Electrophotographic photoreceptor, process cartridge including the same, and image formation apparatus

Abstract

To provide an electrophotographic photoreceptor which has excellent light resistance, has no deterioration in electrical characteristics during repeated use, and can continuously obtain good image quality, a process cartridge and an image formation apparatus including the same.SOLUTION: An electrophotographic photoreceptor comprises at least a laminated photosensitive layer in which a charge generation layer and a charge transport layer are sequentially laminated on a conductive support, or at least the laminated photosensitive layer and a surface protective layer laminated on the laminated photosensitive layer. Both or either of the charge transport layer and the surface protective layer have a maximum absorption in a wavelength range of 580-609 nm in a spectral absorption spectrum, and contains a specific tetraazaporphyrin complex that satisfies a relationship of 2.0<λ610 / λ620 when the absorbances at wavelengths of 610 nm and 620 nm are defined as λ610 and λ620, respectively.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to an electrophotographic photoreceptor, a process cartridge including the same, and an image forming apparatus. More specifically, the present disclosure relates to an electrophotographic photoreceptor having excellent light resistance, no deterioration of electrical characteristics during repeated use, and capable of continuously obtaining good image quality, a process cartridge including the same, and an image forming apparatus.

Background Art

[0002] In recent years, as the electrophotographic photoreceptor, an organic photoreceptor using an organic photoconductive material (hereinafter referred to as "electrophotographic photoreceptor" or simply "photoreceptor") has been widely used. However, the organic photoreceptor has a problem of light resistance that the photosensitive layer deteriorates due to light. Normally, the photoreceptor is used in a state shielded from light inside an image forming apparatus such as a copying machine or a laser printer, and is not exposed to external light such as a fluorescent lamp. However, during the assembly of the machine (image forming apparatus) or when replacing the photoreceptor, for example, when a paper jam occurs and paper is taken out of the machine, it will be exposed to external light. Since the light intensity of the external light is extremely strong compared to the exposure intensity for image formation inside the machine, when the photoreceptor is exposed to the external light, it may be severely damaged and cause problems in image formation.

[0003] The light of a fluorescent lamp has particularly strong spectral absorption near wavelengths of 550 and 610 nm, and the light resistance of the photoreceptor can be efficiently improved by blocking the light of this wavelength. Therefore, for example, in JP 2010-164639 A (Patent Document 1), a technique has been proposed in which a specific electron transport material (ETM) is added to the photosensitive layer to improve the light resistance of the photoreceptor.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In an image forming apparatus, light having a wavelength of around 620 nm is used as the charge eliminating light for canceling the charge of the photoreceptor after image formation. Therefore, if the light of the fluorescent lamp is blocked and at the same time the charge eliminating light is blocked, the charge will not be canceled during charge elimination, the residual potential will increase, and the potential stability of the photoreceptor will deteriorate. Therefore, in the light shielding of the photoreceptor, it is important to minimize the amount of charge eliminating light blocked and block external light such as fluorescent lamp light. In prior arts such as the above-mentioned Patent Document 1, since it has a broad maximum absorption in the vicinity of 600 nm wavelength, a large amount of ETM needs to be added to obtain sufficient light resistance. For this reason, the ETM itself becomes a trap, and the repeated potential stability deteriorates. In addition, there has been a problem that sufficient abrasion resistance cannot be obtained due to an increase in the ratio of low molecular components in the photosensitive layer.

[0006] Therefore, the present disclosure has been made to solve the above problems, and an electrophotographic photoreceptor having excellent light resistance, no deterioration of electrical characteristics during repeated use, and capable of continuously obtaining good image quality, a process cartridge including the same, and an image forming apparatus are provided.

Means for Solving the Problems

[0007] As a result of intensive studies to solve the above problems, the inventors of the present invention have found that by incorporating a tetraazaporphyrin complex having a sharp absorption peak (maximum absorption wavelength) at a specific wavelength in the charge transport layer, damage to the photosensitive layer by external light is suppressed and the above problems can be solved, and thus the present invention has been completed.

[0008] Thus, according to the present disclosure, there is provided an electrophotographic photoreceptor including at least a laminated photosensitive layer in which a charge generation layer and a charge transport layer are sequentially laminated on a conductive support, or at least including the laminated photosensitive layer and a surface protection layer laminated on the laminated photosensitive layer. At least one of the charge transport layer and the surface protection layer has a maximum absorption in the spectral absorption spectrum in the wavelength range of 580 to 609 nm, and when the absorbances at wavelengths 610 nm and 620 nm are λ610 and λ620, respectively, the following formula: 2.0 < λ610 / λ620 satisfies the relationship of the general formula (I):

[0009] [Chemical formula]

[0010] (In the formula, X1 to X4 are the same or different and are a halogen atom; or a linear, branched or cyclic alkyl group which may be substituted with a halogen atom, and Y1 to Y4 are the same or different and are a hydrogen atom; a linear or branched alkoxy group having 1 to 3 carbon atoms which may be substituted with a halogen atom or an alkoxy group; an aryloxy group; an aryl group which may have a substituent; a heteroaryl group; an alkylthio group; or an arylthio group, and M is a divalent metal atom, a monosubstituted trivalent metal atom, a disubstituted tetravalent metal atom or an oxy metal atom) An electrophotographic photoreceptor is provided, which comprises a tetraazaporphyrin complex represented by the formula.

[0011] Further, according to the present disclosure, there is provided a process cartridge comprising the above electrophotographic photoreceptor and at least one selected from a charging means for charging the electrophotographic photoreceptor, a developing means for developing an electrostatic latent image formed by exposure to form a toner image, and a cleaning means for removing toner remaining on the electrophotographic photoreceptor.

[0012] Furthermore, according to the present disclosure, there is provided an image forming apparatus comprising at least the above electrophotographic photoreceptor, a charging means for charging the electrophotographic photoreceptor, an exposure means for exposing the charged electrophotographic photoreceptor to form an electrostatic latent image, a developing means for developing the electrostatic latent image to form a toner image, and a transfer means for transferring the toner image onto a recording medium.

Advantages of the Invention

[0013] According to the present disclosure, there can be provided an electrophotographic photoreceptor having excellent light resistance, no deterioration in electrical characteristics during repeated use, and capable of continuously obtaining good image quality, a process cartridge including the same, and an image forming apparatus.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0015] The photoreceptor of the present disclosure is an electrophotographic photoreceptor including at least a laminated photosensitive layer in which a charge generation layer and a charge transport layer are sequentially laminated on a conductive support, or including at least the laminated photosensitive layer and a surface protection layer laminated on the laminated photosensitive layer, in which both or either one of the charge transport layer and the surface protection layer has a maximum absorption in the wavelength range of 580 to 609 nm in the spectral absorption spectrum, and when the absorbances at wavelengths 610 nm and 620 nm are λ610 and λ620, respectively, the following formula: 2.0 < λ610 / λ620 is satisfied, and the general formula (I):

[0016]

Chemical formula

[0017] (In the formula, X1 to X4 are the same or different and are a halogen atom; or a linear, branched or cyclic alkyl group which may be substituted with a halogen atom, and Y1 to Y4 are the same or different and are a hydrogen atom; a linear or branched alkoxy group having 1 to 3 carbon atoms which may be substituted with a halogen atom or an alkoxy group; an aryloxy group; an aryl group which may have a substituent; a heteroaryl group; an alkylthio group; or an arylthio group, and M is a divalent metal atom, a monosubstituted trivalent metal atom, a disubstituted tetravalent metal atom or an oxy metal atom) Characterized by containing a tetraazaporphyrin complex represented by the following formula.

[0018] Hereinafter, the constituent requirements characteristic of the photoreceptor of the present disclosure will be described, and then (1) the photoreceptor, (2) the process cartridge including the same, and (3) the image forming apparatus will be described. Note that the embodiments and examples described below are merely specific examples of the present invention, and the present invention is not limited thereto.

[0019] An object of the present invention is to block external light having a wavelength of around 610 nm as much as possible from the photoreceptor, particularly its charge generation layer, and reduce the adverse effects caused by the external light. The object is achieved by incorporating a specific tetraazaporphyrin complex having a sharp absorption at around a wavelength of 600 nm as described above into both or either one of the charge transport layer and the surface protection layer of the photoreceptor. Therefore, in the photoreceptor of the present disclosure, as long as the effect of achieving the object is not inhibited, both or either one of the charge transport layer and the surface protection layer may contain other light-absorbing compounds, for example, known light-absorbing compounds as described later.

[0020] The optical properties of the charge transport layer and the surface protection layer of the photoreceptor are reflected by the optical properties of compounds such as the tetraazaporphyrin complex and the light-absorbing compound added to those layers. Therefore, the charge transport layer and the surface protection layer of the photoreceptor of the present disclosure have a maximum absorption in the wavelength range of 570 to 615 nm, and when the absorbances at wavelengths 610 nm and 620 nm are λ610 and λ620, respectively, the following formula: 2.0 < λ610 / λ620 preferably satisfies the relationship. When the maximum absorption wavelength (hereinafter also referred to as "λ max ") is less than 570 nm or exceeds 615 nm, or when λ610 / λ620 is less than 2.0 or exceeds 5.0, the excellent effects of the present disclosure may not be fully obtained. Therefore, it is more preferable to satisfy the relationship of 2.0 < λ610 / λ620 < 5.0.

[0021] <Tetraazaporphyrin complex> The tetraazaporphyrin complex of the present disclosure is represented by the general formula (I) as described above. The substituents and the central metal will be described. In the formula, X1 to X4 are the same or different and are a halogen atom; or a linear, branched or cyclic alkyl group which may be substituted with a halogen atom, Y1 to Y4 are the same or different and are a hydrogen atom; a linear or branched alkoxy group having 1 to 3 carbon atoms which may be substituted with a halogen atom or an alkoxy group; an aryloxy group; an aryl group which may have a substituent; a heteroaryl group; an alkylthio group; or an arylthio group, and M is a divalent metal atom, a monosubstituted trivalent metal atom (trivalent monosubstituted metal atom), a disubstituted tetravalent metal atom (tetravalent disubstituted metal atom) or an oxy metal atom.

[0022] Examples of the halogen atom of the substituents X1 to X4 include fluorine, chlorine, bromine, iodine and the like. Examples of the linear alkyl group of the substituents X1 to X4 include linear alkyl groups having 1 to 5 carbon atoms such as methyl, ethyl, n-propyl, n-butyl and n-pentyl. Examples of the branched alkyl groups for the substituents X1 to X4 include branched alkyl groups having 1 to 10 carbon atoms such as isopropyl, isobutyl, sec-butyl, tert-butyl, neopentyl, tert-pentyl, isopentyl, sec-pentyl, dimethylbutyl, isohexyl, methylhexyl, ethylhexyl, dimethylhexyl, trimethylhexyl, methylheptyl, dimethylheptyl, trimethylheptyl, ethylheptyl, methyloctyl, and methylnonyl.

[0023] Examples of the cyclic alkyl groups for the substituents X1 to X4 include cyclic alkyl groups having 1 to 10 carbon atoms such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cyclopeptyl, cyclooctyl, cyclononyl, and cyclodecyl. Examples of the linear, branched or cyclic alkyl groups substituted with a halogen atom of the substituents X1 to X4 include halogenated alkyl groups having 1 to 5 carbon atoms such as chloromethyl, dichloromethyl, fluoromethyl, trifluoromethyl, pentafluoroethyl, and nonafluorobutyl. Among the above substituents X1 to X4, from the viewpoint of the stability of the tetraazaporphyrin complex, linear, branched or cyclic alkyl groups having 3 to 10 carbon atoms are preferred, and tert-butyl is particularly preferred.

[0024] Examples of the linear alkoxy groups for the substituents Y1 to Y4 include linear alkoxy groups having ١ to 3 carbon atoms such as methoxy, ethoxy, and propoxy. Examples of the branched alkoxy groups for the substituents Y1 to Y4 include branched alkoxy groups having 1 to 10 carbon atoms such as isopropoxy, isobutoxy, sec-butyloxy, tert-butyloxy, neopentyloxy, tert-pentyloxy, isopentyloxy, sec-pentyloxy, dimethylbutyloxy, isohexyloxy, methylhexyloxy, ethylhexyloxy, dimethylhexyloxy, trimethylhexyloxy, methylheptyloxy, dimethylheptyloxy, trimethylheptyloxy, ethylheptyloxy, methyloctyloxy, and methylnonyloxy.

[0025] Examples of the alkoxy group substituted with a halogen atom of substituents Y1 to Y4 include linear or branched halogenated alkoxy groups having 1 to 10 carbon atoms such as fluoromethoxy, difluoromethoxy, trifluoromethoxy, pentafluoroethoxy, tetrafluoroethoxy, trifluoroethoxy, difluoroethoxy, fluoroethoxy, tetrafluoro-1-propoxy, pentafluoro-1-propoxy, heptafluoro-1-butoxy, hexafluoro-1-butoxy, octafluoro-1-pentyloxy, nonafluoro-1-hexyloxy, nonafluoro-1-heptyloxy, dodecafluoro-1-heptyloxy, pentafluoro-1-octyloxy, tridecafluoro-1-octyloxy, hexadecafluoro-1-nonyloxy, tridecafluoro-1-nonyloxy, nonafluoro-1-nonyloxy, heptadecafluoro-1-decyloxy, heptadecafluoro-1-decyloxy.

[0026] Examples of the alkoxy group substituted with an alkoxy group of substituents Y1 to Y4 include alkoxyalkoxy groups having 1 to 10 carbon atoms such as methoxyethoxy, ethoxyethoxy, 3-methoxypropyloxy, 3-(isopropyloxy)propyloxy.

[0027] Examples of the aryloxy group of substituents Y1 to Y4 include aryloxy groups having 6 to 10 carbon atoms such as phenoxy, 2-methylphenoxy, 4-methylphenoxy, 4-tert-butylphenoxy, 2-methoxyphenoxy, 4-isopropylphenoxy.

[0028] Examples of the aryl group which may have a substituent of substituents Y1 to Y4 include aryl groups having 6 to 10 carbon atoms such as phenyl, nitrophenyl, cyanophenyl, hydroxyphenyl, methylphenyl, dimethylphenyl, trimethylphenyl, dichlorophenyl, methoxyphenyl, ethoxyphenyl, trifluoromethylphenyl, N,N-dimethylaminophenyl, naphthyl, nitronaphthyl, hydroxynaphthyl.

[0029] Examples of the heteroaryl groups for the substituents Y1 to Y4 include heteroaryl groups having 6 to 10 carbon atoms such as pyrrolyl, thienyl, furanyl, oxazolyl, isoxazolyl, oxadiazolyl, imidazolyl, benzoxazolyl, benzothiazolyl, benzimidazolyl, benzofuranyl, and indolyl.

[0030] Examples of the alkylthio groups for the substituents Y1 to Y4 include alkylthio groups having 1 to 10 carbon atoms such as methylthio, ethylthio, n-propylthio, isopropylthio, n-butylthio, isobutylthio, sec-butylthio, tert-butylthio, n-pentylthio, isopentylthio, 2-methylbutylthio, 1-methylbutylthio, neopentylthio, 1,2-dimethylpropylthio, and 1,1-dimethylpropylthio.

[0031] Examples of the arylthio groups for the substituents Y1 to Y4 include arylthio groups having 1 to 10 carbon atoms such as phenylthio, 4-methylphenylthio, 2-methoxyphenylthio, and 4-tert-butylphenylthio.

[0032] Among the above substituents Y1 to Y4, from the viewpoint of the stability of the tetraazaporphyrin complex, a hydrogen atom, a linear alkoxy group substituted with a halogen atom, and an aryl group which may have a substituent are preferable, and a hydrogen atom, trifluoroethoxy, chlorophenyl, fluorophenyl, and naphthyl are particularly preferable. The substituents X1 to X4 and Y1 to Y4 preferably have a structure in which they interfere with each other and are difficult to move and bulky. In the tetraazaporphyrin complex of the present disclosure, it is preferable that the substituents X1 to X4 in the general formula (I) are linear, branched or cyclic alkyl groups, and the substituents Y1 to Y4 are a hydrogen atom, a linear alkoxy group substituted with a halogen atom, or an aryl group which may have a substituent.

[0033] Examples of the divalent metal of the central metal M include Cu, Zn, Fe, Co, Ni, Ru, Rh, Pd, Pt, Mn, Sn, Mg, Hg, Cd, Ba, Ti, Be, Ca, and Pb.

[0034] Examples of the monosubstituted trivalent metal (trivalent monosubstituted metal atom) of the central metal M include Al-F, Al-Cl, Al-Br, Al-I, Ga-F, Ga-Cl, Ga-Br, Ga-I, In-F, In-Br, In-I, Tl-F, Tl-Cl, Tl-Br, Tl-I, Al-C6H5, Al-C6H4(CH3), In-C6H5, In-C6H4(CH3), Mn(OH), Mn(OC6H5), Mn[OSi(CH3)3], Fe-Cl, and Ru-Cl.

[0035] Examples of the disubstituted tetravalent metal (tetravalent disubstituted metal atom) of the central metal M include, for example, CrCl2, SiF2, SiCl2, SiBr2, SiI2, SnF2, SnCl2, SnBr2, ZrCl2, GeF2, GeCl2, GeBr2, GeI2, TiF2, TiCl2, TiBr2, Si(OH)2, Sn(OH)2, Ge(OH)2, Zr(OH)2, Mn(OH)2, TiA2, CrA2, SiA2, SnA2, GeA2 [A represents an alkyl group, phenyl group, naphthyl group, and derivatives thereof], Si(OA l )2, Sn(OA l )2, Ge(OA l )2, Ti(OA l )2, Cr(OA l )2 [A l represents an alkyl group, phenyl group, naphthyl group, trialkylsilyl group, dialkylalkoxysilyl group, and derivatives thereof], Si(SA 2 )2, Sn(SA 2 )2, Ge(SA 2 )2 [A 2 represents an alkyl group, phenyl group, naphthyl group, and derivatives thereof].

[0036] Examples of the oxy metal of the central metal M include VO, MnO, and TiO. Among the above-mentioned central metals M, from the viewpoint of the stability of the tetraazaporphyrin complex, Cu, Zn, Fe, Co, Ni, Pd, Mn, Mg, VO, and TiO are preferable, Cu, Pd, and VO are more preferable, and VO is particularly preferable. Therefore, the tetraazaporphyrin complex of the present disclosure is preferably a complex in which the central metal in the general formula (I) is a vanadium oxy group.

[0037] The tetraazaporphyrin complex of the present disclosure can be synthesized, for example, by the method described in JP-A-2007-99744. Examples of the tetraazaporphyrin complex of the present disclosure include complexes A to H having substituents and central metals as shown in Table 1, but are not limited thereto. Among these, complexes A to F are preferable from the viewpoint of the stability of the tetraazaporphyrin complex, and complexes A and B are particularly preferable. Table 1 also shows the optical properties (maximum absorption wavelength, absorbance ratio λ610 / λ620, half-value width at the maximum absorption wavelength) of the tetraazaporphyrin complex. In the photoreceptor of the present disclosure, these complexes can be used alone or in combination of two or more.

[0038]

Table 1

[0039] [Maximum absorption wavelength] The tetraazaporphyrin complex of the present disclosure has a maximum absorption in the wavelength range of 580 to 609 nm in the spectroscopic absorption spectrum. When the maximum absorption wavelength is less than 580 nm, the effect of blocking the light wavelength component near 610 nm is weak (low), and the light resistance may deteriorate. On the other hand, when the maximum absorption wavelength exceeds 609 nm, the amount of blocking the removal light increases, which may lead to deterioration of the potential stability. The preferable range of the maximum absorption is 590 to 605 nm.

[0040] Damage caused to the photoreceptor by external light such as fluorescent light occurs when the external light passes through the charge transport layer, and the transmitted light acts on the charge generating substance to generate charge traps. Since the light of a fluorescent lamp has a particularly strong light wavelength component near a wavelength of 610 nm, when such light passes through the charge transport layer, it acts on the charge generating material to generate charge traps. FIG. 1 is a diagram showing the spectral absorption spectrum of the tetraazaporphyrin complex A represented by the general formula (I) of the present disclosure. As shown in this figure, the tetraazaporphyrin complex of the present disclosure has absorption near a wavelength of 600 nm, and by adding it to the charge transport layer or the surface protection layer, it is considered to function as a light absorption compound and effectively block the action of the above light wavelength component on the charge generating substance.

[0041] In addition, in an image forming apparatus, light near a wavelength of 620 nm is used for charge elimination light. If the charge elimination light is blocked too much, charges cannot be canceled during charge elimination, leading to an increase in the residual potential and deterioration of the potential stability of the photoreceptor. Therefore, it is important to minimize the amount of charge elimination light blocked and block the light of the fluorescent lamp. Since the polyazaporphyrin complex of the present disclosure has a sharp peak near a wavelength of 600 nm, the amount of its addition can be suppressed compared to conventional light absorption compounds. As a result, the amount of charge elimination light near a wavelength of 620 nm blocked is reduced, so it is considered that the adverse effect on the electrical characteristics (potential stability) can be reduced.

[0042] [Ratio of absorbance λ610 at wavelength 610 nm to absorbance λ620 at wavelength 620 nm] The shape of the peak of the spectral absorption spectrum can be defined by the ratio of the absorbance (λ610) at a wavelength of 610 nm to the absorbance (λ620) at 620 nm. The polyazaporphyrin complex of the present disclosure satisfies the following formula: 2.0 < λ610 / λ620 in the spectral absorption spectrum. When the ratio is 2.0 or less, the shape of the peak of the spectral absorption spectrum becomes broad, and in order to obtain the desired blocking effect for the light wavelength component near 610 nm, it is necessary to increase the addition amount of the polyazaporphyrin complex. As a result, the amount of the electrophotorefractive light near 620 nm blocked also increases, and the potential stability of the photoreceptor may deteriorate.

[0043] [Half-width at half-maximum of the maximum absorption wavelength] The tetraazaporphyrin complex of the present disclosure preferably has a half-width of 20 nm or less at the maximum absorption wavelength of the spectral absorption spectrum. When the half-width is 20 nm or less, the shape of the peak of the spectral absorption spectrum becomes sharp, the amount of the electrophotorefractive light near 620 nm blocked decreases, and the influence on the potential stability can be reduced. On the other hand, when the half-width exceeds 20 nm, the shape of the peak of the spectral absorption spectrum becomes broad, the amount of the electrophotorefractive light blocked increases, and it may have an adverse effect on the potential stability.

[0044] [Content of the tetraazaporphyrin complex] The tetraazaporphyrin complex of the present disclosure is preferably contained in a proportion of 0.10 to 0.70% by mass based on the total solid content of the charge transport layer. When the content ratio of the tetraazaporphyrin complex is less than 0.10% by mass, the effect of light resistance may not be sufficiently obtained (small). On the other hand, when the content ratio of the tetraazaporphyrin complex exceeds 0.70% by mass, the amount of the electrophotorefractive light blocked increases, and it may have an adverse effect on the potential stability. A more preferable content ratio is 0.12 to 0.69% by mass, and still more preferably 0.16 to 0.50% by mass.

[0045] The tetraazaporphyrin complex is preferably contained in a proportion of 0.30 to 5.0% by mass based on the total solid content of the surface protection layer. When the content ratio of the tetraazaporphyrin complex is less than 0.30% by mass, the effect of light resistance may not be sufficiently obtained (small). On the other hand, when the content ratio of the tetraazaporphyrin complex exceeds 5.0% by mass, the amount of the electrophotorefractive light blocked increases, and it may have an adverse effect on the potential stability. A more preferable content ratio is 0.48 to 4.5% by mass, and even more preferably 0.52 to 3.0% by mass.

[0046] <Light-absorbing compound> In the photoreceptor of the present disclosure, it is preferable that either or both of the charge transport layer and the surface protection layer further contain a light-absorbing compound having a maximum absorption in the wavelength range of 370 to 560 nm in the spectral absorption spectrum. The light-absorbing compound used in combination with the tetraazaporphyrin complex of the present disclosure is not particularly limited in its structure, etc., and may have charge transport properties together with light absorption properties. For example, perimidine compounds, azoquinone compounds, pyrazolone compounds, thiadiazole derivatives, benzophenone derivatives, benzotriazole derivatives, hydrazone derivatives, butadiene derivatives, monoazo derivatives, diphenoquinone derivatives, naphthoquinone derivatives, azo derivatives, and known light-absorbing compounds of arylamine derivatives can be mentioned. In the photoreceptor of the present disclosure, one of these light-absorbing compounds can be used alone or in combination of two or more.

[0047] Specific examples of the light-absorbing compound include the following structural formula (a):

Chemical formula

[0048]

Chemical formula

[0049]

Chemical formula

[0050] [Chemical formula] The thiadiazole compound represented by (λ max = 374 nm), and the following structural formula (e):

[0051] [Chemical formula] The benzotriazole compound (e) represented by (λ max = 340 nm), etc. may be mentioned.

[0052] More specifically, perimidine compound (a) (C.I. Solvent Red 179, manufactured by American Dyestuff, product name: Amesolve Red A), thiadiazole compound (d) (manufactured by Tokyo Chemical Industry Co., Ltd., product code: T3922), benzotriazole compound (e) (manufactured by Chemipro Kasei Co., Ltd., product name: KEMISORB 71) may be mentioned. In addition, the azoquinone compound (b) can be synthesized, for example, by the method described in JP-A-2014-189516, and the pyrazolone compounds (c) and (c') can be synthesized, for example, by the method described in Japanese Patent No. 4041741.

[0053] As for the light absorption compound, a light absorption compound having a maximum absorption in the wavelength range of 370 to 560 nm in the spectral absorption spectrum is preferable in terms of the light blocking effect of light near 550 nm. Among the above light absorption compounds, the perimidine compound (a) is preferable. If the maximum absorption wavelength is less than 370 nm, the effect of blocking the light wavelength component near 550 nm is weak (low), and the light resistance may deteriorate. On the other hand, if the maximum absorption wavelength exceeds 560 nm, the amount of light blocking the electro-optical light increases, which may lead to deterioration of the potential stability. A more preferable range of the maximum absorption wavelength is 450 to 550 nm, and an even more preferable range of the maximum absorption wavelength is 480 to 530 nm.

[0054] The content ratio of the light absorption compound in the charge transport layer and the surface protection layer may be appropriately set according to the light characteristics of the light absorption compound so that the desired spectral absorption spectrum of the photoreceptor of the present disclosure can be obtained.

[0055] [Light Characteristics of Charge Transport Layer and Surface Protection Layer] In the photoreceptor of the present disclosure, it is preferable that in the spectral absorption spectrum, when the absorbances at wavelengths of 610 nm and 550 nm are A610 and A550 respectively for either or both of the charge transport layer and the surface protection layer, the following formula: 0.25 ≦ (A610 / A550) ≦ 1.00 is satisfied. When the ratio A610 / A550 is less than 0.25, the effect of blocking the light wavelength component near the wavelength of 610 nm is weak (low), and the light resistance may deteriorate. On the other hand, when the ratio A610 / A550 exceeds 1.00, the amount of the erased light blocked increases, which may lead to the deterioration of the potential stability. A more preferable ratio A600 / A550 is 0.30 to 0.95, and a further preferable ratio is 0.35 to 0.75.

[0056] (1) Electrophotographic Photoreceptor The photoreceptor of the present disclosure includes at least a laminated photosensitive layer in which a charge generation layer and a charge transport layer are sequentially laminated on a conductive support, or at least includes the laminated photosensitive layer and a surface protection layer laminated on the laminated photosensitive layer. The photoreceptor of the present disclosure will be described below with reference to the drawings, but the present invention is not limited thereto. FIG. 2 is a schematic cross-sectional view showing the configuration of the main part of the photoreceptor F01 of the present disclosure. The photoreceptor F01 includes a laminated photosensitive layer in which an undercoat layer F21, a charge generation layer F22 containing a charge generating substance, and a charge transport layer F23 containing a charge transporting substance are laminated in this order on a conductive support F1. In the figure, Fa indicates the surface of the photoreceptor. As will be described below, the photoreceptor of the present disclosure may include an undercoat layer between the conductive support and the laminated photosensitive layer.

[0057] [Conductive Support F1] The conductive support (also referred to as "conductive substrate") has the function of an electrode of the photoreceptor and the function of a support member, and the constituent material thereof is not particularly limited as long as it is a material used in the relevant technical field. Specifically, metal materials such as aluminum, aluminum alloy, copper, zinc, stainless steel, and titanium, and polymer materials such as polyethylene terephthalate, nylon, and polystyrene, hard paper, and glass, etc. on which a layer of a conductive compound such as a metal foil laminate, metal vapor deposition treatment, or a conductive polymer, tin oxide, indium oxide, etc. is vapor-deposited or coated are mentioned. Among these, aluminum is preferable from the viewpoint of ease of processing, and aluminum alloys such as JIS3003 series, JIS5000 series, and JIS6000 series are particularly preferable. The shape of the conductive support is not limited to a cylindrical shape (drum shape) as shown in the photoreceptor 1 of FIG. 3, and may be a sheet shape, a columnar shape, an endless belt shape, etc. Also, on the surface of the conductive support, if necessary, within a range not affecting the image quality, for preventing interference fringes by laser light, an anodic oxidation film treatment, a surface treatment by chemicals or hot water, etc., a coloring treatment, or a diffuse reflection treatment such as roughening the surface may be performed.

[0058] <Undercoat layer F21> The photoreceptor of the present disclosure preferably includes an undercoat layer (also referred to as "intermediate layer") between the conductive support and the photosensitive layer. The undercoat layer generally covers the unevenness on the surface of the conductive support to make it uniform, enhances the film-forming property of the laminated photosensitive layer, here the charge generation layer, suppresses the peeling of the laminated photosensitive layer from the conductive support, and improves the adhesiveness between the conductive support and the laminated photosensitive layer. Specifically, injection of charges from the conductive support into the laminated photosensitive layer is prevented, a decrease in the chargeability of the laminated photosensitive layer is prevented, fogging of the image (so-called black spots) can be prevented, and good electrophotographic characteristics such as chargeability can be maintained throughout the life. The undercoat layer can be formed, for example, by dissolving a binder resin in an appropriate solvent to prepare a coating solution for the undercoat layer, applying this coating solution to the surface of the conductive support, and removing the organic solvent by drying.

[0059] As the binder resin, in addition to the same binder resin as that contained in the laminate photosensitive layer described later, natural polymer materials such as casein, gelatin, polyvinyl alcohol, and ethyl cellulose can be mentioned, and one or more of these can be used. When forming the photoreceptor layer on the undercoat layer, the binder resin is required to have properties such as not being dissolved or swollen in the solvent used, having excellent adhesiveness to the conductive support, and having flexibility. Therefore, among the above binder resins, polyamide resins are preferred, and alcohol-soluble nylon resins are particularly preferred. Examples of alcohol-soluble nylon resins include homopolymer or copolymer nylons such as 6-nylon, 66-nylon, 610-nylon, 11-nylon, and 12-nylon, and resins obtained by chemically modifying nylon such as N-alkoxymethyl-modified nylon.

[0060] Examples of the solvent for dissolving or dispersing the binder resin include alcohols such as water, methanol, ethanol, and butanol, glymes such as methyl carbitol and butyl carbitol, chlorine-based solvents such as dichloroethane, chloroform, or trichloroethane, acetone, dioxolane, and mixed solvents obtained by mixing two or more of these solvents. Among these solvents, non-halogenated organic solvents are preferably used in consideration of the global environment.

[0061] In addition, the undercoat layer coating solution may contain inorganic compound fine particles. The inorganic compound fine particles can easily adjust the volume resistance value of the undercoat layer, further suppress the injection of charges into the laminate photosensitive layer, and maintain the electrical properties of the photoreceptor under various environments. Examples of the inorganic compound fine particles include fine particles such as titanium oxide, aluminum oxide, aluminum hydroxide, and tin oxide.

[0062] The ratio (A / B) of the total mass A of the binder resin and the inorganic compound fine particles to the mass B of the solvent in the coating liquid for the undercoat layer is preferably from 1 / 99 to 40 / 60, and particularly preferably from 2 / 98 to 30 / 70. Also, the ratio C / D of the mass C of the binder resin to the mass D of the inorganic compound fine particles is preferably from 1 / 99 to 90 / 10, and particularly preferably from 5 / 95 to 70 / 30. In order to disperse the inorganic compound fine particles in the coating liquid for the undercoat layer, known apparatuses such as a ball mill, a sand mill, an attritor, a vibration mill, an ultrasonic disperser, and a paint shaker may be used.

[0063] The coating method of the coating liquid for the undercoat layer may be appropriately selected according to the physical properties and productivity of the coating liquid, etc. For example, a spray method, a bar coating method, a roll coating method, a blade method, a ring method, and a dip coating method may be mentioned. Among these, the dip coating method is a method of forming a layer on the surface of the conductive support by immersing the conductive support in a coating tank filled with the coating liquid and then pulling it up at a constant speed or a sequentially changing speed. It is relatively simple and excellent in terms of productivity and cost, so it can be suitably used for the production of the photoreceptor. The apparatus used for the dip coating method may be provided with a coating liquid dispersing apparatus typified by an ultrasonic generator in order to stabilize the dispersibility of the coating liquid.

[0064] The solvent in the coating film may be removed by natural drying, or the solvent in the coating film may be forcibly removed by heating. The temperature in such a drying process is not particularly limited as long as it can remove the solvent used, but about 50 to 140 °C is appropriate, and about 80 to 130 °C is particularly preferred. When the drying temperature is less than 50 °C, the drying time may be prolonged, and the solvent may not evaporate sufficiently and may remain in the photoreceptor layer. Further, when the drying temperature exceeds about 140 °C, the electrical characteristics during repeated use of the photoreceptor may deteriorate, and the obtained image may deteriorate. Such temperature conditions are common not only for the undercoat layer but also for layer formation and other processes such as the laminated photosensitive layer described later.

[0065] The film thickness of the undercoat layer is not particularly limited, but is preferably 0.01 to 20 μm, more preferably 0.05 to 10 μm. If the film thickness of the undercoat layer is less than 0.01 μm, it will not substantially function as an undercoat layer, and it will not be able to cover the defects of the conductive support to obtain a uniform surface property, and there is a possibility that the injection of charges from the conductive support into the laminated photosensitive layer cannot be prevented. On the other hand, if the film thickness of the undercoat layer exceeds 20 μm, it is difficult to form a uniform undercoat layer, and there is also a possibility that the sensitivity of the photoreceptor decreases. In addition, when the constituent material of the conductive support is aluminum, a layer containing anodized aluminum (anodized aluminum layer) can be formed and used as the undercoat layer.

[0066] <Charge generation layer F22> The charge generation layer has a function of generating charges by absorbing light irradiated by a light emitting device such as a light beam of a semiconductor laser in an image forming apparatus or the like, and is mainly composed of a charge generating substance, and contains a binder resin and additives as necessary.

[0067] As the charge generating substance, compounds used in the art can be used. Specifically, azo pigments such as monoazo pigments, bisazo pigments, and trisazo pigments; indigo pigments such as indigo and thioindigo; perylene pigments such as perylene imide and perylene anhydride; polycyclic quinone pigments such as anthraquinone and pyrenequinone; phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine such as titanyl phthalocyanine; organic photoconductive materials such as squarylium dyes, pyrylium salts, thiopyrylium salts, and triphenylmethane dyes; and inorganic photoconductive materials such as selenium and amorphous silicon. Those having sensitivity in the exposure wavelength range can be appropriately selected and used. These charge generating substances can be used alone or in combination of two or more. Among these charge generating substances, the following general formula (A):

[0068]

Chemical formula

[0069] (In the formula, X 1 ~X 4 are the same or different and are a halogen atom, an alkyl group or an alkoxy group, and r, s, y and z are the same or different and are integers from 0 to 4), it is preferable to use titanyl phthalocyanine represented by the formula. Titanyl phthalocyanine is a charge generating material that has high charge generation efficiency and charge injection efficiency in the emission wavelength regions (near-infrared light) of currently commonly used laser light and LED light. By absorbing light, it can generate a large amount of charges and efficiently inject the generated charges into the hole transporting material without accumulating them inside.

[0070] The titanyl phthalocyanine represented by the general formula (A) can be produced by a known production method such as the method described in Phthalocyanine Compounds by Moser, Frank H and Arthur L. Thomas, Reinhold Publishing Corp., New York, 1963. For example, in the case of unsubstituted titanyl phthalocyanine where r, s, y and z are 0 among the titanyl phthalocyanine compounds represented by the general formula (A), phthalonitrile and titanium tetrachloride are heated and melted or heated and reacted in a suitable solvent such as α-chloronaphthalene to synthesize dichlorotitanium phthalocyanine, and then it can be obtained by hydrolysis with a base or water. Also, a titanyl phthalocyanine composition can be produced by heating and reacting isatin and a titanium tetraalkoxide such as tetrabutoxytitanium in a suitable solvent such as N-methylpyrrolidone.

[0071] As methods for forming a charge generation layer, there are a method of vacuum-depositing a charge generating substance on a conductive support, a method of applying a coating solution for a charge generation layer, which is obtained by dispersing a charge generating substance in a solvent, on a conductive support, and the like. Among these, a method in which a charge generating substance is dispersed in a binder resin solution obtained by mixing a binder resin in a solvent by a conventionally known method and the coating solution for a charge generation layer is applied on a conductive support is preferable. Hereinafter, this method will be described.

[0072] The binder resin is not particularly limited, and any resin known in the art can be used. For example, resins such as polyester, polystyrene, polyurethane, phenol resin, alkyd resin, melamine resin, epoxy resin, silicone resin, acrylic resin, methacrylic resin, polycarbonate, polyarylate, polyphenoxy, polyvinyl butyral, and polyvinyl formal, and copolymer resins containing two or more of the repeating units constituting these resins can be mentioned. Examples of the copolymer resin include insulating resins such as vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride copolymer resin, and acrylonitrile-styrene copolymer resin. These resins can be used alone or in combination of two or more.

[0073] Examples of the solvent include halogenated hydrocarbons such as dichloromethane and dichloroethane, ketones such as acetone, methyl ethyl ketone, and cyclohexanone, esters such as ethyl acetate and butyl acetate, ethers such as tetrahydrofuran (THF) and dioxane, alkyl ethers of ethylene glycol such as 1,2-dimethoxyethane, aromatic hydrocarbons such as benzene, toluene, and xylene, or aprotic polar solvents such as N,N-dimethylformamide and N,N-dimethylacetamide. These solvents can be used alone or in combination of two or more.

[0074] The blending ratio of the charge generating substance and the binder resin is preferably such that the proportion of the charge generating substance is in the range of 10 to 99% by mass. If the proportion of the charge generating substance is less than 10% by mass, the sensitivity may decrease. On the other hand, if the proportion of the charge generating substance exceeds 99% by mass, not only does the film strength of the charge generation layer decrease, but also the dispersibility of the charge generating substance decreases, coarse particles increase, and surface charges other than those to be erased by exposure decrease, resulting in many image defects, particularly fogging of the image called black spots where toner adheres to the blank area and minute black dots are formed.

[0075] Before dispersing the charge generating substance in the binder resin solution, the charge generating substance may be previously pulverized by a pulverizer. Examples of the pulverizer used for the pulverization treatment include a ball mill, a sand mill, an attritor, a vibration mill, and an ultrasonic disperser. Examples of the disperser used for dispersing the charge generating substance in the binder resin solution include a paint shaker, a ball mill, or a sand mill. As the dispersion conditions at this time, appropriate conditions may be selected so that impurities are not mixed in due to wear of the container used and the members constituting the disperser. Examples of the coating method for the coating solution for the charge generation layer include the same methods as those for the coating solution for the undercoat layer, and the dipping coating method is particularly preferred.

[0076] The film thickness of the charge generation layer is not particularly limited, but is preferably 0.05 to 5 μm, more preferably 0.1 to 1 μm. If the film thickness of the charge generation layer is less than 0.05 μm, the efficiency of light absorption may decrease, and the sensitivity of the photoreceptor may decrease. On the other hand, if the film thickness of the charge generation layer exceeds 5 μm, the charge transfer inside the charge generation layer becomes the rate-determining step in the process of erasing the charges on the surface of the laminated photoreceptor layer, and the sensitivity of the photoreceptor may decrease.

[0077] <Charge transport layer F23> The charge transport layer has a function of accepting charges generated by a charge generating substance and transporting them to the surface of the photoreceptor, and contains a charge transport substance, a binder resin, a tetraazaporphyrin complex, optionally a light absorption compound, and an additive as required. In the photoreceptor of the present disclosure, it is an essential requirement that the tetraazaporphyrin complex is contained in both or either one of the charge transport layer and the surface protection layer. For example, when the photoreceptor has a surface protection layer that does not contain a tetraazaporphyrin complex, the tetraazaporphyrin complex becomes an essential component of the charge transport layer, while when the photoreceptor has a surface protection layer that contains a tetraazaporphyrin complex, the tetraazaporphyrin complex becomes an optional component of the charge transport layer. The tetraazaporphyrin complex functions as a light absorption compound, but the photoreceptor of the present disclosure may contain a known light absorption compound other than the tetraazaporphyrin complex as long as its effect is not inhibited. The tetraazaporphyrin complex and the known light absorption compound are as described above.

[0078] As the charge transport substance, compounds used in the art can be used. Specifically, carbazole derivatives, pyrene derivatives, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidazolone derivatives, imidazolidine derivatives, bisimidazolidine derivatives, styryl compounds, hydrazone compounds, polycyclic aromatic compounds, indole derivatives, pyrazoline derivatives, oxazolone derivatives, benzimidazole derivatives, quinazoline derivatives, benzofuran derivatives, acridine derivatives, phenazine derivatives, aminostilbene derivatives, triarylamine derivatives, triarylmethane derivatives, phenylenediamine derivatives, stilbene derivatives, butadiene derivatives, enamine derivatives, benzidine derivatives, polymers having groups derived from these compounds in the main chain or side chain (such as poly-N-vinylcarbazole, poly-1-vinylpyrene, ethylcarbazole-formaldehyde resin, triphenylmethane polymer, poly-9-vinylanthracene, etc.), polysilane, and the like. These charge transport materials can be used alone or in combination of two or more kinds.

[0079] Among these various charge transport materials, those having stilbene derivatives, butadiene derivatives, enamine derivatives, and those in which a plurality of these compounds are bonded are preferable in terms of electrical properties, durability, and chemical stability. Since they have light absorption in the wavelength range of 300 to 480 nm and have a wide range of absorption as hole transport materials, stilbene derivatives are more preferable. The following general formula (II):

Chemical formula

[0080] (In the formula, R 1 , R 2 , R 5 and R 6 are the same or different and are an alkyl group, an alkoxy group, an aryl group, or an aralkyl group; m, n, p, and q are the same or different and are integers from 0 to 3; R 3 and R 4 are the same or different and are a hydrogen atom or an alkyl group). The stilbene compound represented by [formula] is particularly preferred in that it has a small increase in residual potential and a small deterioration in sensitivity and can exhibit good electrophotographic characteristics.

[0081] The substituents R in general formula (II) 1 , R 2 , R 5 and R 6 as well as the indices m, n, p and q will be described. Examples of the alkyl group include alkyl groups having 1 to 6 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, and n-hexyl. Examples of the alkoxy group include alkoxy groups having 1 to 6 carbon atoms such as methoxy, ethoxy, n-propoxy, isopropoxy, tert-butoxy, n-pentyloxy, and n-hexyloxy. Examples of the aryl group include phenyl, naphthyl, anthryl, phenanthryl, fluorenyl, biphenylyl, o-terphenyl, and the like. Examples of the aralkyl group include benzyl, phenethyl, benzhydryl, trityl, and the like. Examples of the halogen atom include fluorine, chlorine, bromine, iodine, and the like.

[0082] The indices m, n, p and q are the same or different and are integers from 0 to 3, and when this index is 2 or more, each substituent may be different from each other. Also, as the alkyl groups of the substituents R 3 and R 4 in general formula (II), for example, alkyl groups having 1 to 3 carbon atoms such as methyl, ethyl, n-propyl, and isopropyl can be mentioned. The stilbene compound represented by general formula (II) can be synthesized, for example, by the method described in Japanese Patent No. 3272257.

[0083] Examples of the stilbene compound represented by the general formula (II) include the following compounds 2-1 to 2-3, and compound 2-1 is particularly preferred in terms of printing resistance when used in a laminated photosensitive layer.

[0084] [Chemical formula]

[0085] The binder resin is not particularly limited, and a resin having binding properties used in the technical field can be used, and those having excellent compatibility with the charge transport material are preferred. Specifically, vinyl polymer resins such as polymethyl methacrylate, polystyrene, and polyvinyl chloride, and copolymer resins thereof, as well as polycarbonate, polyester, polyester carbonate, polysulfone, phenoxy resin, epoxy resin, silicone resin, polyarylate, polyamide, polyether, polyurethane, polyacrylamide, phenolic resin, polyphenylene oxide, and other resins, and thermosetting resins obtained by partially crosslinking these resins can be mentioned. These binder resins can be used alone or in combination of two or more. Among these, polystyrene, polycarbonate, polyarylate, and polyphenylene oxide are preferred because they have a volume resistivity of 10 13 Ω or more, are excellent in electrical insulation, and are also excellent in film-forming properties, potential characteristics, etc. Polycarbonate and polyarylate are more preferred, and polycarbonate is particularly preferred.

[0086] Examples of the solvent include aromatic hydrocarbons such as benzene, toluene, xylene, and monochlorobenzene; halogenated hydrocarbons such as dichloromethane and dichloroethane; ethers such as tetrahydrofuran, dioxane, and dimethoxymethyl ether; and aprotic polar solvents such as N,N-dimethylformamide. Further, solvents such as alcohols, acetonitrile, or methyl ethyl ketone can be additionally added and used as necessary. These solvents can be used alone or in combination of two or more kinds. Among these solvents, in consideration of the global environment, for example, non-halogenated organic solvents can be preferably used.

[0087] The charge transport layer may contain additives such as a plasticizer, a leveling agent, and an antioxidant as necessary to improve film-forming properties, flexibility, and surface smoothness. Examples of the plasticizer include dibasic acid esters such as phthalic acid esters, fatty acid esters, phosphate esters, chlorinated paraffins, and epoxy type plasticizers. Examples of the leveling agent include silicone-based leveling agents. Examples of the antioxidant include tribenzylamine.

[0088] Further, the charge transport layer may contain fine particles of an organic compound or an inorganic compound in order to enhance mechanical strength and improve electrical characteristics. Examples of the organic filler material include fluororesin powders such as polytetrafluoroethylene, silicone resin powders, and a-carbon (amorphous carbon) powders. Examples of the inorganic filler material include metal powders such as copper, tin, aluminum, and indium, and metal oxides such as silica, tin oxide, zinc oxide, titanium oxide, indium oxide, antimony oxide, bismuth oxide, antimony-doped tin oxide, and tin-doped indium oxide, and inorganic materials such as potassium titanate.

[0089] The charge transport layer is formed, for example, in the same manner as when forming the aforementioned charge generation layer, by dissolving or dispersing a charge transport material, a binder resin, a tetraazaporphyrin complex, and further a light absorption compound and, if necessary, an additive in an appropriate solvent to prepare a coating solution for the charge transport layer, and applying this coating solution onto the charge generation layer by a spray method, a bar coating method, a roll coating method, a blade method, a ring method, or a dip coating method. Among these coating methods, the dip coating method is particularly suitable for forming the charge transport layer because it is excellent in various aspects as described above.

[0090] The blending ratio of the charge transport material and the binder resin is preferably such that the proportion of the charge transport material is in the range of 33 to 83% by mass. If the proportion of the charge transport material is less than 33% by mass, the abrasion resistance may be lowered. On the other hand, if the proportion of the charge transport material exceeds 83% by mass, the electrical characteristics may deteriorate. The contents of the tetraazaporphyrin complex and the light absorption compound are as described above.

[0091] The film thickness of the charge transport layer is not particularly limited, but is preferably 18 μm to 42 μm, more preferably 25 to 37 μm. If the film thickness of the charge transport layer is less than 18 μm, the effect of light resistance may not be sufficiently obtained. On the other hand, if the film thickness of the charge transport layer exceeds 42 μm, the electrical characteristics may deteriorate.

[0092] <Surface protection layer (not shown in FIG. 2)> The photoreceptor of the present disclosure may have a surface protection layer on the laminated photosensitive layer. The surface protection layer has a function of improving the durability of the photoreceptor and contains a binder resin, a tetraazaporphyrin complex, optionally a light absorption compound, and, if necessary, an additive. In the photoreceptor of the present disclosure, it is an essential requirement that the tetraazaporphyrin complex is contained in both or either one of the charge transport layer and the surface protection layer. For example, when the photoreceptor has a charge transport layer that does not contain the tetraazaporphyrin complex, the tetraazaporphyrin complex becomes an essential component of the surface protection layer. On the other hand, when the photoreceptor has a charge transport layer that contains the tetraazaporphyrin complex, the tetraazaporphyrin complex becomes an optional component of the surface protection layer. Regarding the tetraazaporphyrin complex and the light-absorbing compound, they conform to the charge transport layer.

[0093] As the binder resin, a resin having binding properties used in the art can be used. Examples include resins such as polystyrene, polyacetal, polyethylene, polycarbonate, polyarylate, polysulfone, polypropylene, and polyvinyl chloride. These binder resins can be used alone or in combination of two or more. Among these, considering the wear characteristics and electrical properties, polycarbonate and polyarylate are particularly preferred. In addition, the surface protection layer may contain one or more of the same charge transport substances as the charge transport layer for stabilizing the electrical properties. Regarding the charge transport substances, they conform to the charge transport layer.

[0094] Furthermore, the surface protection layer may contain a filler material for the purpose of improving the wear resistance. Examples of the filler material include organic filler materials such as fluororesin powder like polytetrafluoroethylene, silicone resin powder, and a-carbon powder, metal powders such as copper, tin, aluminum, and indium, and metal oxides such as silica, tin oxide, zinc oxide, titanium oxide, indium oxide, antimony oxide, bismuth oxide, antimony-doped tin oxide, and tin-doped indium oxide, and inorganic filler materials such as potassium titanate. From the viewpoint of the hardness of the filler, inorganic filler materials are particularly preferred.

[0095] In addition, the filler material may be surface-treated with inorganic or organic substances from the viewpoint of improving dispersibility in the coating liquid for coating formation. For example, those treated with a silane coupling agent for water repellency treatment, those treated with a fluorine-based silane coupling agent, those treated with a higher fatty acid, and those with the filler surface treated with alumina, zirconia, tin oxide, or silica can be mentioned. From the viewpoints of the light transmittance and abrasion resistance of the surface protective layer, the average primary particle diameter of the filler is preferably 0.01 to 0.5 μm.

[0096] The higher the content ratio of the filler material in the surface protective layer, the better the abrasion resistance, but it may cause adverse effects such as deterioration of electrical characteristics and a decrease in the writing light transmittance of the surface protective layer. Therefore, the filler material is generally 50% by mass or less, preferably 30% by mass or less, based on the total solid content of the surface protective layer. The contents of the tetraazaporphyrin complex and the light-absorbing compound are as described above.

[0097] The surface protective layer can be formed, for example, by dissolving a binder resin in an appropriate solvent to prepare a coating liquid for the surface protective layer, applying this coating liquid to the surface of the laminated photosensitive layer, and removing the organic solvent by drying. Specific formation methods follow those of the undercoat layer, charge generation layer, and charge transport layer. The film thickness of the surface protective layer is not particularly limited, but is preferably 3.0 to 7.0 μm, more preferably 4.0 to 6.0 μm. When the film thickness of the surface protective layer exceeds 3.0 μm, the effects of durability and light resistance may not be sufficiently obtained. On the other hand, when the film thickness of the surface protective layer exceeds 7.0 μm, the electrical characteristics may deteriorate.

[0098] (2) Process cartridge The process cartridge of the present disclosure is characterized by including at least one selected from the photosensitive member of the present disclosure, charging means for charging the photosensitive member, developing means for developing the electrostatic latent image formed by exposure to form a toner image, and cleaning means for removing the toner remaining on the photosensitive member.

[0099] For example, the process cartridge of the present disclosure is configured by integrating the photoreceptor, charging means (charger), developing means (developer), and cleaning means (cleaner) of the present disclosure onto a support member. When such a process cartridge is incorporated into the image forming apparatus 100, each part that is a component of the process cartridge will be provided in the image forming apparatus 100. Since the process cartridge is detachable from the image forming apparatus 100, replacement during consumption becomes easy.

[0100] (3) Image forming apparatus The image forming apparatus of the present disclosure is characterized by including at least the photoreceptor of the present disclosure, charging means for charging the photoreceptor, exposure means for exposing the charged photoreceptor to form an electrostatic latent image, developing means for developing the electrostatic latent image to form a toner image (visualizing), and transfer means for transferring the toner image onto a recording medium. The image forming apparatus of the present disclosure may include means selected from fixing means for fixing the transferred toner image onto the recording medium to form an image, cleaning means for removing and recovering the toner remaining on the photoreceptor, and discharging means for discharging the surface charges remaining on the photoreceptor. Hereinafter, the image forming apparatus of the present disclosure and its operation will be described with reference to the drawings, but the image forming apparatus of the present invention is not limited thereto.

[0101] FIG. 3 is a schematic side view of the configuration of the main part of the image forming apparatus 100 of the present disclosure. The image forming apparatus (laser printer) 100 in FIG. 3 includes the photoreceptor 1 (corresponding to F01 in FIG. 2) of the present disclosure, exposure means (semiconductor laser) 31, charging means (charger) 32, developing means (developer) 33, transfer means (transfer charger) 34, a conveyance belt (not shown), fixing means (fuser) 35, and cleaning means (cleaner) 36. Reference numeral 51 indicates a recording medium (recording paper or transfer paper).

[0102] The photoreceptor 1 is rotatably supported by the main body of the image forming apparatus 100, and is rotationally driven in the direction of arrow 41 around the rotation axis 44 by a driving means (not shown). The driving means is configured to include, for example, an electric motor and a reduction gear, and rotates the photoreceptor 1 at a predetermined peripheral speed by transmitting the driving force to the conductive support that constitutes the core of the photoreceptor 1. The charging means 32, the exposure means 31, the developing means 33, the transfer means 34, and the cleaning means 36 are provided in this order along the outer peripheral surface of the photoreceptor 1 from the upstream side to the downstream side in the rotation direction of the photoreceptor 1 indicated by the arrow 41.

[0103] The charger 32 is a charging means for uniformly charging the outer peripheral surface of the photoreceptor 1 to a predetermined potential. Examples of the charging means include a non-contact charging method such as a corona charging method using a charging charger, and a contact charging method using a charging roller or a charging brush, for example.

[0104] The exposure means 31 includes a semiconductor laser as a light source, and irradiates the surface of the photoreceptor 1 between the charger 32 and the developer 33 with the laser beam light output from the light source, thereby performing exposure on the outer peripheral surface of the charged photoreceptor 1 according to the image information. The light is repeatedly scanned in the direction in which the rotation axis 44 of the photoreceptor 1 extends, which is the main scanning direction, and these are imaged to sequentially form an electrostatic latent image on the surface of the photoreceptor 1. That is, a difference occurs in the charge amount of the photoreceptor 1 uniformly charged by the charger 32 due to the irradiation and non-irradiation of the laser beam, and an electrostatic latent image is formed.

[0105] The developer 33 is a developing means for developing the electrostatic latent image formed on the surface of the photoreceptor 1 by the developer (toner). It is provided facing the photoreceptor 1, and includes a developing roller 33a that supplies toner to the outer peripheral surface of the photoreceptor 1, and a casing 33b that rotatably supports the developing roller 33a around a rotation axis parallel to the rotation axis 44 of the photoreceptor 1 and houses a developer containing toner in its internal space.

[0106] The transfer charger 34 is a transfer means for transferring a toner image, which is a visible image formed on the outer peripheral surface of the photoreceptor 1 by development, onto a transfer paper 51, which is a recording medium supplied from the direction of arrow 42 between the photoreceptor 1 and the transfer charger 34 by a conveying means (not shown). The transfer charger 34 is, for example, a contact type transfer means that includes a charging means and transfers the toner image onto the transfer paper 51 by applying a charge of the opposite polarity to the toner to the transfer paper 51.

[0107] The cleaner 36 is a cleaning means for removing and collecting the toner remaining on the outer peripheral surface of the photoreceptor 1 after the transfer operation by the transfer charger 34, and includes a cleaning blade 36a for peeling off the toner remaining on the outer peripheral surface of the photoreceptor 1, and a recovery casing 36b for accommodating the toner peeled off by the cleaning blade 36a. Further, this cleaner 36 is provided together with a charge elimination lamp (not shown).

[0108] In addition, the image forming apparatus 100 is provided with a fixing device 35, which is a fixing means for fixing the transferred image, on the downstream side through which the transfer paper 51 that has passed between the photoreceptor 1 and the transfer charger 34 is conveyed. The fixing device 35 includes a heating roller 35a having a heating means (not shown), and a pressure roller 35b provided opposite to the heating roller 35a and pressed against the heating roller 35a to form a contact portion. Reference numeral 37 indicates separation means for separating the transfer paper and the photoreceptor, and reference numeral 38 indicates a housing (casing) for accommodating each means of the image forming apparatus.

[0109] The image forming operation by this image forming apparatus 100 is performed as follows. First, when the photoreceptor 1 is rotationally driven in the direction of arrow 41 by a driving means, the surface of the photoreceptor 1 is uniformly charged to a positive predetermined potential by a charger 32 provided on the upstream side in the rotational direction of the photoreceptor 1 with respect to the light imaging point by the exposure means 31.

[0110] Next, light corresponding to the image information is irradiated from the exposure means 31 onto the surface of the photoreceptor 1. Due to this exposure, the surface charges of the portions of the photoreceptor 1 irradiated with light are removed, a difference occurs between the surface potential of the portions irradiated with light and the surface potential of the portions not irradiated with light, and an electrostatic latent image is formed. Toner is supplied from the developing device 33 provided on the downstream side in the rotation direction of the photoreceptor 1 from the imaging point of the light by the exposure means 31 to the surface of the photoreceptor 1 on which the electrostatic latent image is formed, and the electrostatic latent image is developed to form a toner image.

[0111] In synchronization with the exposure of the photoreceptor 1, the transfer paper 51 is supplied between the photoreceptor 1 and the transfer charger 34. The transfer charger 34 applies charges of the opposite polarity to the supplied transfer paper 51, and the toner image formed on the surface of the photoreceptor 1 is transferred onto the transfer paper 51. The transfer paper 51 onto which the toner image is transferred is conveyed by the conveying means to the fixing device 35, and is heated and pressurized when passing through the contact portion between the heating roller 35a and the pressure roller 35b of the fixing device 35, and the toner image is fixed on the transfer paper 51 to become a firm image. The transfer paper 51 on which the image is thus formed is discharged to the outside of the image forming apparatus 100 by the conveying means.

[0112] On the other hand, the toner remaining on the surface of the photoreceptor 1 even after the transfer of the toner image by the transfer charger 34 is peeled off from the surface of the photoreceptor 1 by the cleaner 36 and recovered. The charges on the surface of the photoreceptor 1 from which the toner has been thus removed are removed by the light from the charge removal lamp, and the electrostatic latent image on the surface of the photoreceptor 1 disappears. Thereafter, the photoreceptor 1 is further rotationally driven, and a series of operations starting from charging are repeated to continuously form images.

[0113] The image forming apparatus 100 described above is a monochrome image forming apparatus (printer), but it may also be, for example, an intermediate transfer type color image forming apparatus capable of forming color images. Specifically, it may be a so-called tandem type full-color image forming apparatus having a configuration in which multiple electrophotographic photosensitive members on which toner images are respectively formed are arranged side by side in a predetermined direction (for example, horizontal direction H or approximately horizontal direction H). Furthermore, the image forming apparatus 100 may also be another color image forming apparatus, a copier, a multifunction machine, or a facsimile machine. [Example]

[0114] The photoreceptor of the present disclosure will be specifically described below using examples and comparative examples, but the present invention is not limited to these examples as long as they do not depart from the gist of the invention. In the examples and comparative examples, a photoreceptor without a surface protective layer was used, but the same effect can be obtained by using a photoreceptor with a surface protective layer. In the examples and comparative examples, the materials used and the physical properties of the resulting photoreceptors were measured by the following methods.

[0115] (1) Maximum absorption wavelength λ of tetraazaporphyrin complexes and light-absorbing compounds max and half-width Using an ultraviolet-visible spectrophotometer (Shimadzu Corporation, UV-VIS SPECTROPHOTOMETER, model: UV-2450), the spectral absorption spectra of the tetraazaporphyrin complex and the light-absorbing compound are measured in the wavelength range of 400 to 900 nm. From the results obtained, the maximum absorption wavelength was determined as λ max Let us assume that. For tetraazaporphyrin complexes, the half-width (nm) is defined as the distance between two intersections formed by a line parallel to the horizontal axis drawn at half the absorption coefficient (absorbance) at the maximum (maximum) absorption wavelength (peak) of the spectroscopic absorption spectrum and the peak. Also, the absorption spectrum of the charge transport layer is measured by collecting 0.10 g of the charge transport layer of the photoreceptor, dissolving it in 20 g of THF, and measuring the spectral absorption spectrum with an optical path length of 10 mm in the wavelength range of 400 to 900 nm. From the obtained results, the maximum absorption wavelength is set as λ max and so on. Let the absorbance at a wavelength of 620 nm of the absorption spectrum be A620 and the absorbance at 610 nm be A610, and calculate the absorbance ratio.

[0116] (2) Absorption spectrum of the charge transport layer Collect 0.10 g of the charge transport layer from the produced photoreceptor and dissolve it in 20 g of the solvent tetrahydrofuran. Set the obtained solution in the ultraviolet-visible spectrophotometer of (1) above, and measure the spectral absorption spectrum with an optical path length of 10 mm in the wavelength range of 400 to 900 nm. From the obtained results, calculate the absorbance ratio (A610 / A550) with the absorbances at wavelengths of 610 nm and 550 nm being A610 and A550, respectively.

[0117] [Example 1] (Formation of the undercoat layer) 3 parts by mass of titanium oxide (manufactured by Ishihara Sangyo Co., Ltd., product name: Type-Pake TTO-D-1) and 2 parts by mass of copolymer polyamide (nylon) (manufactured by Toray Industries, Inc., product name: Amilan (registered trademark), grade: CM8000) were added to 25 parts by mass of methyl alcohol, and dispersed for 8 hours with a paint shaker to prepare 3 liters of the coating solution for the undercoat layer. Fill the obtained coating solution for the undercoat layer into a coating tank, immerse a drum-shaped support made of aluminum with a diameter of 30 mm and a length of 255 mm as the conductive support F1, then pull it up, and naturally dry the obtained coating film to form an undercoat layer F21 with a film thickness of 1 μm on the conductive support F1.

[0118] (Formation of the charge generation layer) Previously, titanyl phthalocyanine represented by the following structural formula, which is used as a charge generating substance, was prepared.

Chemical formula

[0119] 29.2 g of diiminophthalimide and 200 ml of sulfolane were mixed, and 17.0 g of titanium tetraisopropoxide was further added. The mixture was reacted at 140 °C for 2 hours under a nitrogen atmosphere. After allowing the obtained reaction mixture to cool, the precipitate was collected by filtration, washed successively with chloroform and a 2% aqueous hydrochloric acid solution, and further washed successively with water and methanol, and then dried to obtain 25.5 g of blue-violet crystals. As a result of chemical analysis of the obtained compound, it was confirmed to be titanyl phthalocyanine represented by the above structural formula (yield 88.5%).

[0120] 1 part by mass of the obtained titanyl phthalocyanine and 1 part by mass of a butyral resin (manufactured by Sekisui Chemical Co., Ltd., product name: Esrec BM-2) were added to 98 parts by mass of methyl ethyl ketone, and dispersed for 2 hours using a paint shaker to prepare 3 liters of a coating solution for the charge generation layer. The obtained coating solution for the charge generation layer was applied onto the undercoat layer F21 by the same dipping method as in the case of forming the undercoat layer, and the obtained coating film was naturally dried to form a charge generation layer F22 with a film thickness of 0.3 μm.

[0121] (Formation of Charge Transport Layer) Next, 10.0 g of a compound 2-1 (stilbene derivative) represented by the following structural formula as a hole transport material, 0.30 g of tribenzylamine (manufactured by Tokyo Chemical Industry Co., Ltd., product code: T0341) as an antioxidant, 14.0 g of polycarbonate (manufactured by Teijin Chemicals Ltd., product name: Panlite (registered trademark) TS2050) as a binder resin, a tetraazaporphyrin complex A (λ max = 604 nm) 0.052 g, and 0.520 g of a perimidine compound (a) (λ max = 480 nm, C.I. Solvent Red 179, manufactured by American Dyestuff, product name: AmesolveRedA) as a light-absorbing compound were added to 99.49 g of tetrahydrofuran, and mixed to prepare approximately 125 g of a coating solution for the charge transport layer.

[0122] [Chemical Formula]

[0123]

Chem.

[0124]

Chem.

[0125] The obtained coating solution for the charge transport layer was applied onto the charge generation layer F22 by the same dipping method as in the case of forming the undercoat layer, and the obtained coating film was dried at a temperature of 115°C for 1.5 hours to form a charge transport layer F23 with a film thickness of 35 μm, and the photoreceptor F01 of Example 1 shown in FIG. 2 was produced. In addition, the above-mentioned complex A and compound 2-1 (stilbene derivative) were prepared in advance and used based on the methods described in JP-A-2007-99744 and Japanese Patent No. 3272257, respectively. Also, for the following complexes B to K, those prepared in advance were used based on the method described in JP-A-2007-99744 in the same manner as the above-mentioned complex A.

[0126] FIG. 1 is a diagram showing the spectral absorption spectrum of the tetraazaporphyrin complex A of the present disclosure. From this figure, it can be seen that the maximum absorption wavelength of complex A is 604 nm, the half-value width is 17 nm, and the absorbance ratio λ610 / λ620 is 2.9. FIG. 4 is a diagram showing the spectral absorption spectrum of the charge transport layer of the photoreceptor (Example 1) of the present disclosure. From this figure, it can be seen that the absorbance ratio (A610 / A550) of the charge transport layer is 0.59, the maximum absorption wavelength of the charge transport layer is 600 nm, and the absorbance ratio λ610 / λ620 is 0.248.

[0127] [Example 2] In the preparation of the coating solution for the charge transport layer, a photoreceptor of Example 2 was produced in the same manner as in Example 1, except that complex B (λ max = 603 nm) represented by the following structural formula was used instead of complex A. [Chemical formula]

[0128] [Example 3] In the preparation of the coating liquid for the charge transport layer, a photoreceptor of Example 3 was produced in the same manner as in Example 1, except that complex C (λ max = 584 nm) represented by the following structural formula was used instead of complex A. [Chemical formula]

[0129] [Example 4] In the preparation of the coating liquid for the charge transport layer, a photoreceptor of Example 4 was produced in the same manner as in Example 1, except that complex D (λ max = 609 nm) represented by the following structural formula was used instead of complex A. [Chemical formula]

[0130] [Example 5] In the preparation of the coating liquid for the charge transport layer, a photoreceptor of Example 5 was produced in the same manner as in Example 1, except that a thiadiazole compound (d) (λ max = 374 nm, dye, manufactured by Tokyo Chemical Industry Co., Ltd., product code: T3922) represented by the following structural formula was used instead of the perimidine compound (a) as the light-absorbing compound. [Chemical formula]

[0131] [Example 6] In the preparation of the coating liquid for the charge transport layer, a photoreceptor of Example 6 was produced in the same manner as in Example 1, except that a pyrazolone compound (c) (λ max = 553 nm) represented by the following structural formula was used instead of the perimidine compound (a) as the light-absorbing compound. The above pyrazolone compound (c) was prepared in advance and used based on the method described in Japanese Patent No. 4041741. [Chemical formula]

[0132] [Example 7] In the preparation of the coating solution for the charge transport layer, except that the perimidine compound (a) as the light absorption compound was replaced with a benzotriazole compound (e) as the light absorption compound represented by the following structural formula (λ max = 340 nm, manufactured by Chemipro Kasei Co., Ltd., product name: KEMISORB 71), a photoreceptor of Example 7 was produced in the same manner as in Example 1. [Chemical formula]

[0133] [Example 8] In the preparation of the coating solution for the charge transport layer, except that the perimidine compound (a) as the light absorption compound was replaced with a pyrazolone compound (c') represented by the following structural formula (λ max = 580 nm), a photoreceptor of Example 8 was produced in the same manner as in Example 1. The pyrazolone compound (c') was prepared in advance and used based on the method described in Japanese Patent No. 4041741. [Chemical formula]

[0134] [Example 9] In the preparation of the coating solution for the charge transport layer, a photoreceptor of Example 9 was produced in the same manner as in Example 1, except that 0.520 g of the compound (a) as the light absorption compound was changed to 0.375 g, and 99.49 g of tetrahydrofuran was changed to 98.91 g.

[0135] [Example 10] In the preparation of the coating liquid for the charge transport layer, a photoreceptor of Example 10 was produced in the same manner as in Example 1, except that 0.520 g of compound (a) as the light-absorbing compound was changed to 1.060 g and 99.49 g of tetrahydrofuran was changed to 101.65 g.

[0136] [Example 11] In the preparation of the coating liquid for the charge transport layer, a photoreceptor of Example 11 was produced in the same manner as in Example 1, except that 0.520 g of compound (a) as the light-absorbing compound was changed to 0.258 g and 99.49 g of tetrahydrofuran was changed to 98.44 g.

[0137] [Example 12] In the preparation of the coating liquid for the charge transport layer, a photoreceptor of Example 12 was produced in the same manner as in Example 1, except that 0.520 g of compound (a) as the light-absorbing compound was changed to 1.150 g and 99.49 g of tetrahydrofuran was changed to 102.01 g.

[0138] [Example 13] In the preparation of the coating liquid for the charge transport layer, a photoreceptor of Example 13 was produced in the same manner as in Example 1, except that complex E (λ max = 593 nm) represented by the following structural formula was used instead of complex A.

Chemical formula

[0139] [Example 14] In the preparation of the coating liquid for the charge transport layer, a photoreceptor of Example 14 was produced in the same manner as in Example 1, except that complex F (λ max = 595 nm) represented by the following structural formula was used instead of complex A.

Chemical formula

[0140] [Example 15] In the preparation of the coating liquid for the charge transport layer, a photoreceptor of Example 15 was produced in the same manner as in Example 1, except that complex G (λ maxA photoreceptor of Example 14 was produced in the same manner as in Example 1, except that light having a wavelength of 593 nm was used. [Chemical formula]

[0141] [Example 16] A photoreceptor of Example 16 was produced in the same manner as in Example 1, except that in the preparation of the coating solution for the charge transport layer, 0.052 g of complex A was changed to 0.030 g and 99.49 g of tetrahydrofuran was changed to 99.40 g.

[0142] [Example 17] A photoreceptor of Example 17 was produced in the same manner as in Example 1, except that in the preparation of the coating solution for the charge transport layer, 0.052 g of complex A was changed to 0.150 g and 99.49 g of tetrahydrofuran was changed to 99.89 g.

[0143] [Example 18] A photoreceptor of Example 18 was produced in the same manner as in Example 1, except that in the preparation of the coating solution for the charge transport layer, 0.052 g of complex A was changed to 0.022 g and 99.49 g of tetrahydrofuran was changed to 100.61 g.

[0144] [Example 19] A photoreceptor of Example 19 was produced in the same manner as in Example 1, except that in the preparation of the coating solution for the charge transport layer, 0.052 g of complex A was changed to 0.177 g and 99.49 g of tetrahydrofuran was changed to 99.99 g.

[0145] [Example 20] In the preparation of the coating solution for the charge transport layer, a photoreceptor of Example 20 was produced in the same manner as in Example 1, except that complex H represented by the following structural formula (λ max = 585 nm) was used. [Chemical formula]

[0146] [Example 21] In the preparation of the coating liquid for the charge transport layer, except for not adding the light absorption compound and changing 99.49 g of tetrahydrofuran to 97.41 g, the photoreceptor of Example 21 was produced in the same manner as in Example 1.

[0147] [Comparative Example 1] In the preparation of the coating liquid for the charge transport layer, except for using Complex I (λ max = 596 nm) represented by the following structural formula instead of Complex A, the photoreceptor of Comparative Example 1 was produced in the same manner as in Example 1. [Chemical Formula]

[0148] [Comparative Example 2] In the preparation of the coating liquid for the charge transport layer, except for using Complex J (λ max = 579 nm) represented by the following structural formula instead of Complex A, the photoreceptor of Comparative Example 2 was produced in the same manner as in Example 1. [Chemical Formula]

[0149] [Comparative Example 3] In the preparation of the coating liquid for the charge transport layer, except for using Complex K (λ max = 610 nm) represented by the following structural formula instead of Complex A, the photoreceptor of Comparative Example 3 was produced in the same manner as in Example 1. [Chemical Formula]

[0150] [Comparative Example 4] In the preparation of the coating liquid for the charge transport layer, except for using an anthraquinone-based dye (λ max = 590 nm, C.I. Solvent Violet 31, manufactured by Kowa Chemical Industry Co., Ltd., product name: KP Plast Violet R) instead of Complex A, the photoreceptor of Comparative Example 4 was produced in the same manner as in Example 1.

[0151] [Evaluation] The light resistance and (2) sensitivity stability of the produced photoreceptors of Examples 1 to 21 and Comparative Examples 1 to 4 were evaluated as follows, and a comprehensive evaluation was performed based on the results.

[0152] (1) Light resistance The photoreceptor to be evaluated was wrapped in light-shielding paper with a 10 mm × 30 mm window opened, and exposed to the light of a fluorescent lamp with an illuminance of 1000 Lux for 10 minutes and the light of a fluorescent lamp with an illuminance of 400 Lux for 20 minutes through the window, and then left for 1 minute. Then, the photoreceptor was mounted on the unit of a digital copier (manufactured by Sharp Corporation, model: MX-B455W) modified for testing, a halftone image was printed, and the printing of the exposed part and the non-exposed part was compared and evaluated, and the light resistance of the photoreceptor was evaluated according to the following criteria.

[0153] <Evaluation criteria> VG: No influence on the image under both exposure conditions G: Slight image defects are observed in the exposure at 1000 Lux, but there is no influence on the image in the exposure at 400 Lux, and there is no problem. NB: Slight image defects are observed even in the exposure at 400 Lux, but there is no problem in actual use. B: Clear image defects can be confirmed after light exposure, and there is a problem in actual use.

[0154] (2) Potential stability (sensitivity stability) The photoreceptor to be evaluated was mounted on the unit of a digital copier (manufactured by Sharp Corporation, model: BP-40C26) modified for testing, the developing device was removed from the digital copier, and instead, a surface electrometer (manufactured by Trek Japan Co., Ltd., model: MODEL344) was attached to the developing part. In an environment of temperature 25°C / relative humidity 50%, the initial residual potential and the surface potential of the photoreceptor after energization fatigue were measured, and the difference ΔVr (V) was used to evaluate the sensitivity stability, which is an index of sensitivity deterioration due to repeated use, according to the following evaluation criteria.

[0155] <Evaluation criteria> VG: ΔVr < 60 It can be used without problems even in high-speed multifunction machines or printers that require high sensitivity. G: 60 ≤ ΔVr < 100 It can be used without problems in medium- and low-speed multi-function devices or printers. NB: 100 ≤ ΔVr < 140 In the case of low-speed and inexpensive multi-function devices or printers, it can be used without problems although the density is slightly low. B: 140 ≤ ΔVr Due to poor sensitivity, the density is low and there are problems in actual use.

[0156] (3) Comprehensive evaluation Based on the above evaluation results, the photoreceptor was comprehensively evaluated according to the following criteria. <Evaluation criteria> VG: VG evaluation in all items, very good It can be used without problems even in multi-function devices or printers that require long life and high image quality. G: Although it includes G evaluation in any one item, it is G evaluation or above in all items. It can be used without problems except for multi-function devices and printers that require long life and high image quality. NB: Although it includes NB evaluation in any one item, it is NB evaluation or above in all items. It can be used without problems in inexpensive multi-function devices or printers. B: There is B evaluation in any one item and it cannot be used in actual use. Due to poor sensitivity, the density is low and there are problems in actual use.

[0157] The constituent materials of the charge transport layer, their optical properties and contents, the optical properties of the charge transport layer are shown in Table 2, and the evaluation results of the photoreceptor are shown in Table 3.

[0158]

Table 2

[0159]

Table 3

[0160] From Tables 2 and 3, the following can be understood. (1) The photoreceptors (Examples 1 to 21) having the constituent elements of the present disclosure are excellent in both light resistance and potential stability (sensitivity stability), whereas the photoreceptors (Comparative Examples 1 to 4) not having the constituent elements of the present disclosure are inferior. (2) A photoreceptor (Comparative Example 1) containing a tetraazaporphyrin complex with an absorbance ratio of 610 nm to 620 nm (λ610 / λ620) of 2.0 or less is inferior in light resistance and potential stability. This is thought to be due to the fact that the amount of light blocked at a wavelength of 610 nm is small and the amount of light blocked at a wavelength of 620 nm is large.

[0161] (3) The photoconductor containing a tetraazaporphyrin complex with a maximum absorption wavelength of less than 580 nm (Comparative Example 2) is inferior in light resistance. This is thought to be due to the reduced amount of light blocked at 610 nm. The photoconductor containing a tetraazaporphyrin complex with a maximum absorption wavelength of 580 nm or more but on the lower wavelength side (Example 3) shows a similar tendency, even though it is within a range that does not pose a problem in practical use. (4) The photoconductor containing a tetraazaporphyrin complex whose maximum absorption exceeds 609 nm (Comparative Example 3) is inferior in light resistance. This is thought to be due to the reduced amount of light blocked at 610 nm. The photoconductor containing a tetraazaporphyrin complex whose maximum absorption does not exceed 609 nm but is on the higher wavelength side (Example 4) shows a similar tendency, even though it is within a range that does not cause problems in practical use.

[0162] (5) The photoreceptor not containing the tetraazaporphyrin complex (Comparative Example 4) was inferior in light resistance and potential stability. This is thought to be because the absorption peak was broadened, the amount of light with a wavelength of 610 nm was reduced, and the static elimination light with a wavelength of around 620 nm was blocked. (6) The photoreceptors (Examples 15 and 20) containing tetraazaporphyrin complexes having a half-width at the maximum absorption wavelength exceeding 20 nm are inferior in light resistance.

[0163] (7) Photoconductors containing light-absorbing compounds with maximum absorption on the short wavelength side (Examples 5 and 7) are inferior in light resistance, which is thought to be due to the fact that they block less light around 550 nm wavelength, such as that from fluorescent lamps. (8) Photoreceptors containing a light-absorbing compound with maximum absorption on the long-wavelength side (Examples 6 and 8) are inferior in potential stability, which is considered to be because the charge-removing light near a wavelength of 620 nm is blocked by the light-absorbing compound.

[0164] (9) Photoreceptors (Examples 9 and 11) with a ratio A610 / A550 of the absorbance A610 at a wavelength of 610 nm to the absorbance A550 at a wavelength of 550 nm in the charge transport layer near 1.00 are inferior in light resistance, which is considered to be because the amount of light blocked near a wavelength of 550 nm, such as that from a fluorescent lamp, decreases. (10) Photoreceptors (Examples 10 and 12) with a ratio A610 / A550 of the absorbance A610 at a wavelength of 610 nm to the absorbance A550 at a wavelength of 550 nm in the charge transport layer near 0.25 are inferior in potential stability, which is considered to be because the light-absorbing compound itself becomes a trap.

[0165] (11) A photoreceptor (Example 21) that does not contain a light-absorbing compound having a maximum absorption in the wavelength range of 370 to 560 nm in the spectral absorption spectrum is slightly inferior in light resistance, but overall, it is an excellent photoreceptor in both light resistance and potential stability.

Explanation of symbols

[0166] F01 Electrophotographic photoreceptor F1 Conductive support (conductive substrate) F21 Undercoat layer (intermediate layer) F22 Charge generation layer F23 Charge transport layer Fa Photoreceptor surface

[0167] 1 Photoreceptor 31 Exposure means (semiconductor laser) 32 Charging means (charger) 33 Developing means (developer) 33a Developing roller 33b Casing 34 Transfer means (transfer charger) 35 Fixing means (fuser) 35a Heating roller 35b Pressing Roller 36 Cleaning Means (Cleaner) 36a Cleaning Blade 36b Recovery Casing 37 Separating Means 38 Housing (Casing) 41, 42 Arrow Signs 44 Rotation Axis 51 Recording Medium (Recording Paper or Transfer Paper) 100 Image Forming Apparatus (Laser Printer)

Claims

1. An electrophotographic photoreceptor comprising at least a laminated photosensitive layer in which a charge generation layer and a charge transport layer are sequentially laminated on a conductive support, or an electrophotographic photoreceptor comprising at least the laminated photosensitive layer and a surface protective layer laminated on the laminated photosensitive layer, wherein both or either one of the charge transport layer and the surface protective layer has a maximum absorption in the wavelength range of 580 to 609 nm in the spectral absorption spectrum, and when the absorbances at wavelengths 610 nm and 620 nm are λ610 and λ620, respectively, the following formula: 2.0 < λ610 / λ620 is satisfied, and contains a tetraazaporphyrin complex represented by the general formula (I): 【Chemical 1】 (wherein, X 1 to X 4 are the same or different and are a halogen atom; or a linear, branched or cyclic alkyl group which may be substituted with a halogen atom, Y 1 to Y 4 are the same or different and are a hydrogen atom; a linear or branched alkoxy group having 1 to 3 carbon atoms which may be substituted with a halogen atom or an alkoxy group; an aryloxy group; an aryl group which may have a substituent; a heteroaryl group; an alkylthio group; or an arylthio group, and M is a divalent metal atom, a monosubstituted trivalent metal atom, a disubstituted tetravalent metal atom or an oxy metal atom) An electrophotographic photoreceptor characterized by the above.

2. The electrophotographic photoreceptor according to claim 1, wherein the tetraazaporphyrin complex has a half-value width of 20 nm or less at the maximum absorption wavelength of the spectral absorption spectrum.

3. The electrophotographic photoreceptor according to claim 1 or 2, wherein both or either one of the charge transport layer and the surface protective layer further contains a light absorption compound having a maximum absorption in the wavelength range of 370 to 560 nm in the spectral absorption spectrum.

4. When the absorbances at wavelengths 610 nm and 550 nm are A610 and A550, respectively, in the spectral absorption spectrum of both or either one of the charge transport layer and the surface protective layer, the following formula: 0.25 ≦ (A610 / A550) ≦ 1.00 is satisfied. The electrophotographic photoreceptor according to claim 1 or 2.

5. The electrophotographic photoreceptor according to claim 1 or 2, wherein the tetraazaporphyrin complex is a complex in which the central metal M in the general formula (I) is a vanadium oxy group.

6. The tetraazaporphyrin complex is a substituent X in the general formula (I). 1 ~X 4 is a linear, branched or cyclic alkyl group, and the substituent Y 1 ~Y 4 is an electron photographic photoreceptor according to claim 1 or 2, which is a complex that is a hydrogen atom, a linear alkoxy group substituted with a halogen atom, or an aryl group that may have a substituent.

7. The electrophotographic photoreceptor according to claim 1 or 2, wherein the tetraazaporphyrin complex is contained in a proportion of 0.10 to 0.70% by mass based on the total solid content of the charge transport layer.

8. A process cartridge comprising at least one selected from the electrophotographic photoreceptor according to claim 1 or 2, charging means for charging the electrophotographic photoreceptor, developing means for developing an electrostatic latent image formed by exposure to form a toner image, and cleaning means for removing toner remaining on the electrophotographic photoreceptor.

9. An image forming apparatus comprising at least: the electrophotographic photoreceptor according to claim 1 or 2; charging means for charging the electrophotographic photoreceptor; exposure means for exposing the charged electrophotographic photoreceptor to form an electrostatic latent image; developing means for developing the electrostatic latent image to form a toner image; and transfer means for transferring the toner image onto a recording medium.

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