JPH07152185A - Electrophotographic photoreceptor - Google Patents

Abstract

PURPOSE:To obtain an electrophotographic photoreceptor using an electric charge transferring material having electron transferring ability and to obtain a laminate type electrophotographic photoreceptor for positive electrification having superior electrophotographic performance. CONSTITUTION:A compd. represented by the general formula is incorporated into a photoreceptor. In the formula, each of R1 and R2 is alkyl, H, etc., each of (m) and (n) is an integer of 0-4 and each of R3 and R4 is H, halogen, etc.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an electrophotographic photosensitive member for forming an electrostatic latent image. More specifically, it relates to an electrophotographic photoreceptor having a layer containing a compound having an electron transporting ability.

[0002]

2. Description of the Related Art Conventionally, electrophotographic photoreceptors using organic photoconductors have been variously studied because of their advantages such as pollution-free, high productivity and low cost. It has been put to practical use as a photoconductor. These electrophotographic photoreceptors include a laminated type and a single layer type, but a photoreceptor using an organic photoconductor generally has a charge generation layer that generates a charge by light irradiation and a charge that transports the generated charge. It has a laminated structure consisting of a transport layer. In this case, as the charge transport material used in the charge transport layer, a polymer material such as poly-N-vinylcarbazole or a low molecular weight compound such as pyrazoline, hydrazone or triphenylamine derivative is used.

However, since all of these charge-transporting substances have a hole-transporting ability, most of the developing systems adopting a negative charge on the surface of the photoconductor are adopted.
For this reason, the toner that has been conventionally used in high-speed machines cannot be used, and there are few high-quality toners at present. Further, when the surface of the photoconductor is negatively charged as described above, there is a problem that not only the ozone is generated due to the reaction with oxygen in the air at the time of charging to harm the environment but also the surface of the photoconductor is deteriorated.

On the other hand, a positive charging laminated photoreceptor having a charge transport layer on the lower side and a charge generation layer on the upper side has been developed by reversing the layer structure of the photosensitive layer of the laminated photoreceptor. Since the charging potential is low and the printing durability is poor, a protective layer is further provided on the charge generation layer.

[0005]

In order to solve the above problems, a photoconductor in which a charge transport material having an electron transporting property is used in a charge transport layer and the surface of the photoconductor is positively charged. Should be configured. 2,4,7-Trinitro-9-fluorenone is known as such an electron-transporting material, but its solubility is poor and it is not possible to obtain practical sensitivity by combining it with an existing charge-generating substance. It was In addition, 2, 4,
As a result of improved studies on 7-trinitro-9-fluorenone, in recent years, an electron transporting substance having a solubilizing group introduced into an electron acceptor structure has been proposed. For example, Japanese Patent Laid-Open No. 1-206349
No. 2-135362, No. 2-214866, No. 3-290666 and “Japan Hardcopy '92” Proceedings, 173, (1992). However, in the present situation, when any of the compounds is combined with an existing charge generating substance to form a photoreceptor, the sensitivity is still insufficient in practical use, and a good image cannot be obtained.

In view of the above problems, it is an object of the present invention to provide an electrophotographic photosensitive member using a charge transporting substance having an electron transporting ability.

Another object of the present invention is to provide a laminate type electrophotographic photoreceptor for positive charging, which has excellent electrophotographic performance, that is, high sensitivity, low residual potential and good image characteristics.

[0008]

As a result of research, the present inventors have found that the object of the present invention can be achieved by any one of the following electrophotographic photoreceptors. That is, an electrophotographic photoreceptor having a photosensitive layer provided on a conductive support, wherein the photosensitive layer contains a compound represented by the following general formula [A], particularly [a].

[0009]

[Chemical 3]

In the formula, R ₁ and R ₂ each have an alkyl group which may have a substituent, a vinyl group which may have a substituent, an ester group which may have a substituent, and a substituent. Optionally represents an acyl group, an amide group which may have a substituent, a hydrogen atom, a halogen atom, a cyano group or a nitro group. n and m are 0
Represents an integer of 4.

Further, R ₃ and R ₄ are each a hydrogen atom, a halogen atom, a cyano group, a nitro group or an ester group which may be substituted, an acyl group which may be substituted, an amide group which may be substituted, or a substituent. Represents a vinyl group which may be substituted or a phenyl group which may be substituted.

[0012]

[Chemical 4]

The high performance of the present invention as an electron transport material is
It is considered that this is because the long-term compatibility with the binder is kept stable as compared with the conventional electron transport material.

Next, specific examples of the compound represented by the above general formula and synthetic examples thereof will be shown.

(A) Compound represented by the general formula [A]: Exemplified compound:

[0016]

[Chemical 5]

[0017]

[Chemical 6]

[0018]

[Chemical 7]

[0019]

[Chemical 8]

[0020]

[Chemical 9]

[0021]

[Chemical 10]

[0022]

[Chemical 11]

[0023]

[Chemical 12]

: Synthesis example:

[0025]

[Chemical 13]

In accordance with the above scheme, exemplary compound P-1
Was synthesized. That is, 27.5 g of 4-chlorophthalic anhydride and p-
Chlorophenylacetic acid 34g and sodium acetate 1g 300ml
The mixture was placed in a four-headed flask and heated at 240 ° C. for 3 hours.

Then, the reaction product was cooled to obtain 1 crude crystal. This was recrystallized in ethanol, and 1 was converted into yellow crystals 21
5 g (Y50%) was obtained.

Next, 1: 20.5 g and 120 ml of hydroiodic acid were mixed in 3 parts.
The mixture was placed in a 00 ml three-headed flask and stirred at a reflux temperature for 12 hours.

Then, after standing still for another 12 hours, 500 g of water was added at room temperature to obtain crude crystals. This was dissolved in 25% aqueous ammonia while heating, filtered, and the filtrate was reprecipitated in a 35% aqueous hydrochloric acid solution to obtain 2 crude crystals.

This was recrystallized from cyclohexane to give 2 as colorless crystals (10.8 g, Y52%).

Next, 300 ml of 2: 9 g and 100 ml of polyphosphoric acid
The mixture was placed in a three-headed flask and stirred at 170 ° C. for 3 hours.

Thereafter, water was added, an excess amount of ether was added, and the organic layer washed with 50% aqueous sodium carbonate solution and water was separated, dried over magnesium sulfate, and the ether was distilled off under reduced pressure to obtain 3 crude crystals. Got This was recrystallized from cyclohexane to obtain 6.2 g of 3 as a yellow crystal.

Next, 3: 3 g was heated to 130 ° C., and 2.6 g bromine was added, and the mixture further added 3 parts UV light.
Irradiation was carried out for 0 minutes, the reaction temperature was further raised to 200 ° C., and the reaction continued until hydrogen bromide was not obtained, to obtain crude crystals of 4. This was recrystallized from isopropanol to obtain 2.1 g (y70%) of 4 as a pale yellow crystal.

Then 4-bromo-2,6 dissolved in 20 ml ether.
-Xylenol 2g (0.01mole) and n-butyllithium 1.3g (0.02mole) dissolved in cyclohexane were put in a 200ml four-headed flask, and further, under nitrogen stream, at -20 ° C temperature, 2
Stir for hours. Then, after dissolving 4: 2.1 g (0.03 mol) in 10 ml of ether, the solution was further added, stirred at -20 ° C temperature for 2 hours, and further stirred at room temperature for 1 hour.

Thereafter, ice and diluted acid were added to neutralize the reaction solution, the organic layer was separated, the ether layer was dried over MgSO ₄ , and the ether was distilled off under reduced pressure to obtain 5 crude crystals. This was recrystallized with chloroform, and 5 was colorless crystal, 1.86 g.
(Y66%) obtained.

Finally, 5: 0.75 g (2 mmole) and 60 g of polyphosphoric acid were placed in a three-headed flask and stirred at a temperature of 60 ° C. for 3 hours. The reaction was cooled and 6 crude crystals were obtained. The crude crystals were recrystallized from chloroform to obtain Exemplified Compound P-1 (0.65 g, yield 68%) as yellow crystals.

Since the elemental analysis values agree with the calculated values,
The structure of the exemplified compound P-1 was confirmed. Melting point is 167-168
° C.

[0038] In the electrophotographic photosensitive member of the present invention, as the conductive support, for example, a metal pipe, a metal plate, a metal sheet, a metal foil,
A conductive polymer film, a polymer film provided with a vapor-deposited layer of a metal such as Al, a polymer film coated with a metal oxide, a quaternary ammonium salt, or the like, or paper is used.

In the electrophotographic photosensitive member of the present invention, the photosensitive layer is provided on the conductive support, but the photosensitive layer may have a single layer structure, or a laminated structure in which the charge generating layer and the charge transporting layer are functionally separated. It may be one. An adhesive layer may be provided between the conductive support and the photosensitive layer.

As shown in FIGS. 1 (a) and 1 (b), the photoconductor of the present invention has an electron generating substance (CG
M) as the main component of the electron generating layer (CGL) 2 and the electron transporting material (CTM) as the main component of the electron transporting layer (C)
A photosensitive layer 4 composed of a laminate with TL) 3 is provided. The photosensitive layer 4 may be provided via an intermediate layer 5 provided on the conductive support 1, as shown in FIGS. Thus, when the photosensitive layer 4 has a two-layer structure, a photoreceptor having the most excellent electrophotographic characteristics can be obtained. In addition, in the present invention, as shown in FIGS.
The photosensitive layer 4 in which the particulate CGM 7 is dispersed in the layer 6 containing as a main component may be provided directly on the conductive support 1 or via the intermediate layer 5.

Further, a protective layer (OCL) may be provided on the photosensitive layer 4 if necessary.

CGL which constitutes the two-layered photosensitive layer 4
2, CTL3 can be formed by the following method depending on the characteristics of CTM and CGM, directly on the conductive support 1 which is the lower layer surface, or on the intermediate layer such as an adhesive layer or a barrier layer if necessary. it can.

(1) Vapor deposition method (2) Coating method a) Method of coating a solution coating in which CGM and CTM are dissolved in a suitable solvent.

B) A method in which CGM and CTM are made into fine particles in a dispersion medium by a ball mill, a homomixer or the like and, if necessary, mixed and dispersed with a binder to apply a dispersion coating material.

Examples of the vapor deposition method include a vacuum vapor deposition method, a sputtering method, an ion plating method, a CVD method and the like, and a coating method includes a dipping method, a spray method, an air doctor method, a doctor blade method and a reverse method. An appropriate method is selected according to the physical properties of the coating material such as the roll method.

The adhesive layer is formed of resin alone, coated with a low resistance compound such as tin oxide, indium oxide, or titanium oxide dispersed in resin, or coated with aluminum oxide, zinc oxide, silicon oxide, or the like. The vapor deposition film of
The resin used for the adhesive layer is not particularly limited, and examples thereof include vinylidene chloride-vinyl chloride copolymer, water-soluble polyvinyl butyral resin, alcohol-soluble polyamide resin, vinyl acetate-based resin, polyvinyl alcohol, nitrocellulose, and polyimide resin. To be

The thickness of the binder layer is preferably about 0.01 to 10 μm, and particularly preferably 0.01 to 1 μm.

When the photosensitive layer is a single layer, a photosensitive layer composed of a known material such as polyvinylcarbazole and the like, containing the compound represented by the general formula [A] as a sensitizer, or Examples thereof include those in which the compound represented by the general formula [A] is contained as an electron transporting substance in a photosensitive layer containing a known charge generating substance.

On the other hand, when the photosensitive layer is a laminated type,
The electron generating layer may be obtained by vapor deposition of an electron generating substance on a conductive support, or may be formed by applying a coating liquid containing an electron generating substance and a binder resin as main components. .

Any known charge generating substance and binder resin can be used.

For example, as the charge generating substance, an inorganic semiconductor such as Te-Se, an organic semiconductor such as polyvinylcarbazole, a bisazo compound, a trisazo compound, a metal-free phthalocyanine compound, a metal phthalocyanine compound,
Organic pigments such as pyrylium compounds, squarylium compounds, cyanine compounds, perylene compounds and polycyclic quinone compounds can be used. Among them, preferable charge generating substances include, for example, Y-type titanyl phthalocyanine pigments having an X-ray diffraction peak at 27.2 ° in JP-A-64-17066,
A having an X-ray diffraction peak at 26.3 ° in JP-A-62-67094
Type titanyl phthalocyanine pigment, B type titanyl phthalocyanine pigment having an X-ray diffraction peak at 28.7 ° of JP-A-61-239248, metal-free phthalocyanine pigment of JP-B-49-4338, and copper phthalocyanine of JP-A-57-163239. Pigments, vanadyl phthalocyanine pigments of JP-A-57-148747, perylene pigments of JP-A-49-128734, condensed polycyclic pigments of JP-A-47-18544, and bisazo pigments of JP-A-1-150145. . As the binder resin, polystyrene, silicone resin, polycarbonate resin, acrylic resin, methacrylic resin, polyester, vinyl polymer, cellulose resin, butyral resin, silicone modified butyral resin, alkyd resin and the like can be used.

The thickness of the charge generation layer is preferably about 0.01 to 10 μm, and particularly preferably 0.05 to 2 μm.

A charge transport layer is formed on the charge generation layer. The charge transport layer is composed of the compound represented by the general formula [A] and a binder resin, and contains the compound represented by the general formula [A], the binder resin, and a suitable solvent. Apply the coating liquid as the main component to the applicator, bar coater,
It is formed by coating the charge generation layer with a dip coater or the like. In this case, the mixing ratio of various compounds and the binder resin is preferably 1: 100 to 100: 1 by weight ratio, and particularly preferably 1:20 to 20: 1.

As the charge transport material and the binder resin used in the charge transport layer, any known materials can be used. For example, as the binder resin, acrylonitrile-butadiene copolymer, styrene-butadiene copolymer, vinyltoluene-styrene copolymer, styrene-modified alkyd resin, silicone-modified alkyd resin, soybean oil-modified alkyd resin, vinylidene chloride-vinyl chloride Resin, polyvinyl butyral, nitrated polystyrene, polymethylstyrene, polyisoprene, polyester, phenol resin, ketone resin, polyamide, polycarbonate, polythiocarbonate, polyacrylate, polyhaloacrylate, vinyl acetate resin, polystyrene,
Examples thereof include polyallyl ether, polyvinyl acrylate, polysulfone and polymethacrylate. Among them, biphenyl Z type polycarbonate is particularly preferable. or,
An ambipolar photoreceptor may be prepared by adding an electron donating substance to the charge transport layer. Further, an antioxidant or a radical trap agent may be added to the charge transport layer.

The thickness of the charge transport layer is preferably 2 to 100 μm, particularly preferably 5 to 50 μm.

In the electrophotographic photosensitive member of the present invention,
A barrier layer may be provided on the conductive support. The barrier layer is
It is effective in preventing the injection of unnecessary charges from the conductive support and has the effect of improving the image quality. Materials for forming the barrier layer include metal oxide such as aluminum oxide, acrylic resin, phenol resin, polyester resin, polyurethane and the like. The barrier layer may be provided on the adhesive layer or may be provided on the upper side.

[0057]

EXAMPLES Next, the present invention will be specifically described by way of examples. In this example, "part" means "part by weight".

(I) Sensitivity Evaluation Examples 1 to 10 A 0.5 μm thick intermediate layer made of polyamide resin “CM8000” (manufactured by Toray Industries, Inc.) was provided on a PET film on which aluminum was vapor-deposited, and “Chemical formula 14” was formed thereon. Perylene pigment G-shown in
1: 1 part, polyvinyl butyral resin "ESREC BL
S "(manufactured by Sekisui Chemical Co., Ltd.) and 50 parts of methyl ethyl ketone as a dispersion medium dispersed in a sand mill were applied using a wire bar to form a charge generation layer having a thickness of 0.3 μm. Next, 1 part of the exemplified compound shown in Table 1 and 1.5 parts of a polycarbonate resin "Iupilon Z-200" (manufactured by Mitsubishi Gas Chemical Co., Inc.) are dissolved in 10 parts of tetrahydrofuran (THF), and blade coating is performed on the charge generation layer to form a film thickness of 20 μm. Was formed on the charge transport layer.

Comparative Example 1 Comparative Compound 1 shown in “Chemical Formula 14” in place of Exemplified Compound P-1
Comparative samples were prepared in the same manner as in Example 1 except that was used.

Evaluation 1 Electrophotographic Photosensitive Samples Obtained in Examples 1 to 10 and Comparative Example 1 Electrostatic Copy Paper Testing Apparatus EPA-8100
(Kawaguchi Electric Co., Ltd.) is used to charge to + 800V and 10lux
Was exposed to the white light, and the exposure amount until the surface potential was halved was determined as the sensitivity. The results are shown in Table 1.

(II) Durability Evaluation Examples 11 to 20 A 0.5 μm-thick intermediate layer made of polyamide resin “X-1874M” (manufactured by Daicel Hüls) was provided on a PET film on which aluminum was vapor deposited. 1 part of pigment X type metal-free phthalocyanine (manufactured by Dainippon Ink and Chemicals, Inc.), 0.4 part of polyvinyl butyral resin "ESREC BX-1" (manufactured by Sekisui Chemical Co., Ltd.), and methyl isopropyl ketone 50 as a dispersion medium.
The liquid in which the parts were dispersed using a sand mill was applied using a wire bar to form a charge generation layer having a thickness of 0.3 μm. Next, 1 part of the exemplified compound in Table 2 and 1.5 parts of polycarbonate resin "Iupilon Z-200" (manufactured by Mitsubishi Gas Chemical Co., Inc.) were dissolved in 10 parts of THF, and blade coating was performed on the charge generation layer to obtain a film thickness of 20 μm.
Was formed on the charge transport layer.

Comparative Example 2 Comparative Compound 2 shown in “Chemical Formula 14” in place of Exemplified Compound P-11
Comparative samples were prepared in the same manner as in Example 11 except that was used.

Evaluation 2 The electrophotographic photoreceptor samples obtained in Examples 11 to 20 and Comparative Example 2 were evaluated by the following actual measurement values at the initial stage and after copying 10,000 sheets with a modified U-BIX 1017 machine manufactured by Konica Corporation. . The results are shown in Table 2.

Vb: Black part potential, Vw: White part potential,
Vr: Residual potential (III) Image quality evaluation Examples 21 to 30 An intermediate layer of 0.5 μm in thickness made of polyamide resin “CM8000” (manufactured by Toray Industries, Inc.) was provided on a cylindrical aluminum substrate, and a Bragg in X-ray diffraction was provided thereon. Angle 2θ 9.5 °, 24.1 °, 27.
A liquid in which 1 part of titanyl phthalocyanine having a peak at 2 °, 0.5 part of silicone butyral resin and 50 parts of methyl isopropyl ketone as a dispersion medium were dispersed using a sand mill was dip coated to form a charge generation layer having a thickness of 0.3 μm.

Next, 1 part of the exemplified compound shown in Table 3 and 1.5 parts of a polycarbonate resin "Iupilon Z-200" (manufactured by Mitsubishi Gas Chemical Co., Inc.) were dissolved in 10 parts of THF and dip-coated on the charge generation layer to form a film having a thickness of 20 μm. A charge transport layer was formed.

Comparative Example 3 A comparative sample was prepared in the same manner as in Example 21 except that Comparative Compound 3 shown in "Chemical Formula 14" was used in place of Exemplified Compound P-21.

Evaluation 3 The electrophotographic photoconductor samples obtained in Examples 21 to 30 and Comparative Example 3 were imaged by a digital copying machine "Konica 9028" modified by Konica Corporation (charge polarity: positive, reverse development). I put it out. These samples were then placed at low temperature (10
(° C.) environment was left for 1 month, and then images were reproduced again under the same conditions. The black spots on the white background portion of these copied images were evaluated. The results are shown in Table 3.

The black spots were evaluated by measuring the size and number of the black spots using an image analyzer "Omnicon 300 type" (manufactured by Shimadzu Corporation), and a black spot having a diameter of 0.05 mm or more was 1 cm ²
It was performed by judging how many there are. The criteria for evaluating the black spots are as shown below. It should be noted that if the result of the black spot determination is ⊚ or ◯, it is practical, but if it is Δ, it is not suitable for practical use, and if it is ×, it is not suitable for practical use.

Number of black spots with a diameter of 0.05 mm or more (pieces / cm ² ) Black spot determination 0 ◎ 1-3 ○ 4-10 △ 11 or more ×

[0070]

[Chemical 14]

[0071]

[Table 1]

[0072]

[Table 2]

[0073]

[Table 3]

As is clear from the above-mentioned tables, the electrophotographic photosensitive member using the electron transporting material of the present invention has higher sensitivity and is more repetitive than the conventional electrophotographic photosensitive member using the charge transporting material. The characteristics of the photoconductor during use are stable, and
It can be seen that the occurrence of image defects is extremely small even after storage at low temperature.

[0075]

INDUSTRIAL APPLICABILITY The compound of the present invention has an electron transporting ability, and can provide a photoconductor for positive charging having high sensitivity, low residual potential, and good image retention.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an exemplary embodiment of a photoconductor of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Conductive support 2 Electron generation layer (CGL) 3 Electron transport layer (CTL) 4 Photosensitive layer 5 Intermediate layer 6 Layer containing electron transport substance 7 Electron generation substance

Claims (2)

[Claims] 1. An electrophotographic photoreceptor having a photosensitive layer provided on a conductive support, wherein the photosensitive layer contains a compound represented by the following general formula [A]. [Chemical 1] In the formula, R ₁ and R ₂ each may have an alkyl group which may have a substituent, a vinyl group which may have a substituent, an ester group which may have a substituent, or a substituent which may have a substituent. It represents an acyl group, an amide group which may have a substituent, a hydrogen atom, a halogen atom, a cyano group or a nitro group. n and m represent the integer of 0-4. Further, R ₃ and R ₄ are a hydrogen atom, a halogen atom, a cyano group, a nitro group or an ester group which may be substituted, an acyl group which may be substituted, an amide group which may be substituted, or a vinyl which may be substituted. Represents a phenyl group which may be substituted. 2. The electrophotographic photosensitive member according to claim 1, wherein the compound represented by the general formula [A] is a compound represented by the following general formula [a]. [Chemical 2] Wherein, R _1, R ₂ is identical to R _1, R ₂ of claim 1.