JP2002214809A - Monolayer electrophotographic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure proper storage stability of a coating liquid for a photosensitive layer, and to provide a monolayer electrophotographic photoreceptor, using titanyl phthalocyanine crystals having superior sensitivity and wear resistance. SOLUTION: The monolayer electrophotographic photoreceptor has a photosensitive layer, comprising a binder resin containing at least an electric charge generating agent and an electric charge transport agent on an electrically conductive substrate, the electric charge generating agent contains titanyl phthalocyanine crystals which does not have a peak in temperature change from 50 deg.C to 400 deg.C, other than a peak due to the evaporation of adsorbed water in differential scanning thermal analysis and the photosensitive layer contains a polyalkylene glycol compound of the formula A1-O-[(CH2)m-O]n-A2 (where A1 and A2 are the same or different and each a 1-50C alkyl or aryl or -CO-R10; R10 is a 1-50C alkyl or aryl; (m) is an integer of 1-5; and (n) is an integer of 2-100).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single-layer type electrophotographic photosensitive member used in an image forming apparatus such as an electrostatic copying machine, a facsimile, a laser beam printer, and the like. The present invention relates to a good single-layer organic electrophotographic photoreceptor.

[0002]

2. Description of the Related Art In the above-mentioned image forming apparatus, various photosensitive members having sensitivity in a wavelength region of a light source used in the image forming apparatus are used. One is an inorganic photoreceptor using an inorganic material such as selenium for the photosensitive layer, and the other is an organic photoreceptor (OPC) using an organic material for the photosensitive layer. Of these, it is easier to manufacture than organic photoreceptors and inorganic photoreceptors, and there are a variety of photoreceptor materials such as charge transport agents, charge generators, binder resins, etc. In recent years, extensive research has been conducted.

An organic photoreceptor has a so-called laminated type photoreceptor having a laminated structure of a charge generating layer containing a charge generating agent and a charge transporting layer containing a charge transporting agent, and a charge generating agent and a charge transporting agent. Is dispersed in a single photosensitive layer, that is, a so-called single-layer type photosensitive member. Of these, the multilayer photoconductor occupies a wide market scale. The mainstream of the laminated photoreceptor is a negatively charged type in which a charge generation layer and a charge transport layer are sequentially provided on a conductive substrate.

On the other hand, a single-layer type photoreceptor contains a charge generating agent, a charge transporting agent, and an organic solvent in an organic solvent such as tetrahydrofuran.
It is prepared by dissolving or uniformly dispersing a binder resin or the like to prepare a coating liquid, applying the coating liquid on a conductive substrate, and drying by heat.

For this reason, a single-layer type photoreceptor has a simple layer structure and is excellent in productivity, can suppress the occurrence of film defects in the photosensitive layer, and can improve optical characteristics since there are few interfaces between layers. It has been in the limelight because of its advantages.

A single-layer type photoreceptor using an electron transporting agent and a hole transporting agent in combination as a charge transporting agent is generally used in a positive charge, but the mobility of the electron transporting agent is higher than that of the hole transporting agent. Therefore, it has the disadvantage that the residual potential is higher and the sensitivity is lower than that of the laminated photoreceptor.

As a measure for improving the sensitivity of the photoreceptor, a charge generating agent sensitive to infrared or near-infrared wavelength light emitted from a semiconductor laser, LED, or the like, which is becoming a mainstream light source in recent image forming apparatuses, is used. Research and development of certain phthalocyanine-based compounds have been actively conducted. And, for example, in Japanese Patent No. 2907121, the Y-type titanyl phthalocyanine crystal has excellent sensitivity characteristics as a charge generating agent as compared with a titanyl phthalocyanine crystal having another crystal type,
It is shown that it contributes to the improvement of the sensitivity of the photoreceptor.

On the other hand, the electrophotographic photosensitive member is used in a repeated process of charging, exposing, developing, transferring, cleaning and removing static electricity in the image forming process. The electrostatic latent image formed by the charge exposure is developed with toner, which is a fine powder. Further, the developed toner is transferred to a transfer material such as paper in a transfer process, but 100% of the toner is not transferred, and a part thereof remains on the photoconductor. Unless the remaining toner is removed, a high-quality image free from dirt or the like cannot be obtained in the repetitive process. Therefore, cleaning of the remaining toner is required.

A typical cleaning process uses a fur brush, a magnetic brush, a blade, and the like. From the viewpoint of cleaning accuracy and rationalization of the apparatus configuration, the blade-shaped resin plate is in direct contact with the photosensitive member. In general, blade cleaning for performing cleaning is selected. Blade cleaning, while high in accuracy, increases the mechanical load on the photoreceptor, resulting in increased wear of the photosensitive layer, lowering of the surface potential, deterioration of sensitivity, etc., resulting in high quality. It is difficult to obtain a proper image.

Various methods are known for improving the abrasion resistance of the photoreceptor, but the simplest method is to add various lubricants such as polyethylene glycol, stearic acid and lauric acid to the photosensitive layer. It has been proposed to.

[0011]

In order to solve the above-mentioned problems, a single-layer type photoreceptor is manufactured by using the Y-type titanylphthalosinine crystal as a charge generating agent by the above-mentioned method using tetrahydrofuran. The sensitivity of the single-layer type photoreceptor manufactured using the coating liquid left for a certain period of time (for example, 24 hours) after the production is remarkably deteriorated, as compared with the single-layer type photoreceptor manufactured using the immediately subsequent coating liquid. Have been found by the present inventors' studies.

That is, since the coating liquid for preparing a single-layer photoreceptor prepared using the Y-type titanyl phthalosinine crystal disclosed in Japanese Patent No. 2907121 has poor storage stability, the standing time of the coating liquid is prolonged. Thus, a single-layer type photoconductor having good sensitivity characteristics cannot be obtained.

On the other hand, in order to improve the abrasion resistance of the single-layer type photoreceptor, the aforementioned polyethylene glycol, stearic acid,
The addition of various lubricants such as lauric acid improved the abrasion resistance of the photoreceptor, but also revealed that the sensitivity was significantly deteriorated by the present inventors.

An object of the present invention is to provide a single-layer electrophotographic photoreceptor using a titanyl phthalocyanine crystal, which has excellent storage stability of a coating solution for a photosensitive layer, and extremely excellent sensitivity and abrasion resistance. It is to provide.

[0015]

Means for Solving the Problems and Effects of the Invention As a result of intensive studies to solve the above problems, the present inventors have found that a conductive substrate contains at least a charge generating agent and a charge transporting agent. A photosensitive layer made of a binder resin,
In the differential scanning calorimetry, the charge generating agent contains a titanyl phthalocyanine crystal having no temperature change peak from 50 ° C. to 400 ° C., except for a peak accompanying vaporization of adsorbed water, and the photosensitive layer A single-layer type electrophotographic photoreceptor characterized by containing a polyalkylene glycol compound represented by the general formula [1] has good storage stability of a coating solution for a photosensitive layer, and has sensitivity and abrasion resistance. Have found a new fact that they are extremely excellent, and have completed the present invention.

General formula [1];

Embedded image (In the general formula [1], A ¹ and A ² are the same or different and represent an alkyl group or an aryl group having 1 to 50 carbon atoms, or a group: —CO—R ^10. R ¹⁰ has 1 to 50 carbon atoms. Wherein m is 1 to 5, n is 2 to
Indicates an integer of 100. )

That is, the conventional Y-type titanyl phthalocyanine crystal has poor stability in an organic solvent such as tetrahydrofuran contained in a coating solution. Therefore, when the coating liquid is stored for a certain period of time, the crystal form of the coating liquid undergoes a crystal transition from the Y-type to the β-type, which has poor sensitivity characteristics.

Therefore, the present inventors have proposed to improve the stability of a Y-type titanyl phthalocyanine crystal in an organic solvent.
The physical properties were examined.

As a result, of the following two physical properties,
A titanyl phthalocyanine crystal that satisfies at least one of them is excellent in stability in an organic solvent as compared with a conventional Y-type titanyl phthalocyanine crystal, hardly causes crystal transition, and excellent in storage stability of a coating liquid. Was found. The crystal does not have a temperature change peak from 50 ° C. to 400 ° C. in the differential scanning calorimetry analysis, except for a peak accompanying vaporization of the adsorbed water. After immersion in an organic solvent for 24 hours, the recovered crystals are
It has a maximum peak at least at a Bragg angle 2θ ± 0.2 ° = 27.2 ° and has no peak at 26.2 °.

On the other hand, according to the present invention, the polyalkylene compound has a role as a mere lubricant,
A hydrophilic functional group (for example, a hydroxyl group, a carbonyl group, or the like) in the binder resin and an ester group or an ether group in the polyalkylene glycol compound represented by the general formula [1] form a van der Waals force, a hydrogen bond, or a chemical bond. By forming a three-dimensional network structure in a pseudo manner, the film hardness of the binder resin and, consequently, the entire photosensitive layer is increased, the amount of abrasion is small, and the abrasion resistance of the single-layer type electrophotography is excellent. A photoreceptor can be obtained.

[0021]

Next, the single-layer type electrophotographic photosensitive member according to the present invention will be described in detail. As described above, the single-layer type electrophotographic photoreceptor of the present invention includes a photosensitive layer made of a binder resin containing at least a charge generating agent and a charge transporting agent on a conductive substrate, wherein the charge generating agent is In the scanning calorimetric analysis, except for the peak accompanying the vaporization of the adsorbed water, 50
The photosensitive layer contains a titanyl phthalocyanine crystal having no temperature change peak from ℃ to 400 ° C., and the photosensitive layer contains a polyalkylene glycol compound represented by the general formula [1].

<Charge Generator> The charge generator used in the single-layer electrophotographic photosensitive member of the present invention contains a titanyl phthalocyanine crystal satisfying at least one of the following two physical properties as described above. I do. The crystal does not have a temperature change peak from 50 ° C. to 400 ° C. in the differential scanning calorimetry analysis, except for a peak accompanying vaporization of the adsorbed water. After immersion in an organic solvent for 24 hours, the recovered crystals are
It has a maximum peak at least at a Bragg angle 2θ ± 0.2 ° = 27.2 ° and has no peak at 26.2 °.

The titanyl phthalocyanine crystal is formed from a titanyl phthalocyanine compound represented by the general formula [2] and has a CuKα (wavelength 1.541 °) characteristic X-ray diffraction spectrum having at least a Bragg angle of 2
A crystal having a maximum peak at θ ± 0.2 ° = 27.2 ° and having no peak at 26,2 ° is preferably used.

General formula [2];

Embedded image (In the general formula [2], X ¹ , X ² , X ³ and X ⁴ are the same or different and represent a halogen atom, an alkyl group, an alkoxy group, a cyano group or a nitro group, and a, b, c and d are The same or different, and represents an integer of 0 to 4.)

In the above, examples of the organic solvent include at least one selected from the group consisting of dichloromethane, toluene and 1,4-dioxane, in addition to the above-mentioned tetrahydrofuran.

Examples of the halogen atom corresponding to X ^{1 to} X ⁴ in the general formula [2] include fluorine, chlorine, bromine, iodine and the like. Examples of the alkyl group include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl,
Examples thereof include an alkyl group having 1 to 6 carbon atoms such as pentyl and hexyl. Further, as the alkoxy group, for example, methoxy, ethoxy, n-propoxy, isopropoxy, n-
Butoxy, isobutoxy, sec-butoxy, tert
-An alkoxy group having 1 to 6 carbon atoms such as butoxy, pentyloxy and hexyloxy.

As a preferred example of the titanyl phthalocyanine compound, X ^{1 to} X ⁴ in the general formula [2] are all the same groups X, and a to d indicating the number of the substituents are all the same numbers. e, a general formula [2-1];

Embedded image (In the general formula [2-1], X represents a halogen atom, an alkyl group, an alkoxy group, a cyano group or a nitro group;
Represents an integer of 0 to 4. )).

Further, the above e is 0,

Embedded image Unsubstituted titanyl phthalosinine is most preferably used.

The charge generator used in the single-layer type electrophotographic photoreceptor of the present invention may use the above-mentioned titanyl phthalocyanine crystal alone or may contain at least the above-mentioned titanyl phthalocyanine crystal. Two or more generators can be used in combination. When two or more kinds are used as a mixture, it is preferable that the titanyl phthalocyanine crystal is contained in an amount of 50 wt% or more based on the total charge generating agent weight.

Other known charge generating agents include, for example, phthalocyanine pigments such as metal-free phthalocyanine and hydroxygallium phthalocyanine, perylene pigments, bisazo pigments, diketopyrrolopyrrole pigments, metal-free naphthalocyanine pigments, and metal naphthalocyanine Organic photoconductors such as pigments, squaraine pigments, trisazo pigments, indigo pigments, azurenium pigments, cyanine pigments, pyrylium pigments, anthanthrone pigments, triphenylmethane pigments, sulene pigments, toluidine pigments, pyrazoline pigments, and quinacridone pigments And selenium, selenium-tellurium,
Examples include inorganic photoconductive materials such as selenium-arsenic, cadmium sulfide, and amorphous silicon.

The charge generating agent is used in an amount of 0.1 to 20 wt%, more preferably 0.5 to 15 wt%, based on the total weight of the binder resin.
%.

<Polyalkylene Glycol Compound> The polyalkylene glycol compound used in the single-layer type electrophotographic photoreceptor of the present invention is represented by the following general formula [1]:
It is characterized in that the terminal hydroxyl group (-OH group) has been subjected to an esterification treatment or an etherification treatment. When the esterification treatment or the etherification treatment is not performed and the terminal group remains as a hydroxyl group, the sensitivity of the single-layer type photoreceptor is significantly deteriorated. That is, the addition of the above-mentioned polyethylene glycol significantly deteriorates the sensitivity.

As a cause of the deterioration in sensitivity, when the above treatment is not carried out and a hydroxyl group remains, the polyalkylene glycol compound has high hydrophilicity and is used for the photosensitive layer of a single-layer photosensitive member such as a polycarbonate resin. In the binder resin having a relatively high hydrophobicity, the compatibility of the polyalkylene glycol compound is reduced, the aggregation of the polyalkylene glycol compound molecules is likely to occur, and the aggregate of the compound molecules acts as a charge trap. Conceivable.

The content of the polyalkylene glycol compound is appropriately set according to the structure of the polyalkylene glycol compound and the structure of the binder resin, and is not particularly limited.
It is preferable that the content is not less than t% and not more than 500 wt%.

That is, as described above, the charge generator is preferably contained in an amount of 0.1 to 20% by weight based on the total weight of the binder resin. 05-100
Most preferably, the content is 1 wt%, more preferably 1 to 15 wt%.

When the content of the polyalkylene glycol compound exceeds 500 wt% with respect to the content of the charge generating agent,
The dispersibility and solubility of the charge generating agent and the charge transporting agent contained in the binder resin are reduced, and the sensitivity is deteriorated. On the other hand, when the content of the polyalkylene glycol compound is less than 50 wt% with respect to the content of the charge generating agent, the number of bonds between the ester group or the ether group of the polyalkylene glycol compound and the hydrophilic functional group of the binder resin decreases. ,
No effect on improving wear resistance and gas resistance.

<Binder Resin> As the binder resin used for the single-layer type electrophotographic photoreceptor of the present invention, various resins conventionally used for the photosensitive layer can be used. For example, styrene-butadiene copolymer, styrene-acrylonitrile copolymer, styrene-maleic acid copolymer, acrylic copolymer, styrene-acrylic acid copolymer, polyethylene, ethylene-vinyl acetate copolymer,
Chlorinated polyethylene, polyvinyl chloride, polypropylene, ionomer, vinyl chloride-vinyl acetate copolymer,
Thermoplastic resins such as polyester, alkyd resin, polyamide, polyurethane, polycarbonate, polyarylate, polysulfone, diallyl phthalate resin, ketone resin, polyvinyl butyral resin, polyether resin,
Resins such as a silicone resin, an epoxy resin, a phenol resin, a urea resin, a melamine resin, a cross-linkable thermosetting resin, and a photo-curable resin such as epoxy acrylate and urethane-acrylate can be used. These binder resins may be used alone or in a combination or blend of two or more.

In particular,

Embedded image A binder resin containing a biphenyl-type polycarbonate having a repeating structural unit represented by the following formula (1) is preferably used. The biphenyl-type polycarbonate is effective in improving abrasion resistance because of its high rigidity in molecular structure.

Further,

Embedded image The most preferred is a copolymerized polycarbonate resin of the above biphenyl-type polycarbonate and bisphenol Z represented by

The biphenyl-type polycarbonate is effective for improving the abrasion resistance, but has a problem that the compatibility with the polyalkylene glycol compound represented by the general formula [1] is slightly inferior. If the compatibility between the polyalkylene glycol compound and the binder resin is low, the sensitivity tends to deteriorate as described above. On the other hand, the bisphenol Z-type polycarbonate has good compatibility with the polyalkylene compound. For this reason, by using the copolymerized polycarbonate resin of the biphenyl-type polycarbonate and bisphenol Z, it is possible to achieve both improvement in abrasion resistance and improvement in sensitivity.

The molar copolymerization ratio of the above-mentioned biphenyl type polycarbonate and bisphenol Z type polycarbonate is preferably from 5:95 to 50:50.

The weight average molecular weight of all the binder resins in the above examples is 10,000 to 500,000, and furthermore, 3
It is preferably from 000 to 200,000.

<Charge Transport Agent> Examples of the charge transport agent used in the single-layer type electrophotographic photoreceptor of the present invention include conventionally known electron transport agents and hole transport agents. In particular, in the case of a single-layer type photoreceptor, it is preferable to mix and contain a hole transporting agent and an electron transporting agent in the photosensitive layer in order to improve sensitivity or charge stability.

[Hole transport agent] Examples of the hole transport agent usable in the single-layer type electrophotographic photoreceptor of the present invention include:
N, N, N ′, N′-tetraphenylbenzidine derivative, N, N, N ′, N′-tetraphenylphenylenediamine derivative, N, N, N ′, N′-tetraphenylnaphthylenediamine derivative, N, N Oxadiazole compounds such as N, N ', N'-tetraphenylphenanthrylenediamine derivative, 2,5-di (4-methylaminophenyl) -1,3,4-oxadiazole, 9- (4 Styryl compounds such as -diethylaminostyryl) anthracene, carbazole compounds such as polyvinylcarbazole, organic polysilane compounds, 1-phenyl-3- (p-
Dimethylaminophenyl) pyrazoline compounds such as pyrazoline, hydrazone compounds, indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, triazole compounds and the like. Examples include a nitrogen cyclic compound and a condensed polycyclic compound.

In particular, the hole transporting agent preferably contains a compound represented by the general formula [3], [4], [5] or [6].

General formula [3];

Embedded image (In the general formula [3], R ³⁰ , R ³¹ , R ³² and R ³³ are the same or different and represent an alkyl group, an alkoxy group, an aryl group, an aralkyl group, or a halogen atom;
n, p and q are the same or different and represent an integer of 0-3. R ³⁴ and R ³⁵ are the same or different and each represent a hydrogen atom or an alkyl group. Also, -X-

Embedded image Or

Embedded image Is shown. )

General formula [4];

Embedded image (In the general formula [4], R ⁴⁰ and R ⁴² represent the same or different alkyl groups which may have a substituent, and R ⁴¹ and R ^42
43 is the same or different and represents a hydrogen atom or an alkyl group which may have a substituent. )

General formula [5];

Embedded image (In the general formula [5], R ⁵⁰ , R ⁵¹ , R ⁵² , R ⁵³ and R
⁵⁴ is the same or different and is a hydrogen atom, a halogen atom,
It represents an alkyl group or an alkoxy group which may have a substituent. )

General formula [6];

Embedded image (In the general formula [6], R ⁶⁰ , R ⁶¹ , R ⁶² , R ⁶³ and R ⁶⁴ are the same or different and represent a halogen atom, an alkyl group, an alkoxy group or an aryl group which may have a substituent. A, b, c and d are the same or different and each represents an integer of 0 to 5, and e represents an integer of 0 to 4. a, b, c
Or, when d is 2 or more, each of R ⁶⁰ , R ⁶¹ , R ⁶² , R ⁶³ and R ⁶⁴ may be different. )

The hole transporting agent represented by the general formula [3], [4], [5] or [6]
Since the holes have extremely high mobility and transport holes efficiently, it is effective for improving the sensitivity of the photoreceptor.

In the present invention, only one type of hole transporting agent may be used, or two or more types may be used in combination.

[Electron Transporting Agent] Examples of the electron transporting agent usable in the single-layer type electrophotographic photoreceptor of the present invention include diphenoquinone derivatives and benzoquinone derivatives.
Azoquinone derivatives described in 00-147806 and JP-A-2000-242009, monoquinone derivatives, dinaphthylquinone derivatives, tetracarboxylic diimide derivatives, carboxylic imide derivatives, stilbenquinone described in JP-A-2000-075520 and JP-A-2000-258936 Derivatives, anthraquinone derivatives, malononitrile derivatives, thiopyran derivatives, trinitrothioxanthone derivatives, 3,4,5,7-tetranitro-9-fluorenone derivatives, dinitroanthracene derivatives, dinitroacridine derivatives, nitroantaraquinone derivatives, dinitroanthraquinone derivatives, tetra Cyanoethylene, 2,
Various compounds having electron-accepting properties, such as 4,8-trinitrothioxanthone, dinitrobenzene, dinitroanthracene, dinitroacridine, nitroanthraquinone, dinitroanthraquinone, succinic anhydride, maleic anhydride, and dibromomaleic anhydride, may be mentioned.

In particular, the electron transporting agents are represented by the general formulas [7], [8], [9], [10] and [1].
1], a compound represented by the general formula [12] or the general formula [13].

General formula [7];

Embedded image (In the general formula [7], R ⁷⁰ and R ⁷¹ represent the same or different alkyl groups which may have a substituent.)

General formula [8];

Embedded image (In the general formula [8], R ⁸⁰ and R ⁸¹ represent the same or different monovalent hydrocarbon groups which may have a substituent.)

General formula [9];

Embedded image (In the general formula [9], R ⁹⁰ represents a halogen atom, an optionally substituted alkyl group or an aryl group, and R ⁹¹ represents an optionally substituted alkyl group or an aryl group, or a group: .R ^91a showing a -O-R ^91a represents an alkyl group or an aryl group which may have a substituent.)

General formula [10];

Embedded image (In the general formula [10], R ¹⁰⁰ , R ¹⁰¹ , R ¹⁰² , and R ¹⁰³ are
It represents the same or different alkyl groups which may have a substituent. )

General formula [11];

Embedded image (In the general formula [10], R ^{110 to} R ¹¹³ are the same or different and each represent a hydrogen atom, an alkyl group having 1 to 12 carbon atoms,
To 12 alkoxy groups, aryl groups which may have a substituent, cycloalkyl groups, aralkyl groups which may have a substituent, and halogenated alkyl groups. The substituent represents a halogen atom, an alkoxy group having 1 to 6 carbon atoms, a hydroxyl group, a cyano group, an amino group, a nitro group, or a halogenated alkyl group. )

General formula [12];

Embedded image (In the general formula [12], R ¹²⁰ and R ¹²¹ are the same or different and each represent a hydrogen atom, an alkyl group having 1 to 12 carbon atoms,
To 12 alkoxy groups, aryl groups which may have a substituent, cycloalkyl groups, aralkyl groups which may have a substituent, and halogenated alkyl groups. R ^{122 to} R ¹²⁶ are
Same or different, hydrogen atom, halogen atom, carbon number 1
Alkyl group of 12 to 12, alkoxy group having 1 to 12 carbon atoms,
It represents an aralkyl group which may have a substituent, a phenoxy group which may have a substituent, and an alkyl halide group, and two or more groups may combine to form a ring. The substituent represents a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a hydroxyl group, a cyano group, an amino group, a nitro group, or a halogenated alkyl group. )

General formula [13];

Embedded image (In the general formula [13], R ^{130 to} R ¹³³ are the same or different and each represent a hydrogen atom, an alkyl group having 1 to 12 carbon atoms,
To 12 alkoxy groups, aryl groups which may have a substituent, cycloalkyl groups, aralkyl groups which may have a substituent, and halogenated alkyl groups. R ¹³⁴ and R ¹³⁵ are
The same or different and represent a hydrogen atom and an alkyl group having 1 to 12 carbon atoms. R ^{136 to} R ¹⁴² are the same or different and each represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryl group which may have a substituent, a halogenated alkyl group; Is shown. The substituent is a halogen atom, an alkyl group having 1 to 6 carbon atoms, 1 to 6 carbon atoms.
Represents an alkoxy group, a hydroxyl group, a cyano group, an amino group, a nitro group, and a halogenated alkyl group. )

The general formulas [7], [8], [9], [10], [11], [1]
The electron transporting agent represented by 2] or the general formula [13] has an extremely high mobility and efficiently transports electrons, and is therefore effective for improving the sensitivity of the photoreceptor.

In the present invention, only one electron transport agent may be used, or two or more electron transport agents may be used in combination.

The hole transporting agent is preferably contained in an amount of 5 to 500% by weight, more preferably 25 to 200% by weight, based on the total weight of the binder resin. The electron transport agent is 5 to 100% by weight, and more preferably 10 to 80% by weight based on the total weight of the binder resin.
%. When the hole transporting agent and the electron transporting agent are used in combination, the total amount of the hole transporting agent and the electron transporting agent is 20 to 50 based on the total binder resin weight.
The content is preferably 0 wt%, more preferably 30 to 200 wt%.

In particular, in the single-layer type electrophotographic photoreceptor of the present invention, as described above, a hole transporting agent and an electron transporting agent are mixed and used as the charge transporting agent, and the solid content concentration of the charge transporting agent is Most preferably, the total solid content is 30 wt% or more and 50 wt% or less.

It is generally known that when the content of the charge transporting agent increases, the abrasion resistance of the photosensitive layer decreases.
For this reason, it is ideal to reduce the solids concentration of the charge transport agent in order to improve the abrasion resistance. However, if the solids concentration of the charge transport agent is reduced, the sensitivity decreases.

However, a hole transporting agent having a large hole transporting ability, for example, a hole transporting agent represented by the general formula [3], [4], [5] or [6], or having a large electron transporting ability, For example, an electron transporting agent represented by general formula [7], general formula [8], general formula [9], general formula [10], general formula [11], general formula [12] or general formula [13] is used. By doing, 30 wt% to the total solid content concentration
The sensitivity is good even at a solid concentration as low as 50 wt% or less, and as a result, a single-layer type photoconductor having good abrasion resistance can be obtained.

The thickness of the photosensitive layer of the single-layer type photosensitive member of the present invention is 5 to 5.
It is preferably about 100 μm, more preferably about 10 to 50 μm.

In the photosensitive layer, in addition to the components described above, various conventionally known additives such as an antioxidant, a radical scavenger, a singlet quencher, Deterioration inhibitors such as UV absorbers, softeners,
Plasticizers, surface modifiers, extenders, thickeners, dispersion stabilizers, waxes, acceptors, donors, and the like can be added. Also, in order to improve the sensitivity of the photosensitive layer, for example,
Known sensitizers such as terphenyl, halonaphthoquinones, and acenaphthylene may be used in combination with the charge generator.

A barrier layer may be formed between the support and the photosensitive layer as long as the characteristics of the photosensitive member are not impaired.

As the support on which the photosensitive layer is formed, various conductive materials can be used.
Iron, aluminum, copper, tin, platinum, silver, vanadium,
Molybdenum, chromium, cadmium, titanium, nickel,
Examples of the material include simple metals such as palladium, indium, stainless steel, and brass; plastic materials on which the above metals are deposited or laminated; glass coated with aluminum iodide, tin oxide, indium oxide, and the like.

The shape of the support may be any of a sheet shape, a drum shape and the like, depending on the structure of the image forming apparatus to be used. The support itself has conductivity, or the surface of the support has What is necessary is just to have electroconductivity. The support preferably has a sufficient mechanical strength when used.

When the photosensitive layer is formed by a coating method, the above-described charge generating agent, charge transporting agent, binder resin, etc., together with a suitable solvent, can be used in a known manner, for example, a roll mill, a ball mill, an attritor, a paint coater. What is necessary is just to disperse and mix using an acre, an ultrasonic disperser or the like to prepare a dispersion, apply it by a known means, and dry it.

Various organic solvents can be used as the solvent for preparing the above-mentioned dispersion liquid, for example, alcohols such as methanol, ethanol, isopropanol and butanol, and aliphatic solvents such as n-hexane, octane and cyclohexane. Hydrocarbons, aromatic hydrocarbons such as benzene, toluene, and xylene; halogenated hydrocarbons such as dichloromethane, dichloroethane, chloroform, carbon tetrachloride, and chlorobenzene; dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, and diethylene glycol dimethyl ether. Ethers, ketones such as acetone, methyl ethyl ketone and cyclohexanone, esters such as ethyl acetate and methyl acetate, 1,4-dioxane, 1,3-dioxolan, dimethylforma Aldehyde, dimethylformamide, dimethylsulfoxide and the like. These solvents are used alone or in combination of two or more. In particular, tetrahydrofuran, dichloromethane, toluene, and 1,4-dioxane are preferably used as a coating solvent for producing a single-layer photoreceptor.

Further, in order to improve the dispersibility of the charge generating agent, the charge transporting agent and the like and the smoothness of the surface of the photosensitive layer, a surfactant, a leveling agent and the like may be used.

[0075]

The present invention will be described below with reference to production examples, examples and comparative examples. Note that the following embodiments are merely examples embodying the present invention, and do not limit the technical scope of the present invention.

<Production Example 1> Preparation of unsubstituted titanyl phthalocyanine crystal (TiOPc-1) (1) Synthesis of titanyl phthalocyanine compound In a flask purged with argon, 25 g of 1,3-diminoisoindoline and titanium tetra 22 g of butoxide,
300 g of diphenylmethane and 150 g with stirring.
The temperature was raised to ° C. Next, the temperature was raised to 215 ° C. while distilling off the vapor generated from the reaction system to the outside of the system, and the mixture was stirred and reacted for 4 hours while maintaining the temperature. After the reaction is over, 1
At the time of cooling to 50 ° C., the reaction mixture was taken out of the flask, filtered through a glass filter, and the obtained solid was washed with N, N-dimethylformamide and methanol in that order, and then dried under vacuum to obtain 24 g of a purple solid. I got (2) Pigmentation pretreatment 10 g of the purple solid obtained in the synthesis of the titanyl phthalocyanine compound was added to N, N-dimethylformamide 10
Then, the mixture was heated to 130 ° C. with stirring, and stirred for 2 hours. Next, after 2 hours, heating was stopped, and after cooling to 23 ± 1 ° C., stirring was also stopped. In this state, the liquid was allowed to stand for 12 hours to perform a stabilization treatment. Then, the stabilized liquid is separated by filtration through a glass filter, and the obtained solid is washed with methanol.
Vacuum drying was performed to obtain 9.85 g of crude crystals of the titanyl phthalosinine compound. (3) Pigmentation treatment 5 g of the crude crystal of the titanylphthalosinine compound obtained in the above-mentioned pigmentation pretreatment was added to and dissolved in 100 ml of a mixed solvent of dichloromethane and trifluoroacetic acid (volume ratio: 4: 1). Next, the solution was dropped into a mixed solvent of methanol and water (volume ratio 1: 1), stirred at room temperature for 15 minutes, and allowed to stand at room temperature for 30 minutes to recrystallize. Next, the above-mentioned liquid was separated by filtration with a glass filter, and the obtained solid was washed with water until the washing liquid became neutral. Then, in the presence of water without drying, the solid was dispersed in 200 ml of chlorobenzene, and the resulting solid was washed for 1 hour. Stirred. After the liquid was filtered off with a glass filter, the obtained solid was vacuum-dried at 50 ° C. for 5 hours to obtain 4.2 g of unsubstituted titanyl phthalocyanine crystals (blue powder).

<Production Comparative Example 1> Preparation of unsubstituted titanyl phthalocyanine crystal (TiOPc-2) Crystal of unsubstituted titanyl phthalocyanine 4 was prepared in the same manner as in Production Example 1 except that the pretreatment step for pigmentation was omitted. .
2 g were obtained.

<Production Comparative Example 2> Preparation of unsubstituted titanyl phthalocyanine crystal (TiOPc-3) A titanyl phthalocyanine crystal was prepared according to Application Production Example 1 described in Japanese Patent No. 2907121. That is, amorphous titanyl phthalosinine 2 synthesized before the pretreatment for pigmentation synthesized in the same manner as in Production Example 1 above.
g was placed in a glass beaker and diethylene glycol dimethyl ether was added until the total volume was 200 ml. Then, this was stirred at 23 ± 1 ° C. for 24 hours to obtain an unsubstituted titanylphthalosinine crystal.

The CuKα characteristic X-ray diffraction spectrum and differential scanning calorimetry (DSC) of the unsubstituted titanyl phthalocyanine crystals obtained in the above Production Examples and Production Comparative Examples were measured according to the following methods.

<Measurement of CuKα characteristic X-ray diffraction spectrum>
60% after production obtained in each of the above production examples and production comparative examples.
0.5 g of unsubstituted titanyl phthalosinine crystal within 10 minutes was analyzed with an X-ray diffractometer (RINT1100 manufactured by Rigaku Corporation).
And the initial measurement was performed. Then, 0.5 g of each crystal was respectively dispersed in 5 g of tetrahydrofuran used for a coating liquid in Examples described later, and under the conditions of a temperature of 23 ± 1 ° C. and a relative humidity of 50 to 60%.
After storing in a closed system for 24 hours, tetrahydrofuran was removed and measurement was performed again.

The initial measurement and the re-measurement were performed under the following measurement conditions. X-ray tube: Cu Tube voltage: 40 kV Tube current: 30 mA Start angle: 3.0 ° Stop angle: 40.0 ° Scanning speed: 10 ° / min

<Differential Scanning Calorimetry (DSC)> Differential scanning calorimeter (TAS-200, manufactured by Rigaku Corporation)
Using 8230D), differential scanning calorimetry was performed on the unsubstituted titanyl phthalosinine crystals obtained in the above Production Examples and Production Comparative Examples. The measurement conditions are shown below. Sample pan: Al Heating rate: 20 ° C / min

The above measurement results are shown in FIGS. In addition, unsubstituted titanyl phthalosinine crystal (TiOPc-
Table 1 shows the correspondence between (1) to (3) and each figure.

[0084]

[Table 1]

FIG. 2 shows that 6% after the production obtained in the production example.
TiOPc-1 within 0 minutes has a Bragg angle 2θ ± 0.
Since there were strong peaks at 2 ° = 9.5 °, 24.1 ° and 27.2 °, and no peak at 26.2 °, it was confirmed to have a Y-type crystal form.

Also, when TiOPc-1 was immersed in tetrahydrofuran for 24 hours, as shown in FIG. 3, no peak was generated at a Bragg angle of 2θ ± 0.2 ° = 26.2 °. Has maintained the Y-form, and it has been confirmed that it has not been transformed into another crystal form such as the β-form.

Further, as shown in FIG. 1, TiOPc-1 has a peak concentration of 50 to 40 except for a peak at around 90 ° C. associated with the vaporization of the adsorbed water.
Since no peak of the temperature change was exhibited up to 0 ° C., it was confirmed that the material was stable without crystal transition.

On the other hand, TiOPc-2 and -3 obtained in Production Comparative Examples 1 and 2 were immersed in tetrahydrofuran for 24 hours as shown in FIGS. Since the peak at 2θ ± 0.2 ° = 27.2 ° became smaller and a strong peak was generated at 26.2 ° instead, it was concluded that the crystal was not able to maintain the Y-form and had transitioned to the β-form. confirmed.

4 and 7 show that TiOPc-2,-
3 was analyzed by differential scanning calorimetry. As a result, in addition to the peak around 90 ° C. accompanying the vaporization of the adsorbed water,
It showed a peak around ℃, and it was confirmed that crystal transition occurred.

<Examples 1 to 12> 3.5 parts by weight of the unsubstituted titanyl phthalocyanine: TiOPc-1 obtained in Production Example 1 above as a charge generating agent, and ETM-1 and -2 as electron transporting agents. 35 parts by weight of the selected one and 6 as the hole transporting agent selected from HTM-1 and -2.
5 parts by weight, weight average molecular weight 10 as binder resin
Copolymer polycarbonate resin of 0000 biphenyl type polycarbonate and bisphenol Z: Resin
-1 (molar copolymerization ratio a: b = 20.0: 80.0) to 1
00 parts by weight, 3 parts by weight of the polyalkylene glycol compound represented by the general formula [1] (one selected from PEG-1, -2 and -3), and the above material as tetrahydrofuran 8
The resulting mixture was dispersed or dissolved in a ball mill together with 00 parts by weight for 24 hours to prepare a single-layer type photosensitive layer coating solution. Then, 24 hours after the preparation, this coating solution was applied onto an aluminum tube as a support by a dip coating method, and dried with hot air at 125 ° C. for 45 minutes to obtain a film thickness of 27.
A single-layer type photoreceptor having a single photosensitive layer of μm was prepared.

Comparative Examples 1-3 Unsubstituted titanyl phthalocyanines obtained in Production Comparative Example 1 were used as charge generating agents:
Except for using TiOPc-2, a single-layer type photoreceptor was manufactured in the same manner as in Examples 1, 5, and 9.

<Comparative Examples 4 to 6> As the charge generator, the unsubstituted titanyl phthalocyanine obtained in Production Comparative Example 2 was used:
Except for using TiOPc-3, a single-layer type photoreceptor was manufactured in the same manner as in Examples 1, 5, and 9.

Comparative Example 7 A single-layer type photoreceptor was prepared in the same manner as in Examples 1, 5, and 9 except that no polyalkylene glycol compound was contained.

<Comparative Examples 8 and 9> The terminal hydroxyl group (-OH
Polyalkylene glycol compound (PEG-4, -5) whose ester group has not been esterified or etherified.
Examples 1, 5, and 9 except that
A single-layer type photoreceptor was prepared in the same manner as described above.

<ETM-1>

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<ETM-2>

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<HTM-1>

Embedded image

<HTM-2>

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<Resin-1>

Embedded image

<PEG-1>

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<PEG-2>

Embedded image

<PEG-3>

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<PEG-4>

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<PEG-5>

Embedded image

The following evaluation tests were carried out on the single-layer type electrophotographic photosensitive members of the above Examples and Comparative Examples.

<Abrasion Resistance Evaluation Test> A digital copier (“Creage 7340” manufactured by Kyocera Mita Co., Ltd.) having blade cleaning means was used to perform a printing test of 250,000 sheets of A4 landscape size paper. The film thickness of the photosensitive layer before and after the test was measured, and the amount of change in the film thickness was calculated. The smaller the change in film thickness, the better the abrasion resistance.
The following were acceptable, and those greater than 3 μm were not acceptable.

<Sensitivity Evaluation Test> Using a drum sensitivity tester manufactured by GENTEC, an applied voltage was applied to the photoreceptor surface of each of the examples and comparative examples before the printing test, and the surface was +700.
V (single-layer type photoreceptor). Then, monochromatic light having a wavelength of 780 nm (half-width 20) extracted from white light of a halogen lamp as an exposure light source using a bandpass filter.
nm, 1.0 μJ / cm ² ), and the surface potential at the point of time 0.5 seconds after the start of exposure is determined as the residual potential (V _L ).
Was measured. The lower the residual potential V _{L, the} higher the sensitivity of the photoreceptor.

Tables 2 to 4 show the evaluation results. FIG.
In the case of using ETM-1 as an electron transporting agent and HTM-1 as a hole transporting agent, unsubstituted titanyl phthalosinine (TiOPc-1 to -3) and a polyalkylene glycol compound (no addition, PEG- The relationship between the combinations of 1 to -5) and the wear resistance and sensitivity was shown.

[0109]

[Table 2]

[0110]

[Table 3]

[0111]

[Table 4]

As shown in Tables 2 and 3 or FIG. 10, TiOPc-2 obtained in Production Comparative Examples 1 and 2 was used as a charge generating agent.
Although the abrasion loss of the single-layer type photoreceptor using -3 did not change, the residual potential was 110 V or more, and the sensitivity was remarkably deteriorated. This is because the coating solution was allowed to stand for 24 hours after blending,
It is considered that iOPc-2 and -3 were not able to maintain the Y-form in tetrahydrofuran and translocated to the β-form.

According to Table 2, Table 4 or FIG. 10, when no polyalkylene glycol compound was added (Comparative Example 7),
Although the residual potential did not change, the wear amount of the photosensitive layer was 3 μm or more, and the wear resistance was significantly deteriorated. Further, when a polyalkylene glycol compound whose terminal hydroxyl group (-OH group) was not subjected to esterification treatment or etherification treatment was used (Comparative Examples 8 and 9), the amount of wear did not change.
Despite the use of TiOPc-1, which does not undergo a crystal transition from Y-type to β-type even when left in tetrahydrofuran, the residual potential was 110 V or more, and the sensitivity was significantly deteriorated.

[0114]

As described above, a photosensitive layer composed of a binder resin containing at least a charge generating agent and a charge transporting agent is provided on a conductive substrate. 5 except for the peak accompanying the vaporization of
A single-layer type containing a titanyl phthalocyanine crystal having no temperature change peak from 0 ° C. to 400 ° C., and wherein the photosensitive layer contains a polyalkylene glycol compound represented by the general formula [1]. The electrophotographic photoreceptor has excellent storage stability of the coating solution for the photosensitive layer, and extremely excellent sensitivity and abrasion resistance.

[0115]

[Brief description of the drawings]

FIG. 1 is a chart showing the results of DSC analysis of an unsubstituted titanyl phthalocyanine crystal (TiOPc-1) obtained in Production Example 1.

FIG. 2 is a chart showing a spectrum of X-ray diffraction of TiOPc-1 obtained in Production Example 1 immediately after synthesis.

FIG. 3 is a chart showing a spectrum of X-ray diffraction measured again after immersing TiOPc-1 obtained in Production Example 1 in tetrahydrofuran for 24 hours.

FIG. 4 is a chart showing the results of DSC analysis of an unsubstituted titanyl phthalocyanine crystal (TiOPc-2) obtained in Production Comparative Example 1.

FIG. 5 is a chart showing a spectrum of X-ray diffraction of TiOPc-2 obtained in Production Comparative Example 1 immediately after synthesis.

FIG. 6 is a chart showing a spectrum of X-ray diffraction measured again after immersing TiOPc-2 obtained in Production Comparative Example 1 in tetrahydrofuran for 24 hours.

FIG. 7 is a chart showing the results of DSC analysis of the unsubstituted titanyl phthalocyanine crystal (TiOPc-3) obtained in Production Comparative Example 2.

FIG. 8 is a chart showing a spectrum of X-ray diffraction of TiOPc-3 obtained in Production Comparative Example 2 immediately after synthesis.

FIG. 9 is a chart showing a spectrum of X-ray diffraction measured again after immersing TiOPc-3 obtained in Production Comparative Example 2 in tetrahydrofuran for 24 hours.

FIG. 10 shows an unsubstituted titanyl phthalosinine (TiOPc-1 to -3) and a polyalkylene glycol compound (no addition, PEG-) when ETM-1 is used as an electron transporting agent and HTM-1 is used as a hole transporting agent. 6 is a bar graph showing the relationship between combinations of 1 to -5) and wear resistance and sensitivity.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kazuya Hamazaki 1-2-28 Tamazo, Chuo-ku, Osaka F-term in Kyocera Mita Corporation (reference) 2H068 AA04 AA19 AA21 AA31 BA39 BB40 EA12 EA14 EA16 FA30

Claims (5)

[Claims] A photosensitive layer comprising a binder resin containing at least a charge generating agent and a charge transporting agent is provided on a conductive substrate, and the charge generating agent is subjected to differential scanning calorimetric analysis in accordance with evaporation of adsorbed water. Other than peaks, 50 ° C to 400 ° C
A single-layer type electrophotographic photoreceptor comprising a titanyl phthalocyanine crystal having no peak in temperature change up to the above, and wherein the photosensitive layer contains a polyalkylene glycol compound represented by the general formula [1]. General formula [1]; (In the general formula [1], A ¹ and A ² are the same or different and represent an alkyl group or an aryl group having 1 to 50 carbon atoms, or a group: —CO—R ^10. R ¹⁰ has 1 to 50 carbon atoms. Wherein m is 1 to 5, n is 2 to
Indicates an integer of 100. ) 2. The titanyl phthalosinine crystal is formed from a titanyl phthalocyanine compound represented by the general formula [2], and has a CuKα characteristic X-ray diffraction spectrum having at least a Bragg angle of 2θ ± 0.2 ° = 27.2 °. The single-layer type electrophotographic photoreceptor according to claim 1, wherein the photoreceptor has a maximum peak and no peak at 26.2 °. General formula [2]; (In the general formula [2], X ¹ , X ² , X ³ and X ⁴ are the same or different and represent a halogen atom, an alkyl group, an alkoxy group, a cyano group or a nitro group, and a, b, c and d are The same or different, and represents an integer of 0 to 4.) 3. After immersion in an organic solvent for 24 hours, the recovered titanyl phthalocyanine crystal has a maximum peak at least at a Bragg angle 2θ ± 0.2 ° = 27.2 ° and a peak at 26,2 °. 3. The single-layer type electrophotographic photoreceptor according to claim 2, wherein the electrophotographic photoreceptor does not have any. 4. The method according to claim 1, wherein the organic solvent is tetrahydrofuran, dichloromethane, toluene and 1,4-dioxane.
The single-layer type electrophotographic photosensitive member according to claim 3, wherein the photosensitive member is at least one member selected from the group consisting of 1,3-dioxolane. 5. The single-layer type electrophotographic photoreceptor according to claim 1, wherein the electrophotographic photoreceptor is used in an image forming apparatus for collecting untransferred toner by blade cleaning means.