JPH01230053A - Electrophotographic sensitive body containing compound having hindered phenol structure - Google Patents

Abstract

PURPOSE:To prevent degradation in electrostatic chargeability in spite of repetitive use by incorporating a hindered phenol compd. having a specific structural unit into a photosensitive body contg. a charge transfer material having >=5.45 ionization potential and charge generating material in a photosensitive layer. CONSTITUTION:This electrophotographic sensitive body contains the charge transfer material having >=5.45 ionization potential and the charge generating layer in the photosensitive layer and the hindered phenol compd. having the structural unit expressed by formula I or formula II is incorporated into this electrophotographic sensitive body. In formula, R1, R7 denote a hydrogen atom., etc.; R2, R3. R12 denote a branched alkyl group; R3-R6, R9-R11, R13-R16 denote a hydrogen atom. or substituent; (m), (n) denote 0 or positive integer; m+n is 2-4; Y denotes a combination group; (p) denotes 0 or 1. The charge generat ing material is, for example, the azo compd. expressed by formula III. In formu la, Y1', Y2', Y3' are H; A is expressed by formula III'-8. The fatigue and deterio ration are thereby decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to electrophotographic photoreceptors, and more particularly to improvements in organic photoconductive electrophotographic photoreceptors.

[Conventional technology]

In an electrophotographic copying machine using the Carlson method, after the surface of a photoreceptor is charged, an electrostatic latent image is formed by exposure, the electrostatic latent image is developed with toner, and then the visible image is transferred to paper or the like. Transfer and fix. At the same time, the photoreceptor is subjected to removal of adhered toner, neutralization of static electricity, and surface cleaning, and is used repeatedly over a long period of time.

Therefore, as an electrophotographic photoreceptor, it not only has electrophotographic properties such as good charging characteristics and sensitivity, and low dark decay, but also has good printing durability, abrasion resistance, moisture resistance, etc. after repeated use. Physical properties, ozone generated during corona discharge,
It is also required to have good resistance to ultraviolet rays and the like during exposure (environmental resistance).

Conventionally, as electrophotographic photoreceptors, inorganic photoreceptors having a photosensitive layer mainly composed of an inorganic photoconductive substance such as selenium, zinc oxide, or cadmium sulfide have 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, Japanese Patent Publication No. 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 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, substances that develop each function can be selected 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 No. 8, there is amorphous selenium. This is combined with an organic charge transport material.

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

However, in the electrophotographic process, since ozone and other active substances are generated during charging by corona discharge, there is a problem in that charging characteristics and sensitivity deteriorate due to the influence of these active substances.

In particular, during repeated use, the charging characteristics deteriorate significantly as the exposure time to ozone and other active substances increases cumulatively.

In order to prevent such deterioration of electrophotographic properties, it has been proposed to add various antioxidants to photoreceptors.

However, although many of these antioxidants improve ozone resistance, they tend to cause a decrease in sensitivity in the initial characteristics, and at best, it is difficult to keep the decrease in sensitivity to a level that is impractical for practical use. .

As a result of intensive research, the present inventors have found that when a compound containing a hindered phenol structure is added to an electrophotographic photoreceptor containing a charge transport substance with an ionization potential of 5.45 or more, this photoreceptor has excellent environmental resistance. Not only that, but the sensitivity was also improved compared to before the addition, and the present invention was achieved.

[Purpose of the invention]

An object of the present invention is to provide an electrophotographic photoreceptor with high sensitivity, excellent environmental resistance, and less deterioration in charging ability during repeated use.

[Structure of the invention]

An object of the present invention is to provide an electrophotographic photoreceptor comprising a charge transport material and a charge generation material having an ionization potential (hereinafter referred to as Ip) of 5.45 or more in the photoreceptor layer. The following general formula [■a] or [Ibl
This is achieved by an electrophotographic photoreceptor characterized by containing a hindered phenol compound having at least one structural unit represented by:

General formula [Ia] General formula [Ibl In general formula [1ai and [Ibl, R1 and R
7 each represents a hydrogen atom or an alkyl group, R, R8
and R12 each represent a branched alkyl group, R1, R
R8, R6, R9, RlO%RII, R131R+a
and R+6 each represent a hydrogen atom or a substituent, m and n each represent 0 or a positive integer, and m+n is 2 to 4
It is. Y represents a linking group, and p represents 0 or 1.

A hindered phenol compound having at least one structural unit represented by the above general formula [Ia] or [Ibl] (
The "hindered phenol compound" in the term "hindered phenol compound" (hereinafter sometimes referred to as the "hindered phenol compound" of the present invention) refers to a phenolic hydroxyl group or a hydrogen atom of the hydroxyl group substituted with a group represented by R1 or Ra above. A phenolic compound characterized by the presence of a bulky atomic group at the ortho position of the group, which has the general formula [Ia] or [
At least one structural unit represented by Ibl is included in the molecular structure.
The compound having this is a hindered phenol compound.

Although the mechanism of the effect of the bulky atomic group is not clear, it is thought that the steric hindrance controls the thermal vibration of the phenolic hydroxyl group and prevents the influence of external active substances.

In general formulas [Ia] and [Ibl, R1 and R
A is preferably a hydrogen atom. The alkyl group represented by R and R7 has 1 to 40 carbon atoms and may have a substituent. The substituent may be any one such as a galyl group, an alkoxy group, an acid amide group, or a halogen atom.

Further, the branched alkyl group represented by R6 and R12 is a branched alkyl group having 1 to 40 carbon atoms, such as (1
) Butyl, (sec) Butyl, (sec) Octyl, (
1) Octyl group and the like.

R3~Ra and R*~RI 1 and R13~R1s
Possible substituents include, for example, aryl groups, alkoxy groups, acid amide groups, and halogen atoms.

Further, the linking group Y changes depending on the value of mSn. Typical examples of Y include methylene group, ethylene group, propylene group, phenylene group, sulfide, polysulfide, and the like.

Further, in embodiments of the present invention, the photoconductive material contained in the photosensitive layer preferably comprises a charge generating material (commonly designated as CGM) and a charge transporting material (commonly designated as CTM).

As the CTM, a styryl CTM represented by the following general formula [1] is particularly preferable.

General formula [II] In the general formula [■], Ar represents an aryl group or a heterocyclic residue, Ar2 represents an alkyl group or an aryl group, and R, , R, □, R1, and R14 are each hydrogen Represents an atom, alkyl group or aryl group.

Ar, , Ar2, R, l1% R12, R+, and R1
The above group represented by 4 further includes an alkyl group, an alkoxy group,
It may have a substituent selected from a halokene atom, a cyano group, and an amine group which may be substituted with an alkyl group or an aryl group. n represents O or 1.

At least one of A r 2, R1, and R1 has an amino group that may be substituted with an alkyl group or an aryl group.

The CGM is preferably an azo CGM represented by the following general formula [III].

General formula [I] In the formula, R2o'=R25 each represents a hydrogen atom or a substituent, and the substituents include an alkyl group, an alkokene group, an aryl group, an aralkyl group, a halokene atom, an acid amide group, a nitrile group, etc. can be mentioned.

Cp represents a coupler residue in an azo coupling reaction.

A preferable example of Cp is etc.

-G is -CONH-A or -CH-N -NH
-A2, where A1 and A2 each represent a substituted or unsubstituted aromatic group, preferably an alkyl group,
Examples include phenyl groups and naphthyl groups with or without substituents such as alkoxy groups, halogen atoms, cyan groups, nitro groups, and amino groups.

By adding a hindered phenol compound having a structural unit represented by the general formula [Ia] or [Ib] in the molecule to the photoreceptor, environmental resistance is improved, especially against ozone generated during corona discharge. The durability of the material is improved.

However, a photoreceptor to which a hindered phenol compound having a structural unit represented by the general formula [I a] or [I b] is added causes a slight decrease in sensitivity.

As a result of further investigation, the inventors found that Ip was 5.
It has been found that when the hindered phenol compound of the present invention is added to a photoreceptor containing a CTM of 45 or more, not only the above-mentioned effects are excellent, but also the sensitivity is further improved compared to before addition.

Furthermore, compared to conventional photoreceptors, the combined use of an azo compound represented by the general formula [II[] reduces deterioration of acceptance potential and sensitivity during repeated use.

In the present invention, Ip means that a compound is irradiated with light, photoelectrons are measured while changing the wavelength (energy), and the energy at which photoelectrons begin to be generated is taken as the ip of the compound.

As a specific method for measuring Ip of CTM, the following method can be used.

Ip measurement method Ip measurement device: Surface analyzer AC- manufactured by Riken Keiki Co., Ltd.
1 (This device counts photoelectrons due to ultraviolet excitation in the atmosphere and analyzes the sample surface, and uses a low-energy electron counting device.)Environmental temperature and relative humidity at the time of measurement: 20'0.60% Counting time: lO seconds/l
Point light intensity setting: 50. u W/ am' Light intensity correction 2 Corrected with the attached program using the above settings Energy scanning range: 3.4 to 6.2 eV Ultraviolet spot diameter: 1 m
m5Q Unit photon: 1×10”/cm2・sec The measurement sample was placed on an aluminum PAN with a depth of 1 and a diameter of 7 mm.
Add M powder and set the distance between the cTM powder surface and the ultraviolet irradiation position to be 2 mm.

Calculate Ip according to the attached work function calculation program.
, F7''K (CP S :count value) versus ultraviolet excitation energy is extrapolated to a point where it intersects with the background, and that point is designated as Ip.

FIG. 4 is a graph showing an example of a curve showing the relationship between lower F and ultraviolet excitation energy (eV) measured by the above method, and a method of determining Ip from the curve. In Figure 4, 10 was measured! Excitation energy for ultraviolet light (eV
), 11 is a straight line portion of curve 10, 12
is the background part of the curve IO, 13 is the straight part 1
The value on the horizontal axis (ultraviolet excitation energy axis) of the intersection 13, which is the intersection between the extension line of 1 and the extension line of the background portion 12, is xp.

The present invention will be explained in more detail below.

The photoreceptor of the present invention, for example, as shown in FIG. 1, contains CGM and, if necessary, a binder resin on a conductive support l (including those in which a conductive layer is provided on a non-conductive support). A photosensitive photosensitive material having a laminated structure in which a charge generation layer 2 (hereinafter sometimes referred to as CGL) is a lower layer, and a charge transport layer 3 (hereinafter sometimes referred to as CTL) containing CTM and a binder resin as necessary is an upper layer. As shown in FIG. 2, a layer 4 is provided, a layer 4 is provided on a support 1, and a photosensitive layer 4 having a laminated N groove structure with CTL 3 as a lower layer and CGL 2 as an upper layer is provided, and a third layer 4 is provided.
As shown in the figure, a photosensitive layer 4 having a single layer structure containing CG L, CTM and, if necessary, a binder resin is provided on a support 1, and the like.

Further, CGL may contain both CGM and CTM, a protective layer (OCL) may be provided on the photosensitive layer, and an intermediate layer may be provided between the support and the photosensitive layer.

The hindered phenol compound of the present invention can be used in the CGL, CTL, intermediate layer, single-layer photosensitive layer or O
It may be contained in any layer of CL, or may be contained in multiple layers. The effects of the present invention are more pronounced in the following cases:
This is a photoreceptor having a laminated structure in which CGL is an upper layer and CTL is a lower layer.

Next, typical examples of hindered phenol compounds having a structural unit represented by the general formula [Ia] or [Ib] that are preferably used in the present invention will be shown, but the present invention is not limited thereto.

Exemplary compound H SaH.

(t) C4Hs H Shinl H CH2CH2COOC1aH3r I -10 H H3 ■-20 C4H1(t) C61(+ +(t) ■-22 ■-23 H ■-25 ■-26 0UBH+y ■-27 0I ■-28 These The compounds are generally commercially available, such as Irganox-245,259,565,1010,103
5,1076,1081S1098.1222.133
0, MD1024 (Ciba Geigy), Mark AO
-20, AO-30, AO-40, AO-50, AO-
60 (Adeka Argus), Sumilizer BMTSS
, BP-76, MDP-5SGM, BBM-S,
WX-R (Sumitomo Chemical Co., Ltd.) is available, and the amount of the conventionally known compound of the present invention can be determined depending on the layer structure of the photoreceptor, the CT
Although it varies depending on the type of M, when added to CGL, the amount is 0.1 to 200 parts by weight, particularly preferably 0.1 to 100 parts by weight, per 100 parts by weight of CGM.

When added to CTL, CTM 10 (0.01 to 70 parts by weight, particularly preferably 0.1 to 50 parts by weight per 1 part) is used.

When included in an intermediate layer such as a subbing layer or a protective layer, 0.01 to 200 parts by weight per 100 parts by weight of the binder resin constituting the core layer.
Parts by weight.

Next, when using the exemplified compound represented by the above general formula [II] in the practice of the styryl system represented by the above general formula [■], Ip of the exemplified compounds meets the conditions of the present invention. Select and use the ones that will be used.

Next, specific examples of the azo compound represented by the general formula [III] are shown below.

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.
, either the single-layer photosensitive layer or the OCL, or multiple layers may contain one or more electron-accepting substances for the purpose of improving sensitivity, reducing residual potential or fatigue during repeated use, etc. can.

Electron-accepting substances that can be used in the photoreceptor of the present invention include:
For example, succinic anhydride, maleic anhydride, dibromaleic anhydride, phthalic anhydride, tetrachlorophthalic anhydride,
Tetrabromo-7thalic anhydride, 3-nitrophthalic anhydride,
4-nitrophthalic anhydride, pyromellitic anhydride, mellitic anhydride, tetracyanoethylene, tetracyanoquinodimethane, O-dinitrobenzene, m-dinitrobenzene, 1.3.51-dinitrobenzene, varanitrobenzonitrile, Picryl chloride, quinone chloroimide,
Chloranil, flumanil, 2-methylnaphthoquinone, dichlorodicyanobarabenzoquinone, anthraquinone, dinitroanthraquinone, trinitrofluorenone, 9-
Fluorenonedene [dicyanomethylenemalonodinitrile], polynitro-9-fluorenonedene [dicyanomethylenemalonodinitrile], picric acid, 0-nitrobenzoic acid, p-nitrobenzoic acid, 3,5-dinitrobenzoic acid, pentafluoro Benzoic acid, 5-nitrosalicylic acid,
Examples include 3,5-dinitrosalicylic acid and phthalic acid.

Additionally, silicone oil may be present as a surface modifier. Further, an ammonium compound may be contained as a durability improver.

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 resin, epoxy resin, polyurethane resin, phenol resin,
Contains two or more of addition polymerization type resins, polyaddition type resins, polycondensation type resins, and repeating units of these resins such as polyhydroxystyrene resins, polyester resins, alkyd resins, polycarbonate resins, silicone resins, and melamine resins. In addition to insulating resins such as copolymer resins, such as vinyl chloride-vinyl acetate copolymer resins and vinyl chloride-vinyl acetate-maleic anhydride copolymer resins, polymeric organic semiconductors such as poly-N-vinylcarbazole are also used. Can be mentioned.

In addition, the intermediate layer functions as an adhesive layer or a barrier layer, and in addition to the binder resin, examples include polyvinyl alcohol, ethyl cellulose, carboxymethyl cellulose, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate. -Maleic anhydride copolymer, casein, N
-Alkoxymethylated nylon, starch, etc. are 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 CGL can be provided by vacuum-depositing the above-mentioned CGM on the support, or by applying a solution or dispersion of CGM alone or together with a suitable binder resin in a suitable solvent and drying it.

A ball mill, homomixer, sand mill, ultrasonic disperser, attritor, etc. are used for dispersing CGM.

Examples of solvents used to form CGL include N, N
-Dimethylformamide, benzene, toluene, xylene, monochlorobenzene, 1,2-dichloroethane, dichloromethane, 1,1,2-trichloroethane, tetrahydro7rane, methyl ethyl ketone, ethyl acetate, butyl acetate, and the like.

CGM per 100 parts by weight of binder resin in CGL is 20
The amount is preferably at least 25 parts by weight, particularly preferably 25 to 400 parts by weight.

The thickness of the CGL formed as described above is preferably 0.01-10 μm, particularly preferably 0.1-5 μm.
It is.

Further, CTL can be formed by applying and drying the above-described CTM in the same manner as the above-mentioned CGL, that is, by melting and dispersing the above-mentioned CTM alone or together with the above-mentioned binder resin.

CTM per 100 parts by weight of binder resin in CTL is 20
~200 parts by weight, preferably 30 to 150 parts by weight.

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

In the present invention, the binder of the protective layer provided as necessary has a volume resistivity of 108 Ω·cm or more, preferably 10”Ω·Cl11 or more, and more preferably 10130·cm or more.
A transparent resin with a thickness of 0 m or more is used. Further, the binder may be a resin that is cured by light or heat, and 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, Examples include polyester resins, alkyd resins, melamine resins, photocurable cinnamic acid resins, and copolymerized or cocondensed resins thereof, and all other photocurable 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-vinyl acetate copolymer resin. Polymer resin, vinyl chloride-vinyl acetate-maleic anhydride copolymer resin, poly-N
- Polymeric organic semiconductors such as vinyl carbazole and other thermoplastic resins used in electrophotographic materials can all be used.

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, applied by dip coating, spray coating, blade coating, roll coating, etc., and dried to a thickness of 2 μm or less. ,
Preferably, the layer thickness is 1pm or less.

〔Example〕

EXAMPLES The present invention will be explained below with reference to Examples, but the embodiments of the present invention are not limited thereby. In addition, in the following examples, Ip of CTM was measured by the method described above.

Example 1 Polyvinyl butyral resin rXYX was deposited on a conductive support made of a polyester film deposited with aluminum.
Made of LJ (manufactured by Union Carbide), thickness 0.2μ
An intermediate layer of m was formed.

Next, 1 part by weight of Exemplified Compound (I'-4) was added to a solution consisting of 0.5 parts by weight of polycarbonate resin "Panlite L-1250J (manufactured by Ondai Kasei Co., Ltd.) and 120 parts by weight of 1,2-dichloroethane using a sand mill. The solution dispersed for 10 hours was applied using a wire bar to form a CGL of 0.2 μm.

Next, exemplified compound (1-13) was added to a solution prepared by dissolving 12 parts by weight of exemplified compound (n-13) and 15 parts by weight of polycarbonate resin "Panlite K-1300J (manufactured by Ondai Kasei Co., Ltd.) in 120 parts by weight of 1,2-dichloroethane. 1.2 parts by weight of No. 15) was added and coated using a blade coater to form a CTL with a thickness of 23 μm to obtain a photoreceptor of the present invention.

This is called sample 1.

Comparative Example 1 A photoreceptor for comparison was obtained in the same manner as in Example 1 except for the exemplified compound (I-15).

This will be referred to as comparative sample 1.

Examples 2 to 5 and Comparative Examples 2 to 7 CGM exemplified compound (III'-4) in Example 1,
Table 1 shows the example compound (U-13) of CTM and the example compound (I-15) of the hindered phenol compound of the present invention.
Electrophotographic photoreceptors (Samples 2 to 5, Comparative Samples 2 to 7') were obtained in the same manner as in Example 1, except that the following changes were made.

Example 8 Vinyl chloride-vinyl acetate-
A 1 μm thick intermediate layer made of vinyl alcohol co-merged r S-LEC A-5J (manufactured by Tsukisui Kagaku Co., Ltd.) was formed. Next, 1 part by weight of the exemplary compound (■'-4) was mixed with 0.8 parts by weight of polyvinyl formal resin "Denka Formal #20J (manufactured by Denki Kagaku Kogyo Co., Ltd.) and 10 parts by weight of 1,2-dichloroethane.
A CGL with a thickness of 0.3 μm was formed by spray coating a solution in which 0 was dispersed for 48 hours using a ball mill.

Next, exemplified compound (I-10) was added to a solution prepared by dissolving 10 parts by weight of exemplified compound (n-3) and 12.5 parts by weight of polyester resin "Vylon 200J (manufactured by Toyobo Co., Ltd.) in 100 parts by weight of 1,2-dichloroethane. 3 parts by weight was added and coated using a blade coater to form a CTL with a thickness of 20 μm.
A photoreceptor of the present invention was obtained. This is sample 8
shall be.

Comparative Example 8 A comparative photoreceptor was obtained in the same manner as in Example 8 except for the exemplified compound (I-10). Example 9 This is used as comparative sample 8. On a conductive support made of a polyester film deposited with aluminum, 1 part by weight of the exemplified compound (III'-8) and polycarbonate resin "Panlite L-1250J" were added.
0.5 parts by weight of Exemplary Compound (I-15) and 100 parts by weight of 1,2-dichloroethane were dispersed for 10 hours using a sand mill and coated with a wire bar to a thickness of 0.3 μm. CGL was formed. Next, a solution of 12 parts by weight of Exemplified Compound (II-2), 15 parts by weight of polycarbonate resin Panlite, and 0.12 parts by weight of Exemplified Compound (1-15) dissolved in 100 parts by weight of 1,2-dichloroethane was added. A CTL having a thickness of 25 μm was formed by coating using a blade coater to obtain a photoreceptor of the present invention.This will be referred to as sample 9.

Comparative Example 9 A comparative photoreceptor was obtained in the same manner as in Example 9, except that the exemplified compound (I-15) in Example 9 was removed from CGL and CTL. This will be referred to as comparative sample 9.

Example IO A 0.3 μm thick intermediate layer made of polyvinyl formal “Vinylex LJ (manufactured by Tsukisui Kagaku Co., Ltd.) was formed on a conductive support made of a polyester film on which aluminum was vapor-deposited.

Next, 1 part by weight of Exemplified Compound (II'-2), polyvinyl butyral resin "Nisrex BLSJ (ff
(manufactured by Suikagaku Co., Ltd.) 1 part by weight and 1 part of 1,2-dichloroethane
A liquid obtained by dispersing 00 parts by weight using an ultrasonic dispersion machine was applied with a wire bar to form a CGL having a thickness of 0.3 μm.

Next, a solution consisting of 10 parts by weight of Exemplified Compound (II-14), 12 parts by weight of polycarbonate resin "Panlite L-1250J" and 100 parts by weight of 1,2-dichloroethane was applied with a blade to form a CTL having a thickness of 18 μm.

Next, 1 part by weight of polyester resin "Vylon 200J, 0.4 part by weight of Exemplary Compound (1-14) and 1.
A solution consisting of 100 parts by weight of 2-dichloroethane was coated with a blade to form a protective layer with a thickness of 0.5 μm, thereby obtaining a photoreceptor of the present invention. This is referred to as sample IO.

Comparative Example 10 A comparative photoreceptor was obtained in the same manner as in Example 10 except that the protective layer was not formed.

This is referred to as a comparison sample IO.

Evaluation 1 The samples obtained in Examples 1-10 and Comparative Examples 1 to 1O above were evaluated as follows. That is, ozone gas generated in an ozone generator (Japan Ozone Co., Ltd. Model 0-12) was introduced into an electrostatic tester (Model SP-428, manufactured by Kawaguchi Electric Seisakusho) equipped with a sample, and the ozone gas inside was introduced. The concentration was 90 ppm.

First, the surface potential (initial potential) VO after being negatively corona charged for 5 seconds under a discharge condition of 40 μA and then left for 5 seconds
(V) Subsequently, white light exposure was performed to measure the exposure amount E, 72 (4ux-sec) required to lower the surface potential from the initial voltage V0 to 1/2.

Then, repeat this operation 100 times, measure the initial potential V10° after 100 times, and find the retention rate V of the initial potential. .

/ VO was determined and evaluated as ozone resistance.

The results are shown in Table 2.

Table 2 Example 11 5 parts by weight of exemplified compound (III-2) and exemplified compound (n-18, I p = 5.50 eV) were placed on a conductive support made of a polyester film on which aluminum was vapor-deposited.
8 parts by weight, 1 part by weight of Exemplified Compound (I-5), polycarbonate resin [10 parts by weight of Panlite L-1250J and 200 parts by weight of 1,2-dichloroethane were dispersed in a sand mill for 8 hours, and the resulting solution was applied with a blade. Thickness 15μ
A photosensitive layer of m was formed. This is designated as sample 11.

Comparative Example 11 A comparative photoreceptor was obtained in the same manner as in Example 11, except that Exemplary Compound (I-5) was omitted. This will be referred to as comparative sample 11.

Evaluation 2 In the samples of Example 11 and Comparative Example 11, the negative corona charge in Evaluation 1 was changed to positive corona charge. The sensitivity was determined by measuring the potential vL 3.0 seconds after exposure using an actual device. Other evaluations were made in the same manner as in Evaluation 1.

The results are shown in Table 3.

Table 3 From the results of Example 1 to Comparative Example 11, it can be seen that the present invention is effective in both positive and negative corona discharges.

〔Effect of the invention〕

As described above, in the photoreceptor of the present invention, the effect of improving sensitivity and the effect of excellent environmental resistance can be obtained.

In particular, in the present invention, by adding the hindered phenol compound of the present invention to a photoconductor containing a CTM with an Ip of 5.45 or more, not only can sensitivity be improved, but also charging due to ozone and other active substances generated during charging. A remarkable improvement effect on phenomena such as a decrease in performance and an increase in dark room conductivity can be obtained. Further, the photoreceptor of the present invention has the effects of improving the charging potential and reducing dark decay, exhibits excellent initial characteristics, and exhibits excellent characteristics with extremely little fatigue and deterioration due to repeated use.

[Brief explanation of the drawing]

1 to 3 are cross-sectional views of examples of embodiments of the photoreceptor of the present invention. FIG. 4 is a graph for explaining the method for measuring rp. ■... Conductive support 2... Charge generation layer (CGL) 3... Charge transport layer (CTL) 4... Photosensitive layer 5... CGM 6... CTM

Claims (2)

[Claims] (1) In an electrophotographic photoreceptor comprising a charge transporting substance and a charge generating substance having an ionization potential of 5.45 or more in the photosensitive layer, the electrophotographic photoreceptor contains the following general formula [
An electrophotographic photoreceptor comprising a hindered phenol compound having at least one structural unit represented by [Ia] or [Ib]. General formula [I a] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ General formula [I b] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [In the formula, R_1 and R_7 each represent a hydrogen atom or an alkyl group, and R_2 , R_8 and R_1_2 each represent a branched alkyl group, R_3, R_4, R_5, R
_6, R_9, R_1_0, R_1_1, R_1_3,
R_1_4 and R_1_5 each represent a hydrogen atom or a substituent, m and n each represent 0 or a positive integer,
m+n is 2-4. Y represents a linking group, and p represents 0 or 1. ] (2) The electron transport material according to claim 1, wherein the charge transport material is a styryl compound represented by the following general formula [II], and the charge generating material is an azo compound represented by the following general formula [III]. Photographic photoreceptor. General formula [II] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [In the formula, Ar_1 represents an aryl group or a heterocyclic residue, Ar_2 represents an alkyl group or an aryl group, and R_
1_6, R_1_7, R_1_8 and R_1_9 each represent a hydrogen atom, an alkyl group or an aryl group. Ar_1, Ar_2, R_1_6, R_1_7, R_1
The above groups represented by _8 and R_1_9 may further have a substituent selected from an alkyl group, an alkoxy group, a halogen atom, a cyano group, and an amino group optionally substituted with an alkyl group or an aryl group. n is 0
Or represents 1. At least one of Ar_1, Ar_2, R_1_6 and R_1_9 has an amino group as a substituent. ] General formula [III] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ [In the formula, R_2_0, R_2_1, R_2_2, R_2
_3, R_2_4 and R_2_5 each represent a hydrogen atom or a substituent, and Cp represents a coupler residue in an azo coupling reaction. ]