JP6183201B2 - Electrophotographic photoreceptor and image forming apparatus - Google Patents

Description

  The present invention relates to an electrophotographic photosensitive member that can be used in the field of light printing or the like and capable of forming a halftone image with extremely high image quality, and an image forming apparatus including the electrophotographic photosensitive member.

In an electrophotographic image forming apparatus, in recent years, an electrophotographic photoreceptor (hereinafter simply referred to as “photoreceptor”) which is an organic photoreceptor having an organic photosensitive layer in which a charge transport layer is laminated on a charge generation layer as an image carrier. Is also used extensively.
In general, in an electrophotographic photosensitive member, for example, when the photosensitive member is replaced and exposed to external light such as white light for a long time, an electric charge is generated unintentionally, and this is accumulated inside the charge generation layer. Therefore, there is a problem that so-called light fatigue (photo memory) occurs, in which the uniformity of charging on the photosensitive member is disturbed at the next charging.
This light fatigue is manifested as density unevenness in the formed image, and particularly appears in an intermediate density image and a halftone image.
In addition, this photo fatigue is particularly noticeable in a photoreceptor using a highly sensitive phthalocyanine compound as a charge generating substance, for example, a substance composed of 2,3-butanediol adduct titanyl phthalocyanine and non-added titanyl phthalocyanine. .

  In order to solve such a problem, for example, Patent Documents 1 to 3 disclose a method for suppressing light fatigue by adding an orange dye to a photosensitive layer such as a charge transport layer or a protective layer.

However, in all of these published technologies, light fatigue has been improved. On the other hand, when a photoconductor is used for a long period of time in a severe environment such as high temperature and high humidity, the chargeability is reduced and the residual potential is reduced. There was a problem related to potential stability, such as a tendency to increase.
For this reason, in order to adopt it as an organic photoconductor such as a high-speed digital copying machine that requires high image quality, high speed, and high durability, it is necessary to improve the light fatigue characteristics and ensure further repeated potential stability. There is.

JP 63-92956 A JP-A-10-228121 JP-A-11-109666

  The present invention has been made based on the circumstances as described above, and an object thereof is to obtain a halftone image that has excellent resistance to light fatigue and suppresses occurrence of density unevenness due to light fatigue. Another object of the present invention is to provide an electrophotographic photoreceptor excellent in potential stability during repeated use and an image forming apparatus provided with the electrophotographic photoreceptor.

The electrophotographic photoreceptor of the present invention is an electrophotographic photoreceptor in which at least a charge generation layer and a charge transport layer are laminated in this order on a conductive support,
The charge generation layer contains a phthalocyanine compound as a charge generation material;
The layer located on the surface side of the charge generation layer contains a compound represented by the following general formula (1),
The charge transport layer contains at least a charge transport material, and the charge transport material is different from the compound represented by the general formula (1).

[Wherein, n is 1 or 2, and R ¹ may have an alkyl group that may have a substituent, a monovalent aromatic group that may have a substituent, or a substituent. Represents a heterocyclic group, and when n = 1, the two R ^{1 s} may be the same or different from each other, and may be bonded to each other to form a ring structure. R ² represents an alkyl group which may have a substituent or a monovalent aromatic group which may have a substituent, and R ³ represents an alkyl group which may have a substituent or a substituent. The monovalent aromatic group which may have or the heterocyclic group which may have a substituent is represented. Ar represents a divalent aromatic group which may have a substituent. ]

In the electrophotographic photoreceptor of the present invention, R ¹ in the general formula (1) is a phenyl group which may have a substituent or an alkyl group having 1 to 5 carbon atoms which may have a substituent. And R ² is an optionally substituted phenyl group or an optionally substituted alkyl group having 1 to 3 carbon atoms, and R ³ is an optionally substituted phenyl. It is preferable that it is a C1-C3 alkyl group which may have a group or a substituent, and said Ar is a phenylene group.

In the electrophotographic photosensitive member of the present invention, when the layer located on the surface side of the charge generation layer containing the compound represented by the general formula (1) is a charge transport layer,
It is preferable that the content rate of the compound represented by the said General formula (1) is 0.1-10 mass parts with respect to 100 mass parts of binder resin which forms the said charge transport layer.

In the electrophotographic photoreceptor of the present invention, a protective layer containing a compound represented by the general formula (1) and located on the surface side of the charge generation layer is formed on the charge transport layer. One day,
It is preferable that the content rate of the compound represented by the said General formula (1) is 0.5-20 mass parts with respect to 100 mass parts of binder resin which forms the said protective layer.

  In the electrophotographic photoreceptor of the present invention, the charge transport material is preferably a compound having a triarylamine structure.

  In the electrophotographic photoreceptor of the present invention, the phthalocyanine compound is preferably composed of a 2,3-butanediol adduct titanyl phthalocyanine and an unadded titanyl phthalocyanine.

The image forming apparatus of the present invention includes an electrophotographic photosensitive member, means for forming an electrostatic latent image on the electrophotographic photosensitive member, means for developing the electrostatic latent image with toner to form a toner image, and formed toner. Means for transferring the image to the image support, means for fixing the transferred toner image on the image support,
The electrophotographic photosensitive member is the above-described electrophotographic photosensitive member.

  According to the electrophotographic photoreceptor of the present invention, the compound represented by the general formula (1) (hereinafter also referred to as “specific pyrazolone dye”) is contained in a layer located on the surface side of the charge generation layer. Thus, it is possible to obtain a halftone image having excellent resistance to light fatigue and suppressing occurrence of density unevenness due to light fatigue, and excellent potential stability can be obtained even during repeated use.

2 is a partial cross-sectional view showing an example of the configuration of the electrophotographic photosensitive member of the present invention. FIG. (1) X-ray diffraction spectrum of 9.5 ° type 2,3-butanediol adduct titanyl phthalocyanine, (2) X-ray diffraction of 8.3 ° type 2,3-butanediol adduct titanyl phthalocyanine. The spectrum is shown. 1 is a cross-sectional view for explaining an example of a configuration of an image forming apparatus on which an electrophotographic photosensitive member of the present invention is mounted.

  Hereinafter, the present invention will be specifically described.

[Photoreceptor]
The photoconductor of the present invention is an organic photoconductor in which at least a charge generation layer and a charge transport layer are laminated in this order on a conductive support, and the above-mentioned general photoconductor layer is disposed on the surface side of the charge generation layer. A specific pyrazolone dye represented by the formula (1) is contained.

  For example, as shown in FIG. 1, the photoreceptor of the present invention has an intermediate layer 1b, a charge generation layer 1c, a charge transport layer 1d, and a protective layer 1e laminated in this order on a conductive support 1a. 1 is formed, and the charge generating layer 1c and the charge transport layer 1d constitute an organic photosensitive layer 1α that is indispensable for the structure of the organic photoreceptor.

(Conductive support)
The conductive support constituting the photoconductor of the present invention is in the form of a sheet or a cylinder, and as the conductive support, a cylindrical support is used from the viewpoint of reducing the size of the image forming apparatus. preferable.
The cylindrical conductive support is capable of forming an endless image by rotating, and preferably has a straightness in the range of 0.1 mm or less and a deflection of 0.1 mm or less. When a material exceeding the straightness and shake range is used, it is difficult to form a good image.

The conductive support preferably has a ten-point average roughness (RzJIS) of 0.3 to 2.5 μm. “10-point average roughness (RzJIS)” is the notation described in the appendix of JIS B0601-2001, and only the reference length is extracted from the roughness curve in the direction of the average line, and the average line of this extracted portion Measured in the direction of vertical magnification from the highest sum of the absolute values of the altitude of the highest peak to the fifth and the average of the absolute values of the lowest of the lowest to the fifth This value is expressed in micrometers (μm).
When the ten-point average roughness (RzJIS) of the conductive support is in the above range, even when a laser light source is used as the exposure light source, occurrence of moire in the image can be prevented. Even if the conductive support is roughened as described above, leakage such as dielectric breakdown can be prevented by forming a thick intermediate layer.

  The conductive support is not particularly limited as long as it has conductivity. For example, aluminum, nickel or the like formed into a drum shape, aluminum, tin oxide, indium oxide or the like is vapor-deposited on a plastic drum. And those obtained by applying a conductive substance to paper or a plastic drum. Among these, it is preferable to use a material obtained by molding aluminum into a drum shape. The conductive support formed by forming aluminum in a drum shape includes aluminum as a main component, and includes those in which components such as manganese, zinc, and magnesium are mixed.

The conductive support preferably has a specific resistance at room temperature of 10 ³ Ω · cm or less.

(Method for producing conductive support)
For example, in the case of producing a cylindrical support, the conductive support is produced by cutting the surface of a raw pipe made of a cylindrical pipe so as to have the above ten-point average roughness (RzJIS). be able to.
Specifically, the contact angle of a cutting bit such as a diamond sintered bit when shaping the surface of the basic tube by a bit cutting process, the type of cutting bit used, and the polishing conditions of the cutting bit edge are changed. By doing so, the conductive support can be adjusted to have a specific ten-point average roughness (RzJIS).
The tool cutting of the conductive support adjusts the ten-point average roughness of the surface and oxidizes the surface of the conductive support to bring the dimensional accuracy such as the outer diameter of the conductive support to a desired level. It is performed for the purpose of making it fresh except for the film, and making the surface of the conductive support a desired shape.

(Middle layer)
The intermediate layer provides a barrier function and an adhesive function between the conductive support and the organic photosensitive layer. From the viewpoint of preventing various failures, it is preferable to provide such an intermediate layer.

  The intermediate layer is particularly preferably one in which titanium oxide fine particles are dispersed in a binder resin such as a polyamide resin. The average particle size of the titanium oxide fine particles is preferably in the range of 10 nm to 400 nm in terms of number average primary particle size, and more preferably in the range of 15 nm to 200 nm. When the number average primary particle size of the titanium oxide fine particles is in the above range, good dispersion stability of the titanium oxide fine particles in the intermediate layer is obtained, and in addition to the effect of suppressing the occurrence of black spots by the intermediate layer, Good environmental properties and cracking resistance are obtained. When the number average primary particle size of the titanium oxide fine particles is less than 10 nm, the effect of suppressing the occurrence of moire by the intermediate layer is small. On the other hand, when the number average primary particle size of the titanium oxide fine particles is larger than 400 nm, precipitation of the titanium oxide fine particles in the coating liquid for forming the intermediate layer is likely to occur, and as a result, the dispersibility of the titanium oxide fine particles in the intermediate layer. Therefore, there is a possibility that the finally obtained photoreceptor cannot sufficiently suppress the occurrence of black spots.

  The titanium oxide fine particles may be used in any shape such as dendritic, acicular and granular, and may be any crystalline type such as anatase type, rutile type and amorphous type, Two or more crystal types may be mixed and used. Among these, as the titanium oxide fine particles, it is particularly preferable to use those having a rutile type crystal shape and a granular shape.

  The titanium oxide fine particles are preferably surface-treated. Among these, it is preferable that the surface treatment is performed a plurality of times and the last surface treatment is a surface treatment using a reactive organosilicon compound among the plurality of surface treatments. Of the plurality of surface treatments, at least one surface treatment is a surface treatment selected from alumina treatment, silica treatment and zirconia treatment, and the last surface treatment uses a reactive organosilicon compound. What is surface treatment is more preferable.

  Alumina treatment, silica treatment, and zirconia treatment are treatments that deposit alumina, silica, or zirconia on the surface of untreated titanium oxide fine particles. Alumina, silica, and zirconia that are deposited on these surfaces are alumina and silica. And hydrated zirconia. The surface treatment using a reactive organosilicon compound means that the treatment liquid contains a reactive organosilicon compound.

  According to the titanium oxide fine particles subjected to a plurality of surface treatments as described above, the surface of the obtained titanium oxide fine particles is uniformly surface-coated, and by adding the titanium oxide fine particles to the intermediate layer, intermediate Good dispersibility of the titanium oxide fine particles in the layer is obtained, and the finally obtained photoreceptor can sufficiently suppress the occurrence of black spots.

  Preferable reactive organosilicon compounds used for the surface treatment include various alkoxysilanes such as methyltrimethoxysilane, n-butyltrimethoxysilane, n-hexylyltrimethoxysilane, dimethyldimethoxysilane, and methylhydrogenpolysiloxane. It is done.

  The intermediate layer as described above is prepared by, for example, preparing a coating solution for forming an intermediate layer by dissolving a binder resin in a known solvent, and coating the coating solution for forming an intermediate layer on the surface of the conductive support. And the coating film can be dried.

  The solvent used for forming the intermediate layer is not particularly limited. For example, n-butylamine, diethylamine, ethylenediamine, isopropanolamine, triethanolamine, triethylenediamine, N, N-dimethylformamide, acetone, methyl ethyl ketone, methyl isopropyl ketone, Cyclohexanone, benzene, toluene, xylene, chloroform, dichloromethane, 1,2-dichloroethane, 1,2-dichloropropane, 1,1,2-trichloroethane, 1,1,1-trichloroethane, trichloroethylene, tetrachloroethane, tetrahydrofuran, dioxolane, Use dioxane, methanol, ethanol, butanol, isopropanol, ethyl acetate, butyl acetate, dimethyl sulfoxide, methyl cellosolve, etc. It can, among these, toluene, tetrahydrofuran, dioxolane, etc. are preferably used. These solvents can be used alone or as a mixed solvent of two or more.

  Although it does not specifically limit as a coating method of the coating liquid for intermediate | middle layer formation, For example, the dip coating method, the spray coating method, etc. are mentioned.

  The layer thickness of the intermediate layer is preferably from 0.1 to 30 μm, and more preferably from 0.3 to 15 μm.

(Charge generation layer)
The charge generation layer constituting the photoconductor of the present invention contains a charge generation material (CGM) and, if necessary, contains a binder resin and other additives as a dispersion medium. You can also.

The charge generation layer constituting the photoreceptor of the present invention contains a phthalocyanine compound as a charge generation material, and in particular, a pigment containing at least 2,3-butanediol adduct titanyl phthalocyanine and unadded titanyl phthalocyanine as the phthalocyanine compound. (Hereinafter also referred to as “specific titanyl phthalocyanine mixed pigment”).
In the present invention, 2,3-butanediol adduct titanyl phthalocyanine refers to a compound obtained by adding 2,3-butanediol to unadded titanyl phthalocyanine.
The pigment containing 2,3-butanediol adduct titanyl phthalocyanine and unadded titanyl phthalocyanine is a mixture of at least unadded titanyl phthalocyanine and 2,3-butanediol adduct titanyl phthalocyanine in one pigment particle. It means a pigment contained in a state or mixed crystal state.
By containing a specific titanyl phthalocyanine mixed pigment as a charge generating substance, the desired sensitivity can be obtained in the resulting photoreceptor, and the humidity dependency of the sensitivity can be reduced. That is, for example, when it becomes clear on the next day when there was rainfall at night, the high humidity atmosphere of the previous night is maintained in the sealed portion of the photoconductor, for example, in the vicinity of the developing device. A sensitivity difference will be generated between the selected portion and the portion. When an intermediate density image is formed in a state where such a sensitivity difference has occurred, a belt-like image defect due to the sensitivity difference may occur in the image. This can be suppressed when a titanyl phthalocyanine mixed pigment is used.

  The 2,3-butanediol adduct titanyl phthalocyanine is used as a raw material (2R, 3R) -2,3-butanediol or (2S, 3S) -2,3-butanediol (hereinafter referred to as “raw butanediol compound”). Depending on the difference in the addition ratio), the 2,3-butanediol adduct titanyl phthalocyanine in the present invention may be of any crystal type, From the viewpoint of obtaining good sensitivity and repeated potential stability, it is preferable to use an 8.3 ° type which will be described in detail later.

Specifically, when the raw material butanediol compound is reacted in excess with unadded titanyl phthalocyanine, the Bragg angle 2θ: 9.5 in the X-ray diffraction spectrum as shown in FIG. A crystal type having a characteristic peak at ° (± 0.2 °) (hereinafter referred to as “9.5 ° type”) is obtained. In addition to 9.5 °, the 9.5 ° type 2,3-butanediol adduct titanyl phthalocyanine has an X-ray diffraction spectrum of 16.4 °, 19.1 °, 24.7 °, 26.5. A peak is seen at °. Note that the characteristic peak in the X-ray diffraction spectrum means a peak that is clearly different from the background variation.
The 9.5 ° type 2,3-butanediol adduct titanyl phthalocyanine does not have Ti = O absorption near 970 cm ⁻¹ in the IR spectrum, and O—Ti—O absorption appears near 630 cm ^−1. Analysis (TG) shows that there is an approximately 11% mass loss at 390-410 ° C. (possibly due to desorption of butylene oxide by thermal decomposition), and from the mass spectrum results, unadded titanyl phthalocyanine and raw material butane It is presumed that the diol compound has a structure dehydrated and condensed at 1/1.

When the raw butanediol compound is reacted in an amount of 1 mol or less with respect to 1 mol of unadded titanyl phthalocyanine, the Bragg angle 2θ: 8 in the X-ray diffraction spectrum as shown in FIG. A crystal type having a characteristic peak at 3 ° (± 0.2 °) (hereinafter referred to as “8.3 ° type”) is obtained. In the X-ray diffraction spectrum of the 8.3 ° -type 2,3-butanediol adduct titanyl phthalocyanine, peaks were observed at 24.7 °, 25.1 °, and 26.5 ° in addition to 8.3 °. It is done.
The 8.3 ° type 2,3-butanediol adduct titanyl phthalocyanine has an absorption of Ti = O near 970 cm ⁻¹ and an O—Ti—O absorption near 630 cm ⁻¹ in the IR spectrum. In the thermal analysis, mass loss at 390 to 410 ° C. is less than 11%, and from the result of mass spectrum, butanediol / titanyl phthalocyanine = 1/1 adduct and titanyl phthalocyanine form a mixed crystal at a certain ratio. Presumed to be. The addition ratio of the raw material butanediol compound is estimated to be 40 to 70 mol% from the mass reduction at 390 to 410 ° C. in the thermal analysis.

  As the phthalocyanine compound used as the charge generating substance, a phthalocyanine pigment other than the above-mentioned specific titanyl phthalocyanine mixed pigment can be used, and these can be used in combination. Moreover, a phthalocyanine compound and an azo pigment, a perylene pigment, an azulenium pigment, or the like can be used in combination. These can be used individually by 1 type or in combination of 2 or more types.

  When the charge generation layer is configured to contain a binder resin, a known resin can be used as the binder resin. For example, a formal resin, a butyral resin, a silicone resin, a silicone-modified butyral resin, a phenoxy resin, and the like can be used. It is preferable because the increase in residual potential due to repeated use in the obtained photoreceptor can be extremely suppressed.

  The mixing ratio of the binder resin and the charge generating material is preferably 20 to 600 parts by mass, and more preferably 50 to 500 parts by mass with respect to 100 parts by mass of the binder resin. When the mixing ratio of the binder resin and the charge generating material is in the above range, high dispersion stability is obtained in the coating solution for forming the charge generating layer, which will be described later, and the electric resistance is suppressed low in the formed photoreceptor. Thus, an increase in residual potential due to repeated use can be extremely suppressed.

(Method for forming charge generation layer)
The charge generation layer constituting the photoconductor of the present invention is prepared by adding and dispersing a charge generation material in a solvent to prepare a coating solution for forming a charge generation layer, and applying this coating solution for forming a charge generation layer on the surface of the intermediate layer. It can form by apply | coating and forming a coating film and drying this coating film. When the charge generation layer is configured to contain a binder resin, the charge generation layer forming coating solution may be configured as a solution in which the binder resin is dissolved in a solvent.

  Examples of the solvent used for forming the charge generation layer include ketone solvents such as methyl ethyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, cyclohexanone, and acetophenone, ether solvents such as tetrahydrofuran, dioxolane, and diglyme, methyl cellosolve, and ethyl cell. Examples include alcohol solvents such as sorb and butanol, ester solvents such as ethyl acetate and t-butyl acetate, aromatic solvents such as toluene and chlorobenzene, and halogen solvents such as dichloroethane and trichloroethane. It is not limited to. These may be used alone or in combination of two or more. In the case where the charge generation layer is configured to contain a binder resin, a solvent capable of dissolving the binder resin may be used as a solvent.

As a means for dispersing the charge generating material, it is preferable to use a method that has a low share at the time of dispersion. Specifically, an ultrasonic dispersion method or a medium with a small specific gravity (such as glass (specific gravity 2.5) beads). It is preferable to use a media dispersion method using.
The media dispersion method is a method in which beads are filled as a medium in a container, and an agitation disk attached perpendicularly to a rotation axis is rotated at a high speed to crush and disperse aggregated particles.

  By adopting a dispersion method having a low share as described above, a state in which the secondary agglomerated particles and coarse particles are sufficiently crushed can be obtained, while the specific titanyl phthalocyanine mixed pigment constituting the charge generation material can be obtained. Thus, it is possible to prepare a coating solution for forming a charge generation layer, in which the crystal structure is prevented from changing and the characteristics thereof are impaired, and therefore, the formed photoreceptor can have good sensitivity and repeated potential stability.

  Examples of the method for applying the charge generation layer forming coating solution include the same methods as those described as the method for applying the intermediate layer forming coating solution.

  The thickness of the charge generation layer varies depending on the characteristics of the charge generation material, the characteristics of the binder resin, the mixing ratio, and the like, but is preferably 0.1 to 2 μm, more preferably 0.15 to 1.5 μm.

(Charge transport layer)
The charge transport layer constituting the photoconductor contains a charge transport material (CTM) in the binder resin. Further, in the photoconductor of this example, the charge transport layer is represented by the above general formula (1). Specific pyrazolone pigments.

According to the photoreceptor in which the specific pyrazolone dye is contained in the charge transport layer, it is possible to obtain a halftone image having excellent resistance to light fatigue and suppressing density unevenness due to light fatigue and repeated use. Excellent potential stability is sometimes obtained.
This is presumed to be due to the following reason. That is, when a phthalocyanine compound is used as the charge generation material, the phthalocyanine compound is likely to be light-fatigue, and particularly has a characteristic that is remarkably easy to light-fatigue with respect to light having a wavelength range of 400 nm to 500 nm. Will occur. However, since the specific pyrazolone dye is contained in the charge transport layer that is located on the surface side of the charge generation layer, the specific pyrazolone dye efficiently emits light in the wavelength range of 400 nm to 500 nm. As a result, it is possible to prevent the charge generation layer from being irradiated with light having a wavelength range of 400 nm to 500 nm. Occurrence can be suppressed. In addition, the specific pyrazolone dye is considered to be excellent in potential stability during repeated use because it is less likely to become a charge trap site in the added layer, in this example, the charge transport layer. The reason why a specific pyrazolone dye is difficult to become a charge trap site is unknown, but the HOMO energy level of the charge transport material and the specific pyrazolone dye is relatively close, and the HOMO orbit of the specific pyrazolone dye is This is probably due to the distribution suitable for charge transport.
In particular, when a specific titanyl phthalocyanine mixed pigment is used as a charge generation material, the specific titanyl phthalocyanine mixed pigment has a characteristic that it easily undergoes light fatigue. can do.

In the above general formula (1) showing a specific pyrazolone pigment, n is 1 or 2.
R ¹ represents an alkyl group that may have a substituent, a monovalent aromatic group that may have a substituent, or a heterocyclic group that may have a substituent, and n = 1. Sometimes, two R ^{1 s} may be the same or different from each other, and may be bonded to each other to form a ring structure. R ¹ is preferably a phenyl group which may have a substituent or an alkyl group having 1 to 5 carbon atoms which may have a substituent.
R ² represents a monovalent alkyl group which may have a substituent or an aromatic group which may have a substituent, and has a phenyl group or a substituent which may have a substituent. It is preferably an alkyl group having 1 to 3 carbon atoms.
R ³ represents an alkyl group that may have a substituent, a monovalent aromatic group that may have a substituent, or a heterocyclic group that may have a substituent. It is preferably a C1-C3 alkyl group that may have a phenyl group or a substituent.
Ar represents a divalent aromatic group which may have a substituent, and is preferably a phenylene group.

  The specific pyrazolone dye represented by the general formula (1) can be synthesized by dehydration condensation of an aldehyde compound and a pyrazolone compound according to the scheme represented by the following reaction formula (1).

[In Reaction Formula (1), n is 1 or 2, and R ¹ has an alkyl group that may have a substituent, a monovalent aromatic group that may have a substituent, or a substituent. And when n = 1, two R ^{1 s} may be the same or different from each other, and may be bonded to each other to form a ring structure. . R ² represents an alkyl group which may have a substituent or a monovalent aromatic group which may have a substituent, and R ³ represents an alkyl group which may have a substituent or a substituent. The monovalent aromatic group which may have or the heterocyclic group which may have a substituent is represented. Ar represents a divalent aromatic group which may have a substituent. ]

  As specific examples of the specific pyrazolone dyes, compounds represented by the following formulas (1) to (35) (pyrazolone dyes (1) to (35)) can be used.

The content ratio of the specific pyrazolone-based pigment is not limited as long as it contains an amount that allows the transmittance of incident light in the wavelength range of 450 nm to 500 nm to be, for example, 50% or less. It is preferable that it is 0.1-10 mass parts with respect to 100 mass parts of binder resin in, More preferably, it is 0.5-5 mass parts.
When the content ratio of the specific pyrazolone pigment in the charge transport layer with respect to 100 parts by mass of the binder resin is 0.1 parts by mass or more, the charge generation layer absorbs light in a wavelength region of 450 nm to 500 nm and the 450 nm to 500 nm. The effect which suppresses that the light of this wavelength range is irradiated can be acquired. When the content ratio of the specific pyrazolone dye in the charge transport layer with respect to 100 parts by mass of the binder resin is 10 parts by mass or less, sufficient carrier mobility can be obtained in the charge transport layer.

  The charge transport material is a material that transports charges (holes). As the charge transport material, a material different from the specific pyrazolone dye represented by the general formula (1) is used. For example, a triphenylamine derivative, a hydrazone compound, a styryl compound, a benzidine compound, a butadiene compound, or the like may be used. Among these, it is preferable to use a compound having a triarylamine structure.

  As the binder resin for forming the charge transport layer, any of thermoplastic resin and thermosetting resin may be used. Specifically, for example, polyester resin, polystyrene resin, acrylic resin, vinyl chloride resin, vinyl acetate. Examples thereof include resins, polyvinyl butyral resins, epoxy resins, polyurethane resins, phenol resins, alkyd resins, polycarbonate resins, silicone resins, melamine resins, and polyarylate resins. Among these, it is preferable to use a polycarbonate resin because the water absorption is low and the charge transport material can be dispersed with high dispersibility.

  The charge transport layer may contain other components such as an antioxidant, if necessary.

The mixing ratio of the charge transport material to the binder resin is preferably 10 to 200 parts by mass, more preferably 20 to 100 parts by mass with respect to 100 parts by mass of the binder resin.
When the mixing ratio of the charge transport material is too small, sufficient charge transportability cannot be obtained, and there is a possibility that charges generated in the charge generation layer cannot be sufficiently transported to the surface of the photoreceptor. On the other hand, when the mixing ratio of the charge transport material is excessive, a decrease in mechanical strength and an increase in residual potential due to repeated use tend to be remarkable.

  The layer thickness of the charge transport layer varies depending on the characteristics of the charge transport material, the characteristics of the binder resin, the mixing ratio, and the like, but is preferably 10 to 40 μm, for example.

The charge transport layer as described above is prepared, for example, by adding and dispersing a charge transport material (CTM) and a specific pyrazolone dye in a binder resin dissolved in a known solvent to prepare a coating solution for forming a charge transport layer. Then, the charge transport layer forming coating solution can be applied to the surface of the charge generation layer to form a coating film, and the coating film can be dried.
Examples of the solvent used for forming the charge transport layer include the same solvents as those used for forming the charge generation layer.
In addition, as the method for applying the charge transport layer forming coating solution, the same method as the method for applying the charge generating layer forming coating solution can be used.

(Protective layer)
The electrophotographic photoreceptor of the present invention may further have a protective layer on the photosensitive layer. The protective layer plays a role of protecting the photoreceptor from the external environment and impact. When a protective layer is formed, the protective layer is preferably composed of inorganic particles and a binder resin, and may contain other components such as an antioxidant and a lubricant as necessary.

(Inorganic particles)
Inorganic particles contained in the protective layer include silica, alumina, strontium titanate, zinc oxide, titanium oxide, magnesium oxide, lead oxide, niobium oxide, molybdenum oxide, vanadium oxide, tin oxide, antimony oxide, indium oxide, bismuth oxide. Particles such as indium oxide doped with tin, tin oxide doped with antimony or tantalum, and zirconium oxide can be preferably used. In particular, it is preferable to use fine particles such as hydrophobic silica, hydrophobic alumina, hydrophobic zirconia, and fine powder sintered silica having a hydrophobic surface.

  The size of the inorganic particles is not particularly limited, but the number average primary particle size is preferably 1 to 300 nm, and particularly preferably 5 to 100 nm.

  Here, the number average primary particle diameter of the inorganic particles is magnified 10,000 times with a transmission electron microscope, 300 particles are randomly observed as primary particles, and measured as the number average diameter of the horizontal ferret diameter by image analysis. The value is obtained by calculating the value.

(Inorganic particles surface-treated with a treatment agent having a radical polymerizable functional group)
These inorganic particles are preferably surface-treated with a treatment agent having a radical polymerizable functional group, particularly a surface treatment agent having an acryloyl group or a methacryloyl group.

  Examples of the surface treatment agent having the acryloyl group or methacryloyl group include the compounds described below.

_{S-1: CH 2 = CHSi} (CH 3) (OCH 3) 2
_{S-2: CH 2 = CHSi} (OCH 3) 3
S-3: CH ₂ = CHSiCl _{3
S-4: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) (OCH 3) 2
_{S-5: CH 2 = CHCOO} (CH 2) 2 Si (OCH 3) 3
_{S-6: CH 2 = CHCOO} (CH 2) 2 Si (OC 2 H 5) (OCH 3) 2
_{S-7: CH 2 = CHCOO} (CH 2) 3 Si (OCH 3) 3
_{S-8: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) Cl 2
_{S-9: CH 2 = CHCOO} (CH 2) 2 SiCl 3
_{S-10: CH 2 = CHCOO} (CH 2) 3 Si (CH 3) Cl 2
S-11: CH ₂ = CHCOO (CH ₂ ) ₃ SiCl _{3
S-12: CH 2 = C} (CH 3) COO (CH 2) 2 Si (CH 3) (OCH 3) 2
_{S-13: CH 2 = C} (CH 3) COO (CH 2) 2 Si (OCH 3) 3
_{S-14: CH 2 = C} (CH 3) COO (CH 2) 3 Si (CH 3) (OCH 3) 2
_{S-15: CH 2 = C} (CH 3) COO (CH 2) 3 Si (OCH 3) 3
_{S-16: CH 2 = C} (CH 3) COO (CH 2) 2 Si (CH 3) Cl 2
_{S-17: CH 2 = C} (CH 3) COO (CH 2) 2 SiCl 3
_{S-18: CH 2 = C} (CH 3) COO (CH 2) 3 Si (CH 3) Cl 2
_{S-19: CH 2 = C} (CH 3) COO (CH 2) 3 SiCl 3
_{S-20: CH 2 = CHSi} (C 2 H 5) (OCH 3) 2
_{S-21: CH 2 = C} (CH 3) Si (OCH 3) 3
_{S-22: CH 2 = C} (CH 3) Si (OC 2 H 5) 3
_{S-23: CH 2 = CHSi} (OCH 3) 3
_{S-24: CH 2 = C} (CH 3) Si (CH 3) (OCH 3) 2
_{S-25: CH 2 = CHSi} (CH 3) Cl 2
_{S-26: CH 2 = CHCOOSi} (OCH 3) 3
_{S-27: CH 2 = CHCOOSi} (OC 2 H 5) 3
_{S-28: CH 2 = C} (CH 3) COOSi (OCH 3) 3
_{S-29: CH 2 = C} (CH 3) COOSi (OC 2 H 5) 3
_{S-30: CH 2 = C} (CH 3) COO (CH 2) 3 Si (OC 2 H 5) 3
_{S-31: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) 2 (OCH 3)
_{S-32: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) (OCOCH 3) 2
_{S-33: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) (ONHCH 3) 2
_{S-34: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) (OC 6 H 5) 2
_{S-35: CH 2 = CHCOO} (CH 2) 2 Si (C 10 H 21) (OCH 3) 2
_{S-36: CH 2 = CHCOO} (CH 2) 2 Si (CH 2 C 6 H 5) (OCH 3) 2

  As the surface treatment agent, a silane compound having a reactive organic group capable of radical polymerization may be used other than S-1 to S-36. These surface treatment agents can be used alone or in admixture of two or more.

  The amount of the surface treatment agent to be treated with the inorganic particles is not particularly limited, but it is preferable to use 0.1 to 200 parts by mass of the surface treatment agent with respect to 100 parts by mass of the inorganic particles before the treatment.

(Surface treatment method using a treatment agent having a radical polymerizable functional group)
Hereinafter, a method for producing inorganic particles surface-treated with a treating agent having a radical polymerizable functional group will be described by taking tin oxide particles as an example.

  Tin oxide particles surface-treated with a radically polymerizable treating agent can be obtained by subjecting tin oxide particles to a surface treatment using a silane compound having the radical polymerizable functional group (the above exemplified compound) or the like. I can do it. When this surface treatment is performed, a wet media dispersion type apparatus is used by using 0.1 to 200 parts by weight of a silane compound as a surface treatment agent and 50 to 5000 parts by weight of a solvent with respect to 100 parts by weight of tin oxide particles before the treatment. It is preferable to use and process.

  Hereinafter, a surface treatment method for producing tin oxide particles surface-treated with a silane compound having a radically polymerizable functional group that is uniform and more finely described will be described.

  That is, a slurry (solid particle suspension) containing tin oxide particles and a surface treatment agent of a silane compound having a radical polymerizable functional group is wet-pulverized to refine the tin oxide particles and simultaneously Surface treatment proceeds. Thereafter, since the solvent is removed to form powder, tin oxide particles that are surface-treated with a uniform and finer silane compound can be obtained.

  Wet media dispersion type equipment, which is the surface treatment equipment used, is to crush the agglomerated particles of inorganic particles by filling beads in the container as media and rotating the stirring disk mounted perpendicular to the rotation axis at high speed. This is an apparatus having a step of pulverizing and dispersing, and as a constitution thereof, there is no problem as long as the inorganic particles are sufficiently dispersed and subjected to surface treatment when the surface treatment is performed on the inorganic particles. Various types such as horizontal type, continuous type and batch type can be adopted. Specifically, a sand mill, ultra visco mill, pearl mill, glen mill, dyno mill, agitator mill, dynamic mill and the like can be used. These dispersive devices are pulverized and dispersed by impact crushing, friction, cutting, shear stress, etc., using a grinding medium such as balls and beads.

  As the beads used in the wet media dispersion type apparatus, a ball made of glass, alumina, zircon, zirconia, steel, flint stone or the like can be used, but it is particularly preferable to use a product made of zirconia or zircon. . Further, as the size of the beads, those having a diameter of about 1 to 2 mm are usually used, but in the present invention, those having a diameter of about 0.1 to 1.0 mm are preferably used.

  Various materials such as stainless steel, nylon and ceramic can be used for the disk and container inner wall used in the wet media dispersion type apparatus. In the present invention, the disk and container inner wall made of ceramic such as zirconia or silicon carbide are particularly used. Is preferred.

  By the wet treatment as described above, tin oxide particles surface-treated with the surface treatment agent can be obtained.

  As described above, tin oxide particles have been described. Since inorganic particles such as alumina, zinc oxide, titanium oxide, and silica also have hydroxyl groups on the surface in the same manner as tin oxide, the surface is treated with a surface treatment agent in the same manner as tin oxide. Treated particles can be obtained.

(Binder resin for protective layer)
The binder resin used for the protective layer may be a thermoplastic resin or a thermosetting resin. For example, polyvinyl butyral resin, epoxy resin, polyurethane resin, phenol resin, polyester resin, alkyd resin, polycarbonate resin, silicone resin, melamine resin and the like can be mentioned. A component obtained by curing a curable compound is also preferable. These binder resins can also be used in combination.

(Curable compound)
Examples of the curable compound that can be used in the protective layer include a radical polymerizable compound. As the radical polymerizable compound, a polymerizable monomer having at least one of an acryloyl group and a methacryloyl group as a radical polymerizable reactive group. Is preferred. Here, the number of reactive groups (functional groups) possessed by the radical polymerizable compound is not particularly limited, but from the viewpoint of film strength, the protective layer is coated with a coating liquid containing a trifunctional or higher functional radical polymerizable compound. It is preferably formed by curing.

  Examples of these polymerizable monomers include the following compounds.

However, in the chemical formulas showing the exemplary compounds M1 to M15, R represents an acryloyl group (CH ₂ ═CHCO—), and R ′ represents a methacryloyl group (CH ₂ ═CCH ₃ CO—).

  The above radical polymerizable compounds are known and can be obtained as commercial products.

  In addition to these, the protective layer containing the curable compound may contain a polymerization initiator, lubricant particles, and the like as necessary.

(Polymerization initiator)
As a method for curing reaction of a curable compound that can be used in the protective layer, the curing reaction can be performed by a method using an electron beam cleavage reaction or a method using light or heat in the presence of a radical polymerization initiator. . When the curing reaction is performed using a radical polymerization initiator, any of a photopolymerization initiator and a thermal polymerization initiator can be used as the polymerization initiator. Further, both light and heat initiators can be used in combination.

  As polymerization initiators, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylazobisvaleronyl), 2,2′-azobis (2-methylbutyronitrile) ), Benzoyl peroxide (BPO), di-tert-butyl hydroperoxide, tert-butyl hydroperoxide, chlorobenzoyl peroxide, dichlorobenzoyl peroxide, bromomethylbenzoyl peroxide, lauroyl peroxide And thermal polymerization initiators such as products.

  Examples of the photopolymerization initiator include diethoxyacetophenone, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone-1 (Irgacure 369: manufactured by BASF Japan Ltd.), 2-hydroxy-2-methyl -1-phenylpropan-1-one, 2-methyl-2-morpholino (4-methylthiophenyl) propan-1-one, 1-phenyl-1,2-propanedione-2- (o-ethoxycarbonyl) oxime, etc. Acetophenone or ketal photoinitiators, benzoin, benzoin methyl ether, Benzoin ether photopolymerization initiators such as zoin ethyl ether, benzoin isobutyl ether, benzoin isopropyl ether, benzophenone, 4-hydroxybenzophenone, methyl o-benzoylbenzoate, 2-benzoylnaphthalene, 4-benzoylbiphenyl, 4-benzoylphenyl Benzophenone photopolymerization initiators such as ether, acrylated benzophenone, 1,4-benzoylbenzene, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichloro Examples thereof include thioxanthone photopolymerization initiators such as thioxanthone.

  Other photopolymerization initiators include ethyl anthraquinone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide, bis (2,4,6-trimethylbenzoyl) phenylphosphine Oxide (Irgacure 819: manufactured by BASF Japan), bis (2,4-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, methylphenylglyoxyester, 9,10-phenanthrene, acridine compound, triazine And imidazole compounds. Moreover, what has a photopolymerization acceleration effect can also be used individually or in combination with the said photoinitiator. Examples include triethanolamine, methyldiethanolamine, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, ethyl (2-dimethylamino) benzoate, 4,4'-dimethylaminobenzophenone, and the like.

  The polymerization initiator used in the present invention is preferably a photopolymerization initiator, preferably an alkylphenone compound or a phosphine oxide compound, more preferably an initiator having an α-hydroxyacetophenone structure or an acylphosphine oxide structure. preferable.

  These polymerization initiators may be used alone or in combination of two or more. Content of a polymerization initiator is 0.1-40 mass parts with respect to 100 mass parts of polymeric compounds, Preferably it is 0.5-20 mass parts.

(Lubricant particles)
It is also possible to contain various lubricant particles in the protective layer. For example, fluorine atom-containing resin particles can be added. Examples of the fluorine atom-containing resin particles include tetrafluoroethylene resin, trifluorinated ethylene chloride resin, hexafluoroethylene chloride propylene resin, vinyl fluoride resin, vinylidene fluoride resin, ethylene difluoride dichloride resin, and these One or two or more types are preferably selected from the copolymers, but tetrafluoroethylene resin and vinylidene fluoride resin are particularly preferable.

(solvent)
Solvents used for forming the protective layer include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-2-propanol, benzyl alcohol, methyl isopropyl ketone, and methyl isobutyl ketone. , Methyl ethyl ketone, cyclohexane, toluene, xylene, methylene chloride, ethyl acetate, butyl acetate, 2-methoxyethanol, 2-ethoxyethanol, tetrahydrofuran, 1-dioxane, 1,3-dioxolane, pyridine and diethylamine. It is not limited to. The said solvent may be used individually by 1 type, or may be used with the form of a 2 or more types of mixture.

(Formation of protective layer containing curable compound)
The protective layer is prepared by adding a radical polymerizable curable compound, surface-treated inorganic particles or inorganic particles having a reactive group, and if necessary, known resins, polymerization initiators, lubricant particles, antioxidants, etc. The coating solution thus prepared can be applied to the surface of the photosensitive layer by a known method, subjected to natural drying or heat drying, and then subjected to a curing treatment.
The thickness of the protective layer is preferably 0.2 to 15 μm, and more preferably 0.5 to 10 μm.

  In the present invention, the protective layer is cured by irradiating the coating film with active rays to generate radicals and polymerize, and then cure by forming a cross-linking bond between the molecules and within the molecule by a cross-linking reaction. It is preferable to produce. The active ray is preferably light such as ultraviolet light or visible light, or an electron beam, and ultraviolet light is particularly preferred from the standpoint of ease of use.

As the ultraviolet light source, any light source that generates ultraviolet light can be used without limitation. For example, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, a flash (pulse) xenon, an ultraviolet LED, or the like can be used. Irradiation conditions vary depending on each lamp, but the irradiation amount of active rays is usually 1 to 20 mJ / cm ² , preferably 5 to 15 mJ / cm ² . The output voltage of the light source is preferably 0.1 to 5 kW, and particularly preferably 0.5 to 3 kW.

  As an electron beam source, there is no particular limitation on the electron beam irradiation apparatus, and generally, an electron beam accelerator for electron beam irradiation is a curtain beam type that is relatively inexpensive and can provide a large output. Used. The acceleration voltage during electron beam irradiation is preferably 100 to 300 kV. The absorbed dose is preferably 0.005 Gy to 100 kGy (0.5 to 10 Mrad).

  The irradiation time of the active ray is a time for obtaining the necessary irradiation amount of the active ray, specifically, preferably 0.1 second to 10 minutes, and more preferably 1 second to 5 minutes from the viewpoint of curing efficiency or work efficiency. It is said.

  According to the photoreceptor as described above, it is possible to obtain a halftone image having excellent resistance to light fatigue and suppressing density unevenness due to light fatigue, and excellent potential stability even during repeated use. It is done.

[Image forming apparatus]
FIG. 3 is an explanatory sectional view showing an example of the configuration of an image forming apparatus on which the electrophotographic photosensitive member of the present invention is mounted.
This image forming apparatus is called a tandem type color image forming apparatus. Each of the image forming units 10Y, 10M, 10C, and 10Bk that forms yellow, magenta, cyan, or black toner images, and these image forming units. Image formation comprising an intermediate transfer unit 7 for transferring toner images of respective colors formed on 10Y, 10M, 10C, and 10Bk onto the image support P, and fixing means 24 for fixing the toner image to the image support P An apparatus main body A is provided, and an original image reading apparatus SC for optically scanning an original and reading image information as digital data (original image data) is disposed above the image forming apparatus main body A.

The image forming unit 10Y will be described in detail below.
Each of the image forming units 10M, 10C, and 10Bk forms a toner image with magenta toner, cyan toner, and black toner instead of yellow toner, and basically has the same configuration as the image forming unit 10Y. Is.

  The image forming unit 10Y is exposed around a drum-shaped photoreceptor 1Y that is an image forming body, a charging unit 2Y that applies a uniform potential to the surface of the photoreceptor 1Y, and a uniformly charged photoreceptor 1Y. Exposure unit 3Y that performs exposure based on the image data signal (yellow) for image formation and forms an electrostatic latent image corresponding to the yellow image, and conveys color toner onto the photoreceptor 1Y to visualize the electrostatic latent image The developing means 4Y for cleaning and the cleaning means 6Y for collecting the residual toner remaining on the photoreceptor 1Y after the primary transfer are arranged to form a yellow (Y) toner image on the photoreceptor 1Y.

  As the charging means 2Y, a corona discharge type charger is used.

  As the exposure unit 3Y, a light emitting device using a light emitting diode as an exposure light source, for example, an LED unit in which light emitting elements made of light emitting diodes are arranged in an array in the axial direction of the photoreceptor 1Y and an imaging element Alternatively, the image forming apparatus shown in FIG. 3 uses a laser irradiation apparatus, such as a laser optical system laser irradiation apparatus using a semiconductor laser as an exposure light source.

  The exposure means 3Y is preferably composed of an apparatus using a semiconductor laser or light emitting diode having an oscillation wavelength of 350 to 850 nm as an exposure light source. By using such an exposure light source with an exposure dot diameter of 10 to 100 μm narrowed down in the writing direction, and performing digital exposure on the photoreceptor 1Y, a high-resolution electrophotographic image of 600 to 2400 dpi or more is provided. Can be obtained.

The exposure method in the exposure means 3Y may be a scanning optical system using a semiconductor laser or a solid type using an LED. Regarding the light intensity distribution, there are a Gaussian distribution, a Lorentz distribution, and the like, but an area of 1 / e ² or more of each peak intensity may be set as the exposure dot diameter.

  In the image forming apparatus of this example, the photosensitive member 1Y, the charging unit 2Y, the developing unit 4Y, and the cleaning unit 6Y in the image forming unit 10Y are provided as an integrated process cartridge.

  The image forming apparatus as described above is configured by integrally combining a photosensitive member in one image forming unit and components such as a developing unit and a cleaning unit as a process cartridge, and this process cartridge is attached to the main body of the image forming apparatus. On the other hand, it may be configured to be detachable. In addition, a process cartridge is formed by integrally supporting at least one of a charging unit, an exposure unit, a developing unit, a transfer unit or a separation unit (not shown), and a cleaning unit in one image forming unit together with a photosensitive member. It may be configured to be detachable from the main body of the image forming apparatus using a guide means.

  The intermediate transfer unit 7 is formed by an endless belt-like intermediate transfer body 70 that is stretched by a plurality of support rollers 71 to 74 and supported so as to be circulated, and image forming units 10Y, 10M, 10C, and 10Bk, respectively. The primary transfer rollers 5Y, 5M, 5C, and 5Bk for transferring the toner image to the intermediate transfer member 70, and the toner image transferred onto the intermediate transfer member 70 by the primary transfer rollers 5Y, 5M, 5C, and 5Bk are image supports. A secondary transfer roller 5b for transferring onto P and a cleaning means 6b for collecting residual toner remaining on the intermediate transfer member 70 are provided.

  The primary transfer roller 5Bk in the intermediate transfer unit 7 is always in contact with the photoconductor 1Bk during the image forming process, and the other primary transfer rollers 5Y, 5M, and 5C are each only when forming a color image. It contacts the corresponding photoreceptors 1Y, 1M, 1C.

  Further, the secondary transfer roller 5b is brought into contact with the intermediate transfer body 70 only when the image support P passes through the secondary transfer roller 5b and the secondary transfer is performed.

  In this image forming apparatus, each of the process cartridges in the image forming units 10Y, 10M, 10C, and 10Bk and other than the secondary transfer roller 5b of the intermediate transfer unit 7 are housed in a housing 8, and the housing 8 is configured to be drawable from the image forming apparatus main body A through the support rails 82L and 82R.

  In the image forming apparatus of the present invention, the photoconductors 1Y, 1M, 1C, and 1Bk of the image forming units 10Y, 10M, 10C, and 10Bk are the photoconductors of the present invention containing the specific pyrazolone dye. It is characterized by. In the image forming apparatus of the present invention, among the image forming units 10Y, 10M, 10C, and 10Bk of all the image forming units 10Y, 1M, 1C, and 1Bk, all of the photoconductors 1Y, 1M, 1C, and 1Bk are described above. However, if at least one of the photoconductors 1Y, 1M, 1C, and 1Bk is composed of the photoconductor of the present invention, it is excellent in resistance to light fatigue and light. A halftone image in which the occurrence of density unevenness due to fatigue is suppressed can be obtained, and an effect of obtaining excellent potential stability even during repeated use can be obtained.

  The image forming apparatus of the present invention is generally applicable to electrophotographic apparatuses such as electrophotographic copying machines, laser printers, LED printers, and liquid crystal shutter printers, and further, displays, recordings, light printing, plate making and the like using electrophotographic technology. It can be widely applied to devices such as facsimiles.

  In the image forming apparatus as described above, the surfaces of the photoreceptors 1Y, 1M, 1C, and 1Bk are charged by the charging units 2Y, 2M, 2C, and 2Bk, and the exposure units 3Y, 3M, 3C, and 3Bk are charged with the original image reading device SC. The laser beam is operated according to the exposure image data signal of each color obtained by performing various kinds of image processing on the original image data obtained by the above, specifically, the laser light modulated in accordance with the exposure image data signal. Is output from the exposure light source, and the photoconductors 1Y, 1M, 1C, and 1Bk are scanned and exposed by the laser light, so that yellow, magenta, cyan, and black corresponding to the original read by the original image reading device SC are obtained. An electrostatic latent image corresponding to each color is formed on each photoconductor 1Y, 1M, 1C, 1Bk.

Next, the electrostatic latent images formed on the photoreceptors 1Y, 1M, 1C, and 1Bk are developed with the toners of the respective colors in the developing units 4Y, 4M, 4C, and 4Bk, thereby forming toner images of the respective colors. The toner images of the respective colors are sequentially transferred onto the intermediate transfer body 70 by the transfer rollers 5Y, 5M, 5C, and 5Bk, and are superimposed and combined to form a color toner image.
Further, in synchronism with the formation of the color toner image, the image support P such as plain paper or transparent sheet accommodated in the paper feed cassette 20 is fed by the paper feed means 21 and a plurality of intermediate rollers 22A, 22B. , 22C, 22D and the registration roller 23, the color toner images conveyed to the secondary transfer roller 5b and transferred onto the intermediate transfer body 70 by the secondary transfer roller 5b on the image support P in a lump. Transcribed.
The color toner image transferred onto the image support P is fixed by, for example, heating and pressurization in the fixing unit 24 to form a visible image, and then the image support P on which the visible image has been formed is discharged to the discharge roller. 25 is discharged out of the apparatus and placed on the discharge tray 26.

The photoreceptors 1Y, 1M, 1C, and 1Bk after the toner images of the respective colors are transferred to the intermediate transfer member 70 remain on the photoreceptors 1Y, 1M, 1C, and 1Bk by the cleaning units 6Y, 6M, 6C, and 6Bk, respectively. After the toner is removed, it is used to form toner images of the following colors.
On the other hand, the intermediate transfer member 70 after the color toner image is transferred onto the image support P by the secondary transfer roller 5b and the curvature of the image support P is separated is left on the intermediate transfer member 70 by the cleaning means 6b. After the removed toner is removed, it is used for intermediate transfer of the next toner image.

[Toner and developer]
The toner used in the image forming apparatus of the present invention may be a pulverized toner or a polymerized toner, but the image forming apparatus of the present invention is produced by a polymerization method from the viewpoint of obtaining a high quality image. It is preferable to use the polymerized toner.

  A polymerized toner is obtained by generating a binder resin for forming a toner and forming a toner particle shape by performing polymerization of raw material monomers to obtain a binder resin and, if necessary, subsequent chemical treatment in parallel. Means toner.

  More specifically, it means a toner formed through a step of obtaining resin fine particles by a polymerization reaction such as suspension polymerization or emulsion polymerization, and a step of fusing the resin fine particles performed thereafter if necessary.

  The volume average particle diameter of the toner, that is, the 50% volume particle diameter (Dv50) is preferably 2 to 9 μm, more preferably 3 to 7 μm. By setting this range, the resolution can be increased. In addition, by combining with the above range, the amount of toner having a fine particle diameter can be reduced while being a small particle diameter toner, the dot image reproducibility is improved over a long period of time, and the sharpness is excellent. In addition, a stable image can be formed.

  The toner according to the present invention may be used alone as a one-component developer, or may be mixed with a carrier and used as a two-component developer.

  When used as a one-component developer, a non-magnetic one-component developer or a magnetic one-component developer containing about 0.1 to 0.5 μm of magnetic particles in the toner can be used. be able to.

  In addition, when used as a two-component developer by mixing with a carrier, conventionally known magnetic particles of the carrier, such as metals such as iron, ferrite, and magnetite, alloys of these metals with metals such as aluminum and lead, etc. Material can be used. Ferrite particles are particularly preferable. The magnetic particles preferably have a volume average particle size of 15 to 100 μm, more preferably 25 to 80 μm.

  The volume average particle diameter of the carrier can be typically measured by a laser diffraction particle size distribution measuring apparatus “HELOS” (manufactured by SYMPATEC) equipped with a wet disperser.

  The carrier is preferably a carrier in which magnetic particles are further coated with a resin, or a so-called resin dispersion type carrier in which magnetic particles are dispersed in a resin. The resin composition for coating is not particularly limited, and for example, olefin resin, styrene resin, styrene acrylic resin, silicone resin, ester resin, or fluorine-containing polymer resin is used. The resin for constituting the resin-dispersed carrier is not particularly limited, and known resins can be used. For example, styrene acrylic resin, polyester resin, fluorine resin, phenol resin, etc. can be used. it can.

  According to the above image forming apparatus, by having the above photoreceptor, it is possible to obtain a halftone image having excellent resistance to light fatigue and suppressing the occurrence of density unevenness due to light fatigue, and at the time of repeated use. Excellent potential stability can be obtained.

As mentioned above, although embodiment of this invention was described concretely, embodiment of this invention is not limited to said example, A various change can be added.
For example, the structure is not limited to a structure in which a specific pyrazolone dye is contained in the charge transport layer, and the composition is contained in the protective layer or other layers as long as the layer is located on the surface side of the charge generation layer. You may have.
When the specific pyrazolone pigment is contained in the protective layer, the content ratio of the specific pyrazolone pigment is 0.5 to 20 parts by mass with respect to 100 parts by mass of the binder resin forming the protective layer. Is more preferable, and 1 to 10 parts by mass is more preferable.

  Hereinafter, specific examples of the present invention will be described, but the present invention is not limited thereto.

Example 1: Photoconductor Preparation Example 1
(1) Formation of intermediate layer-Polyamide resin "CM8000 (manufactured by Toray Industries, Inc.)" 10 parts by mass-Titanium oxide (number average primary particle size 35 nm, primary surface treatment; silica / alumina treatment,
Secondary surface treatment; methyl hydrogen polysiloxane treatment) An intermediate layer coating solution is prepared by dispersing a composition comprising 30 parts by mass, 90 parts by mass of methanol, and 5 parts by mass of ethanol using a circulating wet disperser. did.
This intermediate layer coating solution [1] is applied on the outer peripheral surface of a conductive support [1] made of a drum-shaped aluminum support by a dip coating method, and dried to form a coating on the conductive support [1]. An intermediate layer [1] having a dry film thickness of 1.8 μm was formed.

(2) Formation of charge generation layer (2-1) Synthesis of amorphous titanyl phthalocyanine 29.2 g of 1,3-diiminoisoindoline was dispersed in 200 ml of orthodichlorobenzene (ODB), and titanium tetra-n-butoxide 20. 4g was added and it heated at 150-160 degreeC for 5 hours in nitrogen atmosphere. After standing to cool, the precipitated crystals were filtered, washed with chloroform, washed with 2% aqueous hydrochloric acid, washed with water, washed with methanol in order, and dried to obtain 26.2 g (yield 91%) of crude titanyl phthalocyanine. Obtained.
Next, this crude titanyl phthalocyanine is added to 250 ml of concentrated sulfuric acid, dissolved by stirring at 5 ° C. or lower for 1 hour, poured into 5 L of water at 20 ° C., and the precipitated crystals are filtered and washed thoroughly with water. 225 g of wet paste product was obtained, frozen in a freezer, thawed, filtered, and dried to obtain 24.8 g of amorphous titanyl phthalocyanine [1] (yield 86%).

(2-2) Generation of charge generation material 10.0 g of amorphous titanyl phthalocyanine [1] and 0.94 g of (2R, 3R) -2,3-butanediol (equivalent ratio to amorphous titanyl phthalocyanine = 0.6) The mixture was mixed in 200 ml of orthodichlorobenzene (ODB), and the mixture was heated and stirred at a reaction temperature of 60 to 70 ° C. for 6.0 hours. After standing overnight, methanol was added to the reaction solution, and the resulting crystals were filtered. The filtered crystals were washed with methanol to obtain 10.3 g of a charge generating material [CG-1].
When the X-ray diffraction spectrum of this charge generation material [CG-1] was measured, clear peaks were observed at 8.3 °, 24.7 °, 25.1 ° and 26.5 °. The measured mass spectrum, show a peak in the 576 and 648, also was measured for IR spectrum, O-Ti-O in the vicinity of 630 cm ^-1 with absorption of Ti = O appears in the vicinity of 970 cm ^-1 Both absorptions appeared. Further, when thermal analysis (TG) was performed, there was a mass loss of about 7% at 390 to 410 ° C. From the above, it was estimated that the charge generation material [CG-1] was a mixed crystal of titanyl phthalocyanine and (2R, 3R) -2,3-butanediol 1: 1 adduct and non-added titanyl phthalocyanine. .
It was 31.2 m < ² > / g when the BET specific surface area of this charge generation material [CG-1] was measured.
The X-ray diffraction spectrum was measured using a sample obtained by applying the charge generation material [CG-1] on a transparent glass plate and drying it. The BET specific surface area was measured using a flow type specific surface area automatic measuring device “Micrometrics Flow Soap Type” (manufactured by Shimadzu Corporation). The same applies to the following.

(2-3) Formation of Charge Generation Layer / Charge Generation Substance [CG-1] (BD-TiOPc / TiOPc Mixed Crystal) 24 parts by mass Polyvinyl butyral resin “ESREC BL-1 (manufactured by Sekisui Chemical Co., Ltd.)” 12 parts by mass・ 3-methyl-2-butanone / cyclohexanone = 4/1 (V / V) A charge generation layer composition [1] consisting of 400 parts by mass was mixed, and a circulating ultrasonic homogenizer “RUS-600TCVP (Japan, Ltd.) The charge generation layer coating solution [1] was prepared by dispersing at a circulating flow rate of 40 L / H for 0.5 hours using “Seiki Seisakusho, 19.5 kHz, 600 W”.
This charge generation layer coating solution [1] was applied onto the intermediate layer [1] by a dip coating method to form a charge generation layer [1] having a dry film thickness of 0.3 μm.

(3) Formation of charge transport layer Next, the following components were mixed and a charge transport material and a binder resin (polycarbonate resin) were dissolved to prepare a charge transport layer coating solution.
The charge transport layer coating solution is applied onto the charge generation layer [1] by a dip coating method and dried at 120 ° C. for 70 minutes to form a charge transport layer [1] having a dry film thickness of 24 μm. A photoreceptor [1] was produced.
-200 parts by mass of a charge transport material represented by the following formula (CTM-1)-300 parts by mass of polycarbonate resin "Z300 (Mitsubishi Gas Chemical Co., Ltd.), refractive index 1.6"-1600 parts by mass of tetrahydrofuran-400 parts by mass of toluene- Silicone oil “KF-50” (manufactured by Shin-Etsu Chemical Co., Ltd.) 1 part by mass, antioxidant “Irganox 1010 (manufactured by Ciba Specialty Chemicals)”
6 parts by mass-specific pyrazolone pigment: the above pyrazolone pigment (1) obtained as follows: 6 parts by mass

(Synthesis of Exemplary Compound (1))
p-Dimethylaminobenzaldehyde: 6.0 g (0.04 mol), 5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one: 7.7 g (0.044 mol) in 100 ml of acetic acid Dissolve in the solution and add 3.6 g (0.044 mol) of sodium acetate. After heating to reflux for 5 hours, the mixture was poured into water, extracted with toluene, washed twice with water, dried using magnesium sulfate, and concentrated to obtain crude crystals. Purification by silica gel column chromatography (eluent toluene) and further recrystallization gave 8.7 g of the compound represented by the exemplified compound (1).

[Example 2]
Photosensitive member [2] was prepared in the same manner as in Preparation Example 1 of the photosensitive member, except that the amount of the specific pyrazolone dye was changed to 3 parts by mass.

[Examples 3 to 9: Photoconductor Preparation Examples 3 to 9]
Photoconductors [3] to [9] were prepared in the same manner as in Photoconductor Preparation Example 2, except that the type of the specific pyrazolone dye was changed according to Table 1.

[Example 10: Photoconductor production example 10]
Photosensitive member [10] was prepared in the same manner as in Preparation Example 2 of the photosensitive member except that a compound represented by the following formula (CTM-2) was used as the charge transport material.

Example 11 Photoconductor Preparation Example 11
In Photoconductor Preparation Example 2, the photosensitizer was similarly used except that a charge generation material [CG-2] (Y-TiOPc) made of Y-type titanyl phthalocyanine obtained by the following synthesis method was used as the charge generation material. A body [11] was prepared.

(Synthesis of charge generation material [CG-2])
Amorphous titanyl phthalocyanine pigment water-containing paste (about 10 g in solid content) is dispersed in a mixture of 100 ml of orthodichlorobenzene and 100 ml of water (the water layer is separated), heated at 70 ° C. for 6 hours, and then poured into methanol. The crystals generated in Step 1 were filtered and dried to obtain a charge generating material [CG-2] composed of Y-type titanyl phthalocyanine.
This Y-type titanyl phthalocyanine was a titanyl phthalocyanine pigment having an X-ray diffraction spectrum having a maximum peak at 27.2 °.

Example 12 Photoconductor Preparation Example 12
In Photoconductor Preparation Example 1, in addition to the addition of the pyrazolone dye represented by formula (1) in the charge transport layer preparation step and the formation of a protective layer on the charge transport layer as follows: In the same manner, a photoreceptor [12] was produced.

(4) Formation of protective layer Inorganic particles (tin oxide particles with a number average primary particle size of 20 nm surface-treated with the same mass of methacryloxypropyltrimethoxysilane (Exemplary Compound S-15)) 150 parts by mass Polymerizable compound ( Illustrative compound (M1)) 100 parts by mass Specific pyrazolone dye: 5 parts by mass of the above pyrazolone dye (1) Polymerization initiator ("Irgacure 819" manufactured by BASF Japan Ltd.) 10 parts by mass 2-butanol 320 Part by weight A coating solution composition comprising 80 parts by weight of tetrahydrofuran was mixed and stirred to sufficiently dissolve and disperse to prepare a coating solution [1] for forming a protective layer.
This protective layer-forming coating solution [1] is applied onto the charge transport layer using a circular slide hopper applicator, and irradiated with ultraviolet rays for 1 minute using a metal halide lamp, thereby providing a protective layer having a dry film thickness of 3.0 μm. [1] was formed.

[Examples 13 to 17]
Photoconductors [13] to [17] were prepared in the same manner as in Photoconductor Preparation Example 12 except that the type of the specific pyrazolone dye was changed according to Table 1.

[Comparative Example 1: Photoconductor Preparation Example 18]
A photoreceptor [18] was prepared in the same manner as in Preparation Example 2 of the photoreceptor except that the pyrazolone dye (1) was not contained.

[Comparative Example 2: Photoconductor Preparation Example 19]
A photoreceptor [19] was prepared in the same manner as in Preparation Example 11 of the photoreceptor except that the pyrazolone dye (1) was not contained.

[Comparative Example 3: Photoconductor Preparation Example 20]
A photoconductor [20] was produced in the same manner as in photoconductor production example 2, except that pyrazolone dye (19) was used as the charge transport material and pyrazolone dye (1) was not contained. .

[Comparative Example 4: Photoconductor Preparation Example 21]
A photoconductor [21] was produced in the same manner as in Photoconductor Production Example 2 except that 1-phenylazo-2-naphthol was used instead of the pyrazolone dye (1).

[Comparative Example 5: Photoconductor Preparation Example 22]
Photosensitive member [22] was prepared in the same manner as in Photosensitive member preparation example 2 except that Solvent Orange 60 was used instead of pyrazolone dye (1).

  The above-mentioned photoreceptors [1] to [22] are mounted on a commercially available full-color multi-function peripheral “bizhub C360” (manufactured by Konica Minolta Co., Ltd.) having basically the same configuration as the image forming apparatus shown in FIG. Evaluation of light fatigue and potential stability was performed.

(1) Evaluation of light fatigue The photoconductors [1] to [22] are covered with black paper provided with a light-shielding window, and exposed to light (500 lux) of a white fluorescent lamp for 15 minutes with the window opened. After that, the photosensitive unit was immediately assembled and mounted on a commercially available full-color multifunction peripheral “bizhub C360” (manufactured by Konica Minolta). Using this, the density of the non-irradiated part is 0 on the A3 size “CF paper” (manufactured by Konica Minolta Business Solutions) in a normal temperature and humidity environment (temperature 23 ° C., humidity 50% RH). 10 black monotone halftone images (tone priority mode) were output so that the image density difference ΔID between the irradiated portion and the non-irradiated portion was measured for each halftone image, and the average value was calculated. . The results are shown in Table 1. In the present invention, the case where ΔID is an absolute value of less than 0.040 is judged as acceptable.

(2) Evaluation of potential stability The photoconductors [1] to [22] are mounted on a commercially available full-color composite machine “bizhub C360” (manufactured by Konica Minolta), and are in a high temperature and high humidity environment (temperature 30 ° C., humidity 85% RH). ), An endurance test was performed in which a character image with an image ratio of 6% was continuously printed 10,000 sheets at A4 horizontal feed, and the magnitude of the potential fluctuation of the surface potential of the exposed portion before and after the endurance test was measured. For measuring the surface potential of the photoreceptor, a modified machine in which the developing means was removed and a surface potential meter was installed at that position was used. Specifically, the charging potential was adjusted to −600 V, the surface potential of the exposed part before and after the durability test was measured, and the amount of change (ΔV) was calculated. The results are shown in Table 1. In the present invention, the case where ΔV is 100 V or less in absolute value is determined as acceptable.

1, 1Y, 1M, 1C, 1Bk photoconductor 1a conductive support 1b intermediate layer 1c charge generation layer 1d charge transport layer 1e protective layer 1α organic photosensitive layer 2Y, 2M, 2C, 2Bk charging means 3Y, 3M, 3C, 3Bk Exposure means 4Y, 4M, 4C, 4Bk Developing means 5Y, 5M, 5C, 5Bk Primary transfer roller 5b Secondary transfer rollers 6Y, 6M, 6C, 6Bk Cleaning means 6b Cleaning means 7 Intermediate transfer unit 8 Housings 10Y, 10M, 10C 10Bk Image forming unit 20 Paper feed cassette 21 Paper feed means 22A, 22B, 22C, 22D Intermediate roller 23 Registration roller 24 Fixing means 25 Paper discharge roller 26 Paper discharge tray 70 Intermediate transfer bodies 71-74 Support rollers 82L, 82R Support rail A Image forming apparatus main body P Image support SC Original image reading apparatus

Claims (7)

An electrophotographic photoreceptor in which at least a charge generation layer and a charge transport layer are laminated in this order on a conductive support,
The charge generation layer contains a phthalocyanine compound as a charge generation material;
The layer located on the surface side of the charge generation layer contains a compound represented by the following general formula (1),
The electrophotographic photoreceptor, wherein the charge transport layer contains at least a charge transport material, and the charge transport material is different from the compound represented by the general formula (1).

[Wherein, n is 1 or 2, and R ¹ may have an alkyl group that may have a substituent, a monovalent aromatic group that may have a substituent, or a substituent. Represents a heterocyclic group, and when n = 1, the two R ^{1 s} may be the same or different from each other, and may be bonded to each other to form a ring structure. R ² represents an alkyl group which may have a substituent or a monovalent aromatic group which may have a substituent, and R ³ represents an alkyl group which may have a substituent or a substituent. The monovalent aromatic group which may have or the heterocyclic group which may have a substituent is represented. Ar represents a divalent aromatic group which may have a substituent. ] R ¹ in the general formula (1) is a phenyl group which may have a substituent or an alkyl group having 1 to 5 carbon atoms which may have a substituent, and R ² has a substituent. A phenyl group which may have a substituent or an alkyl group having 1 to 3 carbon atoms which may have a substituent, and R ³ may have a phenyl group or a substituent which may have a substituent. The electrophotographic photoreceptor according to claim 1, wherein the electrophotographic photoreceptor is an alkyl group having 1 to 3 carbon atoms, and the Ar is a phenylene group. When the layer located on the surface side of the charge generation layer containing the compound represented by the general formula (1) is a charge transport layer,
The content ratio of the compound represented by the general formula (1) is 0.1 to 10 parts by mass with respect to 100 parts by mass of the binder resin forming the charge transport layer. Item 3. The electrophotographic photosensitive member according to Item 2. When the compound represented by the general formula (1) is contained and the layer located on the surface side of the charge generation layer is a protective layer formed on the charge transport layer,
The content ratio of the compound represented by the general formula (1) is 0.5 to 20 parts by mass with respect to 100 parts by mass of the binder resin forming the protective layer. 2. The electrophotographic photosensitive member according to 2.   The electrophotographic photosensitive member according to claim 1, wherein the charge transport material is a compound having a triarylamine structure.   6. The electrophotographic photoreceptor according to claim 1, wherein the phthalocyanine compound is composed of 2,3-butanediol adduct titanyl phthalocyanine and non-added titanyl phthalocyanine. Electrophotographic photosensitive member, means for forming an electrostatic latent image on the electrophotographic photosensitive member, means for developing the electrostatic latent image with toner to form a toner image, and transferring the formed toner image to an image support Means for fixing the transferred toner image on the image support,
The image forming apparatus, wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to claim 1.

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