JP2663162B2 - Electrophotographic photoreceptor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electrophotographic photosensitive member, and more particularly, to an electrophotographic photosensitive member provided with a photosensitive layer containing a carrier generating substance and a carrier transporting substance.

(Prior art)

Conventionally, selenium, zinc oxide,
Those having a photosensitive layer containing an inorganic photoconductor such as cadmium sulfide or silicon as a main component have been widely known.
However, these still have problems in characteristics, production and handling.

On the other hand, a photoconductor having a photosensitive layer containing an organic photoconductive compound as a main component is relatively easy to manufacture, inexpensive, easy to handle, and generally has a higher thermal conductivity than a selenium photoconductor. It has many advantages such as excellent stability, and as such an organic photoconductive compound, poly-N-vinyl carbazole is best known,
A photoreceptor having a photosensitive layer mainly composed of a charge transfer complex formed from this and a Lewis acid such as 2,4,7-trinitro-9-fluorenone has already been put to practical use.

On the other hand, a photoreceptor having a function-separated type photosensitive layer of a laminated type or a single layer type in which a carrier generating function and a carrier transporting function of a photoconductor are respectively assigned to different substances is known, for example, amorphous selenium thin film. A photoreceptor having a photosensitive layer composed of a carrier generating layer composed of a layer and a carrier transporting layer containing poly-N-vinylcarbazole as a main component has already been put to practical use.

However, poly-N-vinyl carbazole lacks flexibility, its film is hard and brittle, and it is easy to cause cracking and film peeling, and the photoreceptor using this has poor durability, and a plasticizer is added. If the disadvantage is improved, the residual potential is increased when the electrophotographic process is performed, and the residual potential is accumulated with repeated use, so that the fog gradually increases and the copied image is damaged.

In addition, since low-molecular organic photoconductive compounds generally do not have a film-forming ability, they are used in combination with an appropriate binder, and the physical properties or photosensitive characteristics of the film are controlled to some extent by selecting the type and composition ratio of the binder. Although it is preferable from the point of view, the types of organic photoconductive compounds having high compatibility with the binder are limited, and there are few binders that can be actually used for forming a photosensitive layer, particularly a photosensitive layer of an electrophotographic photosensitive member.

For example, 2,5-bis (p described in U.S. Pat. No. 3,189,447
-Diethylaminophenyl) -1,3,4-oxadiazole has low compatibility with binders commonly used as materials for the photosensitive layer of the electrophotographic photoreceptor, such as polyester and polycarbonate, and is necessary for improving electrophotographic properties. When the photosensitive layer is formed by mixing at a ratio of, the oxadiazole crystals are deposited at a temperature of 50 ° C. or higher, and there is a disadvantage that the electrophotographic properties such as charge holding power and sensitivity are reduced.

On the other hand, the diarylalkane derivative described in U.S. Pat. No. 3,820,989 has a small compatibility problem with respect to a binder, but has low stability to light, and is repeatedly charged and exposed. When the photosensitive layer is suitable for the photosensitive layer, the sensitivity of the photosensitive layer gradually decreases.

Also, U.S. Pat. No. 3,274,000 and JP-B-47-36428 describe different types of phenothiazine derivatives, but all have the disadvantages of low photosensitivity and low stability upon repeated use.

Further, the stilbene compounds described in JP-A-58-65440 and JP-A-58-190953 have relatively good charge holding power and sensitivity, but are not satisfactory in durability upon repeated use.

As described above, there is no carrier transporting substance that has practically satisfactory characteristics for producing an electrophotographic photoreceptor and sufficiently exhibits the performance of a carrier generating substance.

[Object of the invention]

An object of the present invention is to provide a photosensitive member having high sensitivity.

Another object of the present invention is to provide an electrophotographic photosensitive member having high sensitivity and low residual potential.

Another object of the present invention is to provide a photoreceptor for repetitive transfer electrophotography in which charging, exposure, development, and transfer steps are repeatedly performed. An object of the present invention is to provide an electrophotographic photosensitive member having excellent durability.

[Means for solving the problem]

As a result of intensive studies for the above purpose, it has been found that an electrophotographic photoreceptor containing at least one compound represented by the following general formula [I] has excellent utility.

General formula [I] In the formula, R ₁ and R ₂ are a hydrogen atom, an alkyl group, an aryl group,
Represents an aralkyl group or a heterocyclic group, and these groups may have a substituent. However, R ₁ and R ₂ are not simultaneously hydrogen atoms, and may form a ring together with the carbon atom to which R ₁ and R ₂ are bonded.

R ₃ , R ₄ and R ₅ represent a hydrogen atom, a halogen atom, an alkyl group or an alkoxy group.

Ar ₁ and Ar ₂ represent an alkyl group, an aryl group, or an aralkyl group, and these groups may have a substituent.

 n is an integer of 0 or 1.

In the embodiment of the present invention, the alkyl groups represented by R ₁ and R ₂ are groups such as methyl, ethyl, propyl and butyl, the aryl groups are groups such as phenyl and naphthyl, and the aralkyl groups are benzyl and phenethyl. And a heterocyclic group such as furyl, thienyl and quinolyl.

R ₃ , R ₄ , R ₅ alkyl groups include groups such as methyl, ethyl, propyl, and butyl; halogen atoms include atoms such as fluorine, chlorine, bromine, and iodine; and alkoxy groups include methoxy, ethoxy, propoxy, and butoxy. And so on.

Ar ₁ and Ar ₂ alkyl groups include methyl, ethyl, propyl, and butyl groups, and aryl groups include phenyl and
Examples of each group of naphthyl and the aralkyl group include groups such as benzyl and phenethyl.

Incidentally, R ₁ , R ₂ , Ar ₁ , Ar ₂ may have a substituent, an alkyl group such as methyl, ethyl, propyl, butyl, an alkoxy group such as methoxy, ethoxy, propoxy, fluorine, chlorine, Preferred are a halogen atom such as bromine and iodine, and a dialkylamino group such as dimethylamino and diethylamino.

Next, specific examples of the compound represented by the general formula [I] will be illustrated.

: Exemplified compounds: Synthesis Example (Exemplified Compound (1)) 2.1 g of diethyl benzylphosphonate and 4-formyl-
4.4 g of 4'-diphenylamino-triphenylamine was N,
It was dispersed and dissolved in 200 ml of N-dimethylformamide at room temperature in a nitrogen atmosphere. There potassium-t-butoxide 1.
Add 5g slowly and heat from room temperature to 80 ℃
For about 3 hours.

The reaction solution was poured into water 1 and extracted with chloroform 1,
The organic layer was washed with water and the solvent was removed, and then recrystallized from toluene-acetone to obtain 3.3 g of the desired product.

 The yield was 65.1%.

The parent ion peak (M ⁺ ) of the target substance was detected by FD-mass measurement (M ⁺ ) = 514 (C ₃₈ H ₃₀ N ₂ ). Conventionally, various types of electrophotographic photoreceptor structures have been known. The electrophotographic photoreceptor of the present invention can take any of these forms.

Normally, the configuration is as shown in FIGS. FIGS. 1 and 2 show a photosensitive structure comprising a laminate of a carrier generating layer 2 mainly containing a carrier generating substance and a carrier transporting layer 3 mainly containing a carrier transporting substance on a conductive support 1. Layer 4 is provided.

As shown in FIGS. 3 and 4, the photosensitive layer 4 may be provided via an intermediate layer 5 provided on a conductive support. Thus, when the photosensitive layer 4 has a two-layer structure, a photosensitive member having the best electrophotographic characteristics can be obtained. Alternatively, in the present invention, as shown in FIGS. 5 and 6, a photosensitive layer 4 formed by dispersing the carrier generating substance 7 in a layer 6 containing a carrier transporting substance as a main component is formed on the conductive support 1. It may be provided directly or via the intermediate layer 5. In the present invention, a protective layer 8 may be provided as an outermost layer after FIG.

The following are examples of the carrier generating substance used in the carrier generating layer of the photosensitive layer according to the present invention.

(1) Azo dyes such as monoazo dyes, disazo dyes and trisazo dyes (2) Perylene dyes such as perylene anhydride and perylene imide (3) Indigo dyes such as indigo and thioindigo (4) Anthraquinone and pyrene quinton And polycyclic quinones such as flavanthrones (5) quinocridone dyes (6) bisbenzimidazole dyes (7) indathrone dyes (8) squarylium dyes (9) cyanine dyes (10) azurenium dyes (11) Triphenylmethane dyes (12) Amorphous silicon (13) Phthalocyanine pigments such as metal phthalocyanines and metal-free furocyanines (14) Selenium, selenium-tellurium, selenium-arsenic (15) Cds, Cdse (16) pyrylium salts Dyes, thiapyrylium salt dyes, etc. There can also be used as a mixture of two or more.

Since the stilbene derivative represented by the general formula [I] has no coating forming ability by itself, a photosensitive layer is formed by combining various binders.

Any binder can be used here, but it is preferable to use a high molecular polymer which is hydrophobic, has a high dielectric constant, and forms an electrically insulating film. Examples of such a high-molecular polymer include the following, but are not limited thereto.

(P-1) Polycarbonate (P-2) Polyester (P-3) Methacrylic resin (P-4) Acrylic resin (P-5) Polyvinyl chloride (P-6) Polyvinylidene chloride (P-7) Polystyrene (P -8) Polyvinyl acetate (P-9) Styrene-butadiene copolymer (P-10) Vinylidene chloride-acrylonitrile copolymer (P-11) Vinyl chloride-vinyl acetate copolymer (P-12) Vinyl chloride-acetic acid Vinyl-maleic anhydride copolymer (P-13) Silicone resin (P-14) Silicone-alkyd resin (P-15) Phenol formaldehyde resin (P-16) Styrene-alkyd resin (P-17) Poly-N- Vinyl carbazole (P-18) Polyvinyl butyral (P-19) Polyvinyl formal These binder resins are used alone. Alternatively, they can be used as a mixture of two or more.

Examples of the solvent for forming the carrier generation layer and the transport layer according to the present invention include N, N-dimethylformamide, acetone, methyl ethyl ketone, cyclohexane, benzene, toluene, xylene, chloroform, 1,2-dichloroethane, and 1,2. -Dichloropropane, 1,1,2-trichloroethane, 1,1,1-trichloroethane, trichloroethylene, tetrachloroethane, dichloromethane, tetrahydrofuran, dioxane, methanol, ethanol, isopropanol, ethyl acetate, butyl acetate, dimethyl sulfoxide , Methyl cellosolve, etc., and can be used as a mixture.

When the photoreceptor of the present invention has a laminated structure, the weight ratio of binder: carrier generating substance: carrier transporting substance in the carrier generating layer is preferably from 0 to 100: 1 to 500: 0 to 500.

If the content of the carrier-generating substance is less than this, the photosensitivity is low, causing an increase in the residual potential.

Further, the amount of the carrier transporting material is preferably from 20 to 200 wt.%, More preferably from 30 to 150 wt. Per 100 wt.% (B) of the binder resin in the carrier transporting layer.

The thickness of the carrier generation layer formed as described above is preferably 0.01 to 10 μm, particularly preferably 0.1 to 5 μm.
μm.

The thickness of the carrier transporting layer formed is preferably 5 to 50 μm, particularly preferably 5 to 30 μm.

On the other hand, when the photoconductor of the present invention has a single-layer function-separated structure,
The weight ratio of binder: carrier generating substance: carrier transporting substance in the photosensitive layer is preferably from 0 to 100: 1 to 500: 1 to 500, and the thickness of the formed photosensitive layer is preferably from 5 to 50 μm, particularly preferably from 5 to 50 μm. 3030 μm.

As the conductive support used in the electrophotographic photoreceptor of the present invention, a metal plate including an alloy, a metal drum or a conductive polymer, a conductive compound such as indium oxide or an alloy including aluminum, palladium, gold, etc. Conductive paper by applying, depositing or laminating a thin metal layer,
Plastic films and the like. As the intermediate layer such as the adhesive layer or the barrier layer, in addition to the polymer used as the binder resin, an organic polymer such as polyvinyl alcohol, ethyl cellulose, carboxymethyl cellulose, or aluminum oxide is used.

Organic amines can be added to the photosensitive layer of the present invention for the purpose of improving the carrier generation function of the carrier generation substance, and it is particularly preferable to add a secondary amine.

Such secondary amines include, for example, dimethylamine,
Diethylamine, dipropylamine, diisopropylagine, dibutylamine, diisobutylamine, diamylamine, diisoamylamine, dihexylamine, diisohexylamine, dipentylamine, diisopentylamine, dioctylamine, diisooctylamine, dinonylamine, diisononylamine , Didecylamine,
Examples thereof include diisodecylamine, dimonodecylamine, diisomonodecylamine, didodecylamine, and diisododecylamine.

The amount of the organic amine to be added is preferably equal to or less than the equivalent of the carrier-generating substance, and more preferably 0.2 to 0.005 times.

Further, an antioxidant for preventing ozone deterioration can be added to the photosensitive layer of the present invention.

Representative specific examples of such antioxidants are shown below, but are not limited thereto.

Group (I): hindered phenols dibutylhydroxytoluene, 2,2'-methylenebis (6-t-butyl-4-methylphenol), 4,4'-
Butylidenebis (6-t-butyl-3-methylphenol), 4,4'-thiobis (6-t-butyl-3-methylphenol), 2,2'-butylidenebis (6-t-butyl-4-methylphenol) ), Α-tocopherol, β
-Tocopherol, 2,2,4-tolumethyl-6-hydroxy-7-tert-butylchroman, pentaerythyltetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2, 2'-thiodiethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 1,6-hexanediol bis [3- (3,5-tert-butyl-4-hydroxy) Phenyl)
Propionate], butylhydroxyanisole, dibutylhydroxyanisole, 1- [2-{(3,5-di-
Butyl-4-hydroxyphenyl) propionyloxydiethyl] -4- [3- (3,5-di-butyl-4-hydroxyphenyl) propionyloxy] -2,2,6,6-
Tetramethylpiperidyl and the like.

Group (II): paraphenylenediamines N-phenyl-N'-isopropyl-p-phenylenediamine, N, N'-di-sec-butyl-p-phenylenediamine, N-phenyl-N-sec-butyl-p -Phenylenediamine, N, N'-diisopropyl-p-phenylenediamine, N, N'-dimethyl-N, N'-dibutyl-p
-Phenylenediamine and the like.

Group (III): hydroquinones 2,5-t-octylhydroquinone, 2,6-didodecylhydroquinone, 2-dodecylhydroquinone, 2-dodecyl-5-chlorohydroquinone, 2-t-octyl-5-methylhydroquinone, -(2-octadecenyl) -5-methylhydroquinone and the like.

Group (IV): organic sulfur compounds such as dilauryl-3,3'-thiodipropionate, distearyl-3,3'-thiodipropionate, ditetradecyl-3,3'-thiodipropionate and the like.

Group (V): Organophosphorus compounds Triphenylphosphine, tri (nonylphenyl) phosphine, tri (dinonylphenyl) phosphine, tricresylphosphine, tri (2,4-dibutylphenoxy) phosphine and the like.

These compounds are known as antioxidants for rubbers, plastics, oils and the like, and commercially available products can be easily obtained.

These antioxidants may be added to any of the carrier generation layer, the carrier transport layer, and the protective layer, but are preferably added to the carrier transport layer. In this case, the amount of the antioxidant to be added is 0.1 to 100 w per 100 wt of the carrier transport material.
t, preferably 1 to 50 wt, particularly preferably 5 to 25 wt.

In the present invention, one or two or more kinds of electron accepting substances can be contained in the carrier generating layer for the purpose of improving sensitivity, reducing residual potential or reducing fatigue upon repeated use.

Electron accepting substances that can be used here include
For example, succinic anhydride, maleic anhydride, dibromomaleic anhydride, phthalic anhydride, tetrachlorophthalic anhydride,
Tetrabromophthalic anhydride, 3-nitrophthalic anhydride,
4-nitrophthalic anhydride, pyromellitic anhydride, melitic anhydride, tetracyanoethylene, tetracyamiquinodimethane, o-dinitrobezen, m-dinitrobenzene,
1,3,5-trinitrobenzene, paranitrobenzonitrile, piclinkloride, quinone chlorimide, chloranil, bulumanil, dichlorodicyanoparabenzoquinone, anthraquinone, dinitroanthraquinone, 2,7-
Dinitrofluorenone, 2,4,7-trinitrofluorenone, 2,4,5,7-tetranitrofluorenone, 9-fluorenylidene [dicyanomethylenemalonodinitrile], polynitro-9-fluorenylidene- [dicyanomethylenemalonodinitrile], Picric acid, o-nitrobenzoic acid, p-nitrobenzoic acid, 3,5-dinitrobenzoic acid, pentafluorobenzoic acid, 5-nitrosalicylic acid, 3,5-
Examples thereof include dinitrosalicylic acid, phthalic acid, melitic acid, and other compounds having a high electron affinity.

The amount of the electron-accepting substance to be added is as follows: carrier generating substance: electron-accepting substance = 100: 0.01 to 200, preferably 100:
0.1 to 100.

The electron accepting substance may be added to the carrier transport layer.
The amount of the electron accepting substance added to such a layer is carrier transporting substance: electron accepting substance = 100: 0.01 to 100, preferably 100: 0.1 to 50 by weight ratio.

In addition, the photoreceptor of the present invention may further contain, if necessary, an ultraviolet absorber or the like for the purpose of protecting the photosensitive layer, or may contain a dye for correcting color sensitivity.

The electrophotographic photoreceptor of the present invention is configured as described above, and as is clear from the examples described later, charging characteristics,
It has excellent sensitivity characteristics and image forming characteristics. In particular, it has little fatigue deterioration even when used repeatedly, and has excellent durability.

Further, the electrophotographic photoreceptor of the present invention is not limited to an electrophotographic copying machine, but also includes a laser, a cathode ray tube (CRT), and a light emitting diode (LE).
It can be widely used in application fields such as photoconductors of printers using D) as a light source.

〔Example〕

Hereinafter, the present invention will be described specifically with reference to Examples.
This does not limit the working life of the present invention.

Example 1 An intermediate having a thickness of 0.05 μm and comprising a vinyl chloride-vinyl acetate-maleic anhydride copolymer “ESREC MF-10” (manufactured by Sekisui Chemical Co., Ltd.) was placed on a conductive support obtained by evaporating aluminum on a polyester film. Layer, and dibromoanthranthrone “Monolite Red 2Y” (CINO.593
In a dispersion obtained by adding 1 g of ICI Co., Ltd.) to 30 ml of 1,2-dichloroethane and dispersing with a ball mill, 1.5 g of polycarbonate "PANLITE L-1250" (manufactured by Teijin Chemical Co., Ltd.) was dissolved and thoroughly mixed. The coating solution was applied so that the film thickness after drying was 2 μm, to form a carrier generation layer.

On top of this, 5 g of the exemplified compound (2) and polycarbonate “Z”
−200 ”(Mitsubishi Gas Chemical) with 10 g of tetrahydrofuran 80
The solution dissolved in ml was applied so that the film thickness after drying became 18 μm to form a carrier transport layer, thereby preparing a photoreceptor of the present invention.

The photoreceptor thus obtained was manufactured by Kawaguchi Electric Co., Ltd.
The following characteristics were evaluated using EPA-8100. Charge voltage -6
After charging 5 seconds KV, the illuminance at 5 seconds dark standing then the surface of the photosensitive member was irradiated with a halogen lamp light so as to 2Lux, the initial surface potential V _A, was determined half-life exposure E 1/2.

The residual potential V _R after exposure with an exposure amount of 30 lux sec was determined. Further, the same measurement was repeated 1000 times.

 The results were as shown in Table 1.

Examples 2 to 10 Photoconductors were prepared and measured in the same manner as in Example 1 except that the exemplified compounds shown in Table 2 below were used instead of the exemplified compound (2).

Comparative Example (1) A comparative photoconductor was prepared in the same manner as in Example 1, except that the following compound T-1 was used as a carrier transporting substance.

The comparative photoreceptor was measured in the same manner as in Example 1, and the results shown in Table 3 were obtained.

Example 11 2 g of the bisazo pigment having the above structure and 2 g of the polycarbonate resin “PANLITE L-1250” were mixed with 100 ml of 1,2-dichloroethane and dispersed with a sand grinder for 8 hours. This dispersion was applied onto a conductive support having aluminum evaporated on a polyester film so that the thickness after drying was 1 μm.

Using Exemplified Compound (2) as a carrier transporting substance,
A photoconductor was prepared in the same manner as in Example 1. The same measurement as in Example 1 was performed on this photoreceptor, and the results in Table 4 were obtained.

Examples 12 to 20 Photoconductors were prepared and measured in the same manner as in Example 11, except that the exemplified compounds shown in Table 5 below were used instead of the exemplified compound (2).

Comparative Example (2) A comparative photoconductor was prepared in the same manner as in Example 11, except that the following compound T-2 was used as a carrier transporting substance.

This photoreceptor was measured in the same manner as in Example 1, and the results in Table 6 were obtained.

Example 21 On a conductive support composed of polyethylene terephthalate having a thickness of 100 μm on which aluminum was deposited, a subbing layer having a thickness of about 0.2 μm composed of a polymer of p-hydroxystyrene “Marzen Resin M” (manufactured by Maruzen Oil Co., Ltd.) was formed. A layer was formed.

Next, the polycarbonate resin "Panlite L-1250"
0.5 g (manufactured by Teijin Chemicals Limited), 1 g of β-type copper phthalocyanine and
A dispersion obtained by mixing and dispersing 100 ml of 1,2-dichloroethane in a sand mill for 10 hours is applied on the undercoat layer by a wire bar coating method, and dried at 100 ° C. for 10 minutes to form a film having a thickness of about 0.2.
A μm carrier generation layer was formed.

Furthermore, 12 g of the exemplary compound (6) as a carrier transporting substance
A solution of 15 g of acrylic resin "Dianal BR-80" (manufactured by Mitsubishi Rayon Co., Ltd.) in 100 ml of 1,2-dichloroethane was applied on the carrier generating layer using a doctor blade, and the temperature was 90 ° C. for 1 hour. The carrier was dried to form a carrier transporting layer having a thickness of about 20 μm, thereby producing the photoreceptor of the present invention.

With respect to the photoreceptor of the present invention, the grid voltage was adjusted so that the charged potential became -600 V using a modified "U-Bix1550MR" (manufactured by Konica Corporation) equipped with a laser light source (output: 1 mW) having a wavelength of 780 ± 1 nm. And evaluated. Table 7 below shows the results of the evaluation of the in-machine potential and image defects of the photoconductor.

As is clear from the above results, it was found that the photoreceptor of the present invention had sufficient sensitivity to a semiconductor laser light source.

As is clear from the above Examples and Comparative Examples, the photoreceptor of the present invention is superior in sensitivity and durability as compared with the comparative photoreceptor.

[Brief description of the drawings]

1 to 6 are cross-sectional views of an embodiment of the photoreceptor of the present invention. DESCRIPTION OF SYMBOLS 1 ... Conductive support, 2 ... Carrier transport layer 3 ... Carrier generating layer, 4 ... Photosensitive layer

Claims (1)

(57) [Claims] 1. An electrophotographic photoreceptor comprising at least one compound represented by the following general formula [I]. General formula [I] [Wherein, R ₁ and R ₂ represent a hydrogen atom, an alkyl group, an aryl group,
Represents an aralkyl group or a heterocyclic group, and these groups may have a substituent. However, R ₁ and R ₂ are not simultaneously hydrogen atoms, and may form a ring together with the carbon atom to which R ₁ and R ₂ are bonded. R ₃ , R ₄ and R ₅ represent a hydrogen atom, a halogen atom, an alkyl group or an alkoxy group. Ar ₁ and Ar ₂ represent an alkyl group, an aryl group, or an aralkyl group, and these groups may have a substituent. n is an integer of 0 or 1. ]