JP2003233206A - Electrophotographic photoreceptor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor having high electrification potential and high sensitivity, showing no change in various characteristics even for repeated use, showing favorable electrification property from the first rotation in the process of forming an image using a reversal developing method, and being improved as for image defects. <P>SOLUTION: In the electrophotographic photoreceptor having at least a base coating layer and a photosensitive layer successively deposited on a conductive supporting body, the photosensitive layer contains a phthalocyanine composition having peaks of the Bragg angle (2θ±0.2°) at 7.0°, 9.0°, 14.1°, 18.0°, 23.7° and 27.3° for 1.541 angstrom X-rays of CuKα as a charge generating substance. The base coating layer contains titanium oxide particles which are granular particles having ≤100 nm average particle size of the primary particles or rod-like particles having ≤500 nm average major axial length, ≤100 nm minor average length and 2 to 10 aspect ratio of the primary particles. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member used when forming an image by an electrophotographic process such as a copying machine and a printer.

[0002]

2. Description of the Related Art In recent years, the use of electrophotography is not limited to the field of copying machines, but has spread to fields where photographic technology has been used in the past, such as printing plate materials, slide films, and microfilm, and lasers and LEDs. The application to high-speed printers using CRTs as light sources is also under consideration. Recently, applications of photoconductive materials other than electrophotographic photoreceptors, such as electrostatic recording elements, sensor materials, and EL elements, have begun to be examined. Therefore, demands for photoconductive materials and electrophotographic photoreceptors using them are becoming more sophisticated and wide. Inorganic photoconductive materials such as selenium, cadmium sulfide, zinc oxide, and silicon have been known as electrophotographic photoreceptors, and have been widely studied and put to practical use. While these inorganic materials have many advantages, they also have various drawbacks. For example, selenium has drawbacks that it is difficult to produce under conditions and is easily crystallized by heat or mechanical shock, and cadmium sulfide and zinc oxide have poor moisture resistance and durability. It has been pointed out that silicon has insufficient chargeability and is difficult to manufacture. further,
Selenium and cadmium sulfide also have toxicity issues.

On the other hand, organic photoconductive materials have good film-forming properties, excellent flexibility, light weight, good transparency, and are sensitized to a wide range of wavelengths by a suitable sensitizing method. Since it has advantages such as easy body design, its practical application is gradually gaining attention.

By the way, the photosensitive member used in the electrophotographic technique is generally required to have the following basic properties. That is, (1) high chargeability against corona discharge in the dark, (2) little leakage (dark decay) of the obtained charged charge in the dark, and (3) charge charging by light irradiation. The light is rapidly dissipated, and (4) there is little residual charge after light irradiation.

However, much research has been conducted on photoconductive polymers such as polyvinylcarbazole as an organic photoconductive substance, but these are not necessarily sufficient in film formability, flexibility and adhesiveness. In addition, it is difficult to say that the photoconductor has the basic properties described above.

On the other hand, regarding the organic low-molecular-weight photoconductive compound, by selecting a binder or the like used for forming the photoconductor, the photoconductor having excellent mechanical strength such as film-forming property, adhesive property and flexibility. However, it is difficult to find a compound suitable for retaining the highly sensitive property.

In order to improve such a point, an organic photoreceptor having higher sensitivity characteristics has been developed, in which different substances have a charge generating function and a charge transporting function. A characteristic of such a photoconductor, which is called a function-separated type, is that materials suitable for each function can be selected from a wide range, and many studies have been carried out because a photoconductor having arbitrary performance can be easily produced. Has been promoted.

Of these, the substances in charge of the charge generation function are phthalocyanine pigments, squarylium dyes,
Various substances such as azo pigments and perylene pigments have been studied,
Among them, azo pigments can have various molecular structures, and
It is widely researched because it can be expected to have high charge generation efficiency,
Practical use is also progressing. However, in this azo pigment, the relationship between the molecular structure and the charge generation efficiency has not yet been clarified. The reality is that a vast amount of synthetic research is accumulated to search for the optimum structure, but the basic properties and high durability required for the photoconductors listed above are sufficiently satisfied. Things have not been obtained yet.

Further, in recent years, laser beam printers, etc., which use laser light as a light source instead of conventional white light and have advantages of high speed, high image quality, and non-impact, have become widely used together with the progress of information processing systems. Therefore, there is a demand for development of a material that can withstand the demand. In particular, among laser lights, semiconductor lasers whose technological advances are remarkable due to the increasing application to compact discs, optical discs, etc. in recent years,
It has been actively applied in the printer field as a compact and highly reliable light source material. Since the wavelength of the light source in this case is around 780 nm, there is a strong demand for development of a photoconductor having high sensitivity to long-wavelength light around 780 nm. Among them, particularly, development of a photoconductor using phthalocyanines having light absorption in the near infrared region has been actively conducted.

Phthalocyanines differ not only in absorption spectrum and photoconductivity depending on the type of central metal, but also in phthalocyanines having the same central metal, these various properties are different depending on the crystal form, and a specific crystal form is an electron. It is reported to be selected as a photographic photoreceptor.

Among the metal phthalocyanines, taking titanyloxy phthalocyanine as an example, Japanese Patent Laid-Open No. 61-21705.
In Japanese Patent No. 0, the Bragg angle (2θ ± 0.2 °) in the X-ray diffraction spectrum is 7.6 °, 10.2 °, 22.3.
Α-type titanyloxyphthalocyanine having major diffraction peaks at °, 25.3 ° and 28.6 °, JP-A-62-6.
No. 7094 discloses 9.3 °, 10.6 °, 13.2.
°, 15.1 °, 15.7 °, 16.1 °, 20.8
Β-type titanyloxyphthalocyanines having major diffraction peaks at °, 23.3 °, 26.3 ° and 27.1 ° have been reported, but these do not sufficiently satisfy the required high properties.

In titanyloxyphthalocyanine,
It is reported that the X-ray diffraction spectrum having a peak Bragg angle (2θ ± 0.2 °) of 27.2 ° has high characteristics, but it is reported in JP-A-62-67094. Form II titanyloxyphthalocyanine is inferior in charging property and has low sensitivity. Japanese Patent Laid-Open No. 64-17066
9.5 °, 9.7 °, 11.
7 °, 15.0 °, 23.5 °, 24.1 °, 27.3
Y-type titanyloxyphthalocyanine having a main diffraction peak at ° has problems such as insufficient sensitivity and stability of the dispersion over time.

Further, the electrophotographic photosensitive member using these phthalocyanines has a poor charging property at the developing stage after the charging operation of the first rotation of the image forming process, and finally the charging property becomes stable from the second rotation. There was a flaw. This phenomenon is related to the standing time after the image forming process such as charging and exposure, and the longer the standing time, the worse the charging property at the first rotation. From this, it is considered that this phenomenon is due to accumulation of charges generated by thermal excitation of the charge generating substance in the photosensitive layer or charges injected from the conductive support to the photosensitive layer.

In recent years, the data transfer time and the image processing time have been shortened as the performance of the information processing apparatus has been improved. However, there is a demand to use it for image formation from the first rotation of the photoconductor. However, in the case of the photoreceptor having the poor charging property in the developing stage in the first rotation process as described above, the white background portion is fogged in the image in the first rotation process in the digital image formation of the reversal development method, which is good. The image cannot be obtained.
Therefore, it is necessary to improve the charging property at the developing stage in the first rotation process.

Further, the electrophotographic photosensitive member using the organic photoconductive substance has a drawback that the charging potential and the residual potential are greatly changed by repeating processes such as charging, exposure and charge elimination. When the repeat stability is poor in this way, in the copy actual photography, the contrast of the actual photographed image is lowered due to the repetition, and image fog occurs.

In order to improve the repeated stability, a method of providing an undercoat layer between the conductive support and the photosensitive layer has been proposed. For example, JP-A-59-93453 and JP-A-63-298251 each disclose an undercoat layer in which titanium oxide particles are dispersed. However, even if these are used, the chargeability at the developing stage in the above-described first rotation process cannot be improved.

[0017]

SUMMARY OF THE INVENTION An object of the present invention is to provide a high charging potential, high sensitivity, stable performance without changing characteristics even after repeated use, and image formation using a reversal development method. In order to provide an electrophotographic photosensitive member which shows good chargeability from the first rotation and has improved image defects.

[0018]

As a result of various studies to achieve the above object, the present inventors have found that an undercoat layer containing at least titanium oxide particles and a binder, a photosensitive layer, on a conductive support. An electrophotographic photoreceptor formed by sequentially laminating layers, containing at least one phthalocyanine composition containing titanyloxyphthalocyanine and a metal-free phthalocyanine as a charge generating substance in the photosensitive layer,
The phthalocyanine composition had a Bragg angle (2θ ± 0.2 °) of X-ray of CuKα1.541 Å of 7.
0 °, 9.0 °, 14.1 °, 18.0 °, 23.7
And the titanium oxide particles contained in the undercoating layer have peaks at 27.3 ° and an average primary particle diameter of 100 nm.
The average length of the long axis of the following granular particles or primary particles is 500 nm or less, and the average length of the short axis is 100 nm or less,
The inventors have found that rod-shaped particles having an average aspect ratio of 2 to 10 are effective, and completed the present invention.

[0019]

DETAILED DESCRIPTION OF THE INVENTION Each constituent element of the present invention will be described in detail below.

As the conductive support used in the present invention, various ones can be used including those used in well-known electrophotographic photoreceptors. Specifically, for example, gold, silver, platinum, titanium, aluminum, copper, zinc, iron, drums, sheets, belts or the like of conductive treated metal oxides, or laminates of these thin films, vapor depositions and the like can be mentioned. To be

Further, a conductive substance such as metal powder, metal oxide, carbon black, carbon fiber, copper iodide, charge transfer complex, inorganic salt, and ion conductive polymer electrolyte is coated with a suitable binder to form a polymer matrix. Plastic or ceramic embedded in the inside and subjected to conductive treatment,
Examples thereof include drums, sheets, belts and the like made of paper and the like, and drums, sheets, belts and the like of conductive plastics, ceramics, paper and the like containing such a conductive substance.

The electrophotographic photosensitive member of the present invention has an undercoat layer containing at least titanium oxide particles and a binder between the photosensitive layer and the conductive support.

Titanium oxide particles, compared to other white pigments,
High refractive index, physically and chemically stable, hiding power,
It is used as a pigment having excellent whiteness in printing inks, paints, and various other fields, and as the crystal type, there are rutile type, anatase type, brookite type, and amorphous, and any of them can be used in the present invention.

The particle shape of the titanium oxide particles used in the present invention is granular particles having an average primary particle diameter of 100 nm or less, or an average major axis length of primary particles of 500 nm or less,
It is necessary that the average particle length of the minor axis is 100 nm or less and the average value of the aspect ratio (major axis length / minor axis length) is 2 to 10 in the shape of rod-shaped particles. Here, the term “granular” refers to a shape in which the ratio of the maximum length to the minimum length (maximum length / minimum length) of each primary particle is less than 2, and can be regarded as a pseudo spherical shape. The size and shape of the particles can be easily observed with a transmission electron microscope.

The titanium oxide particles may be those which have not been surface-treated, or those which have been surface-treated with an oxide of aluminum or silicon or an organic compound such as stearic acid in order to improve the dispersibility and dispersion stability. In the present invention, any of them can be used, but it is preferable to use at least zirconium oxide as the surface treatment agent.

As the binder used in the undercoat layer of the present invention, a vinyl compound polymer or copolymer of styrene, vinyl acetate, acrylic ester, methacrylic ester, etc., silicon resin, phenoxy resin, polysulfone, Various polymers such as butyral resin, formal resin, polyester, cellulose ester resin, cellulose ether resin, urethane resin, phenol resin, epoxy resin, polycarbonate, polyarylate, polyamide, polyimide are mentioned, but especially polyamide, especially alcohol-soluble nylon resin Is preferred.

Alcohol-soluble nylon resins are soluble only in lower aliphatic alcohols such as methanol and ethanol. Therefore, as a coating solvent for forming a photosensitive layer on an undercoat layer made of these resins, a solvent other than lower alcohol is used. The solvent selection range can be widened. When the photosensitive layer is coated with a solvent capable of dissolving the undercoat layer, there arises inconveniences such as mixing with the undercoat layer to deteriorate the characteristics and non-uniformity of the coated surface depending on the coating method. Alcohol-soluble nylon resins can be roughly classified into two types, one is nylon 6, nylon 66, and nylon 61.
A type called so-called copolymer nylon, which is obtained by copolymerizing 0, nylon 11, nylon 12, etc., the other is N
It is a type called modified nylon obtained by chemically modifying nylon such as -alkoxymethyl modified nylon and N-alkoxyethyl modified nylon. The alcohol-soluble nylon resin used in the present invention can be used with both of them and exhibits excellent properties.

The ratio of titanium oxide to binder in the undercoat layer of the present invention is 1 to 1000 parts by weight, preferably 1 to 1000 parts by weight, of binder to 100 parts by weight of titanium oxide.
It is used in the range of 300 parts by mass. The thickness of the undercoat layer is determined according to the surface roughness of the conductive support and the electrophotographic characteristics, and is used in the range of 0.1 to 30 μm.

The photosensitive layer is a pigment-dispersed single layer type in which a pigment as a charge generating substance is dispersed and embedded in a binder, or a single layer type in which a charge generating substance and a charge transporting substance are dispersed and mixed and enclosed in a binder. It is composed of a laminated type in which a substance and a charge transport substance are separated and sealed in a binder. The present invention can be applied to any system, but it is preferably used in a system of a function-separated laminated type photoreceptor in which the performances of the charge generating substance and the charge transporting substance are easily utilized to the maximum.

The photosensitive layer of the electrophotographic photosensitive member of the present invention has a Bragg angle (2θ ± 0.2 °) of 7.0 as CuKα1.541 angstrom as a charge generating substance.
°, 9.0 °, 14.1 °, 18.0 °, 23.7 °,
It contains a phthalocyanine composition having a peak at 27.3 °.

The phthalocyanines used in the present invention are
Known manufacturing methods can be used. The manufacturing method is “Phthalocyanine Compou” by FH Moser and AL Chomas.
nds "(1963) describes the production method, and phthalocyanines can be easily obtained according to this method. Specifically, a production method by a condensation reaction of phthalodinitrile and titanium tetrachloride, or PB85172. FIAT. FI
NAL REPORT 1313. Feb. 1.1948
And JP-A-1-142658 and JP-A-1-22214.
The method of producing by reacting 1,3-diiminoisoindoline and tetraalkoxytitanium described in JP-A No. 61 can be mentioned. As the organic solvent used in the reaction, α-chloronaphthalene, β-chloronaphthalene, α-methylnaphthalene, methoxynaphthalene, diphenylnaphthalene, ethylene glycol dialkyl ether, quinoline, sulfolane, dichlorobenzene, N-
A reaction-inert, high-boiling-point solvent such as methyl-2-pyrrolidone or dichlorotoluene is desirable.

The phthalocyanines obtained by the above-mentioned method are treated with acid, alkali, acetone, methanol, ethanol, methyl ethyl ketone, tetrahydrofuran, pyridine, quinoline, sulfolane, α-chloronaphthalene, toluene, xylene, dioxane, chloroform, dichloroethane, N, Purification with N-dimethylformamide, N-methyl-2-pyrrolidone, water or the like gives highly pure phthalocyanines that can be used in electrophotographic applications. Examples of the purification method include a washing method, a recrystallization method, an extraction method such as Soxhlet, a heat suspension method, and a sublimation method. Further, the purification method is not limited to these, and may be any operation as long as it is an operation for removing unreacted substances and reaction byproducts.

The phthalocyanine composition according to the present invention comprises
It is obtained by crystallizing an amorphized phthalocyanine under specific conditions. As an amorphizing method, any method that can be amorphized, such as mechanical grinding treatment and acid pasting method, may be used. For mechanical grinding, ball mill,
Examples thereof include a dry milling method and a wet milling method in an automatic mortar, a paint conditioner and the like. Examples of the grinding aid include, but are not limited to, glass beads, zirconia beads, and salt. The acid pasting method is a method in which phthalocyanines are dissolved in a strong acid such as sulfuric acid, and the solution is poured into a poor solvent such as water to form particles. Any crystal form of the phthalocyanines before being made amorphous may be used.

The solvent used for the crystal transition to obtain the phthalocyanine composition according to the present invention may be water or an organic solvent, which may be used alone or as a mixed solvent of two or more kinds. As the organic solvent, alcohol solvents, ketone solvents, ester solvents, ether solvents,
Examples thereof include amide solvents, halogenated hydrocarbon solvents, hydrocarbon solvents, carboxylic acid solvents, amine solvents, phenol solvents, sulfoxide solvents and sulfone solvents. Further, in order to obtain the phthalocyanines according to the present invention, it is possible to use solids other than the organic solvent. It is preferable that the solid used has a melting point of 100 ° C. or lower, and examples thereof include, but are not limited to, naphthalene and m-terphenyl.

In the case of crystal transition using water, the ratio of phthalocyanines to water is preferably 2 to 100 parts by mass with respect to 1 part by mass of phthalocyanines, but within this range as long as the phthalocyanines can be dispersed. It is not limited. The ratio of the organic solvent or solid used in the crystal transition to the phthalocyanines is 10%.
10 to 5000 parts by mass is preferable with respect to 0 parts by mass,
It is more preferably 50 to 500 parts by mass.

Using these, the temperature at which the amorphous phthalocyanines are transformed into the desired crystal form is -3.
0-100 degreeC is preferable. Further, it is more preferable to carry out the crystal transition while stirring. Examples of the stirring method include a stirrer, a ball mill, a paint conditioner, a sand mill, an attritor, a disperser, and an ultrasonic dispersion, but any method can be used as long as stirring can be performed, and the stirring method is not limited thereto. The time required for the transition is preferably 5 seconds to 120 hours, more preferably 10 seconds to 50 hours, still more preferably 1 minute to 50 hours.

The phthalocyanine composition according to the present invention may further contain phthalocyanines other than titanyloxyphthalocyanine and metal-free phthalocyanine.
Specific examples thereof include vanadyloxyphthalocyanine,
Examples thereof include chloroaluminum phthalocyanine, chlorogallium phthalocyanine, chloroindium phthalocyanine, dichlorogermanium phthalocyanine, hydroxyaluminum phthalocyanine, hydroxygallium phthalocyanine, hydroxyindium phthalocyanine and dihydroxygermanium phthalocyanine.

In the phthalocyanine composition used in the present invention, the ratio of titanyloxyphthalocyanine to phthalocyanines other than titanyloxyphthalocyanine is such that phthalocyanines other than titanyloxyphthalocyanine are 0.1 to 100 parts by mass of titanyloxyphthalocyanine. 50 parts by mass is preferable, and 1 to 40 parts by mass is more preferable. The phthalocyanines other than titanyloxyphthalocyanine may be metal-free phthalocyanines alone or a mixture of the above-mentioned phthalocyanines and metal-free phthalocyanines. When mixed, the ratio is preferably 100 parts by mass or less, and more preferably 50 parts by mass or less, relative to 100 parts by mass of the metal-free phthalocyanine.

The phthalocyanine composition according to the present invention comprises
It may be used in combination with other charge generating substances. Examples of the charge generating substance that may be used include triphenylmethane dyes, zanthene dyes, acridine dyes, thiazine dyes, pyrylium dyes, azurenium dyes, thylium dyes, cyanine dyes, squarium dyes, Examples thereof include pyrrolopyrrole dyes, polycyclic quinone pigments, perylene pigments, perinone pigments, anthraquinone pigments, dioxazine pigments, and azo pigments.
These can be used alone or as a mixture of two or more kinds.

In the function-separated laminate type photoreceptor, the charge generation layer is formed by mixing these charge generation substances and, if necessary, a binder. As the binder, acetal resin, butyral resin, vinyl chloride copolymer resin, silicone resin,
Examples thereof include phenoxy resin, phenol resin, epoxy resin, polycarbonate, polyarylate, polyester, polyamide, polyimide, urethane resin, and acrylic resin. Among these, by using the acetal resin and the butyral resin, the pigment dispersion exhibits very high dispersibility and the coatability becomes good. Furthermore, by producing an electrophotographic photosensitive member using the dispersion, the chargeability, sensitivity, and repeatability are improved. Therefore, in the present invention, it is particularly preferable to use an acetal resin or a butyral resin as the binder. These resins can be used alone or in combination of two or more.

Among the acetal resins, the following general formula (1)
The resin represented by the following is preferable, and among the butyral resins, the resin represented by the following general formula (2) or (3) is preferable.

[0042]

[Chemical 1]

In the formula (1), l, m and n are integers.

[0044]

[Chemical 2]

In the formula (2), p, q and r are integers.

[0046]

[Chemical 3]

In the formula (3), s, t, u and v are integers.

In the case of the function-separated laminated type photoreceptor, the binder is 10 to 50 relative to 100 parts by weight of the charge generating substance.
It is used in an amount of 0 part by mass, preferably 50 to 150 parts by mass. If the ratio of the resin is too high, the charge generation efficiency is lowered, and if the ratio of the resin is too low, the film formability becomes a problem.

In the present invention, when the coating liquid for forming the charge generation layer is produced, it is preferable to disperse the phthalocyanine composition in a solvent containing water. The water used in the present invention may be either light water or heavy water, or may be a mixture of light water and heavy water. If the amount of water added is too small, a transition to another crystal form occurs, and if the amount added is too large, poor dispersion or separation of water from the coating liquid, and precipitation of a binder from the dispersion solvent may occur. Not suitable for body preparation. Therefore, the amount of water used in the present invention is preferably 0.1 to 0.95 parts by mass, more preferably 0.3 to 0.9 parts by mass, and still more preferably 0.1 to 0.9 part by mass with respect to 1 part by mass of the phthalocyanine composition.
5 to 0.85 parts by mass is particularly preferable.

When water is used in the production of the charge generation layer forming coating liquid in the present invention, it is preferable to use a water-soluble solvent as the solvent. Specific examples of the water-soluble solvent include 1,2-dimethoxyethane, tetrahydrofuran,
1,3-dioxolane and the like can be mentioned.

In the present invention, the charge generation layer forming coating liquid is obtained by dispersing the phthalocyanine composition in a solvent. The device used for the dispersion is a ball mill, a paint conditioner, a vertical bead mill, a horizontal bead mill, and a disperser using a dispersion medium such as an attritor. As the material of the dispersion medium, soda glass, low alkali glass, yttria-containing zirconia is preferable,
Beads with a diameter of several mm are often used.

The charge transport material used in the photosensitive layer in the present invention includes a hole transport material and an electron transport material. Examples of the hole transport material include oxadiazoles disclosed in JP-B-34-5466 and JP-B-45-55.
No. 5, etc., triphenylmethanes, Japanese Patent Publication No. 52-41888, etc., pyrazolines, Japanese Patent Publication No. 55-42380, etc., hydrazones, JP-A-56. Oxadiazoles disclosed in JP-A-123544, JP-B-58-32372
Examples thereof include triarylamines disclosed in JP-A No. 58-198043, and stilbenes disclosed in JP-A No. 58-198043. On the other hand, examples of the electron transport substance include chloranil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, and 2,4. , 5,7-Tetranitroxanthone, 2,
4,8-trinitrothioxanthone, 1,3,7-trinitrodibenzothiophene, 1,3,7-trinitrodibenzothiophene-5,5-dioxide and the like can be mentioned. These charge transport materials may be used alone or in combination of two or more.

Among these charge-transporting substances, hydrazones and stilbenes are preferable because they have high charge (hole) mobility and provide an excellent electrophotographic photoreceptor. Among the above-mentioned hydrazones, JP-A-1-100555, JP-A-2-10367, JP-A-2-511163, and JP-A-2
-96767 publication, 2-183260 publication, 2
No. 184856, No. 2-184858, No. 2-184859, No. 2-226160,
The hydrazone compounds described in JP-A-5-188609 and JP-A-7-140686 are particularly preferable. Further, among the above-mentioned stilbenes, JP-A-2-51162, JP-A-2-184857, JP-A-3-75660, JP-A-4-177358, and JP-A-6-194851,
The stilbene compounds described in JP-A Nos. 7-120945, 7-140683, 10-78671 and 10-90923 are particularly preferable.

Further, as a sensitizer for further increasing the sensitizing effect, it is possible to add a certain kind of electron-withdrawing compound. Examples of the electron-withdrawing compound include 2,3-
Dichloro-1,4-naphthoquinone, 1-nitroanthraquinone, 1-chloro-5-nitroanthraquinone, 2-
Quinones such as chloroanthraquinone and phenanthrenequinone, aldehydes such as 4-nitrobenzaldehyde,
9-benzoylanthracene, indandione, 3,5
-Dinitrobenzophenone or 3,3 ', 5
Ketones such as 5'-tetranitrobenzophenone, phthalic anhydride, acid anhydrides such as 4-chloronaphthalic anhydride,
A cyano compound such as terephthalalmalononitrile, 9-anthrylmethylidene malononitrile, 4-nitrobenzalmalononitrile, or 4- (p-nitrobenzoyloxy) benzalmalononitrile, 3-benzalphthalide, 3- (α- Examples thereof include cyano-p-nitrobenzal) phthalide, phthalides such as 3- (α-cyano-p-nitrobenzal) -4,5,6,7-tetrachlorophthalide, and the like.

In the function-separated layered type photoreceptor, the charge transport layer is composed of at least these charge transport materials and a binder. As the binder used in the charge transport layer, polystyrene, acrylic resin represented by polymethylmethacrylate, polycarbonate having a skeleton represented by bisphenol A or Z, polyarylate, polyester, polyphenylene ether, polyether sulfone, polyamide, Polyimide or the like can be used. These binders can be used alone or in combination of two or more.

These binders contained in the charge transport layer are contained in an amount of 0.1 to 20 with respect to 100 parts by mass of the charge transport material.
00 parts by mass is preferable, and 1 to 500 parts by mass is more preferable. If the ratio of the binder is too high, the sensitivity is lowered, and if the ratio of the binder is too low, the repeating properties may be deteriorated or the coating film may be damaged.

The electrophotographic photosensitive member of the present invention is 2,6-, in order to prevent deterioration due to oxidation of the organic compound of the constituent material.
An antioxidant such as di-tert-butyl-p-cresol or DL-α-tocopherol is preferably added to the photosensitive layer, which is a well-known plasticizer for improving film formability, flexibility and mechanical strength. May be used. Further, a surface layer may be provided on the surface of the photosensitive layer in order to improve abrasion resistance and gas barrier property of the photosensitive member.

When the photosensitive layer of the electrophotographic photosensitive member of the present invention is manufactured, the phthalocyanine composition is dispersed in a solvent, and the binder and the charge transport material are dissolved in the solvent before use. Examples of the solvent used include water or an organic solvent,
Used alone or as a mixed solvent of two or more kinds.
Examples of the organic solvent include alcohol solvents such as methanol, ethanol and isopropyl alcohol, ketone solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone, ester solvents such as ethyl formate, ethyl acetate and n-butyl acetate, diethyl ether, 1 , 2-dimethoxyethane, tetrahydrofuran, 1,3-dioxolane,
Ether solvents such as 1,4-dioxane and anisole,
Amide solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, dichloromethane, chloroform, bromoform, methyl iodide, dichloroethane, trichloroethane, trichloroethylene, chlorobenzene, o-dichlorobenzene, Fluorobenzene, bromobenzene, iodobenzene, α-chloronaphthalene and other halogenated hydrocarbon solvents, n-pentane, n-hexane, n-octane, 1,
5-hexadiene, cyclohexane, methylcyclohexane, cyclohexadiene, benzene, toluene, o-
Hydrocarbon solvents such as xylene, m-xylene, p-xylene, ethylbenzene, cumene and the like can be mentioned.
Of these, ketone solvents, ester solvents, and ether solvents are particularly preferable.

The coating solution thus prepared is applied by spin coating,
An electrophotographic photoreceptor is obtained by coating and drying on a conductive support by a known method such as blade coating, knife coating, reverse roll coating, rod bar coating, and spray coating.
Further, particularly when coating on a drum, a dip coating method or the like is used.

[0060]

EXAMPLES The present invention will now be described in more detail by way of examples, which should not be construed as limiting the invention thereto.

Synthesis Example 1 20.0 g of phthalodinitrile was added to α-chloronaphthalene 2
Dissolve in 00 ml, under a nitrogen atmosphere, titanium tetrachloride 9.0
g was added dropwise. After the completion of dropping, the mixture was heated and stirred at 240 ° C.
The reaction was stopped after 3 hours, and the precipitated crystals were collected by filtration and washed well with α-chloronaphthalene and methanol to obtain dichlorotitanyl phthalocyanine. The dichlorotitanyl phthalocyanine was heated to reflux with stirring with 150 ml of concentrated aqueous ammonia. The reaction was stopped after 1 hour, and the crystals were collected by filtration to obtain 17.4 g of titanyloxyphthalocyanine.

Synthesis Example 2 Titanyloxyphthalocyanine obtained in Synthesis Example 1 7.
0 g, metal-free phthalocyanine (manufactured by Dainichi Seika Kogyo; MCP
-80) 3.0 g, 100 m of concentrated sulfuric acid cooled to about 2 ° C
Slowly added to 1 to dissolve. This solution was slowly poured into 1000 ml of cooled ice water to precipitate crystals. The crystals are filtered off and washed with water until neutral, 9.
4 g of crystals were obtained. This crystal is in an amorphous state in which the crystal arrangement is disordered.

Synthesis Example 3 1.0 g of the amorphous phthalocyanine composition obtained in Synthesis Example 2 and 28.0 g of water were placed in a 100 ml flask and heated and stirred at 90 ° C. After 10 minutes, naphthalene 2.
0 g was added, and the mixture was subsequently heated and stirred at the same temperature. After 1 hour, the reaction was stopped and the mixture was allowed to cool to room temperature. The crystals were collected by filtration and washed with methanol. As a result, 0.9 g of crystals was obtained. The obtained crystal form was confirmed by measuring an X-ray diffraction spectrum using CuKα ray (manufactured by Rigaku Denki; X-ray diffractometer RAD-C system). The measurement results are shown in FIG.

[0064]   Measurement conditions X-ray tube: Cu               Voltage: 40.0KV               Current: 100.0mA               Start angle: 3.0 deg.               Stop angle: 40.0 deg.               Step angle: 0.02 deg.

From FIG. 1, this crystal form has a Bragg angle (2θ
± 0.2 °) is 7.0 °, 9.0 °, 14.1 °, 1
It can be seen that there are peaks at 8.0 °, 23.7 °, and 27.3 °.

Example 1 Alcohol-soluble nylon (manufactured by Toray; CM-8000)
50 g of methanol 600 g and 1,3-dioxolane 4
It is dissolved in a mixed solvent with 00 g, primary particles are granular particles having an average particle size of 35 nm, and 50 g of titanium oxide surface-treated with aluminum oxide and zirconium oxide (manufactured by Ishihara Sangyo; TTO-55D) is mixed, 5 using a sand grind mill with 1 mm diameter zirconia beads
Time dispersed. An aluminum drum base pipe is dip-coated with the coating liquid for forming the undercoat layer thus obtained, and a dry film thickness of 1.0 μm
To form an undercoat layer.

Next, butyral resin (manufactured by Sekisui Chemical Co .; BL
-1) 10.0 g and 8.4 g of water were dissolved in 1000 g of 1,3-dioxolane, and 10.5 g of the phthalocyanine composition obtained in Synthesis Example 3 as a charge generating substance, metal-free phthalocyanine (manufactured by Dainichi Seika Kogyo Co., Ltd.) MCP-80) 4.
5 g was mixed and dispersed with low alkali glass beads having a diameter of 1 mm for 4 hours using a sand grind mill. The charge generation layer-forming coating liquid thus obtained was dip-coated on the undercoat layer to form a charge generation layer having a dry film thickness of about 0.4 μm.

Next, 200 g of the stilbene compound represented by (4) and polycarbonate (manufactured by Mitsubishi Gas Chemical Co .; Z-4)
00) 200 g, DL-α-tocopherol (manufactured by Riken Vitamin; E1000) 2 g, tetrahydrofuran 40
It was dissolved in 00 g. The charge transport layer-forming coating liquid was applied onto the charge generation layer by dip coating to form a charge transport layer having a dry film thickness of 25 μm.

[0069]

[Chemical 4]

The electrophotographic photosensitive member thus prepared was stored at room temperature in a dark place for one day and then at room temperature of 23 ° C. and relative humidity of 55%.
Under the conditions of No. 1, using a drum photoreceptor evaluation device (manufactured by Gentech; Cynthia 90), process speed: 190
mm / sec, charging voltage: -7.0 kV, exposure light wavelength: 78
Under the conditions of 0 nm, exposure light intensity: ² μW / cm ² , and light neutralization: tungsten lamp array, the charging, exposure, and neutralization processes were performed, and the half-exposure amount was measured. Further, this process was repeated 10,000 times, and before and after that, the charging potential and the residual potential of the photoconductor were measured. These results are shown in Table 1.
Shown in.

Next, the photosensitive member was left for 1 hour, and the charging and discharging processes were performed again, and the charging potentials at the first and second rotations were measured. The results are shown in Table 2. Further, this photoconductor was mounted on a commercially available copying machine in which a process speed was 190 mm / sec and a reversal development method was used to perform copying from the first rotation of the photoconductor, and a white background image was copied. Table 2 shows the appearance of the obtained copied image.

Example 2 As titanium oxide, the average major axis length of the primary particles was 200 n.
m, short axis average length 35 nm, average aspect ratio 6
Rod-shaped particles of titanium oxide surface-treated with aluminum oxide and zirconium oxide (manufactured by Ishihara Sangyo; TTO-
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that M-1) was used, and after being stored at room temperature in a dark place for one day, the same measurement and evaluation as in Example 1 were performed. The results are shown in Tables 1 and 2.

Example 3 As titanium oxide, the average major axis length of the primary particles was 75 n.
m, short axis average length 15 nm, average aspect ratio 5
Rod-shaped particles of titanium oxide surface-treated with aluminum oxide and lauric acid (Taika; MT-100S)
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the above was used, and after being stored at room temperature in a dark place for one day and night, the same measurement and evaluation as in Example 1 were performed. The results are shown in Tables 1 and 2.

Example 4 50 g of formal resin (manufactured by Denki Kagaku Kogyo; # 20) was dissolved in a mixed solvent of 300 g of methanol and 700 g of toluene, and primary particles were surface-treated with granular particles having an average particle size of 35 nm. Titanium oxide (made by Teika; MT
-500B) 50 g was mixed and dispersed for 5 hours using a sand grind mill together with zirconia beads having a diameter of 1 mm. An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the undercoat layer-forming coating liquid thus obtained was used, and was stored at room temperature in a dark place for one day and then subjected to the same measurement and evaluation as in Example 1. . The results are shown in Tables 1 and 2.

Comparative Example 1 Electrons were obtained in the same manner as in Example 1 except that titanium oxide whose primary particles were granular particles having an average particle diameter of 180 nm and surface-treated titanium oxide (Taika; JA-1) was used as titanium oxide. A photographic photosensitive member was produced and stored in a dark place at room temperature for one day and then the same measurement and evaluation as in Example 1 were performed. The results are shown in Tables 1 and 2.

Comparative Example 2 As titanium oxide, titanium oxide whose primary particles are granular particles having an average particle diameter of 280 nm and whose surface is treated with aluminum oxide and zirconium oxide (Taika; JR-603)
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the above was used, and after being stored at room temperature in a dark place for one day and night, the same measurement and evaluation as in Example 1 were performed. The results are shown in Tables 1 and 2.

[0077]

[Table 1]

[0078]

[Table 2] (Each unit of charge potential after standing for 1 hour is in volts.)

In Comparative Examples 1 and 2 in which titanium oxide of granular particles having an average primary particle diameter of more than 100 nm was used,
Since the electrophotographic photosensitive member has poor sensitivity and repetitive characteristics, the chargeability of the first rotation in image formation using the reversal development method is significantly worse than the chargeability of the second rotation.
When mounted on a copying machine and formed an image, image defects such as fogging occurred. On the other hand, in Examples 1 to 4 in which the titanium oxide according to the present invention was used, both the sensitivity and repeatability of the electrophotographic photosensitive member were good, and the chargeability at the first rotation in the image formation using the reversal development method was also good. Therefore, even if the image is formed by mounting it on a copying machine, there is no problem as long as a few small black dots are seen. The chargeability at the first rotation in the image formation using the reversal development method is relatively good in Examples 1 to 3 in which an alcohol-soluble nylon resin is used as a binder in the undercoat layer. In Examples 1 and 2 in which treated titanium oxide is used, it is particularly good.

Example 5 Alcohol-soluble nylon (manufactured by Toray; CM-8000)
5 g was dissolved in a mixed solvent of 40 g of methanol and 60 g of dichloromethane, and the primary particles had an average particle size of 35 nm.
Titanium oxide surface-treated with aluminum oxide and zirconium oxide (Ishihara Sangyo; TTO-
55D) (5 g) were mixed and dispersed for 5 hours together with zirconia beads having a diameter of 1 mm by a paint conditioner device manufactured by Red Devil. The coating liquid for forming the undercoat layer thus obtained was applied to a metal aluminum thin plate (JI
S standard # 1050), dry film thickness 0.5μm
To form an undercoat layer.

Next, butyral resin (manufactured by Denki Kagaku Kogyo;
# 6000EP) 1.0 g and water 1.2 g are dissolved in 100 g of 1,3-dioxolane, and 1.5 g of the phthalocyanine composition obtained in Synthesis Example 3 is mixed as a charge generating substance, and a paint manufactured by Red Devil Co. 4 with low alkali glass beads with a diameter of 1mm by the conditioner device
Time dispersed. The thus-obtained coating liquid for forming a charge generation layer was applied onto the undercoat layer with an applicator to form an undercoat layer having a dry film thickness of 0.2 μm.

Next, 10 g of the hydrazone compound represented by (5) and polycarbonate (manufactured by Teijin Kasei; Panlite K)
-1300) 10 g, 2,6-di-tert-butyl-
0.1 g of p-cresol was added to tetrahydrofuran 200
g. This charge transport layer forming coating liquid is applied onto the charge generating layer with an applicator to give a dry film thickness of 30 μm.
m charge transport layer was formed.

[0083]

[Chemical 5]

The electrophotographic photosensitive member thus produced was stored at room temperature in a dark place for a whole day and night, and then the same measurement as in Example 1 was carried out. The results are shown in Tables 3 and 4.

Comparative Example 3 Electrophotographic exposure was carried out in the same manner as in Example 5 except that titanyloxyphthalocyanine having a crystal form (form I) whose X-ray diffraction spectrum using CuKα rays shown in FIG. 2 was used as the charge generating substance. After the body was prepared and stored in a dark place at room temperature for one day, the same measurement and evaluation as in Example 1 were performed. The results are shown in Tables 3 and 4.

Comparative Example 4 Electrophotographic exposure was carried out in the same manner as in Example 5 except that titanyloxyphthalocyanine having a crystal form (Y form) whose X-ray diffraction spectrum using CuKα rays shown in FIG. 3 was used as the charge generating substance. After the body was prepared and stored in a dark place at room temperature for one day, the same measurement and evaluation as in Example 1 were performed. The results are shown in Tables 3 and 4.

[0087]

[Table 3]

[0088]

[Table 4] (Each unit of charge potential after standing for 1 hour is in volts.)

In Comparative Examples 3 and 4 in which the specific crystal form of titanyloxyphthalocyanine was used as the charge generating substance, both the sensitivity and the repetitive characteristics of the electrophotographic photosensitive member were poor, and the chargeability at the first rotation in the image formation using the reversal developing method was observed. Is 2
Since the charging property of the rotating eye is significantly worse than that of the rotating eye, an image failure such as fogging occurred when the image was formed by mounting it on a copying machine. On the other hand, in Example 5 in which the charge generating material according to the present invention was used, both the sensitivity and the repeating characteristics of the electrophotographic photosensitive member were good, and the chargeability at the first rotation in image formation using the reversal development method was also good. No image failure was observed when the image was formed by mounting it on a copying machine.

[0090]

As is apparent from the above, according to the present invention, the charging potential is high and the sensitivity is high, and even when repeatedly used, various characteristics are not changed and stable performance can be exhibited. It is possible to provide an electrophotographic photosensitive member which shows good chargeability from the first rotation in the image formation used and has improved image defects.

[Brief description of drawings]

FIG. 1 is the X of the phthalocyanine composition obtained in Synthesis Example 3.
Line diffraction spectrum.

2 is the X of titanyl phthalocyanine used in Comparative Example 3. FIG.
Line diffraction spectrum.

3 is the X of titanyl phthalocyanine used in Comparative Example 4. FIG.
Line diffraction spectrum.

Claims (3)

[Claims] 1. An electrophotographic photoreceptor comprising a conductive support, an undercoating layer containing at least titanium oxide particles and a binder, and a photosensitive layer, which are sequentially laminated. In the photosensitive layer, titanyloxyphthalocyanine is used as a charge generating substance. And at least one phthalocyanine composition containing a metal-free phthalocyanine, wherein the phthalocyanine composition is CuKα
Bragg angle (2θ of 1.541 angstrom X-ray)
± 0.2 °) is 7.0 °, 9.0 °, 14.1 °, 1
The titanium oxide particles having peaks at 8.0 °, 23.7 °, and 27.3 °, and the titanium oxide particles contained in the undercoat layer are granular particles having an average primary particle diameter of 100 nm or less, or primary particles. Is a rod-shaped particle having an average major axis length of 500 nm or less, an average minor axis length of 100 nm or less, and an average aspect ratio of 2 to 10. 2. The electrophotographic photosensitive member according to claim 1, wherein the binder contained in the undercoat layer is an alcohol-soluble nylon resin. 3. The titanium oxide particles contained in the undercoat layer,
The electrophotographic photosensitive member according to claim 1 or 2, which is a titanium oxide particle surface-treated with at least zirconium oxide.