JPH0644157B2 - Electrophotographic photoreceptor for positive charging - Google Patents

Description

The present invention relates to an electrophotographic photoreceptor, and more particularly to a positive charging photoreceptor.

[Conventional technology]

Conventionally, for example, as an electrophotographic photoreceptor, a photoreceptor having a photosensitive layer containing an inorganic photoconductive substance such as selenium, zinc oxide, and cadmium sulfide has been widely used.

On the other hand, the use of various organic photoconductive materials as materials for the photosensitive layer of an electrophotographic photoreceptor has been actively developed and studied in recent years.

For example, JP-B-50-10496 describes an organic photoreceptor having a photosensitive layer containing poly-N-vinylcarbazole and 2,4,7, -trinitro-9-fluorenone. However, this photoreceptor is not always satisfactory in sensitivity and durability. In order to improve such a defect, an attempt has been made to develop an organic photoreceptor having high sensitivity and high durability by separately sharing a charge generating function and a charge transporting function with different substances in a photosensitive layer. ing.

In such a so-called function-separated type electrophotographic photosensitive member, since substances exhibiting respective functions can be selected from a wide range of substances, an electrophotographic photosensitive member having arbitrary characteristics can be prepared relatively easily. It is possible.

Many substances have been proposed as charge generating substances effective for such a function-separated type electrophotographic photoreceptor. An example of using an inorganic substance is amorphous selenium, which is combined with an organic charge transport substance, as described in, for example, Japanese Patent Publication No. 43-16198.

A number of electrophotographic photoreceptors using organic dyes and organic pigments as charge generating substances have also been proposed. For example, one having a photosensitive layer containing a bisazo compound is disclosed in JP-A-47-3.
It is already known from 7543, 55-22834, 54-79632, 56-116040, etc.

By the way, the conventional photoconductor using the organic photoconductive substance is usually used for negative charging.

The reason for this is that when negative charging is used, the mobility of holes in the charge is large, which is advantageous in terms of photosensitivity and the like. However, it has been found that the use of such negative charging has the following problems. That is, there is a problem that ozone is likely to be generated in the atmosphere during negative charging by the charger, which deteriorates environmental conditions. Still another problem is that a positive polarity toner is required for developing the negative charging photoreceptor, but the positive polarity toner is difficult to manufacture in view of the triboelectric charging series for the ferromagnetic particles.

Therefore, it has been proposed to use a photoconductor using an organic photoconductive substance with positive charging. For example, when a photoconductor is formed by laminating a charge transport layer on a charge generation layer, a high electron transport capability such as trinitrofluorenone is used for the charge transport layer in order to efficiently cancel positive charges on the photoconductor surface. However, the substance is carcinogenic and extremely unsuitable for pollution.

Further, as a positive charging photoreceptor, U.S. Pat. No. 3,615,414 discloses a thiapyrylium salt (charge-generating substance) contained in a eutectic complex with a polycarbonate (binder resin). However, this known photoconductor has a drawback that a memory phenomenon is large and a ghost is easily generated. Further, US Pat. No. 3357989 also shows a photoconductor containing phthalocyanine.However, phthalocyanine has the disadvantage that its characteristics vary depending on the crystal type and that the crystal type must be strictly controlled. However, the memory phenomenon is large, and the short wavelength sensitivity is low, so that it is unsuitable for a copying machine using a visible light including the short wavelength as a light source.

Although various attempts have been made to obtain a photoconductor for positive charging as described above, there are many problems to be solved in terms of photosensitivity, memory, pollution and the like.

Therefore, a photosensitive layer having a laminated structure is used in which a charge generation layer containing a charge generation substance that generates holes and electrons upon light irradiation is used as an upper layer (surface layer), and a charge transport layer containing a charge transport substance having a hole transport function is used as a lower layer. It is conceivable to use the photoconductor that it has for positive charging. Furthermore, it is considered that a photoreceptor having a single-layered photosensitive layer containing the charge generating substance and the charge transporting substance can also be used for positive charging. In such a photoconductor for positive charging, if a charge generating substance having an electron-withdrawing group is used in the structure, the movement of electrons for canceling the positive charge on the surface of the photoconductor becomes faster. It is considered that high sensitivity characteristics can be obtained.

However, in each of the positive charging photoreceptors, since a layer containing a charge generating substance is formed as a surface layer, light irradiation,
The presence of a charge-generating substance that is sensitive to external effects such as corona discharge, humidity, and mechanical friction in particular, will be present near the surface layer, and the electrophotographic performance will deteriorate during storage of the photoconductor and during image formation, resulting in poor image quality. Will start to decline.

In the conventional negative charging photoreceptor having the charge transport layer as the surface layer, the effects of the various parts described above are extremely small, and the charge transport layer has a function of protecting the lower charge generating layer.

On the other hand, in the case of a positive charging photoreceptor, the layer containing the charge generating substance, which is the surface layer, is subject to mechanical abrasion and damage due to external action, especially development and cleaning, and image defects such as white spots and white streaks. In addition, deterioration of electrophotographic performance such as surface potential, sensitivity, memory and residual potential will occur.

Therefore, for example, a thin protective layer made of an insulative and transparent resin may be provided to reinforce the layer containing the charge-generating substance. However, the charge generated during light irradiation is blocked by the protective layer and photoconductive There is a problem that is lost.

Further, it is possible to increase the wear resistance and scratch resistance of the charge generation layer by increasing the film thickness of the charge generation layer which is the surface layer, but there is a problem that an increase in the film thickness causes a decrease in sensitivity.

[Object of the Invention]

Therefore, an object of the present invention is to provide an electrophotographic photoreceptor that is suitably configured for positive charging using an organic photoconductive material, has excellent scratch resistance, high sensitivity, durability, and is superior in ozone oxidation resistance. Especially.

[Structure and Operation and Effect of Invention]

An object of the present invention is to provide an electrophotographic photoreceptor in which a charge transport layer, a charge generating layer and, if necessary, a protective layer are sequentially laminated on a conductive support, wherein the charge generating layer contains a charge transporting substance, and This is achieved by a positive charging electrophotographic photoreceptor containing a compound represented by the following general formula in the generating layer or the protective layer.

General formula In the formula, R ₁ , R ₂ , R ₃ and R ₄ each represent an alkyl group having 1 to 18 carbon atoms, and R ₅ represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms.

As described in the prior art, in the positive charging photoreceptor using the organic photoconductive material, the charge generation layer (hereinafter, referred to as CG
(It may be abbreviated as L) becomes a surface layer and thus lacks scratch resistance, and it is necessary to increase the CGL film thickness in order to improve durability. However, increasing the film thickness causes a decrease in sensitivity. As a means for suppressing this decrease in sensitivity, there is the addition of a charge transport substance (hereinafter, sometimes abbreviated as CTM) into CGL, but this CTM is more likely to be oxidized by ozone than a charge generation substance (hereinafter sometimes abbreviated as CGM). Since it has a structure that is easily affected by ozone, it is easily deteriorated by ozone and the durability of the photoreceptor is impaired.

As a result of earnest studies on improvement of ozone degradability, the present inventors have found that by incorporating an alkylidene bisphenol-based compound into CGL, which is the surface layer of a photoreceptor for positive charging,
The inventors have found that the above deterioration can be remarkably reduced and have completed the present invention.

The details of the action and effect are unknown, but ozone is C in CGL.
It is believed that the CTM is protected by acting on the compounds of the invention prior to degrading the TM and guarding against further ozone oxidation.

Since the compound of the present invention prevents the ozone deterioration of CTM by its own oxidation, in a photoreceptor having a protective layer (hereinafter sometimes abbreviated as OCL) provided on CGL, if necessary, it is added to OCL. However, the charge transport layer containing CTM as a main component (hereinafter,
(Sometimes abbreviated as CTL).

Hereinafter, the present invention will be described in more detail.

In the compound represented by the above general formula, R ₁ , R ₂ , R
_The alkyl group represented by ₃ and R ₄ may be linear or branched, and examples thereof include a methyl group, an ethyl group, a propyl group, an i-butyl group, a t-butyl group, a ventil group, a t-pentyl group,
Examples thereof include an octyl group, a t-octyl group and a dodecyl group. The alkyl group represented by R ₅ is preferably a linear alkyl group, and specific examples thereof include a methyl group, an ethyl group, a propyl group, a hexyl group, a nonyl group and a decyl group.

The compound of the present invention can be obtained as an antioxidant for plastics, synthetic fibers, elastomers, waxes, hydraulic oils and the like, but is not limited to U.S. Patent Nos. 2,792,428, 2,796,445, and
2,841,619, JP-B-40-16539, JP-A-50-6338, Journal of the Chemical Society (J.Che
m.Soc.), p. 243, 1954, etc.

Typical specific examples of the compounds preferably used in the present invention are shown below, but the invention is not limited thereto.

When used in CGL, the amount of the compound of the present invention added is 0.1 to 100% by weight, preferably 1 to 50% by weight, particularly preferably 5 to 25% by weight, based on CTM in CGL. When used in OCL, it is 0.1 to 100% by weight, preferably 1 to 50% by weight based on the binder resin in OCL.
% By weight.

Next, the structure of the photoreceptor of the present invention will be described with reference to the drawings. As a photoconductor, for example, as shown in FIG. 1, C on a support 1 (a conductive support or a sheet on which a conductive layer is provided) is used.
A photosensitive layer 4 having a laminated structure in which a charge transport layer 2 containing TM and a binder resin as necessary is used as a lower layer, and a charge generation layer 3 containing CGM and CTM and a binder resin as needed is used as an upper layer. 2, a protective layer (OCL) 4 is provided on the photosensitive layer shown in FIG. 1, and the like, but an intermediate layer may be provided between the support and the photosensitive layer. .

Next, as the charge generating substance suitable for the present invention, any of inorganic pigments and organic dyes can be used as long as they attract visible light and generate free charges. In addition to inorganic pigments such as amorphous selenium, trigonal selenium, selenium-arsenic alloy, selenium-tellurium alloy, cadmium sulfide, cadmium selenide, cadmium sulphide selenide, mercury sulfide, lead oxide, lead sulfide, the following typical examples You may use the organic pigment shown by.

(1) Monoazo pigments, polyazo pigments, metal complex salt azo pigments, pyrazolone azo pigments, azo pigments such as stilbene azo and thiazole azo pigments (2) Perylene pigments such as perylene anhydride and perylene imide (3) Anthraquinone derivatives , Anthraquinone-based or polycyclic quinone-based pigments such as anthanthrone derivative, dibenzpyrenequinone derivative, pyrantrone derivative, violanthrone derivative and isoviolanthrone derivative (4) Indigooid pigment such as indigo derivative and thioindigo derivative (5) Metal phthalocyanine And phthalocyanine pigments such as metal-free phthalocyanine (6) Carbonium pigments such as diphenylmethane pigments, triphenylmethane pigments, xanthene pigments and acridine pigments (7) azine pigments, oxazine pigments and thiazine pigments Quinone imine pigments (8) Methine pigments such as cyanine pigments and azomethyl pigments (9) Quinoline pigments (10) Nitro pigments (11) Nitroso pigments (12) Benzoquinone and naphthoquinone pigments (13) Naphthalimide pigments (14) Perinone-based pigments such as bisbenzimidazole derivatives Various azo pigments having an electron-withdrawing group are used because of good electrophotographic properties such as sensitivity, memory phenomenon, and residual potential, but they are often used in terms of ozone resistance. Cyclic quinone pigments are most preferred.

Although the details are unknown, it is presumed that the azo group is susceptible to ozone oxidation and the electrophotographic properties deteriorate, but the polycyclic quinones are inactive to ozone.

Examples of the azo pigments used in the present invention include those shown in the following exemplary compound groups [I] to [V].

In addition, an exemplary compound consisting of the following polycyclic quinone pigment [VI]
~ [VIII] can be most preferably used as CGM.

Next, the charge-transporting substance that can be used in the present invention is not particularly limited. Lysine derivative, styryl compound, hydrazone compound, pyrazoline derivative, oxazolone derivative, benzothiazole derivative, benzimidazole derivative, quinazoline derivative, benzofuran derivative, acridine derivative, phenazine derivative, aminostilbene derivative, poly-N-vinylcarbazole, poly-1- It may be vinylpyrene, poly-9-vinylanthracene and the like.

However, in addition to the excellent ability of transporting holes generated upon light irradiation to the support side, those suitable for combination with the carrier generating substance are preferably used. Examples of such CTM include the following exemplified compound group [IX] or The still compound represented by [X] is used.

In addition, hydrazone compounds represented by the following exemplified compound groups [XI] to [XV] can also be used as CTM.

Further, a pyrazoline compound represented by the following exemplified compound [XVI] can also be used as the CTM.

Further, as CTM, amino derivatives represented by the following exemplified compound group [XVII] can also be used.

Next, the protective layer which may be used in the present invention has a volume resistance of 10 ⁸ Ωcm or more as a binder, preferably 10 ¹⁰ Ωcm or more,
More preferably, a transparent resin of 10 ¹³ Ω · cm or more is used. The binder contains at least 50% by weight of a resin that is cured by light or heat.

Examples of the resin that is cured by light or heat include thermosetting acrylic resin, silicone resin, epoxy resin, urethane resin, urea resin, phenol resin, polyester resin, alkyd resin, melamine resin, and photocurable cinnamic acid resin. Alternatively, there are copolymerization or co-condensation resins of these, and all of the photo- or thermosetting resins provided for the electrophotographic material can be used. If necessary, the protective layer may contain less than 50% by weight of a thermoplastic resin for the purpose of improving workability and physical properties (preventing cracks, imparting flexibility, etc.). Examples of such thermoplastic resin include polypropylene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, epoxy resin, butyral resin,
Polycarbonate resin, silicone resin, or copolymer resin thereof, for example, vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride copolymer resin, polymer organic semiconductor such as poly-N-vinylcarbazole , And all other thermoplastic resins used for electrophotographic materials are used.

Further, the protective layer may contain an electron accepting substance,
In addition, if necessary, an ultraviolet absorber or the like may be contained for the purpose of protecting the CGM, and it is dissolved in a solvent together with the binder and coated / dried by, for example, dip coating, spray coating, blade coating, roll coating or the like to have a size of 2 μm or less. It is preferably formed to a layer thickness of 1 μm or less.

The layer structure of the photosensitive layer of the photoreceptor of the present invention is a laminated structure as described above, but the charge transport layer, the charge generation layer or the protective layer is intended to improve sensitivity, reduce residual potential or reduce fatigue during repeated use. As, it is possible to contain one kind or two or more kinds of electron accepting substances.

Examples of the electron accepting substance that can be used in the present invention include succinic anhydride, maleic anhydride, dibromomaleic anhydride, phthalic anhydride, tetrachlorophthalic anhydride, tetrabromophthalic anhydride, 3-nitrophthalic anhydride, 4- Nitrophthalic anhydride, Pyromellitic dianhydride, Mellitic anhydride, Tetracyanoethylene, Tetracyanoquinodimethane, o-Dinitrobenzene, m-Dinitrobenzene, 1,
3,5, -Trinitrobenzene, paranitrobenzonitrile, picryl chloride, quinone chlorimide, chloranil, bulmannyl, 2-methylnaphthoquinone, dichlorodicyanoparabenzoquinone, anthraquinone, dinitroanthraquinone, trinitrofluorenone, 9-fluorenylidene (dicyanomethylene Malonodinitrile], polynitro-9-fluorenylidene- [dicyanomethylene malonodinitrile], picinic acid, o-nitrobenzoic acid, p-nitrobenzoic acid, 3,5-dinitrobenzoic acid, pentafluorobenzoic acid, 5-nitro Salicylic acid, 3,5-
Examples thereof include dinitrosalicylic acid and phthalic acid.

Examples of the binder resin usable in the photosensitive layer in the present invention include polyethylene, polypropylene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, epoxy resin, polyurethane resin, phenol resin, polyester resin, alkyd resin, and polycarbonate resin. , Addition resins such as silicone resins and melamine resins, polyaddition resins, polycondensation resins, and copolymer resins containing two or more of the repeating units of these resins, for example vinyl chloride-vinyl acetate copolymers. In addition to insulating resins such as polymer resins and vinyl chloride-vinyl acetate-maleic anhydride copolymer resins, polymer organic semiconductors such as poly-N-vinylcarbazole may be mentioned.

Next, as a conductive support for supporting the photosensitive layer, a metal plate such as aluminum or nickel, a metal drum or a metal foil, a plastic film deposited with aluminum, tin oxide, indium oxide or the like or a paper coated with a conductive substance A film or drum made of plastic, etc. can be used.

The charge transport layer is provided by a method in which the above-mentioned CTM is dissolved or dispersed in a suitable solvent alone or together with a suitable binder resin and then dried.

Examples of the solvent used for forming CTL include N, N-
Examples thereof include dimethylformamide, benzene, toluene, xylene, monochlorobenzene, 1,2-dichloroethane, dichloromethane, 1,1,2-trichloroethane, tetrahydrofuran, methyl ethyl ketone, ethyl acetate and butyl acetate.

The thickness of the formed CTL is preferably 5 to 50 μm, particularly preferably 5 to 30 μm.

CTM of 20 to 2 per 100 parts by weight of binder resin in CTL
The amount is 00 parts by weight, preferably 30 to 150 parts by weight.

If the content ratio of CTM is less than this range, the photosensitivity is poor and the residual potential tends to be high, and if it is more than this range, the solvent solubility is poor.

The charge generation layer should be formed in the same manner as in the case of CTL by coating the above CGM and CTM separately or together or dissolving or dispersing them in a suitable solvent alone or with a suitable binder resin and drying. You can

When forming the CGL by dispersing the CGM, the CGM is preferably a powder or granule having an average particle size of 2 μm or less, preferably 1 μm or less. That is, if the particle size is too large, the dispersion in the layer becomes poor, and the particles partially project on the surface to deteriorate the smoothness of the surface. Toner filming phenomenon is likely to occur due to particles attached.

However, if the above particle size is too small, it tends to aggregate,
It is desirable to set the lower limit of the average grain size to 0.01 μm, because the resistance of the layer increases, the crystal defects increase and the sensitivity and repeatability deteriorate, or there is a limit in miniaturization.

The CGL can be provided by the following method.
That is, the described CGM is made into fine particles in a dispersion medium by a ball mill, a homomixer, etc., and the binder resin and C
This is a method of applying a dispersion liquid obtained by adding TM and mixing and dispersing. In this method, if the particles are dispersed under the action of ultrasonic waves, uniform dispersion is possible.

20 to 200 CGM per 100 weight of binder resin in CGL
Parts by weight, preferably 25-100 parts by weight, with a CTM of 20
˜200 parts by weight, preferably 30 to 150 parts by weight.

If the CGM is less than this, the photosensitivity is low and the residual potential is increased, and if it is more than this, the dark decay is increased and the receptive potential is lowered.

The film thickness of the CGL formed as described above is preferably 1 to 10 μm, particularly preferably 2 to 7 μm.

The film thickness ratio of CGL and CTL is preferably 1: (1-30).

〔Example〕

The present invention will be described below with reference to examples, but the embodiments of the present invention are not limited thereby.

Example 1 Vinyl chloride-vinyl acetate-on a conductive support made of a polyester film laminated with aluminum foil.
A 0.1 μm thick intermediate layer made of a maleic anhydride copolymer (S-REC MF-10, manufactured by Sekisui Chemical Co., Ltd.) was formed.

Next, polycarbonate resin (Panlite L-1250, Teijin Chemicals Ltd.) / CTM (IX-75) = 100/75 (weight ratio)
A 1,2-dichloroethane solution containing 16.5% by weight was dip-coated on the intermediate layer to form a charge transport layer having a thickness of 15 μm. Then, in a ball mill in 1,2-dichloroethane so that the sublimated 4,10-dibromoanthanthrone (VI-3) / Panlite L-1250 = 1/2 (weight ratio) as CGM would be 9% by weight. C that was crushed for 24 hours and then dispersed for 24 hours
75% by weight of TM (IX-75) to Panlite L-1250
And 10% by weight of the exemplified compound (3) was added to CTM. A dispersion liquid prepared by adding monochlorobenzene to this solution so that 1,2-dichlorobenzene / monochlorobenzene = 7/3 (volume ratio) is spray-coated on the CTL and dried to give a charge generation layer of 5 μm. Was formed to obtain a photoreceptor according to the present invention having a photosensitive layer having a laminated structure.

Comparative Example 1 A comparative photoconductor was obtained in the same manner as in Example 1, except that the exemplified compound (3) was omitted.

Example 2 The example compound in place of the example compound (3) in example 1
A photoconductor was obtained in exactly the same manner except that (4) was used.

Example 3 1.55 parts by weight of a thermosetting acrylic-melamine-epoxy (1: 1: 1) resin on a photosensitive layer (the same as the photoreceptor of Comparative Example 1) except for the exemplified compound (3) of Example 1 and Exemplified compound
(3) 0.155 parts by weight of a coating solution prepared by dissolving 0.155 parts by weight in a mixed solvent of monochlorobenzene / 1,1,2-trichloroethane was spray-coated and dried to obtain a photoreceptor having a protective layer with a thickness of 1 μm.

Example 4 A silicone hard coat primer PH91 (manufactured by Toshiba Silicon Co., Ltd.) was formed on the photosensitive layer from which the exemplified compound (3) of Example 1 was removed.
Is sprayed to a thickness of 0.1 μm, and a solution containing silicon hard coat Tosguard 510 (manufactured by Toshiba Silicon Co., Ltd.) and Exemplified Compound (3) is added to the resin so that the amount is 10 parts by weight based on 100 parts by weight of the resin. After coating and drying, a protective layer having a thickness of 1 μm was formed to obtain a photoreceptor.

Example 5 Vinyl chloride-vinyl acetate-on a conductive support made of a polyester film laminated with aluminum foil.
Maleic anhydride copolymer (S-REC MF-10, supra)
To form an intermediate layer having a thickness of about 0.1 μm.

Then, as a coating liquid for CTL, 8% by weight of butyral resin (S-REC BX-1, manufactured by Sekisui Chemical Co., Ltd.) and CTM (IX-7
5) A coating solution obtained by dissolving 6% by weight in methyl ethyl ketone was applied onto the intermediate layer and dried to form a charge transport layer having a thickness of 10 μm. Next, 0.2 g of CGM (IV-7) was added to Paint Conditioner, Red Devil.
(Manufactured by the company) for 30 minutes and add polycarbonate resin (Panlite L-1250, previously mentioned) to this, 1,2-dichloroethane / 1,
8.3 g of a solution prepared by dissolving 0.5% by weight of a 1,2-trichloroethane mixed solvent was added and dispersed for 3 minutes, and then a polycarbonate resin, CTM (IX-75) and Exemplified compound (3) were added to each of 3.3 parts. % By weight, 2.6% by weight and 0.2
19.1 g of a solution obtained by dissolving it in a 1,2-dichloroethane / 1,1,2-trichloroethane mixed solvent so as to be 6% by weight was added and dispersed for another 30 minutes. The dispersion thus obtained is spray-coated on the CTL and dried to 5 μm.
A thick charge generation layer was formed to obtain a photoreceptor having a laminated photosensitive layer.

Comparative Example 2 A comparative photoreceptor was obtained in exactly the same manner as in Example 5, except that the exemplified compound (3) was omitted.

Example 6 The example compound in place of the example compound (3) in the example 5
A photoconductor was obtained in exactly the same manner except that (4) was used.

Example 7 An exemplary compound (3) similar to that of Example 3 was formed on the photosensitive layer (same as the photoreceptor of Comparative Example 2) excluding the exemplary compound (3) of Example 5.
A protective layer containing was installed to obtain a photoreceptor.

Example 8 A protective layer containing the same exemplified compound (3) as in Example 4 was placed on the photosensitive layer excluding the exemplified compound (3) of Example 5,
A photoconductor was obtained.

Comparative Example 3 A comparative photoreceptor was obtained in the same manner as in Example 1 except that the following compound (A) was used in place of the exemplified compound (3).

(Compound A) Comparative Example 4 A comparative photoconductor was obtained in exactly the same manner as in Example 1, except that the following compound (B) was used in place of the exemplified compound (3).

(Compound B) Comparative Example 5 A comparative photoconductor was obtained in the same manner as in Example 1 except that the following compound (C) was used in place of the exemplified compound (3).

(Compound C) Comparative Example 6 A comparative photoreceptor was obtained in exactly the same manner as in Example 1 except that the following compound (D) was used in place of the exemplified compound (3).

(Compound D) The photoreceptor samples obtained as described above were evaluated for ozone resistance by the ozone fatigue tester shown below. That is, an ozone tester (Model O-1-2 manufactured by Nippon Ozone Co., Ltd.) and an ozone monitor (Model EG-2001 manufactured by Ebara Jitsugyo Co., Ltd.) were attached to an electrostatic tester (SP-428 manufactured by Kawaguchi Denki Seisakusho). The device was used. A photosensitive member was mounted at an ozone concentration of 90 ppm, a voltage of +6 KV was applied, and the photosensitive layer was charged by corona discharge for 5 seconds, and then left for 5 seconds (the potential at this time is the initial potential V ₀ ) and then exposed. The operation was repeated 100 times by irradiating light from a tungsten lamp while the illuminance on the layer surface was 14 lux.

When the potential after irradiation 100 times is V ₁ , V ₁ / V ₀ × 100
(%) Represents ozone resistance. V ₁ / V ₀ indicates the degree of potential decrease after 100 times of repetition, and the larger the value, the more preferable.

Further, the exposure amount ▲ E ⁶⁰⁰ ₁₀₀ ▼ (lux seconds) required to attenuate the initial potential from +600 V to +100 V without introducing ozone was also measured. The smaller the value, the higher the sensitivity. These results are shown in the attached table.

It can be seen from the attached table that all of the photoconductors of the present invention are excellent in ozone resistance and electrophotographic properties, whereas the comparative photoconductor is markedly deteriorated by ozone and has poor electrophotographic properties.

[Brief description of drawings]

1 and 2 are sectional views of the positive charging photoreceptor of the present invention. 1 ... Support 2 ... Charge transport layer 3 ... Charge generation layer 4 ... Photosensitive layer 5 ... Charge transport material (CTM) 6 ... Charge generation material (CGM) 7 ... Protective layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-57-14844 (JP, A) JP-A-61-156131 (JP, A)

Claims (1)

[Claims] 1. An electrophotographic photosensitive member comprising a conductive support, and a charge transport layer, a charge generating layer and, if necessary, a protective layer, which are sequentially laminated, wherein the charge generating layer contains a charge transporting substance. An electrophotographic photoreceptor for positive charging, comprising a compound represented by the following general formula in a layer or a protective layer. General formula [In the formula, R ₁ , R ₂ , R ₃ and R ₄ each represent an alkyl group having 1 to 18 carbon atoms, and R ₅ represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. ]