JPH0375657A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To reduce tendency of deterioration of sensitivity even at the time of exposure to light containing ultraviolet rays by incorporating a specified compound having an action of inhibiting the ultraviolet deterioration of an m-phenylenediamine derivative. CONSTITUTION:An organic layer to be used contains as an electric charge transfer material the m-phenylenediamine derivative and further the compound having a triplet excitation energy of 60-68 kcal/mol. Since the range of the triplet excitation energy level is lower than the range of the expected excitation energy of the m-phenylenediamine, the compound takes the excitation energy from the m-phenylenediamine derivative excited by irradiation with ultraviolet rays, thus permitting deterioration due to ultraviolet rays to be made difficult to occur by containing the m-phenylenediamine derivative superior in the action of inhibiting deterioration of chargeability and sensitivity and the like, at the time of repeating an image forming process.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an electrophotographic photoreceptor used in an image forming apparatus such as a copying machine.

<Prior Art> Recently, image forming devices such as copying machines that utilize the so-called Carlson process use a combination of a charge-generating material that generates charges by light irradiation and a charge-transporting material that transports the generated charges. Therefore, a so-called functionally separated type, in which the charge generation function and the charge generation function are separated, is often used because it is easy to increase sensitivity. This functionally separated type photoreceptor is a photoreceptor containing H containing the charge generating material described above.
A laminated type photosensitive layer comprising a Ji 4ij generation layer and a charge transport layer containing a charge transporting material is formed on the surface of a conductive substrate, and a laminated type photosensitive layer comprising a charge generating layer and a charge transporting material. There is a single-layer type in which a single-layer photosensitive layer is formed on the surface of a conductive substrate.

In addition, in the functionally separated photoreceptor, the entire single-layer or laminated photosensitive layer formed on the surface of the conductive substrate is bonded with functional components such as the charge-generating material and the electron transporting material. Organic photoreceptors have an organic layer contained in a resin, and composite photoreceptors have a layer of organic material as part of the laminated photosensitive layer, which has a wide range of materials to choose from and is highly productive. , and has a high degree of freedom in functional design, so it is suitably used.

In addition, recently, when image forming processes such as charging, exposure, and static elimination are repeated, the organic layer in the organic photoreceptor or composite photoreceptor becomes fatigued, resulting in a decrease in charge amount and sensitivity. In order to prevent this, in addition to ordinary charge transport materials, m-
A photoreceptor containing a phenylenediamine compound as a charge transport material has been proposed.

<Problems to be Solved by the Invention> However, the photoreceptor containing the m-phenylenediamine compound described above cannot be exposed to fluorescent lamps, xenon lamps,
Alternatively, when exposed to sunlight or the like, there is a problem in that sensitivity decreases due to ultraviolet rays contained in this light.

The sensitivity reduction (ultraviolet deterioration) due to the above ultraviolet irradiation is m-
A phenylenediamine compound is excited by its own ultraviolet absorption or energy transfer from an ultraviolet absorbing substance such as a charge generating material, causing a trimerization reaction or a decomposition reaction, which becomes a carrier trap that reduces the sensitivity of the photoreceptor. It is thought that the cause is that it changes into a substance.

This invention has been made in view of the above circumstances, and contains an m-phenylenediamine compound that has an excellent effect of preventing a decrease in charge amount and a decrease in sensitivity when the image forming process is repeated. The purpose is to provide electrophotographic photoreceptors that are less susceptible to UV deterioration.

Means and Effects for Solving the Problems In order to solve the above problems, an electrophotographic photoreceptor of the present invention is provided with an organic layer containing an m-phenylenediamine compound as a charge transport material. In the body, the triplet excitation energy is 60 to 68 kcal in the organic layer.
? / aoD.

Note that the value of triplet excitation energy here indicates a value measured in a nonpolar solvent such as a saturated hydrocarbon or benzene, for example.

According to the electrophotographic photoreceptor of the present invention having the above configuration, the range of the triplet excitation energy is the energy level in the expected excited state of the m-phenylenediamine compound (about 68.5±0, 5 kcal /1ao
fl), so it is a triplet excitation energy or a compound within the above range (hereinafter referred to as "specific compound").
is that excitation energy is taken away from the m-phenylenediamine compound excited by ultraviolet irradiation, and the m-phenylenediamine compound is trimerized or decomposed, turning into a substance that becomes a carrier trap that reduces the sensitivity of the photoreceptor. prevent.

The present invention will be explained in detail below.

The m-phenylenediamine-based compound can be used in the following general manner (however,
In the above formula (1), R1, ..., R5 each represent the same or different groups selected from the group consisting of an alkyl group, an alkoxy group, a halogen atom, and a hydrogen atom. 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-tolylene diamine, N, N, N', N' -tetrakis(3-tolyl)-3,5-)lylene diamine, N, N, N'
N'-tetrakis(4-tolyl)-1,3-phenylenediamine, N,N.

N', N'-tetrakis(4-tolyl)-3,5-tolylene diamine, 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)-13-phenylenediamine, N,N'-bis(
4-tolyl)-N,N'-bis(3-tolyl)3.5-
1 lylenediamine, N,N'-bis(4-ethylphenyl)-N,N'-bis(3-ethylphenyl)-1
,3-phenylenediamine, N,N'-bis(4-ethylphenyl)-N1N'-bis(3-ethylphenyl)
-3,5-tolylenediamine, N, N, N'N'
-tetrakis(2,4,6-1-limethylphenyl)-1
, 3-phenylenediamine, N, N, N', N' -
Tetrakis (2,4,6-drimethylphenyl) 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(3-10lophenyl)-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-
Examples include phenylenediamine. Among the above compounds, the groups R1-R5 in the general formula (1) are
Of each benzene ring, a compound bonded to the carbon at the meta position relative to the carbon to which the nitrogen atom is bonded, or a group R1,
R5 is bonded to the carbon in the benzene ring at the rose position relative to the carbon to which the nitrogen atom is bonded, and group R2R4 is bonded to the carbon in the meta position to the carbon to which the nitrogen atom is bonded in the benzene ring. Compounds bonded to carbon have large molecular asymmetry and small interactions between molecules and are difficult to crystallize, so they can be easily dispersed in a binder resin.
These are listed as more preferred. Specifically, N,
N.

N'N'-tetrakis(3-tolyl)-1,:3-
Phenylenediamine, N,N'-bis(4-tolyl)-
More preferred examples include compounds such as N,N'-bis(3-tolyl)-1,3-phenylenediamine.

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

Note that the triplet excitation energy of the above specific compound is 60
If it is less than kcal/mo1, there is a difference in the energy level of the excited state of the m-phenylenediamine compound, so that excitation energy cannot be taken from the m-phenylenediamine compound excited by ultraviolet irradiation. On the other hand, the triplet excitation energy is 68 kcaff
/1oJ7, the triplet excitation energy level of C and C becomes higher than the energy level of the excited state of the m-phenylenediamine-based compound, so on the contrary,
There is a problem in that energy for trimerization and decomposition is imparted to the m-phenylenediamine compound, increasing deterioration. Therefore, the triplet excitation energy of the specific compound is limited to a range of 60 to 68 kcaR/1xof).

The amount of the above-mentioned specific compound added to the m-phenylenediamine compound is not particularly limited, but it is preferably within the range of 20 to 150 parts by weight based on 100 parts by weight of the m-phenylenediamine compound. If the blending amount of the specific compound is less than 20 parts by weight based on 100 parts by weight of the m-phenylenediamine compound, UV deterioration of the m-phenylenediamine compound cannot be sufficiently prevented;
If the amount exceeds 0 parts by weight, the glass transition temperature of the photosensitive layer may decrease, and the heat resistance of the electrophotographic photoreceptor may deteriorate.

The structure of the present invention is applicable to electrophotographic photoreceptors having various types of photosensitive layers including an organic layer (hereinafter referred to as "specific layer") that can contain the m-phenylenediamine compound and a specific compound. Examples of the specific layer include the following layers.

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

(2) 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.

(2) The charge transport layer in a composite 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 constitutes organic layers such as the above-mentioned specific layer, the charge generation layer of the laminated organic photosensitive layer, and the surface protective layer formed as necessary on the outermost layer of each type of photosensitive layer above. Examples of resins include thermosetting silicone resins; epoxy resins; urethane resins; curable acrylic resins; alkyd resins; unsaturated polyester resins; diallyl phthalate resins; phenolic resins; urea resins; benzoguanamine resins; melamine resins; styrene polymers ; Acrylic polymer; Styrene-acrylic copolymer; Olefin polymers 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.

Among the above types of photosensitive layers, in the composite photosensitive layer,
Semiconductor materials constituting the thin film used as the charge generation layer include, for example, α-S, α-AS2 Se3, a-S
Examples include amorphous chalcogenides such as eAsTe and amorphous silicon (α-5L). The thin film-like charge generation layer made of the above-mentioned semiconductor material can be formed on the surface of the conductive base material by a known thin film forming method such as a vacuum deposition method or a glow discharge decomposition method.

In addition, examples of organic or inorganic charge generating materials used for the charge generating layer in a single-layer type organic photosensitive layer (the above-mentioned specific layer ①) or a laminated type organic photosensitive layer include powders of the above-mentioned semiconductor materials; ■-Vt group microcrystals such as , CdS; biryllium salts; azo compounds; bisazo compounds; α type, β
Aluminum phthalocyanine, copper phthalocyanine, metal-free phthalocyanine, which has crystal forms such as type, γ type, etc.
Phthalocyanine compounds such as titanyl phthalocyanine;
Examples include anthanthrone compounds; indigo compounds; triphenylmethane compounds; threne compounds; toluidine compounds; pyrazoline compounds; quinacridone compounds; and pyrrolopyrrole compounds. These charge generating materials can be used alone or in combination.

In addition, it is preferable that other conventionally known charge transport materials (hereinafter simply referred to as "other charge transport materials") be contained in each of the specific layers, together with the m-phenylenediamine compound. Other charge transport materials contained in the specific layer together with the m-phinidine diamine compound include:
For example, fluorenone compounds such as tetracyanoethylene and 2,4.7-trinitro-9-fluorenone; fluorenone compounds such as 9-carbazolyliminofluorene;
Nitrated compounds such as dinitroanthracene; succinic anhydride; maleic anhydride; dibromomaleic anhydride; triphenylmethane compounds, 2,5-di(4-dimethylaminophenyl)-1,,34-oxadiazole, etc. Oxadiazole compounds, styryl compounds such as 9-C4-diethylaminostyryl)anthracene; poly-N-
Carbazole compounds such as vinylcarbazole; pyrazoline compounds such as 1-phenyl-3-(p-dimethylaminophenyl)pyrazoline; 4.4'4'-tris(N
, N-diphenylamino)triphenylamine, 3,3
'-dimethyl-N,N.

N'N' -tetrakis-4-methylphenyl (1
, 1'-biphenyl)-4,4'-diamine; conjugated unsaturated compounds such as 1,1-bis(4-diethylaminophenyl)-4,4-diphenyl-1,3-butadiene; 4- (N.

N-diethylamino)benzaldehyde-N, N-
Hydrazone compounds such as diphenylhydrazone; nitrogen-containing cyclic compounds such as indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, pyrazoline compounds, triazole compounds, etc. Compounds include fused polycyclic compounds and the like. Note that among the other charge transport materials mentioned above, the polymeric material having photoconductivity, such as the poly-N-vinylcarbazole, can also be used as the adhesive resin of the specific layer.

The blending 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 in terms of weight ratio, particularly 8
It is preferably within the range of 0:2o to 5o:5o.

If the blending ratio of the other charge transport material and the m-phenylenediamine compound is less than 95:5, the effect of preventing a decrease in charge amount and sensitivity when the image forming process is repeated will be insufficient. On the other hand, if the blending ratio exceeds 25=75, the sensitivity of the photoreceptor may become insufficient.

Among the above-mentioned types of photosensitive layers, the content of the charge generating material in the single layer type organic photosensitive layer is within the range IJB of 2 to 20 parts by weight, particularly 3 to 20 parts by weight, based on 100 parts by weight of the binder resin.
Preferably, the amount is within the range of 15 parts by weight. Further, the content of the other charge transport material relative to 100 parts by weight of the binder resin is preferably within the range of 40 to 200 parts by weight, particularly within 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 other charge transporting materials is less than 40 parts by weight, there is a risk that the sensitivity of the photoreceptor may become insufficient or the residual potential may become large. . on the other hand,
If the content of the charge generating material exceeds 20 parts by weight, or if the content of other charge transporting materials exceeds 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, but
The same level as the conventional single-layer organic photosensitive layer, i.e. 10~
It is preferably within the range of 50 μm, especially 15 to 25 μm.

Among the layers constituting the MIFtI type organic photosensitive layer, the content of the charge generation material in the organic charge generation layer is within the range of 5 to 500 parts by weight based on 100 parts by weight of the binder resin.
In particular, it is preferably within the range of 10 to 250 parts by weight. If the content of the charge-generating material is less than 5 parts by weight, the charge-generating ability will be too small, and if it exceeds 500 parts by weight, the adhesion to the base material or other adjacent layers may deteriorate.

The thickness of the charge generation layer is not particularly limited, but is 0.01
It is preferable that the thickness is within the range of 0.1 to 2 μm.

Among the layers constituting the laminated organic photosensitive layer or the composite photosensitive layer, the content of other charge transporting materials in the charge transporting layer based on 100 parts by weight of the binder resin is within the range of 10 to 500 parts by weight, particularly It is preferably within the range of 25 to 200 parts by weight. If the content of the other charge transport material is less than 10 parts by weight, the charge transport ability will not be sufficient, and if it exceeds 500 parts by weight, the mechanical strength of the charge transport layer may decrease.

The thickness of the charge transport layer is not particularly limited, but is 2 to 10
0μm, special 1. : It is preferably within the range of 5 to 30 IIa.

In addition, the surface protective layer that can be formed on the outermost layer of each of the above types of photosensitive layers has the above-mentioned adhesive resin as its main component, and if necessary, it can also contain conductive finishing materials, benzoquinone-based ultraviolet absorbers, etc. An appropriate amount of additives can be included.

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

Note that if an antioxidant is used in combination with the organic layer of each type of photosensitive layer or the surface protective layer, functional components such as charge transport materials, which have structures susceptible to oxidation, may deteriorate due to oxidation. can be prevented.

The antioxidants include 2,6-di-tert-butyl-p-cresol, triethylene glycol-bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate]1.6- Hexanethiol-rubis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], pentaerythrityl-tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]
-butyl-4-hydroxyphenyl)propionate]
, 2.2thio-diethylenebis[3-(3,5-dit
ert-butyl-4-hydroxyphenyl)propione-+-]2,2-thiobis(4-methyl-6-tart
-butylphenol), N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxy-hydrocinnamamide), 1.3.5-trimethyl-2
,4,6-1lis(3,5-tert-butyl-4
-hydroxybenzyl)benzene and other phenolic antioxidants.

The conductive base material on which each of the above types of photosensitive layers is formed can be
It is formed into an appropriate shape, such as a sheet shape or a drum shape, depending on the structure.

The conductive base material may be entirely made of a conductive material such as a metal, or the base material itself may be made of a non-conductive structural material to impart conductivity to its surface. Also good.

In the former case, where the entire conductive base material is made of a conductive material, the conductive materials used include aluminum, copper, tin, platinum, gold, silver, whose surface is alumite-treated or untreated; Metal materials such as vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, and brass are preferred, and aluminum that has been anodized by the sulfuric acid alumite method and sealed with nickel acetate is particularly preferred. .

On the other hand, in the latter case, which imparts conductivity to the surface of a base material made of a non-conductive structural material, the above-mentioned metals or aluminum iodide may be added to the surface of the synthetic resin base material or glass base material. , 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 evaporation method or a wet plating method; A structure in which films of materials are laminated, or a structure in which a substance imparting conductivity is injected into the surface of the synthetic resin base material or glass base material can be adopted.

Note that the conductive base material may be surface-treated with a surface treatment agent such as a silane coupling agent or a titanium coupling agent to improve adhesion to the photosensitive layer, if necessary.

For each organic layer and surface protective layer of each type of photosensitive layer described above, a coating solution 71i for each layer containing each of the above-mentioned components is prepared, and these coating solutions are used to form the above-mentioned layer structure. Each layer can be sequentially coated onto a conductive substrate and dried or cured to form a laminate.

In addition, when preparing the above-mentioned coating liquid, various solvents can be used depending on the type of binder resin and the like used. The above solvents include aliphatic hydrocarbons such as n-hexane, octane and cyclohexane; aromatic hydrocarbons such as benzene, xylene and toluene; halogenated hydrocarbons such as dichloromethane, carbon tetrachloride, chlorobenzene and methylene chloride; methyl Alcohols such as alcohol, ethyl alcohol, isopropyl alcohol, allyl alcohol, cyclopentanol, benzyl alcohol, furfuryl alcohol, diacetone alcohol; dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, etc. Ethers; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone; esters such as ethyl acetate, methyl acetate; dimethyl formamide; dimethyl sulfoxide, etc. Various solvents are listed, and these may be used alone or in combination of two or more. It is used as Further, when preparing the above-mentioned coating liquid, a surfactant, a leveling agent, etc. may be used in combination in order to improve dispersibility, coating properties, etc.

Further, the above coating liquid can be prepared by a conventional method such as a mixer,
It can be prepared using a ball mill, paint shaker, sand mill, attritor, ultrasonic disperser, etc.

<Examples> The present invention will be described in more detail below based on Examples.

Examples 1 to 4 100 parts by weight of poly-(4,4'-cyclohexylidene diphenyl)carbonate (Mitsubishi Gas Kagakusei, trade name Polycarbonate Z) as a binder resin, 4,10-dibromo as a charge generating material -dibenzo [dcr, I
8 parts by weight of 6.12-dione (27-dibromoanthanthrone) and 0.2 parts by weight of X-type metal-free phthalocyanine (manufactured by Dainippon Ink Co., Ltd.), 3.3'-dimethyl-N as a charge transport material ,N,N',N
40 parts by weight of 'tetrakis-4-methylphenyl(1,1'-biphenyl)-4,4'-diamine and N,
N, N', N'-tetrakis(3-tolyl)-1,3
- 40 parts by weight of phenylenediamine, 5 parts by weight of 2,6-tert-butyl-p-cresol (manufactured by Kawaguchi Chemical Co., Ltd., trade name: ANTAGE BHT) as an antioxidant, polydimethylsiloxane (silicone oil) as a plasticizer
Add 20 parts by weight of a specific compound with a triplet excitation energy within the range of 60 to 68 kcal/moff as shown in the table below to 0.1 parts by weight, mix and disperse with a predetermined amount of tetrahydrofuran using an ultrasonic disperser to form a single layer. A coating solution for a mold photosensitive layer was prepared. After coating this coating solution on an A1 aluminum tube with an outer diameter of 78 w and a length of 340 mm, it was heated at 100°C in a dark place.
The mixture was heated and dried for 30 minutes to form a single-layer photosensitive layer with a thickness of about 24 μm, thereby producing a drum-shaped electrophotographic photosensitive member.

Comparative Example 1.2 In the same manner as in Examples 1 to 4 above, except that 20 parts by weight of the compound shown in the following table and having a triplet excitation energy of less than 60 kcai)/mag was used instead of the specific compound. An electrophotographic photoreceptor was produced.

Comparative Example 3.4 In place of the specific compound, a compound 2 with a triplet excitation energy exceeding 68 kcaN/ll1o (l) shown in the following table was used.
Electrophotographic photoreceptors were produced in the same manner as in Examples 1 to 4 above, except that 0 part by weight was used.

Comparative Example 5 Example 1 above except that the specific compound was not blended.
An electrophotographic photoreceptor was produced in the same manner as in 4.

Comparative Example 6 N,N,N',N'-tetrakis(3-tolyl)-1
,3-phenylenediamine is not blended, 3゜3'-dimethyl-N,N,N',N'-tetrakis-4-methylphenyl(1,1"-biphenyl)-4,4'-
An electrophotographic photoreceptor was produced in the same manner as in Comparative Example 5 above, except that 80 parts by weight of diamine was blended as a charge transport material.

The following tests were conducted on the electrophotographic photoreceptors produced in the above Examples and Comparative Examples.

Initial Surface Potential Measurement Each of the electrophotographic photoreceptors described above was loaded into an electrostatic copying tester (Dientic Cynthia 30M, manufactured by Dientic Co., Ltd.), and its surface was positively charged to give a surface potential of V + s, p, (
V) was set at 11.

Half-decreased exposure amount and residual potential measurement Each electrophotographic photoreceptor in the above-mentioned charged state is exposed using a halogen lamp which is the exposure light source of the above-mentioned electrostatic copying tester,
The time required for the surface potential V + s, p, (V) to be halved is determined, and the half-reduction exposure fit E 1/2 (μJ
/-) was calculated.

Further, the surface potential 0.15 seconds after the start of the exposure was determined as residual potential V+r,p (V) δ1.

At two points on each electrophotographic photoreceptor, the surface potentials V , s, p, , V , s,
p, s and \residual potential V +, r, p, )V +br
, I).

After measuring [the above, unit (V)], this electrophotographic photoreceptor was preheated to 60°C in a dark place and stored for 20 minutes. V,
The b side was masked with a light shielding member, and the surface of the electrophotographic photoreceptor was exposed to 15,001 ux of white light including ultraviolet rays for 20 minutes using a white fluorescent lamp. After the exposure, the electrophotographic photoreceptor was left in a dark place at room temperature for 30 minutes and cooled.
The surface potential of the above two places is V 2aS-p,
(Exposed side) , V2bS, I), (Light shielded side), and residual potential V2ar-p, (Exposed side), V 2br,
p, (J side) [unit (V)] was measured.

Based on the above measurement values, calculate the surface potential change value ΔVs, p, (V) after UV irradiation using the formula (a) below, and calculate the surface potential change value ΔVs, p, (V) after UV irradiation using The residual potential change value ΔVr, p, (V) was calculated.

Δvs, p, − (V 2 * s, p, V + * 5 − 1), ) − (V
2bs, p, V +bS-p,)ΔV+-i
(V) - V, s, p, (V) -V3 s, p, ('l
・ (The following table shows the mucilage of C1 or higher. (Left below)... (al Δv r, p, - (V2ar-p, V+mr, p,) (V2
br, p, V+br, p, )...(b) Measurement of surface potential after repeated exposure Each electrophotographic photoreceptor was transferred to a copying machine (manufactured by Sanda Kogyo Co., Ltd., DC-
111 model) and processed 500 copies, it was loaded into an electrostatic copying tester (Dientic Cynthia 30M, manufactured by Gientic Co., Ltd.), the surface of which was positively charged, and the number of copies after repeated exposure was The surface potential V3s,p, (V) was measured.

Further, the surface potential change value ΔVl-3(v) after repeated exposure was calculated using the following formula (C).

From the above results, the triplet excitation energy is 60 kc.
The surface potential and residual potential of the electrophotographic photoreceptors of Comparative Example 1゜2, which used compounds with less than al/mop, were reduced by ultraviolet irradiation to the same extent as Comparative Example 5, which did not contain the specific compound. did.

Also, the triplet excitation energy is 68 kcal/m
The electrophotographic photoreceptors of Comparative Example 3.4 using a compound exceeding
In addition, the surface potential and residual potential decreased significantly. In contrast, the triplet excitation energy is 60-68 kca
The electrophotographic photoreceptors of Examples 1 to 4 using specific compounds within the range of II/1ool all had smaller changes in surface potential and residual potential due to ultraviolet irradiation than the comparative examples above. From this, it was found that the electrophotographic photoreceptors of Examples 1 to 4 were resistant to deterioration by ultraviolet light. In addition, the electrophotographic photoreceptors of Examples 1 to 4 and Comparative Example 5 all had a higher surface potential due to repeated exposure than Comparative Example 6, which did not use an m-phenylenediamine compound as a charge transporting material. The amount of change was small, and from this fact, it was found that the above-mentioned specific compound does not affect the preventive effect of the m-phenylenediamine-based compound against a decrease in the amount of charge, a decrease in sensitivity, and the like.

<Effects of the Invention> The electrophotographic photoreceptor of the present invention is constructed as described above, and contains m-phenylenediamine which is excellent in preventing a decrease in charge amount and a decrease in sensitivity when the image forming process is repeated. Since the layer containing the m-phenylenediamine-based compound contains a specific compound that has the effect of preventing UV deterioration of the m-phenylenediamine-based compound, it can be used particularly when the photoreceptor is heated, such as during operation of an image forming apparatus. In this case, the sensitivity does not easily decrease even when irradiated with light containing ultraviolet light such as a fluorescent lamp, a xenon lamp, or sunlight.

Claims (1)

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