JPS6350849A - Electrophotographic sensitive body for positive charging - Google Patents

Abstract

PURPOSE:To improve the scratch resistance and durability and to provide superior resistance to oxidation by ozone by incorporating an electric charge transferring substance into the electric charge generating layer and a specified compd. into the generating layer or the protective layer. CONSTITUTION:An electric charge transferring layer 2 and an electric charge generating layer 3 are laminated on an electrically conductive support 1 an a protective layer 7 is formed on the layer 3 as required. The electric charge generating layer 3 contains an electric charge transferring substance 5b and the layer 3 or the protective layer 7 contains a compd. represented by formula I (where each of R1-R3 is 1-4C alkyl). When the substance 5b is a styryl or hydrazone compd. and the thickness of the layer 3 is 2-7mum, a more significant effect is shown. Since the compd. represented by the formula I prevents the deterioration of the substance 5b by ozone by self-oxidation, the compd. is preferably incorporated into the protective layer 7 formed on the layer 3 as required but it may be incorporated into the layer 3 or may be further incorporated into the layer 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an electrophotographic photoreceptor, and particularly to a positively 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, or cadmium sulfide has been widely used.

On the other hand, the use of various organic photoconductive substances as materials for photosensitive layers of electrophotographic photoreceptors has been actively developed and researched in recent years.

For example, in Japanese Patent Publication No. 50-10496, poly-N-
vinylcarbazole and 2.4,7. -) Dinitro-9-
A photoreceptor having a photosensitive layer containing fluorenone is described. However, this photoreceptor is not necessarily satisfactory in sensitivity and durability. In order to improve these drawbacks, attempts have been made to develop organic photoreceptors with high sensitivity and durability by assigning the charge generation function and charge transport function to different substances in the photosensitive layer. ing.

In such so-called function-separated type electrophotographic photoreceptors, it is possible to select substances that exhibit each function from a wide range of materials, so it is relatively easy to produce electrophotographic photoreceptors with arbitrary characteristics. It is possible to do so.

Many substances have been proposed as charge-generating substances that are effective for such functionally separated electrophotographic photoreceptors. Examples of using inorganic substances include, for example, Japanese Patent Publication No. 43-1619
As described in Publication No. 8, there is amorphous selenium, which is combined with an organic charge transport material.

In addition, many electrophotographic photoreceptors have been proposed using organic dyes or organic pigments as charge-generating substances.
-37543, 55-22834, 54-79
This is already known from publications such as No. 632 and No. 56-116040.

By the way, the conventional photoreceptor 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 among the charges is large, which is advantageous in terms of photosensitivity and the like. However, it has been found that using such negative charging causes the following problems. That is, there is a problem in that ozone is likely to be generated in the atmosphere during negative charging by the charger, worsening the environmental conditions. Still another problem is that positive polarity toner is required for development of negatively charged photoreceptors, but positive polarity toner is difficult to manufacture in view of the triboelectric charging sequence with respect to ferromagnetic charged particles.

Therefore, it has been proposed to use a positively charged photoreceptor using an organic photoconductive substance. For example, when forming a photoreceptor by laminating a charge transport layer on a charge generation layer, a material having a high electron transport ability, such as trinitrofluorenone, is used in the charge transport layer in order to efficiently cancel the positive charge on the surface of the photoreceptor. However, the substance is carcinogenic and extremely unsuitable from a pollution standpoint.

Furthermore, as a positive charging photoreceptor, U.S. Patent No. 361541
Specification No. 4 discloses a product containing a thiapyrylium salt (charge generating substance) so as to form a eutectic complex with polycarbonate (binder resin). However, this known photoreceptor has disadvantages in that it has a large memory phenomenon and tends to generate ghosts. Also US Patent No. 33579
No. 89 also discloses a photoreceptor containing phthalocyanine, but phthalocyanine has the disadvantage that the characteristics change depending on the crystal type, and the crystal type must be strictly controlled. The phenomenon is large,
Because of its low sensitivity to short wavelengths, it is considered unsuitable for copying machines that use visible light including the short wavelengths as a light source.

As described above, various attempts have been made to obtain photoreceptors for positive charging, but all of them have many problems that need to be improved in terms of photosensitivity, memory, pollution, etc.

Therefore, a photosensitive layer has a laminated structure in which the upper layer (surface layer) is a charge generation layer containing a charge generation substance that generates holes and electrons when irradiated with light, and the lower layer is a charge transport layer containing a Ti charge transport substance having a hole transport function. It is conceivable to use a photoreceptor having the above-mentioned structure 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 be used for positive charging. In addition, in such a photoreceptor that is used for positive charging, if a charge generating substance having, for example, an electron-withdrawing group is used in the structure, the movement of electrons to cancel the positive charge on the surface of the photoreceptor will be accelerated. , it is thought that high sensitivity characteristics can be obtained.

However, in all of the positive charging photoreceptors, a layer containing a charge generating substance is formed as a surface layer.
I-charge-generating substances that are sensitive to external effects such as corona discharge, humidity, and especially mechanical friction are present near the surface layer, which deteriorates the electrophotographic performance during storage of the photoreceptor and during the image formation process, resulting in poor image quality. starts to decrease.

In a negative charging photoreceptor having a conventional charge transport layer as a surface layer, the effects of the various functions described above are extremely small; rather, the charge transport layer has the effect of protecting the charge generating stones in the underlying layer.

On the other hand, in the case of a positively charging photoreceptor, the surface layer containing a charge-generating substance is subject to mechanical abrasion and damage due to external effects, especially development and cleaning, resulting in image defects such as white spots and white streaks. Electrophotographic performance such as surface potential, sensitivity, memory, and residual potential deteriorates.

Therefore, it is conceivable to provide a thin protective layer made of an insulating and transparent resin to reinforce the layer containing the charge-generating substance, but the electric charge generated during light irradiation is blocked by the protective layer and becomes photoconductive. The problem is that the information is lost.

Furthermore, it is possible to improve the abrasion resistance and scratch resistance of the charge generation layer by increasing the thickness of the charge generation layer serving as the surface layer, but there is a problem that the increase in the thickness leads to a decrease in sensitivity.

[Purpose 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 substance, has excellent scratch resistance, high sensitivity, and durability, and also has excellent resistance to ozone oxidation. There is a particular thing.

[Structure and effects of the invention]

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

In the general formula, R, , R, and R1 each have 1 to 4 carbon atoms.
represents an alkyl group.

In addition, when the charge transport material is a styryl-based or hydrazone-based compound, the thickness of the charge generation layer is 2.
The effect of the present invention is more significantly exhibited when the thickness is 7 μm.

As described in the prior art, in a positively charging photoreceptor using an organic photoconductive substance, a charge generation layer (hereinafter referred to as CG
Since the CGL layer (sometimes abbreviated as L) forms the surface layer, it lacks scratch resistance, and in order to improve durability, it is necessary to increase the thickness of the CGL film. However, increasing the film thickness causes a decrease in sensitivity. As a means of suppressing this decrease in sensitivity, there is the addition of a charge transport material (hereinafter sometimes abbreviated as CTM) to CGL, but this CTM has a higher biozone oxidation rate than a charge generating material (hereinafter sometimes abbreviated as CGM). Since it has a structure that easily absorbs ozone, it is easily deteriorated by ozone and the durability of the photoreceptor is impaired.

As a result of intensive studies regarding the improvement of ozone deterioration properties, the present inventors found that 2.4.
It was discovered that the above deterioration can be significantly reduced by containing a 6-trialkylphenol compound, and the present invention was completed.

Although the details of the action and effect are unknown, ozone reduces CGL in CGL.
It is believed that CTM is protected by acting on the compound of the present invention before it deteriorates TM and guarding against further ozone oxidation.

Since the compound of the present invention prevents ozone deterioration of CTM by its own oxidation, it can of course be added to the CGL in photoreceptors in which a protective layer (hereinafter sometimes abbreviated as OCL) is provided on the CGL. However, it may also be added to CGL, and may also be added to charge transport, kidney (hereinafter sometimes abbreviated as CTL) whose main component is CTM.

The present invention will be described in more detail below.

The 2,4.6-)realkylphenol compound represented by the general formula Fuji added to the charge generation layer of the present invention is rubber,
It is easily available as an antioxidant for plastics, oils and fats, etc.

In the general formula, the number of carbon atoms represented by R, , R, and R5 is from 1 to
The alkyl group of 4 may be linear or branched, and specific examples thereof include methyl group, ethyl group, propyl group, i-propyl group, butyl group, 5ec-butyl group, and 1-butyl group.

Among these groups, t-butyl group is particularly preferred.

R+, Rt, and R3 may be the same or different.

Typical specific examples of compounds preferably used in the present invention are shown below, but are not limited thereto. When used in CGL, the amount of addition of the compound of the present invention is
0.1 to 100% by weight, preferably 1 to 5% by weight based on TM
0% by weight, particularly preferably 5 to 25% by weight. In addition, when used in OCL, it is 0.1 to 100 tonne %, preferably 1 to 50 tonne, based on the binder resin in OCL.
Weight%.

Next, the structure of the photoreceptor of the present invention will be explained with reference to the drawings. For example, as shown in FIG. 1, the photoreceptor includes a charge transport layer 2 containing CTM and, if necessary, a binder resin, on a support 1 (a conductive support or a sheet with a conductive layer provided thereon). As shown in FIG.
A protective layer (OCL) 4 is provided on the photosensitive layer shown in the figure, and a single-layer photosensitive layer containing CG lvI, CTM, and a binder resin as necessary is placed on the support as shown in FIG. 4, etc., but OCL may be provided on the photosensitive layer having a single layer structure as shown in FIG. 3, or 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 it absorbs visible light and generates free charges. In addition to inorganic pigments such as amorphous selenium, trigonal selenium, selenium-arsenic alloy, selenium-tellurium alloy, cadmium sulfide, cadmium selenide, cadmium selenide sulfide, mercury sulfide, lead oxide, lead sulfide, the following representative examples Organic pigments such as those shown may also be used.

(1) Azo pigments such as monoazo pigments, polyazo pigments, metal complex azo pigments, pyrazolone azo pigments, stilbene azo and thiazole azo pigments.

(2) Perylene pigments such as perylene anhydride and perylene imide.

(3) anthraquinone derivatives, anthorone derivatives, dibenzpyrenequinone derivatives, vilantrone derivatives,
Anthraquinone or polycyclic quinone pigments such as violanodrone derivatives and isoviolanthrone derivatives (4) Indigoid pigments such as indigo derivatives and thioindigo derivatives (5) Phthalocyanine pigments such as metal phthalocyanines and metal-free phthalocyanines (6) Diphenylmethane pigments pigments, carbonium pigments such as triphenylmethane pigments, xanthine pigments and acridine pigments (7) quinone imine pigments such as azine pigments, oxazine pigments and thiazine pigments (8) methine pigments such as anine pigments and azomethine pigments (9) quinoline Pigments (lO) Nitro pigments (11) Nitroso pigments (12) Benzoquinone and naphthoquinone pigments (13)
Naphthalimide pigments (14) Perinone pigments such as bisbenzimidazole derivatives Various azo pigments having electron-withdrawing groups are used because of their good electrophotographic properties such as sensitivity, memory phenomenon, and residual potential, but they are ozone resistant. From this point of view, polycyclic quinone pigments are most preferred.

Although the details are unknown, this is probably because azo groups are susceptible to ozone oxidation and the electrophotographic properties deteriorate, whereas polycyclic quinones are inert to ozone.

Examples of the azo pigments used in the present invention include those shown in the following exemplary compound groups CI) to (V).

Exemplified compound group [I]: Exemplified compound group [■]; Exemplified compound group [■]: Exemplified compound [■]: Exemplified compound [■]: In addition, the illustrated compound group consisting of the following polyquinone pigments ("
l ) ~ [ ~ 1] are most preferred as CGMs, exemplified compound group [■]: exemplified compound group [■]: exemplified compound group [■]: Next, as charge transport substances that can be used in the present invention, there are no particular restrictions. However, for example, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thianoazole derivatives, triazole derivatives, imidazole derivatives, imidacilone derivatives, imidazolidine derivatives, bisimidazolidine derivatives, styryl compounds, hydrazone compounds, pyrazoline derivatives, oxacilone derivatives, benzothiazole derivatives, benzimidazole derivatives, quinazoline derivatives,
These may include benzofuran derivatives, acridine derivatives, phenazine derivatives, aminostilbene derivatives, poly-N-vinylcarbazole, poly-1-vinylpyrene, poly-9-vinylanthracene, and the like.

However, it is preferable to use a CTM that has an excellent ability to transport holes generated during light irradiation to the support side and is suitable for combination with the carrier-generating substance. Examples of such CTM include the following exemplified compound group (IX) or CX) is used.

Exemplary compound group [■]: Exemplary compound group (X) In addition, the following exemplary compound groups [M] to (XV) as CTM
A hydrazone compound represented by can also be used.

Exemplary compound group [■] Exemplary compound group (X!II): Exemplary compound group (XIV): Exemplary compound group (XV): In addition, pyrazoline compounds shown by the following exemplary compound (X Vl) can also be used as CTM. .

Exemplary Compound Group (XV[): In addition, amine derivatives shown in the following Exemplary Compound Group [X■] can also be used as CTMs.

Exemplary compound group [X■]: \-2-R'' Next, the protective layer that may be used in the present invention has a volume resistivity of 108 Ω·Cm or more as a binder, preferably 101°Ω·
A transparent resin having a resistance of Cm or more, more preferably 10 13 Ω·Cm or more is used. Further, the binder contains at least 50% by weight of a resin that is cured by light or heat.

Examples of such resins that harden with light or heat include thermosetting acrylic resins, phosphor resins, epoxy resins, urethane resins, urea resins, phenol resins, polyester resins, alkyd resins, melamine resins, photocurable/cinnamic acid resins, and the like. Alternatively, copolymerization of these resins includes cocondensation resins, and all of the photo-curable or thermosetting resins used in electrophotographic materials can be used. If necessary, the protective layer may contain less than 50% by weight of a thermoplastic resin for the purpose of improving processability and physical properties (preventing cracks, imparting flexibility, etc.). Such thermoplastic resins include, for example, polypropylene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, epoxy resin, butyral resin, polycarbonate resin, silicone resin, or copolymer resins thereof, such as vinyl chloride resin. Polymeric organic semiconductors such as vinyl acetate copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride copolymer resin, poly-N-vinylcarbazole, and other thermoplastic resins used in electrophotographic materials are all utilized. Ru.

Further, the protective layer may contain an electron-accepting substance,
In addition, if necessary, an ultraviolet absorber or the like may be included for the purpose of protecting the CGM, which is dissolved in a solvent together with the binder, and applied and dried by, for example, dip coating, spray coating, blade coating, roll coating, etc. The layer thickness is 2 μm or less, preferably 1 μm or less.

The layer structure of the photosensitive layer of the photoreceptor of the present invention has a laminated structure and a single layer structure as described above, but the charge transport layer, charge generation layer, or protective layer has a structure for improving sensitivity, residual potential, and resistance to repeated use. One or more electron-accepting substances can be contained for the purpose of reducing fatigue and the like.

Examples of electron-accepting substances that can be used in the present invention include succinic anhydride, maleic anhydride, dibromaleic anhydride, phthalic anhydride, tetrachlorophthalic anhydride, tetrabromophthalic anhydride, 3-nitrophthalic anhydride, 4- Nitrophthalic anhydride, pyromellitic anhydride, mellitic anhydride, tetracyanoethylene, tetracyanoquinodimethane,
0-dinitrobenzene, m-dinitrobenzene, 1.3
゜5, -Trinitrobenzene, varanitrobenzonitrile, picryl chloride, quinone chlorimide, chloranil, brumanil, 2-methylnaphthoquinone, dichlorodicyanobarabenzoquinone, anthraquinone, dinitroanthraquinone, trinitrofluorenone, 9-fluorenonedene [dicyanomethylene malonodinitrile], polynitro-9-fluorenonedene[dicyanomethylene malonodinitrile], picric acid, 0-nitrobenzoic acid, acetic acid, p-nitrobenzoic acid, 3,5-dinitrobenzoic acid, acetic acid, pentafluorochloride Fragrance acid, 5-nitrosalicylic acid, 3
．． Examples include 5-dinitrosalicylic acid and phthalic acid.

Examples of binder resins that can be used in the photosensitive layer in the present invention include polyethylene, polypropylene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate V
MlI! #, addition polymerization type resins, polyaddition type resins, polycondensation type resins such as epoxy resin, polyurethane resin, phenol resin, polyester resin, alkyd resin, polycarbonate resin, silicone resin, melamine resin, and repeating units of these resins. Copolymer resins containing two or more of the following, such as vinyl chloride-vinyl acetate copolymer resins,
In addition to insulating resins such as vinyl chloride-vinyl acetate-maleic anhydride copolymer resin, polymeric organic semiconductors such as poly-N-vinylcarbazole may be used.

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

The charge transport layer is provided by a method of applying the above-mentioned CTM alone or dissolving or dispersing it together with a suitable binder resin in a suitable solvent and drying it.

Examples of solvents used to form CTL include N, N
-dimethylformamide, benzene, toluene, xylene, monochlorobenzene, 1,2-dichloroethane, dichloromethane, 1,1,2-trichloroethane, tetrahydrofuran, methyl ethyl ketone, ethyl acetate, butyl acetate, and the like.

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

CTM per 100 parts by weight of binder resin in CTL is 2
The amount is 0 to 200 parts by weight, preferably 30 to 150 parts by weight.

If the content of CTM is less than this, the photosensitivity will be poor;
The residual potential tends to become high, and if the amount is more than this, the solvent solubility will deteriorate.

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

When CGL is formed by dispersing the above CGM, the CGM is preferably in the form of powder having an average particle size of 2 μm or less, preferably 1 μm or less. That is, if the particle size is too large, dispersion in the layer will be poor, and some of the particles will protrude from the surface, resulting in poor surface smoothness. In some cases, discharge may occur at the protruding parts of the particles, or toner may Particles tend to adhere and toner filming phenomenon occurs easily.

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 sensitivity and repeatability decrease due to increase in crystal defects, or there is a limit to miniaturization.

CGL can be provided by the following method.

That is, the CGM described above is made into fine particles in a dispersion medium using a ball mill, a homomixer, etc., and a binder resin and C
This is a method of applying a dispersion obtained by adding TM and mixing and dispersing it. When the particles are dispersed under the action of ultrasound in this method, uniform dispersion is possible.

CGM per 100 weight of binder tree in CGL is 2
0 to 200 parts by weight, preferably 25 to 100 parts by weight, and 20 to 200 parts by weight of CTM, preferably t: L < i
,! The amount is 30 to 150 parts by weight.

If CGM is less than this, the photosensitivity will be low and the residual potential will increase; if it is more than this, dark decay will increase and the acceptance potential will decrease.

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

In the case of a laminated structure, the film thickness ratio of CGL and CTL is 1:(1~
30) is preferable.

In the case of the single-layer structure, the charge generating substance is contained in the binder resin in a proportion of 20 to 200 parts by weight, preferably 25 to 100 parts by weight, based on 100 parts by weight of the binder resin.

If the content of the charge generating substance is less than this, the photosensitivity will be low and the residual potential will increase, and if it is more than this, the dark decay and acceptance potential will decrease.

Next, the content ratio of the charge transport substance to the binder resin is 20 to 2 parts by weight per 100 parts by weight of the binder resin.
The amount is 1 part by weight, preferably 30 to 150 parts by weight.

If the content of the charge transport substance is less than this, the photosensitivity will be poor and the residual potential will tend to be high, and if it is more than this, the solvent solubility will be poor.

It is preferable that the m ratio of the charge transporting material to the charge generating material in the single-layer photosensitive layer is from 1:3 to 1:2 by weight.

〔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-
Maleic anhydride copolymer (Eslec M P-10,
An intermediate layer having a thickness of 0.1 μm was formed.

Next, polycarbonate resin (Panlite L-1250
, manufactured by Ondai Kasei Co., Ltd.) / CT M (IX-75)-1
1 containing 16.5% by weight of 00/75 (weight ratio),
Dip coating a 2-dichloroethane solution on the intermediate layer,
A charge transport layer with a thickness of 15 μm was formed. Next, 4, IO-dibromoanthrone (Ml) was sublimated as CGM.
CTM (IX-75 ) was added to the exemplified compound (1) in an amount of 75% by weight based on Panlite L-1250 and 10% by weight based on CTM. Monochlorobenzene was added to this solution to prepare a dispersion liquid such that 1,2-dichlorobenzene/monochlorobenzene = 7/3 (volume ratio).
The present invention involves spray coating on the TL and drying to form a charge generating layer of 5 μm, and then forming a photosensitive layer of a laminated structure.

Obtained Yuko body.

Comparative Example 1 A comparative photoreceptor was obtained in exactly the same manner as in Example 1 except that Exemplary Compound (1) was omitted.

Example 2 A photoreceptor was obtained in exactly the same manner as in Example 1 except that Exemplified Compound (3) was used in place of Exemplified Compound (1).

Example 3 Brimer PH91 for silicone hard coat (manufactured by Toshiba Silicon Co., Ltd.) was spray-coated to a thickness of 0.1 μm on the photosensitive layer excluding the exemplified compound (1) of Example 1, and silicone hard coat was further applied on top of it to a thickness of 0.1 μm. A solution containing 10 parts by weight of Coat Toss Guard 51O (manufactured by Toshiba Silicon Corporation) and Exemplary Compound (1) added to 100 parts by weight of resin was spray applied, dried to form a 1 μm thick protective layer, and exposed to light. I got a body.

Example 4 Vinyl chloride-vinyl acetate-
An intermediate layer having a thickness of about 0.1 μm made of maleic anhydride copolymer (Eslebuku MP-1o, supra) was formed.

Next, 8% by weight of butyral resin (S-LEC BX-1, manufactured by Sekisui Chemical Co., Ltd.) and CTM (IX
-75) A coating solution obtained by dissolving 6% by weight in methyl ethyl ketone is applied onto the intermediate layer and dried to form a layer of 10 μm.
A thick charge transport layer was formed. Then CGM(IV-
7”) 0.29 with paint conditioner (Pain
t Conditioner, Red Devi1
(manufactured by) for 30 minutes, and then powdered with polycarbonate resin (
Panlite L-1250, above) was added to 1,2-dichloroethane/1,1,2-trichloroethane mixed solvent at a concentration of 0.5%.
Add 8.39% of the solution by weight and disperse for 3 minutes, then add polycarbonate resin, CT
M (IX-75) and Exemplified Compound (+) in a 1.2-dichloroethane/1,1.2-trichloroethane mixed solvent so that the concentrations were 3.3% by weight, 2.6% by weight, and 0.26% by weight, respectively. Solution obtained by dissolving 19.19
was added and dispersed for an additional 300 minutes. The thus obtained dispersion solution was spray-coated onto the CTL and dried to form a charge generation layer with a thickness of 5 μm, thereby obtaining a photoreceptor having a photosensitive layer having a laminated structure.

Comparative Example 2 A comparative photoreceptor was obtained in exactly the same manner as in Example 4 except that Exemplified Compound (1) was omitted.

Example 5 A photoreceptor was obtained in exactly the same manner as in Example 4 except that Exemplified Compound (3) was used in place of Exemplified Compound (1).

Example 6 Photosensitive layer excluding Exemplified Compound (1) of Example 4 (Comparative Example 2
The same exemplified compound as in Example 3 (same as the photoreceptor)
A protective layer containing +) was provided to obtain a photoreceptor.

The ozone resistance of the photoreceptor sample obtained as described above was evaluated using the following ozone fatigue tester.

In other words, the electrostatic tester (5P-428 newly manufactured by Kawaguchi Electric)
type) and an ozone generator (0-1-2 manufactured by Japan Ozone Co., Ltd.)
model) and ozone monitor (manufactured by Ebara Jitsugyo Co., Ltd.)
G-2001 model) was used.

Attaching the photoreceptor at an ozone concentration of 90 ppm, +6K
After applying a voltage of V and charging the photosensitive layer by corona discharge for 5 seconds, it was left for 5 seconds (the potential at this time was the initial potential of V).

Then, light from a tungsten lamp was irradiated with the surface of the photosensitive layer at an illuminance of 14 lux, and this operation was repeated 100 times.

When the potential after 100 irradiations is V, V, /V, xl
Ozone resistance was expressed as oo (%). V+/Vo
indicates the degree of potential drop after 100 repetitions,
The larger the value, the better.

In addition, the exposure amount Ea00 (lux seconds) required for attenuating the initial potential from +600V to +100V without introducing ozone was also measured. The smaller the number, the higher the sensitivity. These results are shown in the attached table.

It can be seen that while the comparative photoreceptor has excellent electrophotographic properties, ozone deterioration is significant and the electrophotographic properties are not good.

[Brief explanation of drawings]

1 to 3 are cross-sectional views of the positively charging photoreceptor of the present invention. ! ...Support 2..Charge transport layer 3.
...Charge generating layer 4...Photosensitive layer 5...Charge transport material (CTM) 6...Charge generating material (CC:M) 7...Protective layer Applicant Roku Konishi Photo Industry Co., Ltd. Figure 3

Claims (2)

[Claims] (1) In an electrophotographic photoreceptor in which a charge transport layer, a charge generation layer, and, if necessary, a protective layer are sequentially laminated on a conductive support, the charge generation layer contains a charge transport substance, and the charge generation layer contains a charge transport substance. Alternatively, an electrophotographic photoreceptor for positive charging, characterized in that the protective layer contains a compound represented by the following general formula. General formula▲There are numerical formulas, chemical formulas, tables, etc.▼ [In the formula, R_1, R_2 and R_3 each represent an alkyl group having 1 to 4 carbon atoms. ] (2) Claim 1, wherein the charge transport substance is a styryl-based or hydrazone-based compound.
Electrophotographic photoreceptor for positive charging as described in .