JPH07175236A - Electrophotographic photoreceptor - Google Patents

Abstract

PURPOSE:To obtain a laminated electrophotographic photoreceptor for positive charge using a charge transfer material having electron transferring ability and having excellent electrophotographic performance by incorporating plural specific compounds in the electrophotographic photoreceptor. CONSTITUTION:The compounds expressed by a formula I, II or III are incorporated in the photoreceptor. In the formulas, each of Ar1-Ar5 represents (substituted) aromatic group, each of R1-R6 represents hydrogen atom. electron attractive group, (substituted) alkyl group or (substituted) aromatic group and each of X1-X3 represents electron attractive group. Where, when R3 is hydrogen atom or X1 is nitrile group, R1 is hydrogen atom, electron attractive group or (substituted) alkyl group and when R4 is hydrogen atom and X2 is nitrile group, R2 is hydrogen atom, electron attractive group or (substituted) alkyl group. As a result, the compatibility with a binder is kept stable for a long time and the performance as the charge transfer material is improved.

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 containing an electron transporting substance.

[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. Has been put to practical use as a photoconductor. These electrophotographic photoreceptors include a laminated type and a single layer type.

The multi-layer type electrophotographic photosensitive member comprises a charge generating layer for generating charges upon irradiation with light and a charge transporting layer for transferring the generated charges. In this case, examples of the charge transport material used in the charge transport layer include polymer materials such as poly-N-vinylcarbazole and low molecular weight compounds such as pyrazoline, hydrazone and triphenylamine derivatives.

Since all of these charge-transporting substances have a hole-transporting ability, when an electrostatic latent image is formed on an electrophotographic photoreceptor in which a charge-generating layer and a charge-transporting layer are laminated in this order on a conductive support. Is applied with an electrophotographic process for negatively charging the surface of the photoconductor. As a method of charging the surface of the photoconductor, the corona discharge method is currently the mainstream, but ozone is generated when negatively charging the corona, which not only deteriorates the surface of the photoconductor but also harms the environment. There is.

By reversing the layer structure of the photosensitive layer of the laminated photoreceptor,
When the charge transport layer is provided as the lower layer and the charge generation layer is provided as the upper layer, the charging property can be made positive, but there is a problem that the printing durability is significantly deteriorated.

On the other hand, the single-layer type electrophotographic photosensitive material is
The single layer has two functions of charge generation ability and charge transport ability. The photoconductor having such a layer structure can have a positive charging polarity, but it is difficult to improve the performance because the functions are not separated, and few have reached the stage of practical use.

In order to solve the above problems, a charge transporting material having an electron transporting ability is developed and used in a charge transporting layer to make the charging polarity positive, or a single layer type electrophotographic photoreceptor is used. It is only necessary to take measures to improve the performance.

Further, also in the negatively charged electrophotographic photosensitive member containing the hole transporting substance which is currently being developed, it is possible to improve the electrophotographic characteristics during repeated use by incorporating the electron transporting substance into the photosensitive member. it can.

2,4,7-Trinitro-9-fluorenone is known as a charge-transporting substance having an electron-transporting ability, but its use is discontinued because of its toxicity. At present, there are few other useful materials.

[0010]

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

[0011]

As a result of research, the present inventors have found that the object of the present invention can be achieved by any of the following electrophotographic photoreceptors. That is, the object of the present invention can be achieved by containing a compound represented by the following general formula (A), (B) or (C) in an electrophotographic photoreceptor having a photosensitive layer provided on a conductive support. It

[0012]

[Chemical 4]

In the general formula [A], Ar _{1 to} Ar ₃ are substituted or unsubstituted aromatic groups, R _{1 to} R ₄ are hydrogen atoms, electron withdrawing groups, substituted or unsubstituted alkyl groups, substituted or unsubstituted aromatic groups. It represents a substituted aromatic group, and X ₁ and X ₂ represent electron withdrawing groups. However, when R ₃ is a hydrogen atom and X ₁ is a nitrile group, R ₁ is a hydrogen atom, an electron-withdrawing group, a substituted or unsubstituted alkyl group, and when R ₄ is a hydrogen atom and X ₂ is a nitrile group, R
₂ is a hydrogen atom, an electron-withdrawing group, or a substituted or unsubstituted alkyl group.

[0014]

[Chemical 5]

In the general formula [B], Ar _{1 to} Ar ₃ are substituted or unsubstituted aromatic groups, R _{1 to} R ₆ are hydrogen atoms, electron withdrawing groups, substituted or unsubstituted alkyl groups, substituted or unsubstituted aromatic groups. It represents a substituted aromatic group, and X _{1 to} X ₃ represent electron withdrawing groups.

The electron-withdrawing group in the general formulas [A] and [B] is, for example, --CN, --NO ₂ , --COOR ', --SO.
₂ R ', -SOR' (R 'is a substituted or unsubstituted alkyl group,
A substituted or unsubstituted aromatic _{group), - SO 2, -SO 2} NH 2
Alternatively, it represents a halogen atom or the like.

The substituents in the general formulas [A] and [B] are, for example, alkyl, phenyl, alkoxy, acyl and amide groups (each of these groups may be further substituted) or the above-mentioned electron. Represents an attractive group.

[0018]

[Chemical 6]

In the general formula (C), Ar _{1 to} Ar ₅ represent a substituted or unsubstituted aromatic group.

The term "substituent" used herein means alkyl, alkoxy, acyl, ester, phenyl, amide, sulfone, sulfonamide, cyano, nitro, halogen atom and the like.

The high performance of the charge transport material of the present invention is considered to be derived from the fact that the long-term compatibility with the binder is kept stable as compared with the conventional charge transport material.

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

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

[0024]

[Chemical 7]

[0025]

[Chemical 8]

[0026]

[Chemical 9]

: Synthesis example:

[0028]

[Chemical 10]

The compound represented by the general formula [A] of the present invention can be easily synthesized by a known synthetic method, for example, the method described above.

That is, as shown in the above figure, the formyl body 1
5.0 g (0.017 mol) and malononitrile 2 5.3 g (0.08 mol)
Mol) in 50 ml of methanol and stirring was started. A catalytic amount of piperidine was added thereto, and the mixture was stirred at room temperature for 2 hours. The precipitate was collected by filtration, purified by silica gel column chromatogram, and recrystallized from ethyl acetate to obtain 2.9 g of orange crystals (yield 44%).

The thus-obtained crystals show absorption of nitrile at 2220 cm ^-1 in IR spectrum, M ⁺ peak at m / z = 398 in FD-MS spectrum, and elemental analysis values (see the table below). ) Agrees well with the calculated value,
It was confirmed that this was the structure of the exemplified compound A-1.

C H N measured value 78.49% 3.92% 17.59% calculated value 78.57% 3.80% 17.62% (B) Compound represented by general formula [B]: Exemplified compound:

[0033]

[Chemical 11]

[0034]

[Chemical 12]

: Synthesis example:

[0036]

[Chemical 13]

The compound represented by the general formula (B) of the present invention can be easily synthesized by a known synthetic method, for example, the method described above.

That is, as shown in the above figure, the formyl body 1
5.0 g (0.015 mol) and malononitrile 2 7.2 g (0.11
Mol) in 50 ml of methanol and stirring was started. A catalytic amount of piperidine was added thereto, and the mixture was stirred at room temperature for 2 hours. The precipitate was collected by filtration, purified by silica gel column chromatogram, and recrystallized from ethyl acetate to obtain 3.5 g of orange crystals (yield 49%).

The crystal thus obtained shows an absorption of nitrile at 2220 cm ^-1 in the IR spectrum, a peak of M ⁺ at m / z = 474 in the FD-MS spectrum, and elemental analysis values (see the table below). ) Agrees well with the calculated value,
It was confirmed that the structure was Exemplified Compound B-1.

CHN Measured value 76.01% 3.30% 20.68% Calculated value 76.10% 3.19% 20.71% (C) Compound represented by general formula [C]: Exemplified compound:

[0041]

[Chemical 14]

[0042]

[Chemical 15]

[0043]

[Chemical 16]

: Synthesis example:

[0045]

[Chemical 17]

The compound represented by the general formula [C] of the present invention can be easily synthesized by a known synthetic method, for example, the method described above.

That is, as shown in the above figure, the formyl body 1
30.1 g (0.1 mol) and 51.6 g (0.2 mol) of phosphonate 2 were put in 250 ml of tetrahydrofuran, and stirring was started. 4.8 g of sodium hydride was added to this solution under ice cooling.
200 ml of a tetrahydrofuran solution of (0.2 mol) was added dropwise. It returned to room temperature and stirred for 12 hours. After standing at room temperature for one day and night, 300 ml of water was added, and the precipitated crystals were collected by filtration. Recrystallization from ethanol gave 38.4 g of yellow needle crystals (yield
77%).

The thus-obtained crystal shows an absorption spectrum of nitrile at 2220 cm ^-1 in IR spectrum, a peak of M ⁺ at m / z = 500 in FD-MS spectrum, and elemental analysis values (see the table below). ) Agrees well with the calculated value,
It was confirmed that this was the structure of the exemplified compound C-1.

C H N measured value 86.39% 5.11% 8.50% calculated value 86.55% 5.04% 8.41% In the electrophotographic photosensitive member of the present invention, examples of the conductive support include a metal pipe, a metal plate, a metal sheet, and a metal foil. ,
A conductive polymer film, a polymer film provided with a vapor deposition 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.

As shown in FIGS. 1A and 1B, the photoconductor of the present invention comprises a charge generating substance (CGM) on a conductive support 1.
A charge generation layer (CGL) 2 containing C as a main component and a charge transport layer C containing an electron transporting material (n-CTM) as a main component
A photosensitive layer 4 composed of a laminate with TL) 3 is provided. As shown in FIGS. 3C and 3D, the photosensitive layer 4 may be provided on the conductive support 1 with the intermediate layer 5 interposed therebetween. Thus, when the photosensitive layer 4 has a two-layer structure, a photoreceptor having the most excellent electrophotographic characteristics can be obtained. Further, in the present invention,
As shown in FIGS. 1 (e) and (f), a photosensitive layer 4 in which fine particles of CGM 7 are dispersed in the layer 6 containing n-CTM as a main component is provided directly on the conductive support 1 or as an intermediate layer. It may be provided via 5. CGM may be added to CTL in the above structure, or a charge transport material may be added to CGL.

Further, a protective layer (OCL) 8 may be provided on the photosensitive layer 4 if necessary.

An electron transporting substance or a hole transporting substance may be added to this OCL.

A hole-transporting substance may be used in combination with the photoreceptor using the electron-transporting substance of the present invention. In the case of using a hole transporting substance together, the most preferable embodiment is a structure in which an OCL containing an electron transporting substance (n-CTM) is provided on the uppermost layer and a hole transporting layer (p-CTL) 9 is provided on the support side. Is preferred. The specific layer structure is shown in FIG.
A layer structure such as (j) is preferable.

The intermediate layer is formed of resin alone, coated with a dispersion of a low resistance compound such as tin oxide, indium oxide and titanium oxide in resin, or aluminum oxide, zinc oxide, silicon oxide and 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 intermediate 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, the compound represented by the general formulas [A] to [C] is contained in a photosensitive layer containing a known charge generating substance, or a known charge generating substance. And a known charge transporting substance contained in a photosensitive layer.

On the other hand, when the photosensitive layer is a laminated type,
The charge generation layer may be obtained by vapor deposition of a charge generation substance, or may be formed by applying a coating liquid containing a charge generation 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, a preferable charge generating substance is, for example, X at 27.2 ° in JP-A-64-17066.
Y-type titanyl phthalocyanine pigment having a line diffraction peak, A-type titanyl phthalocyanine pigment having an X-ray diffraction peak at 26.3 ° in JP-A-62-67094, JP-A-61-239248
B-type titanyl phthalocyanine pigment having an X-ray diffraction peak of 28.7 ° of No. 4, metal-free phthalocyanine pigment of JP-B-49-4338, copper phthalocyanine pigment of JP-A-57-163239, and vanadyl of JP-A-57-148747. Phthalocyanine pigment, perylene pigment of JP-A-49-128734, JP-A-47-1854
No. 4, condensed polycyclic pigments, JP-A No. 1-150145, and bisazo pigments. 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.

The charge transport layer comprises the above general formulas [A] to [C].
A compound represented by the formula (1) and a binder resin, and a coating solution containing the compound represented by the general formulas [A] to [C], a binder resin, and a suitable solvent as main components, It is formed by coating with an applicator, bar coater, 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, and particularly preferably 1:20 to 20: 1.

Any known binder resin may be used as the binder resin for the charge transport layer. For example, acrylonitrile-butadiene copolymer, styrene-butadiene copolymer, vinyltoluene-styrene copolymer, styrene-modified alkyd resin, silicone-modified alkyd resin, vinylidene chloride-vinyl chloride resin, polyvinyl butyral, nitrated polystyrene, polymethyl. Styrene, polyisoprene, polyester, phenol resin, polyamide, polycarbonate, polythiocarbonate, polyacrylate, polyhaloacrylate, vinyl acetate resin, polystyrene, polyallyl ether,
Examples thereof include polyvinyl acrylate, polysulfone, polymethacrylate and the like.

An electron donating substance antioxidant and a radical trapping 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.

The charge transport material of the present invention can be used in combination with a known charge transport material. Examples of known charge transport substances include, for example, triphenylamine compounds, styryl-triphenylamine compounds, hydrazone compounds,
Examples thereof include a butadiene compound, a carbazole compound, and a condensed polycyclic compound.

[0066]

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

(I) Evaluation of Sensitivity Example A-1 to 7 A 0.5 .mu.m 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 the 18 "perylene pigment C
GM-1 (1 part), polyvinyl butyral resin "ESREC BLS" (manufactured by Sekisui Chemical Co., Ltd.) 0.2 part, and methyl ethyl ketone (50 parts) as a dispersion medium are dispersed using a sand mill, and a liquid is applied using a wire bar to form a film having a thickness of 0.3 μm. A charge generation layer was formed. Then, 1 part of the exemplified compound shown in the middle column of Table 1 and 1.5 parts of a polycarbonate resin "Iupilon Z-200" (manufactured by Mitsubishi Gas Chemical Co., Inc.) were added to tetrahydrofuran (THF) 1
Dissolve in 0 part and apply a blade onto the charge generation layer to obtain a film thickness of 20
A μm charge transport layer was formed.

Comparative Example 1 Instead of Exemplified Compound A-1, Comparative Compound T shown in "Chemical Formula 18"
A comparative sample was prepared in the same manner as in Example 1 except that -1 was used.

Evaluation 1 The electrophotographic photosensitive member samples obtained in Example 1 and Comparative Example 1 were charged to +800 V using an electrostatic copying paper test apparatus EPA-8100 (manufactured by Kawaguchi Electric Co., Ltd.) and 10 lux · sec.
The surface potential V _L after exposure to the white light of was obtained and used as the sensitivity. The results are shown in the right column of Table 1.

Examples A-8 to 14: An intermediate layer made of polyamide resin "CM8000" (manufactured by Toray Industries, Inc.) having a thickness of 0.5 μm was provided on a cylindrical aluminum substrate, and an intermediate layer having a Bragg angle 2θ in X-ray diffraction of 9.5 was provided thereon. °, 24.1 °, 27.
A liquid in which 1 part of titanine phthalocyanine having a peak at 2 °, 0.5 part of silicone-butyral resin, and 50 parts of methyl isopropyl ketone as a dispersion medium are dispersed using a sand mill is applied by dip coating to form a charge generation layer having a thickness of 0.3 μm. did. Next, 1 part of the exemplified compound shown in the middle column of Table 2 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, and a dip 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 2 A comparative sample was prepared in the same manner as in Example A-8 except that Comparative Compound T-2 shown in "Chemical Formula 18" was used in place of Exemplified Compound A-2.

Evaluation 2 The electrophotographic photoreceptor samples obtained in Examples A-8 to 14 and Comparative Example 2 were evaluated in the same manner as in Evaluation 1. The results are shown in Table 2.

[0073]

[Chemical 18]

[0074]

[Table 1]

[0075]

[Table 2]

In the completely same manner, the general formula [B],
The compound of [C] was also evaluated.

B corresponding to Examples A-1 to 7
-1 to 7 and C-1 to 7 "Tables 3 and 5" B-8 to 14 and C corresponding to Examples A-8 to 14
-8 to 14 The results are shown in Tables 3 to 6 as "Tables 4 and 6".

(For the compounds of the general formula [B], the comparative compounds were changed to T-3 and 4.)

[0079]

[Chemical 19]

[0080]

[Table 3]

[0081]

[Table 4]

[0082]

[Table 5]

[0083]

[Table 6]

As is clear from the above tables, by using the electron transporting material of the present invention, it is possible to obtain a positively charged electrophotographic photosensitive member having characteristics superior to those of conventional ones.

[0085]

Industrial Applicability The compound of the present invention has an electron transporting ability and can provide a positive charging photoreceptor having more excellent properties than ever before.

[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]

 1 Conductive Support 2 Charge Generation Layer (CGL) 3 Charge Transport Layer (CTL) 4 Photosensitive Layer 5 Intermediate Layer 6 Layer Based on Electron Transport Material (n-CTM) 7 Charge Generation Material

Claims (3)

[Claims] 1. An electrophotographic photoreceptor having a photosensitive layer provided on a conductive support, which contains a compound represented by the following general formula [A]. [Chemical 1] In the general formula [A], Ar _{1 to} Ar ₃ are substituted or unsubstituted aromatic groups, R _{1 to} R ₄ are hydrogen atoms, electron withdrawing groups, substituted or unsubstituted alkyl groups, substituted or unsubstituted aromatic groups. Represents a group group, and X ₁ and X ₂ represent an electron withdrawing group. Provided that when R ₃ is a hydrogen atom and X ₁ is a nitrile group, R ₁ is a hydrogen atom, an electron-withdrawing group, a substituted or unsubstituted alkyl group, and R ₄
Is a hydrogen atom and X ₂ is a nitrile group, R ₂ is a hydrogen atom, an electron-withdrawing group or a substituted or unsubstituted alkyl group. 2. An electrophotographic photoreceptor having a photosensitive layer provided on a conductive support, which contains a compound represented by the following general formula [B]. [Chemical 2] In the general formula [B], Ar _{1 to} Ar ₃ are substituted or unsubstituted aromatic groups, R _{1 to} R ₆ are hydrogen atoms, electron withdrawing groups, substituted or unsubstituted alkyl groups, substituted or unsubstituted aromatic groups. Represents a group group, and X _{1 to} X ₃ represent an electron withdrawing group. 3. An electrophotographic photoreceptor having a photosensitive layer provided on a conductive support, which contains a compound represented by the following general formula [C]. [Chemical 3] In the general formula [C], Ar _{1 to} Ar ₅ represent a substituted or unsubstituted aromatic group.