographic sensitive body using at least one of stilbene compds. represented by formulae I-III as an electric charge transferring material. In the formulae I-III, each of R1 and R2 is optionally substd. amino, optionally substd. alkoxy, optionally substd. alkyl, optionally substd. phenyl or halogen, R3 is optionally substd. alkyl or optionally substd. phenyl and each of Z1-Z3 is H, halogen, optionally substd. alkyl, optionally substd. alkoxy, alkoxy-carbonyl or cyano.

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 copying machines, printers and the like, and more specifically 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 is about the body.

[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.

Generally, OPC is composed of a photosensitive layer mainly composed of a charge generating substance which generates conductive carriers by light absorption and 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 layered type in which a charge transfer layer containing a charge transfer material as a main component is sequentially stacked (the reverse structure is also possible) and a single layer type in which a charge generation material is dispersed or dissolved in a layer containing a charge transfer material as a main component. There are two types.

The charge polarity when using such an OPC is usually determined depending on whether the charge transfer substance is a hole transfer type or an electron transfer type, and therefore it is difficult to arbitrarily select the polarity. ing.

By the way, as the electrophotographic photosensitive member capable of moving holes and electrons, that is, having photosensitivity under both positive and negative charging, at present, the only pyrylium salt dye, bisphenol A-polycarbonate and triphenylmethane are present. There are only known examples of eutectic complexes composed of a low-molecular-weight toner (Japanese Patent Publication No. 50-38430, J. Appl. Phys. 49 5543, 197).
8). However, the eutectic complex in this example is in a state in which polycarbonate is aggregated, has low mechanical strength, is easily worn, and has a narrow selection range of materials forming the eutectic complex, resulting in poor panchromaticity. There are drawbacks.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a photoconductor for electrophotography which exhibits good sensitivity to both positive and negative charges by using a specific charge transfer substance and has excellent mechanical strength. That is.

[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 general formula (I) And a stilbene compound represented by the general formula (II) (Chemical formula 2) or the general formula (III) (Chemical formula 3).

[Chemical 1] (In the formula, R ₁ represents a substituted amino group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted phenyl group or a halogen atom.
Z ₁ represents hydrogen, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, an alkoxycarbonyl group or a cyano group. )

[Chemical 2] (In the formula, R ₂ represents a substituted amino group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted phenyl group or a halogen atom.
Z ₂ represents hydrogen, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, an alkoxycarbonyl group or a cyano group. )

[Chemical 3] (In the formula, R ₃ represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted phenyl group, Z ₃ represents hydrogen, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, an alkoxy group. Indicates a carbonyl group or a cyano group.)

Examples of the substituted amino group in the above general formula (I) include N, N-dimethylamino group, N, N-diethylamino group, N, N-dibenzylamino group, N, N-diphenylamino group, N, Examples thereof include N-ditolylamino group, N-methyl-N-ethylamino group, N-methyl-N-phenylamino group, N-methyl-N-benzylamino group and N-tolyl-N-phenylamino group. Examples of the substituted alkoxy group include a benzyloxy group, and examples of the substituted alkyl group include a trifluoromethyl group and a benzyl group. Examples of the substituent of the substituted phenyl group include an alkyl group such as a methyl group, an ethyl group and a butyl group, an alkoxy group such as an ethoxy group, a hydroxy group, a halogen atom and a dialkylamino group.

The substituted amino group in the above general formula (II) includes N, N-dimethylamino group, N, N-diethylamino group, N, N-dibenzylamino group, N, N-diphenylamino group, N, Examples thereof include N-ditolylamino group, N-methyl-N-ethylamino group, N-methyl-N-phenylamino group, N-methyl-N-benzylamino group and N-tolyl-N-phenylamino group. Examples of the substituted alkoxy group include a benzyloxy group, and examples of the substituted alkyl group include a trifluoromethyl group and a benzyl group. Examples of the substituent of the substituted phenyl group include an alkyl group such as a methyl group, an ethyl group and a butyl group, an alkoxy group such as an ethoxy group, a hydroxy group, a halogen atom and a dialkylamino group.

Examples of the substituted alkyl group in the above general formula (III) include a trifluoromethyl group and a benzyl group. As the substituent of the substituted phenyl group, an alkyl group such as a methyl group, an ethyl group and a butyl group, an alkoxy group such as a methoxy group and an ethoxy group, a hydroxy group,
Examples thereof include a dialkylamino group and a halogen atom.
Moreover, a benzyloxy group etc. are mentioned as a substituted alkoxy group.

The following table shows specific examples of the stilbene compounds represented by the general formulas (I), (II) and (III) used in the present invention, but the present invention is not limited to them. .

[0013]

[Table 1- (1)]

[Table 1- (2)]

[Table 1- (3)]

[Table 1- (4)]

[Table 1- (5)]

[Table 1- (6)]

[Table 1- (7)]

[Table 1- (8)]

[Table 1- (9)]

[Table 1- (10)]

[Table 1- (11)]

[Table 1- (12)]

[Table 1- (13)]

The electrophotographic photoconductor of the present invention is a photoconductor in which a charge generating substance and a charge transfer substance comprising at least one of the stilbene compounds represented by the general formulas (I) to (III) are present in a single layer. A single-layer type photoreceptor having a layer provided on a substrate, a charge generation layer containing a charge generation substance on a substrate, and at least one of the stilbene compounds represented by the general formulas (I) to (III) It may be a so-called layered type photoreceptor in which a charge transfer layer containing the following charge transfer substance is sequentially provided.

Since the stilbene compound used as the charge transfer material of the present invention has an electron-withdrawing and electron-donating substituent in the molecule, it seems that holes and electrons can be transferred. It is unknown at this time.

Next, the structure of the photoreceptor 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 the one in which a single-layer photosensitive layer 6 containing a charge generating substance, a charge transfer substance and, if necessary, a binder resin is provided 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.

The charge generating substance used in the present invention includes:
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 sulphide 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 organic substances such as 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, addition polymerization type resin such as bisphenol A, bisphenol Z-carbonate, silicone resin, melamine resin,
Polyaddition type resins, polycondensation type resins, and copolymer resins containing two or more repeating units of these resins, for example, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer In addition to insulating resins such as coalescing resins, polymer organic semiconductors such as poly-N-vinylcarbazole can be mentioned.

As the conductor support for supporting the photosensitive layer, a metal plate such as aluminum or nickel, a metal drum or a metal foil, a plastic film on which aluminum, tin oxide or indium oxide is deposited, or a conductive substance is applied. Films such as paper, plastic, or drums 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 transfer 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. When the charge transfer material is contained in the binder resin in the charge transfer layer, the charge transfer material is added in an amount of 20 to 20 with respect to 100 parts by weight of the binder resin.
It is set to 0 parts by weight. At this time, the thickness of the charge transfer layer is preferably 5 to 50 μm, particularly preferably 5 to 30 μm.

The charge generation layer is formed by vacuum-depositing a charge generation substance on a conductive support, or by coating or dissolving a suitable solvent alone or dissolved or dispersed with a suitable binder resin and drying it to form a charge transfer 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-mentioned particle size is too small, it tends to agglomerate rather, the resistance of the layer increases, the crystal defect increases and the sensitivity and repeatability decrease, or there is a limit on miniaturization, so the average The lower limit of the particle size is preferably 0.01 μm.

The charge generating substance 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, or the like,
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. Further, the ratio of the charge generating substance contained in the binder resin is 20 to 200 parts by weight with respect to 100 parts by weight of the binder resin. The film thickness of the charge generation layer formed as described above is preferably 0.1 to 10 μm, particularly preferably 0.
It is 5 to 5 μm.

In the case where the photoreceptor of the present invention is formed in a single layer structure, that is, in FIG. 3, the ratio of the charge generation material and the charge transfer material contained in the binder resin is 100 parts by weight of the binder resin. 20-200
By weight, the charge transfer material is 20 to 200 parts by weight.
The film thickness of the single-layer photosensitive member is 7 to 50 μm, 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, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-
A resin such as a maleic anhydride copolymer, casein, N-alkoxymethylnylon or the like as it is, or a resin in which tin oxide or indium is dispersed, an evaporated film of aluminum oxide, 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 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 also appropriately contain oxygen, nitrogen, halogen, Group III and Group V atoms of the periodic table.

[0026]

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

First, specific synthesis examples of the stilbene compound used in the present invention will be given. [Synthesis Example] Compound No. 17 [4- (N, N-diethylamino)-
Synthetic Method of 4'-Methoxycarbonylstilbene] Commercially available p- (N, N-diethylamino) aldehyde 2.66 g
(0.015 mol) and 4.29 g of diethoxy (p-methoxycarbonylbenzyl) phosphonate (0.01
5 mol) is dissolved in 20 ml of N, N-dimethylformamide and 50 ml of 1,2-dimethoxyethane, 0.8 g (0.02 mol) of sodium hydride is added little by little, and the reaction is carried out at room temperature for 3 hours. After the reaction was completed, 200 ml of ice water and 200 ml of toluene were added to this and well stirred, and the separated toluene layer was washed with water until it became neutral. After the toluene layer was dried over anhydrous magnesium sulfate, the toluene was distilled off, and the residue was subjected to silica gel column chromatography treatment using toluene as a developing solvent, and the obtained crude target product was recrystallized from ethanol to give pure. 2.25 g of the desired product was obtained.

Example 1 A 75 μm thick polyester film on which aluminum was vapor-deposited was coated with a charge generation layer coating solution having the following formulation using a doctor blade to form a dried charge generation layer having a thickness of 0.5 μm. (Formulation of electrogenerating layer forming liquid) 1 part by weight of bisazo pigment of the following formula

[Chemical 4] Bisphenol Z polycarbonate (manufactured by Teijin Kasei Co., Ltd.) 0.5 parts by weight Cyclohexane 30 parts by weight Tetrahydrofuran 68.5 parts by weight Next, the charge transfer layer coating solution prepared by the following formulation is applied onto the charge generation layer with a doctor blade. And the thickness after drying is 1
A charge transfer layer having a thickness of 5 μm was formed to prepare a laminated type electrophotographic photoreceptor.

(Prescription of Charge Transfer Layer Coating Liquid) 4- (N, N-Diethylamino) -4′-methoxycarbonylstilbene 4 parts by weight Polycarbonate Z (manufactured by Teijin Chemicals Ltd.) 6 parts by weight Methylphenyl silicone 0.001 parts by weight (KF50 100CPSi; manufactured by Shin-Etsu Chemical Co., Ltd.) Tetrahydrofuran 40 parts by weight The electrophotographic photoconductor thus obtained was subjected to electrostatic copying paper tester (Kawaguchi Electric Co., Ltd .; SP428 type).
First, a +6 KV corona discharge is performed for 20 seconds to charge it, then dark decay is performed for 20 seconds, and the surface potential Vo at that time is reduced.
(Volts), then exposed by a tungsten lamp for 30 seconds so that the surface illuminance is 20 lux, and recorded the decay and time of the surface potential at that time with a recorder, Vo became 1/2, 1/5 The exposure doses E1 / 2 (lux · sec) and E1 / 5 (lux · sec) required for attenuation and the surface potential V ₃₀ after 30 seconds of exposure were measured.
Next, using the same electrophotographic photosensitive member sample, -6K
Corona discharge V for 20 seconds, subjected to the same measurement as in the case of positive charging was measured Vo, E1 / 2, E1 / 5, V 30. The measurement results are shown in Table 2.

Example 2 A laminated electrophotographic photosensitive member was produced under the same conditions as in Example 1 except that the bisazo pigment of Example 1 was replaced with X-type metal-free phthalocyanine, and the electrophotographic photoreceptor was prepared under the same conditions as in Example 1. Photographic properties were measured. The measurement results are shown in Table 2.

[0031]

[Table 2] 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 device 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, both positive charging and negative charging gave spectral sensitivity almost corresponding to the absorption spectrum of the charge generation layer, and the stilbene compound used in the example has the function of moving electrons and holes. I confirmed that.

[0033]

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.

[0034]

[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 layer of FIG.

FIG. 3 is a schematic cross-sectional view of an electrophotographic photoconductor in which a single photoconductor layer is provided on a support.

[0035]

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Support body 2 ... Charge generation layer 3 ... Charge transport layer 4 ... Photosensitive layer (laminated structure) 5 ... Protective layer 6 ... Photosensitive layer (single layer structure)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tetsuro Suzuki 1-3-6 Nakamagome, Ota-ku, Tokyo Stock company Ricoh Company (72) Masakatsu Shimoda 1-3-6 Nakamagome, Ota-ku, Tokyo Share In Ricoh Company (72) Inventor Masayuki Tsukasa 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (72) Inventor Akio Kojima 1-3-6 Nakamagome, Ota-ku, Tokyo In Ricoh Company

Claims (3)

[Claims] 1. A charge transfer substance represented by the following general formula (I):
(Chemical Formula 1), General Formula (II) (Chemical Formula 2) and General Formula (II)
I) A photoconductor for electrophotography, comprising at least one selected from the stilbene compounds represented by the formula (3). [Chemical 1] (In the formula, R ₁ represents a substituted amino group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted phenyl group or a halogen atom.
Z ₁ represents hydrogen, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, an alkoxycarbonyl group or a cyano group. ) [Chemical 2] (In the formula, R ₂ represents a substituted amino group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted phenyl group or a halogen atom.
Z ₂ represents hydrogen, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, an alkoxycarbonyl group or a cyano group. ) [Chemical 3] (In the formula, R ₃ is a substituted or unsubstituted alkyl group, or
A substituted or unsubstituted phenyl group, Z ₃ is hydrogen,
It represents a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, an alkoxycarbonyl group or a cyano group. ) 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. In the laminated electrophotographic photoreceptor provided with the charge transfer layer, the charge transfer layer has the general formula (I) (formula 1), the general formula (II) (formula 2) and the general formula (III) (formula 3). The electrophotographic photosensitive member having sensitivity to both positive and negative polarities according to claim 1, containing at least one selected from the stilbene compounds represented by the formula (1). 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. In the photoconductor, the charge transfer layer is at least one selected from the stilbene compounds represented by the general formula (I) (formula 1), the general formula (II) (formula 2) and the general formula (III) (formula 3). An electrophotographic photosensitive member having sensitivity to both positive and negative polarities according to claim 1, characterized by containing.