JPH0770038A - Fluorene compound and electrophotographic photoreceptor using the same - Google Patents

Abstract

PURPOSE:To obtain a new fluorene compound capable of giving electrophotographic photoreceptors of high sensitivity with excellent durability when used as charge transport substance. CONSTITUTION:A fluorene compound of formula 1 (R1 is a substituted or nonsubstituted aromatic or heterocyclic group or an alkoxycarbonyl; (x) and (y) are each 0-4 and totaling of them is 1-4) or formula 2 (R2 is an alkyl), e.g. 2,4,7-trinitro-9-fluorenidene(2-methylphenylacetonitrile). The compound of formula 1 or 2 can be obtained by reaction of a fluorenone compound of formula 3 with an acetonitrile derivative of formula 4 or a malonic acid derivative of formula 5. The compound of formula 1 or 2 can be used not only for electrophotographic photoreceptors but also preferably used in the electronic industry for electronic devices such as solar cells and organic EL elements.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charge transport material used in an electrophotographic photoreceptor, and more specifically, the present invention relates to an electrophotographic photoreceptor containing a fluorene compound as a charge transport material.

[0002]

2. Description of the Related Art Conventionally, inorganic photoconductive substances such as selenium, selenium-tellurium alloy, and zinc oxide have been widely used as a photosensitive layer of electrophotographic photoconductors. In recent years, electronic photoconductive substances using organic photoconductive substances have been widely used. Research on photographic photoreceptors has progressed, and some of them have been put to practical use. Here, most of the photoconductors that have been put into practical use are laminated electrophotographic photoconductors that are composed of a photoconductive layer having a charge-generating layer and a charge-transporting layer, and a photoconductive layer made of an inorganic photoconductive material. The electrophotographic photoconductor is actively designed, which is improved in terms of sensitivity and photoconductor life, which are inferior to those of the human body, and is low in cost, and takes advantage of organic photoconductive substances such as safety and versatility. It became so. In this type of laminated electrophotographic photoreceptor, generally, a charge generating layer made of a charge generating substance such as a pigment and a dye, and a charge transporting layer made of a charge transporting substance such as hydrazone and pyrazoline are sequentially formed on a conductive support. Due to the property of the electron-donating charge-transporting substance, it is a hole-transfer type and has sensitivity when negatively charged on the surface of the photoreceptor. However, with negative charging, the corona discharge used during charging is more unstable than with positive charging, and ozone, nitrogen oxides, etc., which are about 10 times as much as during positive charging, are generated, and physical deterioration such as adsorption on the surface of the photosensitive member occurs. It is apt to cause chemical deterioration, and there is a problem that it worsens the environment. Still another problem is that the development of the negative charging photoreceptor requires a positive polarity toner, but the positive polarity toner is difficult to manufacture in view of the triboelectrification series with respect to the ferromagnetic carrier particles, and the high two-component toner is required. In the resistance magnetic brush development method, the negatively charged toner / developer is more stable, and the degree of freedom in selection and use conditions is greater. From this point as well, the applicable range is wide and advantageous for the positively charged type photoreceptor. Therefore, it has been proposed to use a photoconductor using an organic photoconductive substance with positive charging. However, in this case, an electron-withdrawing substance must be used as the charge-transporting substance, but in general, the electron-withdrawing substance is poorly soluble in the solvent and has a problem such as poor compatibility with the resin. Japanese Patent Laid-Open No. 1-206349
A diphenoquinone compound has been disclosed as an electron-withdrawing substance, but it has not been put into practical use because of problems in sensitivity, durability and the like. Further, as a positively charged photoreceptor, U.S. Pat. No. 3,615,414 discloses a thiapyrylium salt (charge-generating substance) contained in a polycarbonate (binder resin) so as to form a eutectic complex. . However, this known photoconductor has a drawback that a memory phenomenon is large and a ghost is easily generated. Therefore, in a laminated structure, a charge generation layer containing a charge generation substance that generates holes and electrons at the time of light irradiation is an upper layer (surface layer), and a charge transport layer containing a charge transport substance having a hole transport ability is a lower layer. It is considered that a photoreceptor having a photosensitive layer can be used for positive charging. However, since the layer containing the charge generating substance is formed as the surface layer in the photoconductor for positive charging, it is vulnerable to external action such as irradiation of short wavelength light such as ultraviolet rays, corona discharge, humidity and mechanical friction during light irradiation. Since such a charge-generating substance is present in the vicinity of the surface layer, electrophotographic performance is deteriorated during storage of the photoconductor and during image formation, and image quality is deteriorated. In the conventional negative charging photoreceptor having the charge transport layer as the surface layer, the influence of the various external effects is extremely small, and rather the charge transport layer has a function of protecting the lower charge generating layer. Therefore, for example, a thin protective layer made of an insulative and transparent resin may be provided to protect the layer containing the charge generating substance from an external action, but the charge generated during light irradiation is blocked by the protective layer. The light irradiation effect is lost, and if the thickness of the protective layer serving as the surface layer is large, the sensitivity is lowered. Although various attempts have been made to obtain a photoconductor for positive charging as described above, there are many problems to be solved in terms of photosensitivity, memory phenomenon, occupational health and the like.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic photosensitive member which comprises a charge generating substance and a charge transporting substance on a conductive support and has high sensitivity and excellent durability.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted extensive research to solve the above-mentioned problems, and as a result, found a specific group of compounds and completed the present invention. That is, according to the present invention, in an electrophotographic photoreceptor comprising a charge generating substance and a charge transporting substance on a conductive support, the fluorene represented by the following general formulas (1) and (2) is used as the charge transporting substance. An electrophotographic photoreceptor containing the compound is provided.

[Chemical 3] (In the formula, R ₁ represents a substituted or unsubstituted aromatic group, a substituted or unsubstituted heterocyclic group, or an alkoxycarbonyl group. X and y each represent an integer of 0, 1, 2, 3 or 4. However, 1 ≦ x + y ≦ 4.)

[Chemical 4] (In the formula, R ₂ represents an alkyl group. However, R ₂ can be bonded to each other to form a ring, and x and y represent an integer of 0, 1, 2, 3 or 4. 1 ≦
x + y ≦ 4. )

In the general formula (1) of the present invention, the aromatic group of R ₁ is a phenyl group or a naphthyl group, the heterocyclic group is a pyridyl group, a furanyl group or a quinolyl group, and an alkoxycarbonyl group. Examples of alkoxy include methoxy, ethoxy, butoxy and t-butoxy. Further, as the substituent of the aromatic group or the heterocyclic group in R ₁ , an alkoxy group such as a methoxy group or an ethoxy group, an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, or a t-butyl group. , Halogen atom such as fluorine atom, chlorine atom or bromine atom, halogenated alkyl group such as trifluoromethyl group, alkoxycarbonyl group such as methoxycarbonyl group, ethoxycarbonyl group, butoxycarbonyl group, cyano group, nitro group, etc. be able to. In the general formula (2), R ₂ is a methyl group, an ethyl group,
It represents an alkyl group such as a propyl group, a butyl group, or a t-butyl group. Here, specific examples of the fluorene compound of the general formula (1) of the present invention are shown in Tables 1 to 19 and the general formula (2)
Specific examples of the fluorene compound of are shown in Tables 20 to 21,
The compounds of the general formulas (1) and (2) are not limited to those shown in these tables. These compounds represented by the general formula (1) or (2) are generally prepared by reacting the following fluorenone compound (3) with the following acetonitrile derivative (4) or malonic acid derivative (5) in the presence of an acidic catalyst or a basic catalyst. Can be obtained by Examples of the acidic catalyst used in the reaction include titanium tetrachloride, zinc chloride and boron trifluoride, and examples of the basic catalyst include N-methylmorpholine, N-methylpiperidine, pyridine, piperidine, and triethylamine. Organic bases such as, acetates such as sodium acetate, potassium acetate or ammonium acetate, sodium carbonate,
Alternatively, an inorganic base such as potassium carbonate can be used. The reaction can usually be carried out without solvent, in a halogen solvent such as dichloromethane or dichloroethane, an ether solvent such as tetrahydrofuran, or an aromatic solvent such as benzene or toluene. Reaction temperature is 0 ℃
To 150 ° C, preferably 0 ° C to 100 ° C.

A typical reaction formula is shown below.

[Chemical 5] Further, the fluorene compound of the present invention can be used not only as an electrophotographic photoreceptor but also as an electronic device such as a solar cell and an organic EL element in the electronics field.

Next, the construction of the electrophotographic photosensitive member of the present invention will be described with reference to the drawings. As the photoreceptor, 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 photoreceptor layer 4 having a laminated structure in which a layer (charge transport layer) 3 containing a charge transport material and optionally a binder resin as an upper layer is provided, and as shown in FIG. Of the above-mentioned photoreceptor layer 4 provided with a protective layer 5, and a photoreceptor having a single layer structure containing a charge generating substance, a charge transporting substance and optionally a binder resin on a support as shown in FIG. Examples thereof include those provided with the layer 6, but a protective layer may be provided on the upper layer of the photoreceptor layer 6 having the single-layer structure shown in FIG. 3, and an intermediate layer may be provided between the support and the photoreceptor layer. May be. As the charge generating substance used in the present invention, both an inorganic substance and an organic substance can be used as long as they absorb visible light and generate a free charge. 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, many Examples thereof include ring quinone dyes, bisbenzimidazole dyes, indanthrone dyes, squarylium dyes, anthraquinone dyes, and phthalocyanine dyes. Examples of the binder resin that can be used in the photoreceptor 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, alkyd resin, Polycarbonate resin,
Addition polymerization type resins such as silicone resins and melamine resins, polyaddition type resins, polycondensation type resins, and copolymer resins containing two or more of repeating units of these resins, for example, vinyl chloride-vinyl acetate copolymer , Vinyl chloride-vinyl acetate-
In addition to an insulating resin such as a maleic anhydride copolymer resin, a polymer organic semiconductor such as poly-N-vinylcarbazole may be used. Next, as a conductive support for supporting the photosensitive layer, a metal plate such as aluminum and nickel, a metal drum or a metal foil, a plastic film on which aluminum, tin oxide, indium oxide, or the like 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 transport layer,
That is, in the case of FIG. 1 and FIG. 2 described above, the charge transport material of the present invention is provided by a method in which a suitable solvent is dissolved or dispersed alone or together with a suitable binder resin, and the resultant is 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. In this charge transport layer, the ratio of the charge transport material contained in the binder resin is 20 to 200 parts by weight with respect to 100 parts by weight of the binder resin. At this time, the thickness of the charge transport layer is preferably 5 to 50 μm, particularly preferably 5
˜30 μm. The charge generation layer may be 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 the same as the charge transport layer. Can be formed. When the charge generation layer is formed by dispersing the charge generation material, the charge generation material has a thickness of 2 μm.
Hereafter, it is preferable to use a powdery material having an average particle diameter of 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. Toner filming phenomenon tends to occur due to particles adhering. However, if the above particle size is too small, it tends to agglomerate rather, the resistance of the layer increases, the crystal defects increase and the sensitivity and repeatability deteriorate, or there is a limit on miniaturization,
The lower limit of the average particle size is preferably 0.01 μm. The charge generation layer can be provided by the following method. That is, the charge generating substance is a method in which fine particles are formed in a dispersion medium by a ball mill, a homomixer, etc., and a dispersion liquid obtained by mixing and dispersing a binder resin and applying the dispersion liquid is applied. 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 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. Next, when the photoreceptor of the present invention is formed in a single layer structure, that is, in 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. Is 20-2
00 parts by weight, and the charge transport 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 binder resin described above, 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 vapor-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-mentioned resin as it is or to disperse a low resistance substance such as tin oxide or indium oxide. Further, an organic plasma-polymerized film can also be used, and the organic plasma-polymerized film may optionally contain oxygen, nitrogen, halogen, and a group III or group V atom of the periodic table.

[0008]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited thereto.

Synthesis Example 1 Compound No. Synthesis of 1 [2,4,7-trinitro-9-fluorenidene (2-methylphenylacetonitrile)]. Commercially available 2,4,7-trinitro-9-fluorenone 6.3
1 g and commercially available o-xylyl cyanide (5.25 g) were stirred in 200 ml of dichloromethane, ice-cooled, and the solution temperature was lowered. The reaction was allowed to stir for 4 hours. Pour the reaction mixture onto ice and add chloroform 5
00 ml and 500 ml of water were added and well stirred, and the separated chloroform layer was washed with water until it became neutral. The chloroform layer was dried over anhydrous magnesium sulfate, the chloroform was distilled off, and then the residue was subjected to silica gel column chromatography using chloroform as a developing solvent, and the obtained crude target product was recrystallized from butyl alcohol. 1.15 g of pure product was obtained. Melting point 211-
212 ° C. Fig. 4 shows the infrared absorption spectrum of this product.
Shown in.

Synthesis Examples 2 to 16 Synthesized using various fluorenone compounds represented by the general formula (3) and various acetonitrile derivatives represented by the general formula (4) or malonic acid derivatives (5). Example 1
Pure product was obtained in the same manner as. Table 22 shows the melting points and the results of elemental analysis of the compounds obtained as described above.

Example 1 5 parts of bisazo dye represented by the following chemical formula (A), 2.5 parts of butyral resin (Denka Vitiral resin # 3000-2: manufactured by Denki Kagaku Kogyo) and 92.5 of tetrahydrofuran.
Parts were dispersed by a ball mill for 12 hours, and then tetrahydrofuran was added so as to have a dispersion liquid concentration of 2% by weight and redispersed to prepare a coating liquid. The prepared dispersion liquid was cast and coated on a 100 μm-thick polyester film on which aluminum was vapor-deposited by a doctor blade to form a charge generation layer having a film thickness after drying of 1.0 μm.

[Chemical 6] On the charge generation layer thus obtained, 6 parts of the exemplified compound (Compound No. 1), 10 parts of a polycarbonate resin (K-1300: manufactured by Teijin Chemicals), methylphenyl-silicon (KF50 100CPS: manufactured by Shin-Etsu Chemical). )
A coating solution having a composition of 0.002 parts and tetrahydrofuran (94 parts) was prepared and cast-coated with a doctor blade,
A charge-transporting layer having a thickness of 20.0 μm after drying was formed to prepare a laminated electrophotographic photoreceptor (photoreceptor No. 1) composed of an aluminum electrode / charge-generating layer / charge-transporting layer.

Examples 2 to 9 Instead of the exemplified compound (Compound No. 1) of Example 1, compound No. 2, 4, 7, 8, 14, 15
In the same manner as in Example 1 except that Nos. 3, 60, and 175 were used, the photoconductor No. 2-9 were produced.

Example 10 A charge was obtained in the same manner as in Example 1 except that 6 parts of a trisazo dye represented by the following chemical formula (B) was used in place of 5 parts of the bisazo dye represented by the chemical formula (A). A generator layer was prepared.

[Chemical 7] On the charge generation layer thus obtained, 6 parts of the exemplified compound (Compound No. 1), a polycarbonate resin (K-
1300: Teijin Chemicals) 10 parts, methylphenyl-silicon (KF50 100CPS: Shin-Etsu Chemical) 0.00
A coating solution consisting of 2 parts and 94 parts of tetrahydrofuran was prepared, and the film thickness after drying was 20.0 in the same manner as in Example 1.
A charge transporting layer having a thickness of μm was formed, and a laminated electrophotographic photoreceptor (photoreceptor No. 10) composed of an aluminum electrode / charge generating layer / charge transporting layer was produced.

Examples 11 to 18 Instead of the exemplified compound of Example 3 (Compound No. 1),
Compound No. in the exemplified compounds. 2, 4, 7, 8, 14, 1
In the same manner as in Example 3, except that Nos. 53, 60, and 175 were used, the photoconductor No. 11-18 were produced. The characteristics of the electrophotographic photosensitive member obtained as described above were evaluated as follows using an electrostatic copying paper test apparatus (Kawaguchi Denki Seisakusho: SP-428). After applying +6 KV corona charge and positively charging, leave it in the dark for 20 seconds, measure the surface potential V ₀ at that time, and then irradiate it with a tungsten lamp so that the surface illuminance becomes 40 lux. , The exposure amount required for V _{0 to} be halved at that time is E _1/2
(1 ux · sec) was measured. The results are shown in Tables 25 and 26.

[0015]

[Table 1]

[0016]

[Table 2]

[0017]

[Table 3]

[0018]

[Table 4]

[0019]

[Table 5]

[0020]

[Table 6]

[0021]

[Table 7]

[0022]

[Table 8]

[0023]

[Table 9]

[0024]

[Table 10]

[0025]

[Table 11]

[0026]

[Table 12]

[0027]

[Table 13]

[0028]

[Table 14]

[0029]

[Table 15]

[0030]

[Table 16]

[0031]

[Table 17]

[0032]

[Table 18]

[0033]

[Table 19] (Below margin)

[0034]

[Table 20]

[0035]

[Table 21]

[0036]

[Table 22]

[0037]

[Table 23]

[0038]

[Table 24]

[0039]

[Table 25]

[0040]

[Table 26]

[0041]

The fluorene compound used as the charge transporting material according to the present invention can be produced by a relatively simple and efficient method and has excellent solubility or dispersibility in the binder resin. Further, the fluorene compound functions as a charge transporting substance having an excellent ability to accept and transport the charge generated by the charge generating substance, and when an electrophotographic photoreceptor containing this fluorene compound is prepared as the charge transporting substance. , With high dark decay rate and high sensitivity.

[Brief description of drawings]

FIG. 1 is a cross-sectional view schematically showing a configuration of an example of a photoconductor of the present invention.

FIG. 2 is a sectional view schematically showing the configuration of another example of the photoconductor of the present invention.

FIG. 3 is a sectional view schematically showing the configuration of still another example of the photoconductor of the present invention.

FIG. 4 is an infrared absorption spectrum diagram of the compound obtained in Synthesis Example 1.

[Explanation of symbols]

1 Support 2 Charge Generation Layer 3 Charge Transport Layer 4 Photosensitive Layer (Layered Structure of Charge Generation Layer 2 and Charge Transport Layer 3) 5 Protective Layer 6 Photosensitive Layer (Single Layer Structure)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ikuko Yamada 1-3-6 Nakamagome, Ota-ku, Tokyo In stock company Ricoh Co., Ltd. (72) Emi Kawahara 1-3-6 Nakamagome, Ota-ku, Tokyo Shares In Ricoh Company (72) Inventor Akio Kojima 1-3-6 Nakamagome, Ota-ku, Tokyo

Claims (3)

[Claims] 1. A fluorene compound represented by the following general formula (1). [Chemical 1] (In the formula, R ₁ represents a substituted or unsubstituted aromatic group or heterocyclic group, or an alkoxycarbonyl group.
x and y represent integers of 0, 1, 2, 3 or 4. However, 1 ≦ x + y ≦ 4. ) 2. A fluorene compound represented by the following general formula (2). [Chemical 2] (In the formula, R ₂ represents an alkyl group. However, R ₂ can also be bonded to each other to form a ring. X and y are 0,
Represents an integer of 1, 2, 3 or 4. However, 1 ≦ x +
y ≦ 4. ) 3. An electrophotographic photoreceptor comprising a charge-generating substance and a charge-transporting substance on a conductive support, containing a fluorene compound represented by the above formula (1) or (2) as the charge-transporting substance. An electrophotographic photoconductor characterized by: