JPH06236054A - Electrophotographic sensitive material - Google Patents

Abstract

PURPOSE:To provide an electrophotoraphic sensitive material having high sensitivity for a wide wavelength range from visible ray to near UV, and stable electrification property by incorporating an azo dye subjected to saltmilling into a photoconductive layer. CONSTITUTION:This electrophotographic sensitive material has a photoconductive layer on a conductive supporting body. At least one of layers which constitute the photoconductive layer contains an azo dye which is subjected to pulverization and mixing under high mechanical force in the presence of salt, so-called saltmilling treatment. As for saltmilling method, such means as a ball mill, vibration mill, Attriter, sand mill, paint shaker, and jet mill are used. The salt used for pulverization is preferably a salt of cation such as Na<+> and K<+>. The azo dye is a trisazo dye expressed by formula or a bisazo dye expressed by formula II. (In formulae, Ar<1>, Ar<2>, Ar<3> are coupler residues.)

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an electrophotographic photoreceptor. More specifically, it relates to an electrophotographic photoreceptor having high sensitivity in a wide wavelength range from a visible light range to a near infrared light range.

[0002]

2. Description of the Related Art In recent years, the development of information processing system machines using electrophotography has been remarkable. In particular, an optical printer that converts information into a digital signal and records information by light has excellent print quality and reliability. This digital recording technology has been applied not only to printers but also to ordinary copying machines, and so-called digital copying machines have been developed. In addition, since a copier equipped with this digital recording technology in addition to the conventional analog copying has various information processing functions, its demand will increase more and more in the future.

As a light source for an optical printer, a semiconductor laser (LD) and a light emitting diode (LED) which are small in size, inexpensive and highly reliable are currently widely used. The emission wavelength of the LED that is often used at present is 660 nm.
The emission wavelength region of D is in the near infrared region. Therefore, development of an electrophotographic photosensitive member having high sensitivity in the visible light region to the near infrared light region is desired.

The photosensitive wavelength range of the electrophotographic photosensitive member is substantially determined by the photosensitive wavelength range of the charge generating material (CGM) used in the photosensitive member. Therefore, conventionally, various azo pigments,
Many CGMs such as polycyclic quinone pigments, trigonal selenium and various phthalocyanine pigments have been developed. Of them,
A large number of pigments have been developed for azo pigments because of the ease of the pigment synthesis reaction and the variety of chemical structures. JP-A-64-7
9753, JP-A-59-129857, JP-B-3-34
503, Japanese Patent Publication No. 4-52459, Japanese Patent Laid-Open No. 62-2673.
The bisazo pigment having a diphenylpolyene skeleton described in 63 and the trisazo pigment described in JP-A-57-195767 are CGMs having a high charge potential retention and having sensitivity in the visible light region to the near infrared light region. However, the sensitivity is not yet sufficient to cope with the downsizing and speeding up of information processing equipment in the future.

US Pat. No. 5,055,368 proposes an electrophotographic photoreceptor containing a dry salt milled titanyl phthalocyanine pigment. Although the phthalocyanine pigment has a sufficiently high sensitivity in a wide photosensitive wavelength range, the production of the photoreceptor The crystal form is liable to change due to organic solvents, etc., and it affects quality stability. Further, it is less stable in holding the charging potential than azo pigments. As described above, a CGM having high sensitivity in the visible light region to the near infrared light region has not yet been developed.

[0006]

Under the circumstances, the present invention provides an electrophotographic photosensitive member which has high sensitivity over a wide wavelength range from the visible light region to the near infrared light region and has stable charging characteristics. The purpose is to do.

[0007]

Means for Solving the Problems As a result of intensive studies by the present inventors, a photosensitive material containing a so-called salt milled azo pigment in which a high mechanical force is applied in the same container to pulverize and mix with a salt. It has been found that the sensitivity of the body is significantly higher than that when a pigment not salt milled is used, and the present invention has been completed. That is, the present invention is an electrophotographic photosensitive member comprising a photoconductive layer formed on a conductive support, wherein at least one layer forming the photoconductive layer contains a salt milled azo pigment. The subject of the invention is an electrophotographic photosensitive member.

As is apparent from the examples described later, the height of the characteristic X-ray diffraction peak of the salt-milled azo pigment is low, which indicates that the pigment has been transformed into an amorphous state or the crystal has become finer. However, the mechanism of this sensitizing effect has not been clarified at present. The salt milling carried out in the present invention means that crude crystals of an azo pigment are put together with salts such as NaCl, KCl and KBr in the same container for milling, and the pigment and the salt are simultaneously compressed, sheared, ground, rubbed, stretched, impacted, It is a method of giving mechanical energy such as vibration.

Specific means for performing salt milling include ball mills, vibration mills, disk vibration mills, attritors, sand mills, paint shakers, jet mills, etc., which are compressed, sheared, ground, rubbed and stretched into pigments and inorganic salts. Any crushing and mixing means that gives mechanical energy such as shock and vibration can be used. As the milling member, commonly used milling materials such as steel, stainless steel, YTZ, partially stabilized zirconia, agate, glass balls and sand can be used. Salts usable in the present invention include NaCl, KCl, KBr, Na ₂ SO ₄ , and K _2.
Inorganic salts such as alkali metal halides such as SO ₄ and CaCO ₃ , carbonates, sulfates, and phosphorus oxides, and CH
₃ Organic salts such as COONa. Particularly, salts of Na + and K + cations are preferable. Next, a specific method of performing salt milling will be described.

An azo pigment and a salt are put in a milling container together with a milling member and milling is performed for a predetermined time. The appropriate amount of salt to be added varies depending on the amount of the azo pigment to be treated, the size of the apparatus used, the treatment time, and the type of pigment, but it is preferable to add an equivalent amount or more to 1000 times the amount of the azo pigment to be added. After the completion of milling, the salt is dissolved in a solvent, and the azo pigment is separated from the salt and the milling member by means such as filtration and centrifugation. Solvents for salts include water and alcohols such as methanol and ethanol,
Ketones such as acetone and methyl ethyl ketone, ethyl acetate, ethylene glycol and the like, or a mixed solvent thereof can be used. The azo pigment separated from the salt or the milling member is dried by heating or by drying under reduced pressure.
In addition to the above-mentioned dry salt milling method, the salt milling method includes a solvent salt milling method in which a salt is milled in the presence of an organic solvent in which it is difficult to dissolve. In the present invention, the sensitizing effect of the azo pigment is promoted by salt milling in the presence of this organic solvent.

As the organic solvent, any solvent in which the salt to be used is sparingly soluble can be used. For example, methanol,
Ethanol, propanol, butanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, THF, cyclohexane, toluene, xylene, methyl cellosolve, ethyl cellosolve, dichloromethane, 1,2-dichloroethylene, 1,1,2-trichloroethylene, or a mixture thereof. A solvent can be used. The solvent salt milling may be carried out by adding an organic solvent together with a milling member, an azo pigment and a salt to a milling container, performing milling for a predetermined time, removing the organic solvent and the salt, and then drying the azo pigment.

The azo pigments used in the present invention are preferably the following pigments. That is, the trisazo pigment represented by the general formula (1) and the bisazo pigment represented by the general formula (2) are preferable.

[0013]

[Chemical 1]

(In the formula, Ar ¹ represents a coupler residue.)

[0015]

[Chemical 2]

(In the formula, Ar ² and Ar ³ represent a coupler residue, and l represents an integer of ^{1 to} 6.) Ar ¹ , Ar ² and
As the coupler residue of Ar ³ , for example,

[0017]

[Chemical 3]

(In the above formula, X represents a polycyclic aromatic ring or hetero ring selected from a naphthalene ring, an anthracene ring, a carbazole ring, a benzocarbazole ring, a dibenzofuran ring and a dibenzothiophene ring, which are bonded to a benzene ring. R ⁴ and R ⁵ represent a necessary residue, R ⁴ and R ⁵ represent a hydrogen atom, a group selected from substituted or unsubstituted alkyl, aryl and heterocyclic groups, and R ⁴ and R ⁵ form a ring together with a nitrogen atom to which they are bonded. R ⁶ and R ⁷ are each a group selected from a substituted or unsubstituted alkyl group and an aryl group,
Y represents a divalent group of an aromatic hydrocarbon or a divalent group of a hetero ring containing a nitrogen atom in the ring, and R ⁸ , R ⁹ , R ¹⁰ and R ¹¹ represent a hydrogen atom, a substituted or unsubstituted alkyl group. , A group selected from an aralkyl group, an aryl group and a heterocycle, R
¹⁰ and R ¹¹ may form a 5- or 6-membered ring, in which case the 5- or 6-membered ring may have a condensed aromatic ring.

Z represents a polycyclic aromatic ring or hetero ring selected from a naphthalene ring, an anthracene ring, a carbazole ring, a benzocarbazole ring, a dibenzofuran ring, a benzonaphthofuran ring and a dibenzothiophene ring, which are bonded to a benzene ring. Indicates the required residue. R ¹³ and R ¹⁵ are aromatic rings such as benzene ring and naphthalene ring and their substitution products, and R ¹² and R ¹⁴ are hydrogen atom, lower alkyl group, carboxyl group or ester thereof. ) Next, a method for producing an electrophotographic photosensitive member using the salt-milled pigment as a charge generating substance as described above will be described.

The photosensitive layer of the electrophotographic photosensitive member of the present invention can be of a dispersion type or a function separation type by combining a charge generating substance and a charge transporting substance. In the case of a dispersion type layer structure, a photosensitive layer in which a charge generating substance and a charge transporting substance are dispersed in a binder is provided on a conductive substrate. In the case of the function separation type, a charge generation layer containing a charge generating substance and a binder is formed on a substrate, and a charge transporting layer containing a charge transporting substance and a binder is formed on the base. In that case, the charge generation layer and the charge transport layer may be laminated in reverse.
In the case of the function separation type, a charge transport material may be contained in the charge generation layer. Particularly, in the case of the positive charging structure, the sensitivity is good. An intermediate layer may be provided between the photosensitive layer and the substrate in order to improve the adhesiveness and the charge blocking property. Further, in order to improve mechanical durability such as abrasion resistance, a protective layer may be provided on the photosensitive layer. As the binder used in the formation of the charge generation layer, the charge transport layer and the dispersion type photosensitive layer, any conventionally known binder having a good insulating property can be used, and there is no particular limitation. . 1
Examples include polycarbonate (bisphenol A type, bisphenol Z type), polyester, methacrylic resin, acrylic resin, polyethylene, polyvinyl chloride, polyvinyl acetate, polystyrene, phenol resin,
Epoxy resin, polyurethane, polyvinylidene chloride, alkyd resin, silicone resin, polyvinyl carbazole, polyvinyl butyral, polyvinyl carbazole,
Polyvinyl butyral, polyvinyl formal, polyarylate, polyacrylamide, polyamide, phenoxy resin and the like are used. These binders can be used alone or as a mixture of two or more kinds.

When a photoconductor is prepared by using the above-mentioned layer structure and substances, the film thickness and the ratio of the substances have preferable ranges. In the case of a negative charge type (lamination of substrate / charge generation layer / charge transport layer), the ratio of the charge generation substance to the binder in the charge generation layer is 20% by weight or more, and the film thickness is 0.01 to 5
μm is preferred. In the charge transport layer, the ratio of the charge transport material to the binder is preferably 20 to 200% by weight, and the film thickness is preferably 5 to 100 μm. Positively charged type (base /
In the case of the charge transport layer / charge generation layer stacking), the ratio of the charge transport material to the binder is 20 in the charge transport layer.
˜200 wt%, and the film thickness is preferably 5 to 100 μm. The charge generation layer preferably contains the charge generation substance in an amount of 20% by weight or more based on the binder. Furthermore, it is preferable to include a charge transporting substance in the charge generating layer, and by containing it, it is effective in suppressing the residual potential and improving the sensitivity. In this case, the charge transport material is preferably contained in the binder in an amount of 20 to 200% by weight.
In the case of a so-called dispersion type photoreceptor in which a charge generating substance and a charge transporting substance are dispersed in a binder resin, the sensitivity layer is subjected to salt milling as the charge generating substance for the binder resin. The pigment content is 5 to 95% by weight, and the film thickness is 1
0 to 100 μm is preferable. In that case, the ratio of the charge transport material to the binder resin is preferably 30 to 200% by weight.

Further, in these photosensitive layers, both of the dispersion type and the function separation type, for the purpose of improving charging property and gas resistance,
So-called antioxidants such as phenol compounds, hydoquinone compounds, hindered phenol compounds, hindered amine compounds, and compounds in which hindered amine and hindered phenol are present in the same molecule can be added.

In the present invention, the conductive substrate has a volume resistance of 10 ¹⁰ Ω · cm or less, such as aluminum, nickel, chromium, nichrome, copper,
A metal such as silver, gold, or platinum, or a metal oxide such as indium oxide or tin oxide, copper iodide, or the like is coated on a film or a cylindrical drum, a belt-shaped film, paper, or the like by an evaporation or a sputtering method. Or aluminum, aluminum alloy, nickel, stainless steel plates, etc. I. , I. I. It is possible to use a raw pipe which has been subjected to a surface treatment by cutting superfinishing, polishing or the like after being made into a raw pipe by a method such as extrusion, drawing or the like. Alternatively, a conductive powder of carbon black, indium oxide, tin oxide or the like dispersed in a suitable resin and coated on plastic or the like may be used. As the charge transport material used in the present invention, any known material can be used. Specific examples thereof include compounds having a basic structure represented by the following general formula (3) (JP-A-1-302260).
(See Japanese Patent Publication).

[0024]

[Chemical 4]

(In the formula, R ¹ and R ⁴ are a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom or a substituted amino group,
R ² and R ³ represent a hydrogen atom, an alkyl group or a substituted or unsubstituted phenyl group.

[0026]

[Chemical 5]

Is a benzene ring, naphthalene group, anthracene ring, indole ring or carbazole ring. n is 0
Alternatively, 1 and m represent an integer of 0, 1, 2, or 3. ) (3)
The preferred ones represented by the formula are shown in the table below.

[0028]

[Table 1]

[0029]

[Table 2]

[0030]

[Table 3]

[0031]

[Table 4]

[0032]

[Table 5]

[0033]

[Table 6]

[0034]

[Table 7]

[0035]

[Table 8]

[0036]

[Table 9]

[0037]

[Table 10]

[0038]

[Table 11]

[0039]

[Table 12]

[0040]

[Table 13]

[0041]

[Table 14]

[0042]

[Table 15]

[0043]

[Table 16]

Other charge transport materials that can be used in the present invention include hole transport materials and electron transport materials. Examples of the hole transport material include compounds represented by the following general formulas (4) to (15).

[0045]

[Chemical 6]

(In the formula, R ¹ is a methyl group, an ethyl group, 2-
Represents a hydroxyethyl group or a 2-chloroethyl group,
R ² represents a methyl group, an ethyl group, a benzyl group, or a phenyl group, and R ³ represents a hydrogen atom, a chlorine atom, a bromine atom, an alkyl group having 1 to 4 carbon atoms, an alkoxyl group having 1 to 4 carbon atoms, or dialkylamino. Represents a group or a nitro group. )

[0047]

[Chemical 7]

(In the formula, Ar represents naphthalene, anthracene, styryl group and their substitution products or pyridines, furans and thiophenes, and R represents an alkyl group or a benzyl group.)

[0049]

[Chemical 8]

(In the formula, R ¹ is an alkyl group, a benzyl group,
Represents a phenyl group or a naphthyl group, R ² represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a dialkylamino group, a diaralkylamino group or a diarylamino group, and n is 1 Represents an integer of 4 and when n is 2 or more, R ² may be the same or different. R ³ represents a hydrogen atom or a methoxy group. )

[0051]

[Chemical 9]

(In the formula, R ¹ represents an alkyl group having 1 to 11 carbon atoms, a substituted or unsubstituted phenyl group or a heterocyclic group, and R ² and R ³ may be the same or different and each is a hydrogen atom. Represents an alkyl group having 1 to 4 carbon atoms, a hydroxyalkyl group, a chloroalkyl group, a substituted or unsubstituted aralkyl group, and R ² and R ³ are bonded to each other to form a heterocycle containing nitrogen. R ⁴ may be the same or different and each represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group or halogen.)

[0053]

[Chemical 10]

(In the formula, R represents a hydrogen atom or a halogen atom, and Ar represents a substituted or unsubstituted phenyl group, naphthyl group, anthryl group or carbazolyl group.)

[0055]

[Chemical 11]

(In the formula, R ¹ is a hydrogen atom, a halogen atom,
Cyano group, alkoxy group having 1 to 4 carbon atoms or 1 to 4 carbon atoms
4 represents an alkyl group of 4 and Ar is

[0057]

[Chemical 12]

R ¹ represents an alkyl group having 1 to 4 carbon atoms,
R ² and R ³ represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms or a dialkylamino group, and n is 1 or 2 and when n is 2. R ³ may be the same or different, and R ⁴ or R ⁵ represents a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, or a substituted or unsubstituted benzyl group. )

[0059]

[Chemical 13]

(Wherein R is a carbazolyl group, a pyridine group, a thienyl group, an indolyl group, a furyl group or a substituted or unsubstituted phenyl group, a styryl group, a naphthyl group or an anthryl group, and these substituents are dialkyl. Amino group, alkyl group, alkoxy group, carboxy group or ester thereof, halogen atom, cyano group, aralkylamino group, N-alkyl-N-aralkylamino group,
It represents a group selected from the group consisting of an amino group, a nitro group and an acetylamino group. )

[0061]

[Chemical 14]

(Wherein R ¹ represents a lower alkyl group, a benzyl group or a substituted or unsubstituted aryl group, and R 1
² represents a hydrogen atom, a lower alkyl group, a lower alkoxy group, a halogen atom, a nitro group, an amino group or an amino group substituted by a lower alkyl group or a benzyl group, and n represents an integer of 1 or 2. )

[0063]

[Chemical 15]

(Wherein R ¹ represents a hydrogen atom, an alkyl group, an alkoxy group or a halogen atom, R ² and R ³ represent an alkyl group, a substituted or unsubstituted aralkyl group or a substituted or unsubstituted aryl group, R ⁴ represents a hydrogen atom or a substituted or unsubstituted phenyl group, and Ar represents a phenyl group or a naphthyl group.)

[0065]

[Chemical 16]

(Where n is an integer of 0 or 1, R ¹ , R ² ,
R ³ represents a hydrogen atom, an alkyl group or a substituted or unsubstituted phenyl group, and A is

[0067]

[Chemical 17]

It represents a 9-anthryl group or a substituted or unsubstituted N-alkylcarbazolyl group, wherein R ⁴ is a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, or

[0069]

[Chemical 18]

(Wherein R ⁵ and R ⁶ represent an alkyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted aryl group, and R ⁵ and R ⁶ may form a ring),
m is an integer of 0, 1, 2 or 3, and when m is 2 or more, R ⁴ may be the same or different. )

[0071]

[Chemical 19]

(In the formula, R ¹ , R ² and R ³ are hydrogen atoms,
It represents a lower alkyl group, a lower alkoxy group, a dialkylamino group or a halogen atom, and n represents 0 or 1. )

[0073]

[Chemical 20]

(In the formula, R ¹ represents a hydrogen atom, an alkyl group, an alkoxy group or a halogen atom, R ² and R ³ may be the same or different, and a hydrogen atom, an alkyl group, an alkoxy group or a halogen atom may be formed. The compound represented by the general formula (4) includes, for example, 9-ethylcarbazole-
3-aldehyde-1-methyl-1-phenylhydrazone, 9-ethylcarbazole-3-aldehyde-1-benzyl-1-phenylhydrazone, 9-ethylcarbazole-3-aldehyde-1,1-diphenylhydrazone and the like. In addition, examples of the compound represented by the general formula (5) include 4-diethylaminostyrene-β-aldehyde-1-methyl-1-phenylhydrazone and 4-methoxynaphthalene-1-aldehyde-1-benzyl-1-phenylhydrazone. and so on. Examples of the compound represented by the general formula (6) include 4-methoxybenzaldehyde-
1-methyl-1-phenylhydrazone, 2,4-dimethoxybenzaldehyde-1-benzyl-1-phenylhydrazone, 4-diethylaminobenzaldehyde-1,
1-diphenylhydrazone, 4-methoxybenzaldehyde-1-benzyl-1- (4-methoxy) phenylhydrazone, 4-diphenylaminobenzaldehyde-1
-Benzyl-1-phenylhydrazone, 4-dibenzylaminobenzaldehyde-1,1-diphenylhydrazone and the like. Further, the compound represented by the general formula (7) includes, for example, 1,1-bis (4-dibenzylaminophenyl) propane, tris (4-diethylaminophenyl) methane and 1,1-bis (4-dibenzylamino). Phenyl) propane, 2,2'-dimethyl-4,4'-bis (diethylamino) -triphenylmethane and the like.

Examples of the compound represented by the general formula (8) include 9- (4-diethylaminostyryl) anthracene and 9-bromo-10- (4-diethylaminostyryl) anthracene. In addition, examples of the compound represented by the general formula (9) include 9- (4-dimethylaminobenzylidene) fluorene and 3- (9-fluorenylidene) -9-ethylcarbazole. General formula (1
Examples of the compound represented by 0) include 1,2-bis (4
-Diethylaminostyryl) benzene and 1,2-bis (2,4-dimethoxystyryl) benzene. Further, the compound represented by the general formula (11) includes, for example, 3
Examples include -styryl-9-ethylcarbazole and 3- (4-methoxystyryl) -9-ethylcarbazole.

The compound represented by the general formula (12) includes
For example, 4-diphenylaminostilbene, 4-dibenzylaminostilbene, 4-ditolylaminostilbene,
1- (4-diphenylaminostyryl) naphthalene, 1
-(4-diethylaminostyryl) naphthylene and the like. The compound represented by the general formula (13) includes, for example, 4′-diphenylamino-α-phenylstilbene,
4′-methylphenylamino-α-phenylstilbene and the like. The compound represented by the general formula (14) includes
For example, 1-phenyl-3- (4-diethylaminostyryl) -5- (4-diethylaminophenyl) pyrazoline, 1-phenyl-3- (4-dimethylaminostyryl) -5- (4-dimethylaminophenyl) pyrazoline, etc. is there. The compound represented by the general formula (15) includes N, N′-diphenyl-N, N′-bis (3-methylphenyl)-[1,1′-bisphenyl] -4,
4'-diamine, N, N'-diphenyl-N, N'-bis (chlorophenyl)-[1,1'-biphenyl]-
4,4'-diamine, 3,3'-dimethylbenzidine and the like.

Other hole transporting substances include, for example, 2,5-bis (4-diethylaminophenyl) -1,
3,4-oxadiazole, 2,5-bis [4- (4-
Diethylaminostyryl) phenyl] -1,3,4-oxydiazole, 2- (9-ethylcarbazolyl-3
-)-5- (4-Diethylaminophenyl) -1,3,
Oxadiazole compounds such as 4-oxadiazole,
2-Vinyl-4- (2-chlorophenyl) -5- (4-
There are low molecular weight compounds such as oxazole compounds such as diethylaminophenyl) oxazole and 2- (4-diethylaminophenyl) -4-phenyloxazole. In addition, poly-N-vinylcarbazole, halogenated poly-
Polymer compounds such as N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, pyreneformaldehyde resin, ethylcarbazoleformaldehyde resin can also be used. Examples of the electron transport substance include chloranil, bromanil, tetracyanoethylene, tetracyanoquinone dimethane, 2,4,7-trinitro-9-
Fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2,4,5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,6
Examples include 8-trinitro-4H-indeno [1,2-b] thiophen-4-one and 1,3,7-trinitrodibenzothiophene-5,5-dioxide.

[0078]

【Example】

 Example 1 1 g of azo pigment P1

[0079]

[Chemical 21]

40 g of NaCl was placed in a 50 cc glass container containing 100 g of PSZ balls of 5 mmφ and ball milling was performed for 5 days. Next, the dispersion liquid of the azo pigment in which NaCl was dissolved with 100 cc of ion-exchanged water was taken out from the glass container, filtered with a paper filter, and further NaCl was dissolved with 900 cc of ion-exchanged water to wash the pigment. The washed pigment was dried under reduced pressure at 120 ° C. for 5 days. This salt milled azo pigment is designated as SP-1. FIG. 1 shows the X-ray diffraction patterns of the pigment before and after the salt milling treatment.

SP-1 0.25 g Polyvinyl butyral resin (XYHL manufactured by UCC) 5.0 g 2% cyclohexanone solution Cyclohexanone 7 g was put in a 50 cc glass container containing 100 mm PSZ balls of 5 mmφ, and ball milling was performed for 5 days. Thereafter, 10 g of cyclohexanone was added, and ball milling was further performed for 1 day to prepare a CGL coating liquid. The above CGL coating liquid was applied onto a 75 μm polyester film vapor-deposited on aluminum with a blade having a gap of 30 μm, and then dried by heating at 80 ° C. for 3 minutes to form CGL. next,
After preparing a CTL coating liquid having the following composition and performing blade coating on the CGL, 80 ° C., 2 minutes Z-type polycarbonate resin (manufactured by Teijin Chemicals) 10 g α-phenyl stilbene compound (1 ) 8g

[0082]

[Chemical formula 22]

Heat and dry with 72 g of toluene, and further heat and dry at 130 ° C. for 5 minutes to obtain about 2
A 0 μm CTL film was formed to prepare a photoconductor.

Example 2 A photoreceptor was prepared in the same manner as in Example 1 except that the α-phenylstilbene compound (1) in the CTL coating liquid of Example 1 was replaced with the α-phenylstilbene compound (2) represented by the following formula. Created.

[0085]

[Chemical formula 23]

Comparative Example 1 A photoconductor was prepared in the same manner as in Example 1 except that SP-1 used in the CGL liquid of Example 1 was replaced with azo pigment P1 which was not subjected to salt milling. Comparative Example 2 A photoconductor was prepared in the same manner as in Example 2 except that the azo pigment P1 not subjected to the salt milling treatment was used instead of SP-1 used in the CGL liquid of Example 2. The photoconductors prepared in Examples 1 and 2 and Comparative Examples 1 and 2 were charged with a static electricity characteristic measuring apparatus EPA8100 manufactured by Kawaguchi Electric Co., Ltd. at -5.5 kV for 2 seconds to obtain a charging potential V ₂ and a photoconductor of -800 volt. After charging, the white sensitivity was measured by irradiating light of 4.5lux of a 2856K tungsten lamp. Furthermore, 780 nm (half width 2
Irradiate through a bandpass filter of 0 nm) 78
The photosensitivity to 0 nm light was measured. The results are shown in Table 1. In ^{Table, E 1/10 (lux.sec)} , E '1/10 (μJ
/ Cm ² ) represents the amount of light necessary for the surface potential to be attenuated to 800 v to 80 v.

[0087]

[Table 17]

FIG. 2 shows the spectral sensitivities of Example 1 and Comparative Example 1. The photosensitivity of the photoreceptor using the salt milled azo pigment is twice as sensitive as that of the untreated pigment in the visible light region to the near infrared light region.

Example 3 A salt-milled pigment SP-2 was prepared in the same manner as in Example 1 except that the following formula P2 was used in place of the azo pigment P1 of Example 1, and the pigment SP-2 was used. Example 1
A photoconductor was prepared in the same manner as in. The charging potential and the sensitivity were measured in the same manner as in Example 1. The results are shown in Table 2.

[0090]

[Chemical formula 24]

Comparative Example 3 A photoconductor was prepared in the same manner as in Comparative Example 1 except that the untreated pigment P2 was used in place of the pigment P1 of Comparative Example 1.
It was measured charge potential V ₂ and E ^1/10 in the same manner as. The results are shown in Table 2. Example 4 A salt-milled pigment SP-3 was prepared in the same manner as in Example 1 except that P3 of the following formula was used instead of the azo pigment P1 of Example 1, and the pigment was used. A photoconductor was prepared in the same manner as in 1. The charging potential and white sensitivity were measured in the same manner as in Example 1. The results are shown in Table 2.

[0092]

[Chemical 25]

Comparative Example 4 A photoconductor was prepared in the same manner as in Comparative Example 1 except that the untreated pigment P3 was used in place of the pigment P1 of Comparative Example 1.
The charging potential and white sensitivity were measured in the same manner as in. The results are shown in Table 2.

[0094]

[Table 18]

Example 5 2.5 g of SP-1 30 g of cyclohexanone was placed in a glass pot container containing agate balls and ball milled for 3 days to prepare a pigment dispersion A liquid. Next, a photosensitive layer coating liquid having the following composition was prepared. Polycarbonate resin (C-1400 manufactured by Teijin Chemicals Ltd.) 5 g α-phenyl stilbene compound (1) 5 g represented by the following chemical structural formula

[0096]

[Chemical formula 26]

2,5 ditertiary butyl hydroquinone 0.05 g The above pigment dispersion A liquid 15 g THF 30 g This photosensitive material was formed on an aluminum-deposited polyester film coated with 0.3 μm of an alcohol-soluble polyamide resin (Amilan CM8000 manufactured by Toray Industries, Inc.) as an intermediate layer. 25 layer coating liquid
80 ° C after coating with a blade having a gap of 0 μm
Was heated and dried for 5 minutes, and further dried for 1 hour at 120 ° C. to form a photosensitive layer film having a thickness of about 20 μm to prepare a photoreceptor. When evaluated in the same manner as in Example 1, V ² = 850v, 78
Sensitivity to 0nm light ^{E 1/10 = 0.68 (μJ} / c
m ² ).

Comparative Example 5 P1 (2.5 g) Cyclohexanone (30 g) was placed in a glass pot container containing agate balls, and ball milling was carried out for 3 days to prepare a pigment dispersion liquid B. Next, a photosensitive layer coating liquid having the following composition was prepared. Polycarbonate resin (C-1400 manufactured by Teijin Chemicals Ltd.) 5 g α-phenyl stilbene compound (1) 5 g represented by the following chemical structural formula

[0099]

[Chemical 27]

2,5 ditertiary butyl hydroquinone 0.05 g Dispersion pigment B liquid 15 g THF 30 g This photosensitive layer was formed on an aluminum-deposited polyester film coated with 0.3 μm of an alcohol-soluble polyamide resin (Amilan CM8000 manufactured by Toray Industries, Inc.) as an intermediate layer. After coating the coating solution with a blade, heat-dry at 80 ° C for 5 minutes, and further 120
It was heated and dried at ℃ for 1 hour to form a photosensitive layer film having a thickness of about 20 μm to prepare a photoreceptor. When evaluated in the same manner as in Example 1,
V ² = 700 V, was ^{E 1/10 = 1.50 (μJ} / cm 2).

Example 6 1 g of azo pigment (P1) 1 g of NaCl 20 g of cyclohexanone 20 g was placed in a 50 cc glass container containing 100 g of PSZ balls of 5 mmφ and ball milling was carried out for 5 days. Next, the azo pigment and NaCl are taken out of the glass container with 50 cc of methyl ethyl ketone and the solvent is removed by filtration. Next, NaCl was dissolved in 500 cc of ion-exchanged water to wash the azo pigment. The washed pigment was dried under reduced pressure at 120 ° C. for 5 days. This solvent salt milled azo pigment is designated as SSP1. Azo pigment SP of Example 1-
A photoconductor was prepared in the same manner as in Example 1 except that SSP-1 was used instead of 1, and the charging property and the sensitivity were measured.

[0102] The V ² = 929 (volts) results and compare the solvent salt milling ^{E 1/10 = 0.52 (lux.sec} ) E '1/10 = 0.45 (μJ / cm 2) Example 1 It can be seen that the sensitization effect is further promoted when dry milling is performed.

Examples 7 to 16 The salt used in the salt milling of the azo pigment P1 was used in Example 1.
Instead of NaCl, NaCO ₃ , NaHSO ₃ , N
aNO ₃ , Na ₂ B ₄ O ₇ · 10H ₂ O, NaPO ₄ · 12H
₂ O, K ₂ SO ₄ , KBr, NaI, KI, CH ₃ COON
P1 was salt milled using a, and a photoreceptor was prepared and evaluated in the same manner as in Example 1 using the soft milled pigment. The results are shown in Table 3.

[0104]

[Table 19]

As is clear from the above results, the photoreceptor prepared by using the azo pigment subjected to the salt milling treatment has no deterioration in the charging characteristic and the sensitivity is remarkably improved.

[0106]

As described above, the electrophotographic photosensitive member of the present invention has markedly improved sensitivity over a wide wavelength range from the visible light region to the near infrared region and has stable charging characteristics.

[Brief description of drawings]

FIG. 1 is an X-ray diffraction pattern (a) of salt-milling pigment SP-1 of Example 1 and an X-ray diffraction pattern before salt-milling.

FIG. 2 is a diagram showing the spectral sensitivity of the electrophotographic photosensitive members of Example 1 and Comparative Example 1.

Claims (4)

[Claims] 1. An electrophotographic photoreceptor comprising a photoconductive layer formed on a conductive support, wherein at least one layer forming the photoconductive layer contains a salt milled azo pigment. An electrophotographic photosensitive member characterized in that 2. The electrophotographic photosensitive member according to claim 1, wherein the pigment is a trisazo pigment. 3. The electrophotographic photosensitive member according to claim 1, wherein the pigment is a bisazo pigment. 4. The salt cation for salt milling is Na.
The electrophotographic photosensitive member according to claim 1, which is + or K +.