JPH06100832B2 - Electrophotographic photoreceptor - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electrophotographic photosensitive member used in an image forming apparatus such as a copying machine.

<Prior Art> Recently, in an image forming apparatus such as a copying machine using a so-called Carlson process, a charge generating material that generates charges by light irradiation and a charge transporting material that transports the generated charges are used together. As a result, a so-called function-separated type in which the charge generation function and the charge transport function are separated is widely used because it is easy to increase the sensitivity. As this function-separated type photoreceptor, a laminated type photosensitive layer having a charge generation layer containing the above charge generation material and a charge transport layer containing a charge transport material was formed on the surface of a conductive substrate. There are a laminated type and a single layer type in which a single layer type photosensitive layer containing a charge generation material and a charge transport material is formed on the surface of a conductive substrate.

Further, in the above-mentioned function-separated type photoreceptor, the entire single-layer type or laminated type photosensitive layer formed on the surface of the conductive substrate is used as a binder resin for the functional components such as the charge generation material and the charge transport material. An organic photoreceptor having an organic layer contained therein, or a part of the laminated photosensitive layer, a composite photoreceptor having the organic layer has a wide selection range of materials, excellent productivity, Moreover, it is preferably used because of its high degree of freedom in functional design.

In addition, recently, when an image forming process such as charging, exposure, and charge elimination is repeatedly performed, the organic layer in the organic photoreceptor or the composite-type photoreceptor fatigues, resulting in a decrease in charge amount and a decrease in sensitivity. In addition to the usual charge transporting materials, in order to prevent
A photoreceptor containing a phenylenediamine compound as a charge transport material has been proposed.

<Problems to be Solved by the Invention> However, the photoconductor containing the m-phenylenediamine compound is a fluorescent lamp or a xenon lamp, especially when the photoconductor is heated, such as when the image forming apparatus is operating.
Alternatively, when sunlight or the like is irradiated, there is a problem that sensitivity is lowered due to ultraviolet rays contained in these lights.

The decrease in sensitivity (ultraviolet ray deterioration) due to the irradiation of ultraviolet rays is m-
A phenylenediamine compound is excited by its own UV absorption or energy transfer from a UV absorbing substance such as a charge generating material, and causes a dimerization reaction or decomposition reaction, and becomes a carrier trap that reduces the sensitivity of the photoconductor. It is thought that the cause is the change to a substance.

The present invention has been made in view of the above circumstances, and contains an m-phenylenediamine-based compound having an excellent action of preventing a decrease in charge amount, a decrease in sensitivity, and the like when the image forming process is repeatedly performed, Moreover, it is an object of the present invention to provide an electrophotographic photosensitive member that is less likely to undergo ultraviolet deterioration.

<Means and Actions for Solving the Problems> An electrophotographic photosensitive member according to the present invention for solving the above problems is provided with an organic layer containing an m-phenylenediamine compound as a charge transport material. In the body, triplet excitation energy is 60 to 68 in the organic layer.
It is characterized by containing a compound within the range of kcal / mol. The value of triplet excitation energy here is
For example, the measured value in a nonpolar solvent such as saturated hydrocarbon or benzene is shown.

According to the electrophotographic photoreceptor of the present invention having the above-mentioned constitution, the range of the triplet excitation energy is from the energy level (about 68.5 ± 0.5 kcal / mol) in the expected excited state of the m-phenylenediamine compound. Since the compound has a triplet excitation energy within the above range (hereinafter referred to as "specific compound"), the triplet excitation energy deprives the m-phenylenediamine type compound excited by ultraviolet irradiation of the excitation energy, and the m-phenylenediamine type compound It is prevented that the compound is dimerized or decomposed into a substance which becomes a carrier trap which lowers the sensitivity of the photoreceptor.

The present invention will be described in detail below.

The m-phenylenediamine compound has the following general formula [I].
It is represented by.

(However, R ^{1 to} R ⁵ in the above formula [I] each represent the same or different group selected from the group consisting of an alkyl group, an alkoxy group, a halogen atom and a hydrogen atom.) The m-phenylenediamine compound As N, N,
N ', N'-tetraphenyl-1,3-phenylenediamine,
N, N, N ', N'-tetrakis (3-tolyl) -1,3-phenylenediamine, N, N, N', N'-tetraphenyl-3,5-tolylenediamine, N, N, N ′, N′-Tetrakis (3-tolyl) -3,5-tolylenediamine, N, N, N ′, N′-tetrakis (4-tolyl) -1,3-phenylenediamine, N, N,
N ', N'-tetrakis (4-tolyl) -3,5-tolylenediamine, N, N, N', N'-tetrakis (3-ethylphenyl) -1,3-phenylenediamine, N, N, N ', N'-tetrakis (4-propylphenyl) -1,3-phenylenediamine, N, N, N', N'-tetraphenyl-5-methoxy-
1,3-phenylenediamine, N, N-bis (3-tolyl)-
N ', N'-diphenyl-1,3-phenylenediamine, N,
N'-bis (4-tolyl) -N, N'-diphenyl-1,3-
Phenylenediamine, N, N'-bis (4-tolyl) -N,
N'-bis (3-tolyl) -1,3-phenylenediamine,
N, N'-bis (4-tolyl) -N, N'-bis (3-tolyl) -3,5-tolylenediamine, N, N'-bis (4-ethylphenyl) -N, N'- Bis (3-ethylphenyl)-
1,3-phenylenediamine, N, N'-bis (4-ethylphenyl) -N, N'-bis (3-ethylphenyl) -3,5-
Tolylenediamine, N, N, N ', N'-tetrakis (2,4,6-
Trimethylphenyl) -1,3-phenylenediamine, N,
N, N ', N'-Tetrakis (2,4,6-trimethylphenyl)
−3,5-Tolylenediamine, N, N, N ′, N′-tetrakis (3,5-dimethylphenyl) -1,3-phenylenediamine, N, N, N ′, N′-tetrakis (3, 5-dimethylphenyl) -3,5-tolylenediamine, N, N, N ', N'-tetrakis (3,5-diethylphenyl) -1,3-phenylenediamine, N, N, N', N ' -Tetrakis (3,5-diethylphenyl) -3,5-tolylenediamine, N, N, N ', N'-tetrakis (3-chlorophenyl) -1,3-phenylenediamine, N, N, N', N'-tetrakis (3-bromophenyl)
-1,3-phenylenediamine, N, N, N ', N'-tetrakis (3-iodophenyl) -1,3-phenylenediamine,
N, N, N ', N'-Tetrakis (3-fluorophenyl)-
1,3-phenylenediamine and the like can be mentioned. Among the above compounds, the groups R ^{1 to} R in the general formula [I]
⁵ is a compound in which a carbon atom in each benzene ring is bonded to a carbon in a meta position with respect to the carbon to which a nitrogen atom is bonded, or a group
R ¹ and R ⁵ are bonded to the carbon of the benzene ring in a position para to the carbon to which the nitrogen atom is bonded, and the groups R ² and R ⁴ are bonded to the carbon of the benzene ring to which the nitrogen atom is bonded. The compound bonded to the carbon in the meta position with respect to the carbon has a large asymmetry of the molecule and a small interaction between the molecules and is difficult to be crystallized, so that the compound can be easily dispersed in the binder resin. To
It can be mentioned as a more preferable one. Specifically, N, N,
N ', N'-tetrakis (3-tolyl) -1,3-phenylenediamine, N, N'-bis (4-tolyl) -N, N'-bis (3-tolyl) -1,3-phenylenediamine Compounds such as are exemplified as more preferable ones.

Further, examples of the specific compound contained in the layer together with the m-phenylenediamine include naphthalene, phenanthrene, m-terphenyl, biphenyl and fluorene.

The triplet excitation energy of the specific compound is 60 kcal.
If it is less than / mol, there is a gap between the energy level of the excited state of the m-phenylenediamine compound and the excitation energy cannot be taken from the m-phenylenediamine compound excited by the ultraviolet irradiation. On the other hand, when the triplet excitation energy exceeds 68 kcal / mol, the level of this triplet excitation energy becomes higher than the energy level of the excited state of the m-phenylenediamine compound, and conversely, m-phenylenediamine There is a problem that energy for dimerization and decomposition is imparted to the system compound to promote deterioration. Therefore, the triplet excitation energy of the specific compound is limited to the range of 60 to 68 kcal / mol.

The blending amount of the above-mentioned specific compound with respect to the m-phenylenediamine compound is not particularly limited, but it is preferably within a range of 20 to 150 parts by weight with respect to 100 parts by weight of the m-phenylenediamine compound. When the content of the specific compound is less than 20 parts by weight based on 100 parts by weight of the m-phenylenediamine compound, ultraviolet deterioration of the m-phenylenediamine compound cannot be sufficiently prevented, and when it exceeds 150 parts by weight. The glass transition temperature of the layer may decrease, and the heat resistance of the electrophotographic photoreceptor may deteriorate.

The constitution of the present invention is applied to electrophotographic photoreceptors having various types of photosensitive layers provided with an organic layer capable of containing the m-phenylenediamine compound and the specific compound (hereinafter referred to as "specific layer"). The specific layer may include the following layers.

A single-layer type organic photosensitive layer containing a charge generating material and a charge transporting material in a binder resin.

The charge transport layer in a laminated organic photosensitive layer in which an organic charge generation layer and an organic charge transport layer are laminated.

The charge transport layer in a composite type photosensitive layer in which a charge generation layer made of a thin film of a semiconductor material and an organic charge transport layer are laminated.

A binder that forms an organic layer such as the specific layer or the charge generation layer of the laminated organic photosensitive layer, and a surface protective layer formed as necessary on the outermost surface layer of each type of the photosensitive layer. Examples of the resin include thermosetting silicone resin, epoxy resin, urethane resin, curable acrylic resin, alkyd resin, unsaturated polyester resin, diallyl phthalate resin, phenol resin, urea resin, benzoguanamine resin, melamine resin, and styrene polymer. Acrylic polymer; Styrene-acrylic copolymer; Olefin polymer such as polyethylene, ethylene-vinyl acetate copolymer, chlorinated polyethylene, polypropylene, ionomer;
Polyvinyl chloride; Vinyl chloride-vinyl acetate copolymer; Polyvinyl acetate; Saturated polyester; Polyamide; Thermoplastic urethane resin; Polycarbonate; Polyarylate;
Polysulfone; ketone resin; polyvinyl butyral; polyether and the like.

Of the photosensitive layers of each type, in the composite type photosensitive layer,
Examples of the semiconductor material forming the thin film used as the charge generation layer include amorphous chalcogenides such as α-Se, α-As ₂ Se ₃ , and α-SeAsTe, and amorphous silicon (α-Si). The thin film charge generation layer made of the above semiconductor material can be formed on the surface of the conductive substrate by a known thin film forming method such as a vacuum vapor deposition method and a glow discharge decomposition method.

Further, as the organic or inorganic charge generating material used for the charge generating layer in the single-layer organic photosensitive layer (the specific layer) or the laminated organic photosensitive layer, for example, the semiconductor material powder; ZnO, II-VI group crystallites such as CdS; pyrylium salt;
Azo compounds; bisazo compounds; phthalocyanine compounds such as aluminum phthalocyanine, copper phthalocyanine, metal-free phthalocyanine, and titanyl phthalocyanine having crystal forms such as α-type, β-type, γ-type; ansanthrone-based compounds; indigo-based compounds; Examples include phenylmethane compounds; threnic compounds; toluidine compounds; pyrazoline compounds; quinacridone compounds; pyrrolopyrrole compounds. These charge generation materials may be used alone or in combination of two or more kinds.

In addition, it is preferable that each of the specific layers usually contains other conventionally known charge transport material (hereinafter, simply referred to as “other charge transport material”) together with the m-phenylenediamine compound. Other charge transport materials contained in the specific layer together with the m-phenylenediamine compound include:
For example, tetracyanoethylene; 2,4,7-trinitro-9-
Fluorenone compounds such as fluorenone; Fluorene compounds such as 9-carbazolyliminofluorene; nitrated compounds such as dinitroanthracene; succinic anhydride; maleic anhydride; dibromomaleic anhydride; triphenylmethane compounds; 2,5 -Di (4-dimethylaminophenyl)
Oxadiazole compounds such as -1,3,4-oxadiazole; styryl compounds such as 9- (4-diethylaminostyryl) anthracene; carbazole compounds such as poly-N-vinylcarbazole; 1-phenyl-3 Pyrazoline compounds such as-(p-dimethylaminophenyl) pyrazolin; 4,4 ', 4 "-tris (N, N-diphenylamino) triphenylamine, 3,3'-dimethyl-N, N, N', N'-tetrakis-4-methylphenyl (1,1'-biphenyl)
Amine derivatives such as -4,4'-diamine; 1,1-bis (4-
Conjugate unsaturated compounds such as diethylaminophenyl) -4,4-diphenyl-1,3-butadiene; hydrazone compounds such as 4- (N, N-diethylamino) benzaldehyde-N, N-diphenylhydrazone; indole compounds, oxazole Compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, pyrazoline compounds, triazole compounds, and other nitrogen-containing cyclic compounds; condensed polycyclic compounds. Among the above charge transport materials, the photoconductive polymer material such as poly-N-vinylcarbazole can also be used as the binder resin for the specific layer.

The mixing ratio of the other charge transport material and the m-phenylenediamine compound in the specific layer is not particularly limited, but is within the range of 95: 5 to 25:75 by weight, particularly 80:20 to 50: Five
It is preferably in the range of 0. When the compounding ratio of the other charge transport material and the m-phenylenediamine compound is less than 95: 5, the effect of preventing the decrease in the amount of charge and the decrease in sensitivity when the image forming process is repeated becomes insufficient, On the other hand, if the blending ratio exceeds 25:75, the sensitivity of the photoreceptor may be insufficient.

In the single-layer organic photosensitive layer among the above-mentioned types of photosensitive layers, the content of the charge generation material relative to 100 parts by weight of the binder resin is in the range of 2 to 20 parts by weight, and particularly 3 to 15 parts by weight. It is preferably within the range. The content of the other charge transport material with respect to 100 parts by weight of the binder resin is preferably in the range of 40 to 200 parts by weight, particularly preferably in the range of 50 to 100 parts by weight. If the content of the charge generating material is less than 2 parts by weight or the content of the other charge transporting material is less than 40 parts by weight,
There is a risk that the sensitivity of the photoconductor will become insufficient or the residual potential will increase. On the other hand, if the content of charge generation material is 20
If the amount is more than 200 parts by weight, or if the content of the other charge transport material is more than 200 parts by weight, the abrasion resistance of the photoreceptor may be insufficient.

The thickness of the single-layer organic photosensitive layer is not particularly limited,
Similar to conventional single layer type organic photosensitive layer, that is, 10 to 50
It is preferably in the range of 15 to 25 μm.

In each of the layers constituting the laminated organic photosensitive layer, the content of the charge generating material in 100 parts by weight of the binder resin in the organic charge generating layer is in the range of 5 to 500 parts by weight, particularly 10 to 250 parts by weight.
It is preferably within the range of parts by weight. If the content of the charge generating material is less than 5 parts by weight, the charge generating ability is too small,
If the amount exceeds 0 parts by weight, the adhesion to the base material and other adjacent layers may deteriorate.

The thickness of the charge generation layer is not particularly limited, but is 0.01 to 3
It is preferably in the range of 0.1 μm, particularly 0.1 to 2 μm.

Among the layers constituting the laminated organic photosensitive layer or the composite type photosensitive layer, the content of the other charge transporting material in the charge transporting layer with respect to 100 parts by weight of the binder resin is in the range of 10 to 500 parts by weight, particularly It is preferably in the range of 25 to 200 parts by weight. If the content of the other charge transporting material is less than 10 parts by weight, the charge transporting ability is insufficient, and if it exceeds 500 parts by weight, the mechanical strength of the charge transporting layer may decrease.

The thickness of the charge transport layer is not particularly limited, but 2-100
It is preferably in the range of 5 μm, particularly 5 to 30 μm.

Further, the surface protective layer that can be formed on the outermost layer of each type of the photosensitive layer contains the binder resin as a main component, and if necessary, the addition of a conductivity-imparting material, a benzoquinone-based ultraviolet absorber, or the like. The agent can be contained in an appropriate amount.

The thickness of the surface protective layer is 0.1 to 10 μm, particularly 2 to 5 μm.
It is preferably within the range of m.

When an antioxidant is used in combination with an organic layer of the above-mentioned photosensitive layers of each type, the surface protective layer, or the like, a functional component such as a charge transport material having a structure susceptible to oxidation is deteriorated by oxidation. Can be prevented.

As the above-mentioned antioxidant, 2,6-di-tert-butyl-p
-Cresol, triethylene glycol-bis [3-
(3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], penta Erythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2,2-thio-diethylenebis [3- (3,5-di-tert-butyl-4-] Hydroxyphenyl) propionate], 2,2-thiobis (4-
Methyl-6-tert-butylphenol), N, N'-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamamide), 1,3,5-trimethyl-2,
Examples include phenolic antioxidants such as 4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene.

The conductive base material on the surface of which each type of photosensitive layer is formed is formed in an appropriate shape such as a sheet shape or a drum shape according to the mechanism and structure of the image forming apparatus in which the electrophotographic photosensitive member is incorporated. It

The conductive base material may be entirely composed of a conductive material such as metal, and the base material itself is formed of a structural material having no conductivity, and the surface thereof is provided with conductivity. Is also good.

The entire conductive substrate is composed of a conductive material, the conductive material used in the former case, the surface is alumite-treated or untreated aluminum, copper, tin, platinum, gold, silver, Metal materials such as vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, and brass are preferable, and in particular, aluminum that is anodized by the sulfuric acid alumite method and sealed with nickel acetate is preferably used. .

On the other hand, in the latter case where conductivity is imparted to the surface of a base material made of a structural material having no conductivity, in the case of the surface of a synthetic resin base material or a glass base material, the above-mentioned metal or aluminum iodide is used. , A structure in which a thin film made of a conductive material such as tin oxide or indium oxide is formed by a known film forming method such as a vacuum deposition method or a wet plating method, the above metal on the surface of the synthetic resin molded article or the glass substrate. A structure in which films of materials or the like are laminated, or a structure in which a substance that imparts conductivity is injected into the surface of the synthetic resin base material or the glass base material can be adopted.

The conductive base material may be subjected to a surface treatment with a surface treatment agent such as a silane coupling agent or a titanium coupling agent, if necessary, to enhance the adhesion to the photosensitive layer.

Organic layers and surface protective layers of the photosensitive layers of each type described above can be prepared by adjusting the coating liquid for each layer containing the above-mentioned components, and forming these coating liquids into the above-mentioned layer constitution. So that each layer is sequentially coated on a conductive substrate,
A laminate can be formed by drying or curing.

When preparing the above-mentioned coating liquid, various solvents can be used depending on the type of binder resin or the like used. Examples of the solvent include aliphatic hydrocarbons such as n-hexane, octane and cyclohexane; benzene, xylene,
Aromatic hydrocarbons such as toluene; halogenated hydrocarbons such as dichloromethane, carbon tetrachloride, chlorobenzene, methylene chloride; methyl alcohol, ethyl alcohol, isopropyl alcohol, allyl alcohol, cyclopentanol, benzyl alcohol, furfuryl alcohol, diacetone Alcohols such as alcohols; ethers such as dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone;
Various solvents may be mentioned, such as esters such as ethyl acetate and methyl acetate; dimethylformamide; dimethylsulfoxide and the like, and these may be used alone or in combination of two or more. Further, when adjusting the above-mentioned coating liquid, a surfactant, a leveling agent, or the like may be used in combination in order to improve dispersibility, coatability, and the like.

Further, the coating solution is a conventional method, for example, a mixer,
It can be prepared using a ball mill, paint shaker, sand mill, attritor, ultrasonic disperser, or the like.

<Example> Hereinafter, the present invention will be described in more detail based on Examples.

Examples 1 to 4 100 parts by weight of poly (4,4'-cyclohexylidenediphenyl) carbonate (manufactured by Mitsubishi Gas Chemical Co., Inc., trade name Polycarbonate Z) as a binder resin and 4,10-dibromo- as a charge generation material. Dibenzo [def, mno] chrysene 6,12
-Dione (2,7-dibromoanthanthrone) 8 parts by weight and X-type metal-free phthalocyanine (manufactured by Dainippon Ink and Chemicals, Inc.) 0.2 parts by weight, 3,3'-dimethyl-N, N, N 'as a charge transport material. N'-tetrakis-4-methylphenyl (1,
1'-biphenyl) -4,4'-diamine 40 parts by weight and N,
40 parts by weight of N, N ', N'-tetrakis (3-tolyl) -1,3-phenylenediamine, 2,6-di-ter as an antioxidant
In 5 parts by weight of t-butyl-p-cresol (Kawaguchi Chemical Co., Ltd., trade name Antage BHT) and 0.1 part by weight of polydimethylsiloxane (silicone oil) as a plasticizer, the triplet excitation energy shown in the following table is 60- 20 parts by weight of the specific compound in the range of 68 kcal / mol was added and mixed with a predetermined amount of tetrahydrofuran by an ultrasonic disperser to prepare a single layer type photosensitive layer coating solution. This coating liquid has an outer diameter of 78 mm and a length of 340 m.
After coating on an aluminum tube of m, 30 at 100 ℃ in the dark.
After heating and drying for 1 minute, a single layer type photosensitive layer having a thickness of about 24 μm was formed to prepare a drum type electrophotographic photosensitive member.

Comparative Examples 1 and 2 An electrophotographic image was obtained in the same manner as in Examples 1 to 4 except that 20 parts by weight of a compound having a triplet excitation energy of less than 60 kcal / mol shown in the following table was used instead of the specific compound. A photoconductor was prepared.

Comparative Examples 3 and 4 The same procedure as in Examples 1 to 4 was repeated except that 20 parts by weight of a compound having a triplet excitation energy of more than 68 kcal / mol was used instead of the specific compound as shown in the following table. A photoconductor was prepared.

Comparative Example 5 Example 1 above except that no specific compound was added.
An electrophotographic photosensitive member was produced in the same manner as in the processes of to 4.

Comparative Example 6 N, N, N ', N'-tetrakis (3-tolyl) -1,3-phenylenediamine was not added, and 3,3'-dimethyl-N, N, N',
An electrophotographic photosensitive member was prepared in the same manner as in Comparative Example 5 except that 80 parts by weight of N'-tetrakis-4-methylphenyl (1,1'-biphenyl) -4,4'-diamine was added as a charge transport material. The body was made.

The following tests were carried out on the electrophotographic photosensitive members produced in the above-mentioned Examples and Comparative Examples.

Initial surface potential measurement Each of the electrophotographic photoconductors described above was loaded into an electrostatic copying tester (Gentec Cynthia 30M, manufactured by Gentech Co., Ltd.) and the surface was positively charged to measure the surface potential V ₁ sp (V). did.

Half-dose exposure amount, residual potential measurement Each electrophotographic photosensitive member in the charged state is exposed using a halogen lamp which is an exposure light source of the electrostatic copying test apparatus,
The time required for the surface potential V ₁ sp (V) to be halved was calculated, and the half-exposure amount E1 / 2 (μJ / cm ² ) was calculated.

Further, the surface potential after 0.15 seconds has elapsed from the start of the exposure,
It was measured as the residual potential V ₁ rp (V).

Measurement of surface potential change value and residual potential change value after UV irradiation At the two points on each of the electrophotographic photoconductors, the surface potentials V _1a sp, V _1b sp, and residual potential were measured in the same manner as in the above respective measurements. After measuring V _1a rp and V _1b rp [above, unit (V)], preheat this electrophotographic photosensitive member to 60 ° C. in the dark, and
It is stored for 60 minutes, then, while keeping the temperature at 60 ° C., the V _1b side of the above two points is masked with a light shield, and the surface of the electrophotographic photosensitive member is 1500 lux using a white fluorescent lamp.
Was exposed to white light including ultraviolet rays for 20 minutes. Then, after exposing the electrophotographic photosensitive member in the dark at room temperature for 30 minutes and cooling, it was loaded into an electrostatic copying tester (Gentec Cynthia 30M manufactured by Gentec Co., Ltd.), and its surface was positively corrected. By charging, the surface potential V _2a sp (exposure side), V _2b sp (light shield side) and the residual potential V _2a rp at the above two locations
(Exposure side), V _2b rp (light shield side) [above, unit (V)]
Was measured.

Based on the above measured values, the surface potential change value ΔVs.p. (V) after ultraviolet irradiation is calculated using the following formula (a), and the residual potential after ultraviolet irradiation is calculated using the following formula (b). Change value ΔVr.p.
(V) was calculated.

ΔV s.p. ＝ (V _2a sp-V _1a sp)-(V _2b sp-V _1b sp)… (a) ΔV r.p. ＝ (V _2a rp-V _1a rp)-(V _2b rp-V _1b rp) (b) Measurement of surface potential after repeated exposure Each of the electrophotographic photoconductors was copied to a copying machine (manufactured by Mita Kogyo Co., Ltd., DC-111).
After performing the copying process of 500 sheets by loading it in the mold machine, an electrostatic copying tester (Gentec Cynthia manufactured by Gentec)
30 M), the surface thereof was positively charged, and the surface potential V ₃ sp (V) after repeated exposure was measured.

Further, the surface potential change value ΔV _1-3 (V) after repeated exposure was calculated using the following formula (c).

ΔV _1-3 (V) = V ₁ sp (V) -V ₃ sp (V) (c) The above results are shown in the following table.

From the results in the above table, the triplet excitation energy is 60 kcal / mol
The electrophotographic photoreceptors of Comparative Examples 1 and 2 using the compound of less than
In all cases, the surface potential and the residual potential were reduced by the ultraviolet irradiation to the same extent as in Comparative Example 5 in which the specific compound was not contained. Also, the triplet excitation energy is 68 kcal / mol
In the electrophotographic photoreceptors of Comparative Examples 3 and 4 using the compounds exceeding the above values, the surface potential and the residual potential were greatly decreased by the ultraviolet irradiation as compared with the above Comparative Example 5. On the other hand, the electrophotographic photoreceptors of Examples 1 to 4 using the specific compound having a triplet excitation energy in the range of 60 to 68 kcal / mol were all exposed to ultraviolet rays as compared with the above-mentioned comparative examples. The amount of change in the surface potential and the residual potential was small, which proved that the electrophotographic photosensitive members of Examples 1 to 4 were not easily deteriorated by ultraviolet rays. Moreover, the above-mentioned Examples 1 to 1
4, the electrophotographic photoreceptors of Comparative Example 5 have smaller surface potential changes due to repeated exposure than Comparative Example 6 in which the m-phenylenediamine compound is not used as a charge transport material. It was found that the above-mentioned specific compound does not affect the preventive action of the m-phenylenediamine compound, such as reduction in charge amount and reduction in sensitivity.

<Effects of the Invention> The electrophotographic photosensitive member of the present invention is configured as described above, and is an m-phenylenediamine having an excellent action of preventing a decrease in charge amount and a decrease in sensitivity when the image forming process is repeated. Since the layer containing the system-based compound contains the specific compound having the action of preventing the ultraviolet degradation of the m-phenylenediamine-based compound, the state where the photoconductor is heated, particularly when the image forming apparatus is operating. In the above, even if a fluorescent lamp, a xenon lamp, or light including ultraviolet rays such as sunlight is irradiated, the sensitivity is less likely to decrease.

Claims (1)

[Claims] 1. An electrophotographic photoreceptor comprising a layer containing a m-phenylenediamine compound as a charge transport material in a binder resin, wherein the triplet excitation energy is 60 to 68 kcal / mol in the layer. An electrophotographic photoreceptor comprising a compound within the range.