JPH04224572A - Tetraphenylfuran derivative and electrophotographic sensitive body containing the same derivative - Google Patents

Abstract

PURPOSE:To obtain a new tetraphenylfuran derivative useful as an electron transfer compound and for an electrophotographic photoreceptor having high sensitivity and excellent characteristics such as high durability. CONSTITUTION:A tetraphenylfuran derivative shown by formula I (R1 and R2 are alkyl, aralkyl or aryl which may be substituted or R1 and R2 together with adjoining nitrogen atom may form ring, k+p+m+n is <=1 to <=4 and each is 0 or 1) such as a compound shown by the formula wherein k=0, p=m=n=0 and R1 and R2 are phenyl. The compound shown by formula I is obtained by reacting a compound shown by formula II with p-toluenesulfonic acid alkyl ester. The new tetraphenylfuran derivative shown by formula I is added as an electron transfer substance to a sensitized layer on an electrically conductive substrate.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel tetraphenylfuran derivative and an electrophotographic photoreceptor containing the same. More specifically, the present invention relates to an electrophotographic photoreceptor containing a novel tetraphenylfuran derivative as a charge transporting substance in a photosensitive layer on a conductive support.

0002

2. Description of the Related Art Conventionally, inorganic photosensitive materials such as selenium, cadmium sulfide, and zinc oxide have been widely used as photosensitive materials for electrophotographic photoreceptors. However, photoreceptors using these photosensitive materials do not fully satisfy the performance requirements for electrophotographic photoreceptors, such as sensitivity, photostability, moisture resistance, and durability. For example, a photoreceptor using a selenium-based material has excellent sensitivity, but the characteristics of the photoreceptor tend to deteriorate due to crystallization due to heat or adhesion of dirt. Furthermore, since it is manufactured by vacuum deposition, it is expensive, and it also has many drawbacks, such as being difficult to process into a belt shape because it is not flexible. Photoreceptors using cadmium sulfide-based materials have problems in moisture resistance and durability, and photoreceptors using zinc oxide have problems in durability.

In order to overcome the drawbacks of photoreceptors using inorganic photosensitive materials, various photoreceptors using organic photosensitive materials have been studied.

In recent years, among photoreceptors developed to improve the above-mentioned drawbacks, a functionally separated photoreceptor in which charge generation function and charge transport function are shared by separate substances has been attracting attention. In this function-separated type photoreceptor, materials having respective functions can be selected from a wide range of materials and combined, making it possible to produce a highly sensitive and highly durable photoreceptor.

[0005]Characteristics required of the charge transport material contained in an electrophotographic photoreceptor include (1) a sufficiently high ability to accept the charge generated by the charge generation material, and (2) a rapid transfer of the received charge. to transport, (
3) Sufficient charge transport should be carried out even in low electric fields, and no charge should remain.

Furthermore, as a photoreceptor, it is required to be stable against light, heat, etc. received during the repeated steps of charging, exposure, development and transfer during copying, and to be durable enough to produce copied images with good reproducibility that are faithful to the original image. be done.

Various compounds have been proposed as charge transport materials. For example, poly-N-vinylcarbazole has long been known as a photoconductive material, and photoreceptors using it as a charge transport material have been put into practical use, but it itself lacks flexibility, is brittle, and is prone to cracking. Since it easily occurs, it has poor durability against repeated use. Also,
When it is used in combination with a binder to improve flexibility, it has the disadvantage of poor electrophotographic properties.

On the other hand, since low molecular weight compounds generally do not have film properties, they are usually mixed with a binder in any desired composition to form a photosensitive layer. A large number of charge transport materials made of low molecular weight compounds have been proposed so far. For example, thiophene-based compounds have been studied as charge transport materials, and include JP-A-63-158560 and JP-A-1-94349.
It is stated in the official gazette such as No. However, the sensitivity has not yet reached a sufficiently good value.

Although many other charge transport materials have been proposed, the current situation is that none of them satisfies the performance required for electrophotographic photoreceptors in practice, and the development of even better photoreceptors is desired. was.

0010

SUMMARY OF THE INVENTION An object of the present invention is to provide novel compounds useful as charge transport materials. Another object of the present invention is to provide an electrophotographic photoreceptor having sufficient sensitivity and excellent durability.

[0011]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present inventors have made extensive studies and found that tetraphenylfuran derivatives represented by a specific structural formula are useful as charge transport compounds, and have high sensitivity and high The inventors have discovered that it is possible to provide an electrophotographic photoreceptor having excellent properties such as durability, and have completed the tetraphenylfuran derivative and electrophotographic photoreceptor of the present invention. That is,

The tetraphenylfuran derivative of the present invention is
It is characterized by being represented by the general formula (I) (Chemical formula 1). Further, the electrophotographic photoreceptor of the present invention is characterized in that the photosensitive layer on the conductive support contains a tetraphenylfuran derivative represented by the general formula (I) (Chemical formula 1).

In the general formula (I), R1 and R2 are methyl group, ethyl group, isopropyl group, butyl group, isobutyl group, pentyl group, hexyl group,
Examples include alkyl groups such as heptyl group and octyl group, aralkyl groups such as benzyl group and phenethyl group, and aryl groups such as phenyl group and naphthyl group.

Further, these groups may have a substituent, and when R1 or R2 is an aryl group, the substituent may be a halogen atom, an alkyl group such as a methyl group, an ethyl group, a butyl group, or an octyl group. , alkoxy groups such as methoxy group, ethoxy group, butoxy group, carbomethoxy group,
Examples include carboxylic acid ester groups such as carboethoxy groups, aralkyl groups such as benzyl groups and phenethyl groups, and aryl groups such as phenyl groups and naphthyl groups, but are not limited to these. Examples of the group in which R1 and R2 combine to form a ring together with a nitrogen atom include a pyrrolidino group and a piperidino group. These examples of R1
and R2, R1 and R2 are preferably aryl groups in terms of high sensitivity and solubility in organic solvents.

The tetraphenylfuran derivative represented by the general formula (I) of the present invention can be synthesized by the following method. For example (1) General formula (II)

[Formula 2] (where k, p, m, and n satisfy 4≧k+p+m+n≧1 and are each integers of 0 or 1), p-toluenesulfonic acid alkyl ester, dialkyl Sulfuric esters, alcohols, alkyl halides, aryl halides, etc. are reacted.

(2) General formula (III)

[Image Omitted] A compound represented by the general formula (IV )

[C4
] (Here, R1 and R2 are the same as in general formula (I).) An amine compound represented by the formula (I) is reacted. It is easily synthesized by methods such as In addition, the halogen atom represented by x in the compound represented by the general formula (III) is more preferably an iodine atom.

The tetraphenylfuran derivatives of the present invention are more specifically shown in Tables 1, 2 and 3, but are not limited thereto.

[0018]

[Table 1]

[0019]

[Table 2]

[0020]

[Table 3]

The electrophotographic photoreceptor of the present invention has the general formula (I
) It consists of a photosensitive layer containing a tetraphenylfuran derivative represented by the following formula and a conductive support. This photosensitive layer consists of a charge transporting compound and a charge generating substance, and the tetraphenylfuran derivative acts as the charge transporting compound. The photosensitive layer may be a mixture of a charge-generating substance and a charge-transporting compound, or it may be composed of a charge-transporting layer and a charge-generating layer. A photosensitive layer is formed by processing.

The charge transport layer of the photoreceptor of the present invention may contain various additives. for example,
Plasticizers such as diphenyl, m-terphenyl, and dibutyl phthalate; surface lubricants such as silicone oil, grafted silicone polymers, and various fluorocarbons;
Examples include potential stabilizers such as dicyanovinyl compounds and carbazole derivatives, and antioxidants such as β-carotene, Ni complexes, and 1,4-diazabicyclo[2,2,2]octane.

The charge generation layer in the photoreceptor of the present invention is made of an inorganic charge generation substance such as selenium, selenium-tellurium, amorphous silicone, pyrylium dye, thiapyrylium dye, azulenium dye, thiacyanine dye,
Cationic dyes such as quinocyanine dyes, squbarium salt dyes, phthalocyanine pigments, anthoanthrone pigments, polycyclic quinone pigments such as dibenzpyrenequinone pigments, pyranthrone pigments, indigo pigments, quinacridone pigments, azo pigments, etc. Materials selected from organic charge-generating substances can be used alone or in combination as a vapor deposited layer or a coating layer.

Among the charge-generating substances mentioned above, there are a wide variety of azo pigments in particular, and typical structural examples of particularly effective azo pigments will be described below. The general formula of an azo pigment is shown below, with the central skeleton being A and the coupler portion being Cp, where n is 1 or 2. Specific examples are given below.

A specific example of A-(-N=N-Cp)nA is:

[C5]

[C6]

[C7]

[0026] Also, as a specific example of Cp,

[Chemical formula 8]

[Chemical formula 9] etc. These central skeleton A and coupler C
P forms a pigment which becomes a charge generating substance by an appropriate combination.

The charge-generating layer can be formed by dispersing the above-mentioned charge-generating substance in a suitable binder and coating it on a support, or by forming a vapor-deposited film using a vacuum vapor deposition device. It can be formed by The binder can be selected from a wide range of insulating resins and organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene and polyvinylpyrene. Preferably polyvinyl butyral, polyarylate (polycondensate of bisphenol A and phthalic acid, etc.), polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide, polyamide,
Examples include polyvinylpyridine, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol, and polyvinylpyrrolidone. The resin contained in the charge generation layer is suitably 80% by weight or less, preferably 40% by weight or less.

Organic solvents used during coating include alcohols such as methanol, ethanol, and isopropanol, ketones such as acetone, methyl ethyl ketone, and cyclohexanone, N,N-dimethylformamide, and N,N-dimethylformamide.
, amides such as N-dimethylacetamide, sulfoxides such as dimethyl sulfoxide, ethers such as tetrahydrofuran, dioxane, ethylene glycol monomethyl ether, esters such as methyl acetate, ethyl acetate, chloroform, methylene chloride, dichloroethylene, Aliphatic halogenated hydrocarbons such as carbon chloride and trichloroethylene, or aromatic compounds such as benzene, toluene, xylene, monochlorobenzene and dichlorobenzene, etc. can be used.

Coating can be carried out using coating methods such as dip coating, spray coating, spinner coating, bead coating, Meyer bar coating, blade coating, roller coating, and curtain coating. . For drying, it is preferable to dry to the touch at room temperature and then heat dry. Heat drying is generally 30~
It is preferable to carry out the heating at a temperature of 200° C. for 5 minutes to 2 hours, either stationary or with ventilation.

The charge generation layer contains as much of the organic photoconductive polymer as possible in order to obtain sufficient absorbance and to inject carriers into the charge transport layer within the lifetime of the generated charge carriers. Thin film layer, e.g. 5 μm or less,
Preferably, it is a thin film layer having a thickness of 0.01 to 1 μm.

A photosensitive layer having such a laminated structure of a charge generation layer and a charge transport layer is provided on a support having a conductive layer. Examples of the support having a conductive layer include those whose support itself is conductive, such as aluminum, aluminum alloy, copper, zinc, stainless steel, panadium, molybdenum, chromium, titanium, nickel, indium, tin oxide, and indium oxide. Plastics (e.g., polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic resin, polyethylene fluoride, etc.), conductive particles (e.g., aluminum powder, titanium oxide, (tin, zinc oxide, carbon black, silver particles, etc.) together with a suitable binder on a plastic or conductive support, a support in which conductive particles are impregnated in plastic or paper, or a conductive polymer. It is possible to use plastics that have

A subbing layer having barrier and adhesive functions may also be provided between the conductive support and the photosensitive layer. The subbing layer is made of casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide (
Nylon 6, nylon 66, nylon 610, copolymerized nylon, alkoxymethylated nylon, etc.), polyurethane, gelatin, aluminum oxide, etc. The thickness of the undercoat layer is 0.1 to 5 μm, preferably 0.1 to 5 μm.
A suitable thickness is 5 to 3 μm.

When using a photoreceptor in which a conductive support, a charge generation layer, and a charge transport layer are laminated in this order, the charge transport compound in the present invention, that is, the tetraphenylfuran derivative represented by the general formula (I) is used to transport holes. Therefore, it is necessary to negatively charge the surface of the charge transport layer, and when exposed to light after charging, holes generated in the charge generation layer are injected into the charge transport layer in the exposed area, and then reach the surface and neutralize the negative charge. The surface potential is attenuated, and an electrostatic contrast is generated between the exposed area and the unexposed area. During development, it is necessary to use positively charged toner.

In another specific example of the photoreceptor of the present invention, the azo pigment described above or the azo pigments described in US Pat. No. 3,554,745, US Pat. No. 3,567,438, US Pat.
Pigments and dyes having photoconductivity such as pyrylium dyes, thiapyrylium dyes, selenapyrylium dyes, benzopyrylium dyes, benzothiapyryllium dyes, naphtopyrylium dyes, and naphthothiapyrylium dyes disclosed in 500 specification etc. It can also be used as a sensitizer.

[0035] In another specific example, US Pat.
A eutectic complex of a pyrylium dye and an electrically insulating polymer having an alkylidene diarylene moiety, such as disclosed in US Pat. No. 84,502, can also be used as a sensitizer. This eutectic complex is, for example, 4-[4-bis(2-chloroethyl)
aminophenyl]-2,6-diphenylthiapyrylium perchlorate and poly(4,4'-isopropylidene diphenylene carbonate) in a halogenated hydrocarbon solvent such as dichloromethane, chloroform, carbon tetrachloride,
1,1-dichloroethane, 1,2-dichloroethane, 1
, 1,2-trichloroethane, chlorobenzene, bromobenzene, 1,2-dichlorobenzene, etc., and then mixed with a non-polar solvent such as hexane, octane, decane, 2,2,4-trimethylbenzene, ligroin, etc. It can be obtained as a particulate eutectic complex by adding, etc.

The electrophotographic photoreceptor in this specific example contains styrene-butadiene copolymer, silicone resin,
Contains vinyl resin, vinylidene chloride-acrylonitrile copolymer, styrene-acrylonitrile copolymer, vinyl acetate-vinyl chloride copolymer, polyvinyl butyral, polymethyl methacrylate, poly-N-butyl methacrylate, polyesters, cellulose esters, etc. as a binder. I can do it.

The electrophotographic photoreceptor of the present invention can be used not only in electrophotographic copying machines, but also in a wide range of electrophotographic applications such as laser beam printers, CRT printers, and electrophotographic plate making systems.

[0038]

[Example] The present invention will be specifically explained below with reference to production examples of tetraphenylfuran derivatives represented by general formula (I) and examples of electrophotographic photoreceptors. It is not limited.

(Production Example 1) (Synthesis of Exemplified Compound No. 10) 2,5-bis(4-iodophenyl)-3,4-
12 g of diphenylfuran, 10 g of N-phenyl-2-naphthylamine, 10 g of anhydrous potassium carbonate, and 8 g of electrolytic copper.
g was dispersed in 50 ml of sulfolane and stirred at 190°C for 40 hours. After cooling, the mixture was poured into 100 ml of water, and the resulting precipitate was filtered out, washed with water and methanol in that order, and then dried. The obtained crude product was extracted with toluene, and the extract was purified by silica gel column chromatography using a toluene:hexane (1:1) mixed solvent as a developing solvent. Recrystallization was performed using a mixed solvent of toluene and acetonitrile to obtain 15 g of pale yellow crystals. Based on the following elemental analysis values, Exemplary Compound No. It was confirmed that it was 10. Elemental analysis value (%) C
52H38N2 O
C H
N Theoretical value 88.35 5.42 3.
96 Analysis value 88
．． 25 5.37 4.04

[0040]
(Production Example 2) (Synthesis of Exemplified Compound No. 1) 2-(4
-aminophenyl)-3,4,5-triphenylfuran (4.1 g) was dissolved in 200 ml of o-dichlorobenzene (hereinafter abbreviated as ODCB), and 5.0 g of iodobenzene,
11 g of anhydrous potassium carbonate, 2.6 g of electrolytic copper, and 18
Add 0.6 g of -crown-6-ether and heat to reflux under a nitrogen atmosphere with vigorous stirring for 48 hours. After removing the solid content by filtration, ODCB was distilled off from the reaction solution by steam distillation. The obtained residue was purified by silica gel column chromatography using toluene as a developing solvent, and recrystallized from a toluene-hexane (1:1) mixed solvent to obtain 2.5 g of pale yellow crystals. Based on the following elemental analysis values, Exemplary Compound No. -1. Elemental analysis value (%) C
40H29NO
C H
N Theoretical value 89.02 5.42 2.60
Analysis value 89.1
3 5.37 2.70

(Production Example 3) (Synthesis of Exemplified Compound No. 6) 2-(4-aminophenyl)-3,4,5-triphenylfuran 4.
1 g and 8.2 g of p-iodoanisole, 3 g of yellow crystals were obtained in the same manner as in Production Example 2. From the elemental analysis values below, Exemplary Compound No. It was confirmed that it was 6. Elemental analysis value (%) C
42H33NO3
C H
N Theoretical value 84.11 5.55 2.
34 Analysis value 84
．． 00 5.57 2.42

[0042]
(Example 1) A coating solution was prepared by dispersing 5 g of a disazo pigment represented by the following structural formula and 2 g of a butyral resin (degree of butyralization: 63 mol %) in 100 ml of cyclohexanone in a sand mill for 24 hours.

embedded image This coating solution was applied onto an aluminum sheet with a wire bar to a dry film thickness of 0.2 μm to form a charge generation layer.

Next, the tetraphenylfuran derivative of the present invention (compound No. 10 in Table 1) was used as a charge transport compound.
10g of polycarbonate (average molecular weight 20,000) and 10g of polycarbonate (average molecular weight 20,000)
Dissolve g in 70 g of chloroform and apply this solution onto the charge generation layer using a wire bar until the dry film thickness is 20 μm.
A charge transport layer was formed to produce an electrophotographic photoreceptor. The electrophotographic photoreceptor thus prepared was statically charged with a corona at -6 KV using an electrostatic copying paper tester Model-EPA-8100 manufactured by Kawaguchi Electric Co., Ltd., and after being held in a dark place for 1 second, the illuminance was It was exposed to light at 5 lux and its charging characteristics were investigated.

As for charging characteristics, the surface potential (Vo) and the exposure amount (E1/2) required to attenuate the potential (V1) to 1/2 when dark decayed for 1 second were measured. Furthermore, in order to measure the fluctuations in dark area potential and bright area potential during repeated use, the electrophotographic photoreceptor prepared in this example was used in the photosensitive drum cylinder of a PPC copier NP-3525 manufactured by Canon Inc. 5,000 copies were made using the same machine, and changes in dark area potential (VD) and light area potential (VL) were measured at the initial stage and after 5,000 copies were made. Note that the initial VD and VL are -700V and -2, respectively.
The voltage was set to 00V.

(Comparative Example 1) In place of the charge transport compound used in Example 1, a compound having the following structure (Japanese Unexamined Patent Publication No. 63-1585
60 Exemplary Compound No. 14)

Using [Chemical 11], an electrophotographic photoreceptor similar to that in Example 1 was prepared,
Electrophotographic properties were similarly measured. The results are shown in Table 4.

(Example 2) Tetraphenylfuran derivative, which is the charge transport compound used in Example 1 (No. 1 in Table 1)
In place of compound No. 1) in Table 2, Electrophotographic photoreceptors were prepared in the same manner as in Example 1 using the 10 compounds, and the electrophotographic properties of each were measured. The results are shown in Table 4.

(Comparative Example 2) In place of the charge transport compound of Example 2, a compound having the following structure (Exemplified Compound No. 9 of JP-A-1-94349) was used.

An electrophotographic photoreceptor was prepared in the same manner as in Example 1 using [Chemical Formula 12],
The electrophotographic properties of each were measured. The results are shown in Table 4.

[0048]

[Table 4] As is clear from the results in Table 4 above, it can be seen that when the tetraphenylfuran derivative of the present invention is used as a charge transport compound, it has good sensitivity and less potential fluctuation during durability. .

(Examples 3 to 16) In each of these Examples, No. 1 in Table 1 used in Example 1 was used. In place of compound 1, (3), (4) shown in Table 1, Table 2, and Table 3,
(5), (6), (7), (8), (9), (10),
The exemplified compounds (11), (12), (22), (23), (28) and (29) were used, and the pigment of the following structural formula was used as the charge generating substance, and the other conditions were as in Example 1. An electrophotographic photoreceptor was produced in the same manner as described above.

embedded image The electrophotographic properties of each photoreceptor were measured in the same manner as in Example 1. The results are shown in Table 5.

[0050]

[Table 5]

(Example 17) An ammonia aqueous solution of casein (11.2 g of casein,
28% ammonia water (1 g, water 222 ml) was applied by a blade coating method to form a subbing layer with a dry film thickness of 1 μm. Next, 10 g of a charge generating substance represented by the following structural formula,

[
embedded image 5 g of butyral resin (degree of butyralization: 63 mol %) and 200 g of cyclohexanone were dispersed for 48 hours using a ball mill disperser. This dispersion was applied onto the previously formed undercoat layer using a blade coating method, and the dry film thickness was 0.
．． A charge generation layer of 15 μm was formed.

Next, No. 1 in Table 1. 10g of compound 2
, 10 of polymethyl methacrylate (average molecular weight 50,000)
g was dissolved in 70 g of chlorobenzene and applied onto the previously formed charge generation layer by a blade coating method to form a charge transport layer with a dry thickness of 19 μm. Corona discharge of -5 KV was applied to the electrophotographic photoreceptor thus prepared. The surface potential at this time was measured (initial potential Vo). Furthermore, the surface potential of this photoreceptor was measured after it was left in a dark place for 1 second. The sensitivity is 1/2 the potential V1 after dark decay.
Exposure amount required to attenuate (E1/2, μJ/cm2
) was evaluated by measuring. At this time, the light source was a gallium/aluminum/arsenic ternary semiconductor laser (
Output: 5 mw, oscillation wavelength 780 nm) was used. Show the results.

(Example 18) 3 g of 4-(4-dimethylaminophenyl)-2,6-diphenylthiapyrylium perchlorate and No. 2 of Table 2. 5 g of compound No. 18 was added to polyester (Polyester Adhesive 49000, manufactured by DuPont) in toluene (50 parts by weight) and dioxane (
50 parts by weight) in 100 ml of the solution and milled with a ball mill for 6
Spread out time. This dispersion was applied onto an aluminum sheet using a wire bar so that the film thickness after drying was 15 μm.

The electrophotographic properties of the electrophotographic photoreceptor thus produced were measured in the same manner as in Example 1. The results are shown below.

(Example 19) A 5% methanol solution of soluble nylon (6-66-610-12 quaternary nylon copolymer) was coated on an aluminum plate, and a subbing layer with a dry film thickness of 0.5 μm was formed. Formed. Next, 5 g of a pigment having the following structural formula was dispersed in 95 ml of tetrahydrofuran using a sand mill disperser for 20 hours.

embedded image Next, No. in Table 1. 5 g of compound 2 and 10 g of bisphenol Z type polycarbonate (viscosity average molecular weight 30,000)
g dissolved in 30 ml of chlorobenzene was added to the previously prepared dispersion, and the mixture was further dispersed in a sand mill for 2 hours. This dispersion was applied to the previously formed undercoat layer so that the film thickness after drying was 20.
It was coated with a wire bar to a thickness of μm and dried. The electrophotographic properties of the electrophotographic photoreceptor thus produced were measured in the same manner as in Example 1. The results are shown below.

[0056]

Effect of the Invention The electrophotographic photoreceptor of the present invention is characterized in that it contains a tetraphenylfuran derivative represented by the general formula (I) as a charge transport compound, and due to the action of this tetraphenylfuran derivative, it can be repeatedly charged. It has excellent durability and high sensitivity, with small fluctuations in bright area potential and dark area potential during continuous image formation by exposure, and performance does not deteriorate with repeated use.

Claims (2)

[Claims] Claim 1 General formula (I) (Formula 1) [Formula 1] (wherein, R1 and R2 are an optionally substituted alkyl group, aralkyl group or aryl group, and R1
and R2 may combine to form a ring together with the nitrogen atom. k, p, m, n satisfy 4≧k+p+m+n≧1,
Each is an integer of 0 or 1. ) Tetraphenylfuran derivative represented by [Claim 2] General formula (I) according to claim 1 (Claim 1
) An electrophotographic photoreceptor comprising a tetraphenylfuran derivative represented by: