JPH01259366A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To stabilize repeatability of an electrophotographic sensitive body without impairing the sensitivity of the sensitive body by incorporating a specified amt. of a phosphonium salt into the electrophotographic sensitive body. CONSTITUTION:Into a photosensitive body, 0.0001-15pts.wt. phosphonium salt(A) basing on 100pts.wt. charge generating material (B) is pref. incorporated, and a compd. expressed by the formula I is pref. incorporated as a component(A). In the formula, each R1-R4 is H, alkyl group, etc.; X<-> is an anion. A compd. expressed by the formula II, etc. may be used for the component(A), which may be incorporated in a stage for dispersing the component(B) (e.g. azo pigment). A charge generating layer 2 is formed, thus, by coating a liquid dispersion contg. the component(A) and (B) on a substrate 1, and a photosensitive layer is prepd. by forming a charge transfer layer 3 thereon.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor with high sensitivity and excellent repeatability.

[Background of the invention]

Conventionally, photosensitive layers used in electrophotographic photoreceptors include Se,
Inorganic photoconductive materials such as C, dS, and ZnO are widely used. However, when these inorganic compounds are used as a photosensitive layer of an electrophotographic photoreceptor, they are not necessarily satisfactory in terms of heat resistance and durability.

In recent years, much research has been conducted into using organic photoconductive substances as photosensitive layers of electrophotographic photoreceptors instead of these inorganic photoconductive substances.

In particular, when an organic photoconductive substance is used as the photosensitive layer of an electrophotographic photoreceptor, it is highly flexible and easy to manufacture.
There is an advantage that a cheaper electrophotographic photoreceptor can be obtained. However, at present, no photoreceptor has been obtained that satisfies all the characteristics required of an electrophotographic photoreceptor, such as sensitivity and durability.

Several techniques are known for improving the durability of electrophotographic photoreceptors using organic photoconductive substances. For example, JP-A-59-157 discloses a technique for improving repeatability by incorporating an N,N-disubstituted dithiocarbamate into a photosensitive layer. However, although this technique is effective to some extent against 03 deterioration, it has the drawbacks of poor storage stability and decreased sensitivity under high temperature and high humidity conditions. Also, JP-A-59-2184
Japanese Patent No. 47 discloses a technique for improving the repeated potential stability by incorporating an amine into the photosensitive layer. However, this technique has the disadvantage of reduced sensitivity. Furthermore, Japanese Patent Application Laid-open No. 58-166351 and No. 58-16635
Publication No. 2 discloses a technique in which a polymer of a specific quaternary ammonium salt is used as a binder resin for a charge generating substance. However, since it is necessary to control the reaction rate, composition, etc. during the manufacturing process, this polymer has the disadvantage of lacking manufacturing stability and resulting in large variations in performance. Electrophotographic photoreceptors have the disadvantage of low sensitivity.

[Problem that the invention seeks to solve]

Therefore, the technical object of the present invention is to stabilize the repeatability characteristics without reducing the sensitivity and to satisfy the characteristics required of an electrophotographic photoreceptor.

[Means to solve the problem]

The present inventor has conducted extensive research in order to solve the above problems, and as a result, has arrived at the present invention.

That is, the electrophotographic photoreceptor according to the present invention is an electrophotographic photoreceptor having at least one photosensitive layer on a conductive substrate, and a phosphonium salt is added to the electrophotographic photoreceptor in an amount of 100 parts by weight of a charge generating substance. 1 at 0.0001 parts by weight or more
It is characterized by containing 5 parts by weight or less, preferably 0.01 parts by weight or more and 10 parts by weight or less.

Typical phosphonium salts used in the present invention (hereinafter referred to as compounds of the present invention) are represented by the following general formula (I):
Examples include compounds represented by:

General formula (I) e R・-v-1・Xo In the formula, R, , R2, R3 and R4 are each a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted represents a cycloalkyl group or a substituted or unsubstituted aryl group. Also R
1 may form a substituted or unsubstituted bridged ring together with R2. Xe represents an anion, xe is R,
It may be bonded to R, , R, or R4 to form an inner salt.

The unsubstituted alkyl group and unsubstituted alkenyl group represented by R, -R, preferably have 1 to 20 carbon atoms, such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group. , tert-butyl group, pentyl group, hexyl group, hegetyl group, octyl group,
2-ethylhexyl group, dodecyl group, hexadecyl group,
Octadecyl group, vinyl group, allyl group, 3-methyl-2
-butenyl group, impropenyl group, 2-butenyl group, etc. Substituted alkyl groups and substituted alkenyl groups include chloro group, bromo group, cyano group, phenyl group, etc. , methoxy group, acyl group, hydroxyl group, etc., such as benzyl group, phenethyl group, trityl group, difninylmethyl group, hydroxyethyl group, methoxyethyl group, cyanoethyl group, acetoxyethyl group, acetylethyl group, chloromethyl group. , styryl group, cinnamyl group, etc.

The unsubstituted cycloalkyl group and unsubstituted monocyclic aryl group represented by R1-R4 preferably have 3 to 12 members, such as cyclopropyl group, cyclohexyl group, phenyl group, cyclotrienyl group, etc. It will be done.

The unsubstituted fused polycyclic aryl group represented by R and -R4 preferably has 7 to 18 carbon atoms, and includes, for example, a naphthyl group, an anthryl group, a phenanthryl group, an indenyl group, and the like.

Substituted cycloalkyl groups and substituted aryl groups include methyl group, ethyl group, fluoro group, pro-7 group, cyan group, phenyl group, methoxy group, acyl group, nitro group, and hydroxyl group. Examples include tolyl group, gysylyl group, cumenyl group, mesityl group, and methoxyphenyl group.

A ring formed by R3 and R3, and R, , R, and R
The bridged ring formed by 1 is a heterocycle containing Pe in the general formula (I) as a ring-constituting atom, and the heterocycle also contains sulfur, oxygen, selenium,
It may contain phosphorus, arsenic, silicon, germanium, boron, etc.

The ring formed by R□, R2 and Pe has 5 to 7 carbon atoms.
The bridged ring formed by R1-R3 and P is preferably one having 6 to 18 carbon atoms, for example, one of the carbon atoms constituting the ring such as norbornyl or adamantyl has the general formula Examples include rings substituted with Pe in (I).

Examples of anions include halogen anions such as fluorine, chlorine, bromine, and iodine, boron tetra7tride, phosphorus hexafluoride, carbonate ion, sulfate ion, phosphate ion, nitrate ion, perchlorate ion, etc. Inorganic acid anions, inorganic anions such as hydroxide ions, carboxylic acid ions such as acetate ions, oxalate ions, propionate ions, benzoate ions,
Examples include sulfonic acid ions such as benzenesulfonic acid, alkoxy ions such as methoxy ions, and ethoxy ions.

The present invention will be explained in detail below.

Preferred embodiments of the layer structure of the photoreceptor of the present invention include:
The following layer structures (1) to (8) can be mentioned.

(1) As shown in FIG. 1, from the upper layer, the charge transport layer 3,
A charge generation layer 2 and a conductive substrate 1 are constructed in this order.

(2) As shown in Figure 2, in the layer configuration shown in (1) above, a subbing layer 4 (a layer having functions such as an intermediate layer and an adhesive layer) is provided between the charge generation layer 2 and the conductive substrate l. What you have.

(3) As shown in FIG. 3, from the upper layer, the charge generation layer 2,
A charge transport layer 3 and a conductive substrate 1 are constructed in this order.

(4) As shown in FIG. 4, in the layer structure shown in (3) above, an undercoat layer 4 (
(layers with functions such as intermediate layer, adhesive layer, etc.)

(5) As shown in FIG. 5, a charge generation layer 2A containing a charge generation substance and a charge transport substance, a charge transport layer 3, and a conductive substrate 1 are constructed in this order from the upper layer.

(6) As shown in FIG. 6, in the layer structure shown in (5) above, an undercoat layer 4 (
(layers with functions such as intermediate layer, adhesive layer, etc.)

(7) As shown in FIG. 7, only a charge generation layer 2 in which a charge generation substance or a charge generation substance and a charge transport substance are uniformly dispersed or dissolved is formed on a conductive substrate 1.

(8) As shown in FIG. 8, in the layer structure shown in (7) above, an undercoat layer 4 (
(layers with functions such as intermediate layer, adhesive layer, etc.)

Further, in the above layer structure, an intermediate layer may be provided between each layer, and a surface protective layer may be formed as the uppermost layer.

As the conductive substrate, metals such as aluminum, brass, and stainless steel are molded into a drum shape, or are used as sheet-like films or foils, and polymeric materials such as polyethylene terephthalate, nylon, polyarylate, polyimide, and polycarbonate are used. It is used by molding an insulating material such as hard paper into a drum shape or by applying a conductive treatment to a sheet-like film. Examples of methods for conductive treatment include impregnation with a conductive substance, lamination of metal foil (for example, aluminum foil), vapor deposition of metal (for example, aluminum, indium, tin peroxide, yttrium, etc.), and conductive processing.

Materials that can be used for the undercoat layer include metal oxides such as aluminum oxide, indium oxide, and titanium oxide, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, epoxy resin, urethane resin, polyester resin, and phenol. Resin, alkyd resin, polycarbonate resin, silicone resin, melamine resin, polyvinyl formal resin, polyvinyl butyral resin, polyvinyl alcohol resin, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, vinylidene chloride - Polymer materials such as acrylonitrile copolymer, styrene-butadiene copolymer, ethyl cellulose,
Celluloses such as carboxymethylcellulose are used, and each can be used alone or in combination of two or more.

The undercoat layer is formed to a predetermined thickness by dissolving the above-mentioned material in an appropriate solvent and coating the solution on the conductive substrate. As for the coating method, when the conductive substrate is drum-shaped,
A dipping method, a spray method, an extrusion method, a slide hopper method, etc. are preferred, and when the conductive substrate is in the form of a sheet, a roll method, extrusion, slide hopper method, etc. are preferably employed. The thickness of the undercoat layer thus formed is preferably in the range of 0.01 to 30 μm, and preferably in the range of 0.05 to 30 μm.
A range of 15 μm is more preferred.

The charge generation layer is preferably formed by coating a charge generation substance alone or dispersed in a binder on a conductive substrate.

Examples of charge-generating substances include guaiazulene pigments (for example, JP-A No. 59-53850), perylene-based pigments (for example, JP-A No. 59-24852 and JP-A No. 47-30330), and phthalocyanine pigments (for example, JP-A No. 53-9536 and JP-A No. 47-30330). 59-
No. 9537), biryllium pigments (e.g. No. 53-40
531), quinacridone pigments (e.g. No. 47-30), quinacridone pigments (e.g. No. 47-30
332), indigo pigments (e.g. 47-30331
), cyanine pigments (for example, No. 54-21343)
, azo pigments (e.g. No. 58-194035, No. 58
-115447, 59-723757, 59-
No. 72376, No. 59-73820), and specifically examples include
Do-ichi
Nv VC
Two
As a means for dispersing the charge-generating substance in the beak, the charge-generating substance is added to a solution of a suitable solvent or binder, and known dispersion means such as a sand mill, a ball mill, and ultrasonic dispersion can be used. As a binder,
Polymer materials such as acrylic resin, methacrylic resin, polyester resin, polycarbonate resin, styrene resin, polyvinyl alcohol resin, and polyvinyl butyral resin are used. Suitable solvents include ■, 2-dichloroethane, chloroform, 1,1.1-trichloroethane,
Examples include dichloromethane, acetone, dioxane, methyl ethyl ketone, tetrahydrofuran, benzene, toluene, xylene, diethyl ether and the like.

The mixing ratio of the charge generating substance and the binder is 0 to 500 parts by weight of the binder to 100 parts by weight of the charge generating substance;
Preferably it is 0 to 200 parts by weight.

The charge generation layer contains the compound of the present invention.

Representative examples of the compounds of the present invention include the following examples.

(1) Ph5PCH2Ph
Br(2) Ph s P CH2C
Hs B r(3) Ph, P
CHs CQ(4) P
h, PCH30He
e(5) Ph, PCH=CH
,Br(6) Ph5PCHBr2
Br(7) (CH,)! PCH
, CH3I and tt2 cylinder (18) (CH3)3PCH(CH3)
2 Br(19) PhC
H*PHs CQ':h(2
2) Ph5Pc4Hs
Br(23) Pb, PCH2CH
2CH(CH3)2 Br(30) Ph5P
CH, +c HzBr Bre (31) Ph5P-(CH2)4-P
Ph3Br' BP (32) Ph, PC, H, A
CQ (33) PhxP C+<Hz
*c! (34) Ph5
P C1@H37CQ(35) Ph5P
CHzPh NO3 (36)
Ph5PCHzPh CHsCHzCOO
(37) Ph5P CH*Ph CHses
Os (3g) CP H2Ca O (Note: rphJ represents a phenyl group.) The compound of the present invention is described in, for example, Organic Reactions Vol.
, 14. p, 396.1 bid, 14. Phosphine compounds and halides can be easily synthesized by heating and stirring them in a suitable solvent (for example, dimethylformamide) as described in the literature such as P. P., 397. However, methods for synthesizing the compounds of the present invention are not limited to these methods.

Commercially available products include those manufactured by Tokyo Kasei Kogyo Co., Ltd., Kanto Kagaku Co., Ltd., and Wako Pure Chemical Industries, Ltd.

The amount of the compound of the present invention added is 0.0001 parts by weight or more and 15 parts by weight or less per 100 parts by weight of the charge generating substance,
Preferably it is 0.001 parts by weight or more and 10 parts by weight or less. The effect of the present invention is less than 0.0001 part by weight.1
If it exceeds 5 parts by weight, sensitivity will decrease. Addition and usage methods include adding it to the solvent when dispersing the charge generating substance, dissolving it in the solvent when dispersing the charge generating substance, and adding it to the dispersion liquid in which the charge generating substance is dispersed. Any method used may be used.

The charge transport layer is formed by dissolving a charge transport material and a binder in a suitable solvent and coating the mixture on the charge generation layer.

Examples of the charge transport substance include triazole derivatives (for example, Japanese Patent Publication No. 34-5467), oxazole derivatives (for example, Japanese Patent Publication No. 35-1125), oxadiazole derivatives (for example, Japanese Patent Publication No. 34-5466), and pyrazoline derivatives (for example, Japanese Patent Publication No. 34-10366). ), imidazole derivatives (for example, JP-A No. 35-11215, JP-A No. 37-16096), fluorenone derivatives (JP-A-52-128373, JP-A No. 54-1983),
No. 110837), carbazole derivatives (e.g. No. 54 No. 110837), carbazole derivatives (e.g.
-59142) and also No. 58-134642, No. 58
-65440 etc. are mentioned.

Preferred charge transport materials in the present invention include the following-
Examples include compounds shown in formulas (1) to (7).

General formula (1) General formula (2) General formula (3) - Numerical formula (4) General formula (5) General formula (6) General formula (7) In the above formula, R81 to R□, R27 to R34, R3, ~R4
4゜R4, -R, ..., R, ...Ras are each a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, a hydroxyl group, a cyano group, a dialkylamino group, a diarylamino group, a dialkylamino group, or a nitro group. represents the group,
Rls represents an alkyl group, a phenyl group which may have a substituent, or a naphthyl group which may have a substituent, and R1,
represents a hydrogen atom, an alkyl group, a cyano group, or a phenyl group that may have a substituent; R3 represents a hydrogen atom, a phenyl group, a cyano group, or an alkyl group that may have a substituent; In the formula, R59+ R@. + R61 is an alkyl group, benzyl group, phenyl group or naphthyl group (
Each may have a substituent. ), and R6□ represents a hydrogen atom alkyl group, alkoxy group, halogen atom, hydroxyl group, dialkylamine group or nitro group.

), R4$1 s2 represents a hydrogen atom or a phenyl group. n represents 0.1 or 2.

Specifically, the following compounds may be mentioned.

(a) (b) (c) (d) (e) (f, ) (g) (h) (i) As a binder, it has high compatibility with the charge transport substance,
Furthermore, materials with high transparency and insulation properties are preferred, and all materials generally used for electrophotographic photoreceptors can be used, such as polyester resin, polyethylene resin, polyamide resin, polycarbonate resin, epoxy resin, polyvinyl butyral resin, polymethyl resin, etc. A methacrylate resin or the like is used.

The content of the charge transport material is 25 to 200 parts by weight, preferably 50 to 100 parts by weight, based on 100 parts by weight of the binder.

The charge generation layer and the charge transport layer can be coated by the same method as the undercoat layer described above, and the thickness of the charge generation layer is 0.01 to 1.
The width of the charge transport layer is preferably 0 μm, more preferably 0.05 to 2 μm, and the width of the charge transport layer is preferably 5 to 50 μm, more preferably 10 to 30 μm.

〔Effect of the invention〕

According to the present invention, it is possible to greatly improve the repeatability of the electrophotographic photoreceptor without decreasing its sensitivity, and it has particularly excellent environmental resistance, and the time elapsed from the time of manufacture to the time of application of the dispersion for the charge generation layer. It is possible to obtain an electrophotographic photoreceptor in which variations in the performance of the electrophotoreceptor due to fluctuations in the temperature, etc. and dark decay properties are improved.

〔Example〕

Preferred examples of the present invention are shown below, but the present invention is not limited thereto.

Example l Polyvinyl formal resin 109 was impregnated with improvator tool 1
000 m4 and coated on an aluminum plate by dip coating to form a subbing layer with a thickness of about 0.15 μm. Next, polycarbonate resin (trade name: Panlite L-1250, (manufactured by Ondai Kasei Co., Ltd.) 59,
As a charge generating substance, (G-7) 109, 1,2-dichloroethane 10100O was ground and dispersed in a ball mill,
A dispersion was obtained.

Add 1.0 g of Exemplary Compound (1) to the obtained dispersion,
After stirring for about 1 hour, it was applied onto the undercoat layer by a dip method and dried at 100° O'1' for 10 minutes to form a charge generation layer with a thickness of about 0.2 μm.

Furthermore, polycarbonate resin (trade name: PA) Light 11300J (manufactured by Teijin Kasei) 1509, charge transport substance (a) 759 and 1,2-dichloroethane lo0
The solution was dissolved in 0 ml of water and applied onto the charge generation layer by a dip coating method, and dried at 110°C for 20 minutes to form a charge transport layer with a thickness of about 21 μm. The photoreceptor thus obtained is referred to as sample 1.

Example 2 Same as Example 1 except that (G-12) was used instead of (G-7) as the charge generating substance, the amount of the exemplary compound was changed to 0.2 g, and (d) was used as the charge transporting substance. A photoreceptor of the present invention was obtained. This is called sample 2.

Example 3 10 g of polyvinyl formal resin was mixed with 1 isopropanol
PET dissolved in 00100O and vapor-deposited with aluminum
The coating was applied onto the base using a roll coater to form an undercoat layer having a thickness of 0.18 μm.

Next, polycarbonate resin (product name: Panlite L
-1250, (manufactured by Ondai Kasei Co., Ltd.) 5 g, as a charge generating substance (G-12) 109, i, 2-dichloroethane 1
0100O was pulverized and dispersed in a ball mill to obtain a dispersion. Adding 0.49% of exemplified compound (2) to the obtained dispersion,
After stirring for about 1 hour, a charge generation layer having a thickness of about 0.18 μm was formed on the undercoat layer by wire bar coating.

Furthermore, polycarbonate resin (product name: Panlite K
-1300J (manufactured by Teijin Chemicals) 150g, charge transport substance (d) 75g, 1,2-dichloroethane 1000g
m<1, and coated on the charge generation layer by a roll coater coating method, and dried at 110°C for 20 minutes to form a charge transport layer with a thickness of about 21 μm. The photoreceptor thus obtained is referred to as sample 3.

Example 4 In Example 3, (21
), the amount of the exemplified compound was (L8 g), and a photoreceptor of the present invention was obtained in the same manner as above. This is referred to as Sample 4.

Example 5 In Example 3, exemplified compound (1) was substituted for exemplified compound (2).
A photoreceptor of the present invention was obtained using the same method except that the amount of the exemplified compound was 0.4 g. This is called sample 5.

Example 6 In Example 3, (26
), the amount of the exemplified compound was 0.4 g, and the other conditions were the same to obtain the photoreceptor of the present invention. This is called sample 6.

Example 7 In Example 3, (37
), the amount of the exemplified compound was 0.49, and the other conditions were the same to obtain the photoreceptor of the present invention. This is called sample 7.

Example 8 In Example 3, (28
), the amount of the exemplified compound was 1.2 g, and the other conditions were the same to obtain the photoreceptor of the present invention. This will be referred to as sample 8.

Example 9 In Example 3, (24
), and the amount of the exemplified compound was adjusted to 1. A photoreceptor of the present invention was obtained in the same manner except for Og. This will be referred to as sample 9.

Example IO In Example 3, instead of exemplified compound (2) f: (2
A photoreceptor of the present invention was obtained using Example 2) in the same manner except that the amount of the exemplary compound was 0.4y. This is designated as sample IO.

Example 11 In Example 3, (15
), the amount of the exemplified compound was 0.49, and the other conditions were the same to obtain the photoreceptor of the present invention. This will be referred to as sample 11.

Example 12 Improper tool 1 of polyvinyl formal resin 109
0100 (PET dissolved in 1 and vapor-deposited with aluminum)
The coating was applied onto the base using a roll coater to form an undercoat layer having a thickness of 0.18 μm.

Next, polycarbonate resin (product name: Panlite L
-1250, (manufactured by Yondai Kasei Co., Ltd.) 59, CG-12 as a charge generating substance) 10 g, Exemplary Compound (5) 0.49.
1000 mα of 1,2-dichloroethane was pulverized and dispersed in a ball mill to obtain a dispersion. The resulting dispersion was coated on the undercoat layer with a wire bar coating method to a thickness of about 0.18 μm.
A charge generation layer was formed.

A photoreceptor of the present invention was obtained in the same manner as in Example 3 except for the above. This will be referred to as sample 12.

Example 13 In Example 12, exemplified compound (2) was replaced with (2
A photoreceptor of the present invention was obtained using Example 1), except that the amount of the exemplary compound was 0.8 g, and the other procedures were the same. This will be referred to as sample 13.

Example 14 In Example 12, (3
A photoreceptor of the present invention was obtained using Example 7), except that the amount of the exemplary compound was 0.8 g, and in the same manner as above. This will be referred to as sample 14.

Comparative Example 1 A comparative photoreceptor was obtained in the same manner as in Example 3, except that exemplified compound (2) was not used. This is designated as comparative sample 1.

Comparative Example 2 A comparative photoreceptor was obtained in the same manner as in Example 3, except that diethylamine was used in place of the exemplified compound (2) in the same lid. This will be referred to as comparative sample 2.

Comparative Example 3 A comparative photoreceptor was prepared in the same manner as in Example 3, except that 3 g of tellurium diethyldithiocarbamate (a compound disclosed in JP-A-59-157) was used instead of Exemplified Compound (2). Obtained. This will be referred to as comparative sample 3.

Comparative Example 4 Dispersion 5 of charge generating substance (G-12) in Example 3
1.0 g of a cationic copolymer represented by the following structural formula and 0.059 g of 2,2'-azobis-2-aminopropane dihydrochloride were added to 0II+12, dissolved at room temperature, and immediately dissolved to 80μ
A 10 μm thick Al1 foil was coated on a support using a doctor spray coating method, and dried by heating at about 85° C. for 2 minutes.

Q0 (The numbers in the above structural formula represent the mole % of each monomer unit.) In this way, a charge generation layer having a thickness of about 0.3 μm was obtained.

(See Example I of JP-A-58-1663ild)
Next, the charge transport layer used in Example 3 was coated on this charge generation layer to obtain a photoreceptor. This will be referred to as comparative sample 4.

Comparative Example 5 A comparative photoreceptor was obtained in the same manner as in Example 3, except that 2.5 g of Exemplary Compound (2) was used. This will be referred to as comparative sample 5.

〔evaluation〕

Each sample obtained above was evaluated as follows. Using Paper Analyzer S P-428 (manufactured by Kawaguchi Electric Co., Ltd.), it was charged for 5 seconds under a discharge condition of 40 μA, and the surface potential immediately after charging [Val], the surface potential after being left in the dark for 5 seconds [Vi], and the surface illuminance were 2. lux, and calculate the exposure amount [E I/2] (Lux-sec) until the surface potential becomes 1/2 Vi, and then calculate the dark decay rate from the formula Va-Vi D-Va X100. [D] was determined. Table these results.
Shown in 1.

Further, a normal Carlson process was carried out using Sample 1-14 and Comparative Samples 1 and 2, and the difference in surface potential immediately after charging between the initial stage and 10,000 times [ΔVb1] and the residual potential after 110,000 times [Vrl] was determined. In addition, the initial value and the value after 10,000 times of irradiation were determined for the surface potential Vv after quantitative irradiation.

These results are shown in Table-1 and Table-2.

Table 1 Table 2 As is clear from Tables 1 and 2, Sample 3 has greatly improved D value and Δvb compared to Comparative Sample 1, and the amount of charge generating material of the present invention is significantly improved. It can be seen that by including the phosphonium salt in an amount within the ratio range, the dark decay characteristics and the repeatability characteristics can be improved.

Furthermore, from a comparison between Sample 1-14 and Comparative Samples 2 to 5, it was found that by incorporating a phosphonium salt in combination within the above-mentioned ratio range to the charge-generating substance, it was possible to improve the repeatability without reducing the sensitivity. It turns out that it is particularly effective.

Example 15.16 and Comparative Example 7.8 The procedure of Example 2 was repeated except that the dispersions obtained in Example 2 and Comparative Example 2 were applied 24 hours and 96 hours after the production of the dispersions, respectively. A photoreceptor was obtained.

Samples 15.16 and comparison samples 7.8
What should I do? By the method described above for these samples.
[Val, [Vil, [E +zz] (L, ux-s
ec) and [D] were measured.

The results are shown in Table-3.

Table 3 From Table 53, it can be seen that the charge generation layer dispersion containing the above-described specific amount of the compound of the present invention is also excellent in storage stability.

Test for storage stability under high temperature and high humidity Sample 4.5.6.7 and Comparative sample 3.5 were stored for one month in an environment with a temperature of 50° C. and relative humidity of 80%, and then these samples were subjected to the above-mentioned method. By [Val, [V i] , [E l/2] (Lux
-sec), [D] were measured.

Table 4 From Table 4, it can be seen that the electrophotographic photoreceptor containing the specified amount of the compound of the present invention also has excellent environmental resistance.

As can be understood from these tables, the photoreceptor of the present invention can greatly improve the repeatability without decreasing sensitivity, and is also stable in terms of storage stability and manufacturing stability. It can be seen that it is in good condition.

Example 17 A photoreceptor of the present invention was obtained in the same manner as in Example 3 except that 0.004 g of Exemplified Compound (2) was added instead of 0.4 g in Example 3. This will be referred to as sample 17.

Comparative Example 9 A comparative photoreceptor was obtained in the same manner as in Example 3 except that dibutylammonium chloride was used in place of Exemplary Compound (2). This will be referred to as comparative sample 9.

Similarly, in Example 3, instead of adding 0.4 g of exemplified compound (2), 0.0049 g of dibutylammonium chloride was added.
A comparative photoreceptor was obtained in the same manner as in Example 3 except for the addition. This is referred to as sample IO.

[Val, [
Vt], [E 112 (Lux-
sec) and [D] were measured.

Table 5 (initial period) As can be seen from Tables 5 and 6, ammonium salts have no effect when used in small amounts, but when used in large amounts, they do not cause a decrease in sensitivity and reduce dark decay, similar to the present invention. You can see the effect of making it smaller.

However, under conditions of 55°C and 90% relative humidity, 1
Sensitivity decreases after storage for several months.

The authors believe that the cause of this is that a large amount of salt has an adverse effect such as promoting oxidation of the aluminum conductive layer surface under high humidity.

From this point of view, the phosphonium salt of the present invention is effective even when added in a small amount, and as a result, environmental resistance, especially under high humidity conditions, can be improved.

[Brief explanation of the drawing]

1 to 8 are schematic sectional views showing embodiments of the layer structure of the photoreceptor of the present invention. 1... Conductive substrate 2.2A... Charge generation layer 3... Charge transport layer 4... Undercoat layer

Claims (2)

[Claims] (1) In an electrophotographic photoreceptor having at least one photosensitive layer on a conductive substrate, a phosphonium salt is added to the electrophotographic photoreceptor in an amount of 0.00 parts by weight per 100 parts by weight of a charge generating substance.
1. An electrophotographic photoreceptor comprising 0.01 parts by weight or more and 15 parts by weight or less. (2) The electrophotographic photoreceptor according to claim (1), wherein the phosphonium salt is represented by the following general formula (I). General formula (I) ▲ Numerical formulas, chemical formulas, tables, etc. Represents a substituted cycloalkyl group or a substituted or unsubstituted aryl group. Further, R_1 may form a substituted or unsubstituted ring together with R_2, and R_1 may be substituted with R_2 and R_3.
X^■ may form a substituted or unsubstituted bridged ring together with R_1, R_
2. May be bonded to R_3 or R_4 to form an inner salt]