Electrophotographic photoreceptor, process cartridge, and image forming device

Abstract

The present invention relates to an electrophotographic photoreceptor, a processing box and an image forming device. The electrophotographic photoreceptor has a conductive substrate and a photosensitive layer provided on the conductive substrate, wherein the outermost surface layer contains fluorine-containing resin particles, a fluorine-based graft polymer and an acidic compound having an acid dissociation constant (pKa) of 3 or less in water at 25°C, and the content of the acidic compound is 100 ppm or more and 10000 ppm or less relative to the outermost surface layer.

Description

Technical Field

[0001] The present invention relates to an electronic photographic photoreceptor, a process cartridge and an image forming device. Background Art

[0002] Conventionally, as an image forming apparatus using the electrophotographic method, an apparatus that includes an electrophotographic photoreceptor and performs steps such as charging, electrostatic latent image formation, development, transfer, and cleaning in sequence is widely known.

[0003] As an electrophotographic photoreceptor, a photoreceptor having an outermost surface layer containing fluorine-containing resin particles is widely known.

[0004] Furthermore, the fluorine-containing resin particles include particles obtained by irradiation with radiation, particles obtained by a polymerization method, and the like.

[0005] For example, Japanese Patent Publication No. 2018-24869 discloses “a method for producing low molecular weight polytetrafluoroethylene, characterized in that it comprises the following steps: step (1), polytetrafluoroethylene, at least one additive selected from the group consisting of hydrocarbons, chlorinated hydrocarbons, alcohols and carboxylic acids (excluding perfluorocarboxylic acids having a carbon number of 8 to 14), and at least one selected from the group consisting of an inert gas (excluding the above-mentioned additive) and an oxygen adsorbent are placed in a closed container; and step (2), the polytetrafluoroethylene is irradiated with radiation to obtain a complex viscosity of 1×10 at 380°C. 2 ~7×10 5 Pa·s of low molecular weight polytetrafluoroethylene. ".

[0006] In addition, Japanese Patent Publication No. 2018-24868 discloses “a method for producing low molecular weight polytetrafluoroethylene, characterized in that it comprises the following steps: step (1), irradiating polytetrafluoroethylene with radiation to obtain a melt viscosity of 1×10 at 380°C. 2 ~7×10 5 Pa·s of low molecular weight polytetrafluoroethylene; step (2), crushing the low molecular weight polytetrafluoroethylene; and step (3), heat treating the low molecular weight polytetrafluoroethylene crushed in step (2). ".

[0007] In addition, Japanese Patent Publication No. 4-20507 discloses "a tetrafluoroethylene copolymer, which is a copolymer of tetrafluoroethylene and at least one perfluoro(alkyl vinyl ether), which contains 1 to 10% by weight of perfluoro(alkyl vinyl ether) units, and the number of -CONH2 terminal groups is 10 6 7 to 20 carbon atoms, excluding -CH2OH and -COF, melt viscosity at 380°C is 0.1×10 4 ~100×10 4 moor. ". Summary of the invention

[0008] Technical problem to be solved by the invention

[0009] The technical problem to be solved by the present invention is to provide an electrophotographic photosensitive body, which can suppress the increase of residual potential compared with the case where the electrophotographic photosensitive body has a conductive substrate and a photosensitive layer arranged on the above-mentioned conductive substrate and the outermost surface layer contains fluorine-containing resin particles and fluorine-based grafted polymers, contains an acidic compound with an acid dissociation constant (pKa) greater than 3 in water at 25°C, the case where the content of acidic compounds with an acid dissociation constant (pKa) of 3 or less in water at 25°C is less than 100 ppm relative to the outermost surface layer, or contains isophthalic acid with an acid dissociation constant (pKa) of 3.54 in water at 25°C.

[0010] Means for solving technical problems

[0011] The above technical problems are solved by the following solutions.

[0012] According to the first embodiment of the present invention, an electrophotographic photosensitive body is provided, which has a conductive substrate and a photosensitive layer arranged on the above-mentioned conductive substrate, and the outermost surface layer of the electrophotographic photosensitive body contains fluorine-containing resin particles, fluorine-based grafted polymers and acidic compounds with an acid dissociation constant (pKa) of 3 or less in water at 25°C, and the content of the above-mentioned acidic compounds is not less than 100 ppm and not more than 10000 ppm relative to the outermost surface layer.

[0013] According to a second aspect of the present invention, the acid dissociation constant (pKa) of the acidic compound is -2.8 to 2.5.

[0014] According to a third aspect of the present invention, the acid dissociation constant (pKa) of the acidic compound is -2 to 1.5.

[0015] According to a fourth aspect of the present invention, the acidic compound is at least one selected from the group consisting of sulfonic acid compounds, carboxylic acid compounds, phosphoric acid compounds, and nitric acid compounds.

[0016] According to a fifth aspect of the present invention, the acidic compound is at least one selected from the group consisting of sulfonic acid compounds and carboxylic acid compounds.

[0017] According to a sixth aspect of the present invention, the sulfonic acid compound is a sulfonic acid compound having a benzene ring, and the carboxylic acid compound is a carboxylic acid compound having 2 to 4 carboxyl groups.

[0018] According to a seventh aspect of the present invention, the content of the acidic compound is 150 ppm to 5000 ppm with respect to the outermost surface layer.

[0019] According to an eighth aspect of the present invention, in the above-mentioned fluorine-containing resin particles, every 10 6 The number of carboxyl groups per carbon atom is 0 to 30, and the amount of the basic compound is 0 ppm to 3 ppm.

[0020] According to a ninth aspect of the present invention, in the above-mentioned fluorine-containing resin particles, every 10 6 The number of carboxyl groups per carbon atom is 0 to 20, and the amount of the basic compound is 0 ppm to 3 ppm.

[0021] According to a tenth aspect of the present invention, in the above-mentioned fluorine-containing resin particles, every 10 6 The amount of carboxyl groups having carbon atoms is 0 to 20, and the amount of the basic compound is 0 ppm to 1.5 ppm.

[0022] According to an eleventh aspect of the present invention, the basic compound is an amine compound.

[0023] According to a twelfth aspect of the present invention, the basic compound is a basic compound having a boiling point of 40°C to 130°C.

[0024] According to the 13th scheme of the present invention, there is provided an electrophotographic photosensitive body, which has a conductive substrate and a photosensitive layer arranged on the above-mentioned conductive substrate, and the outermost surface layer of the electrophotographic photosensitive body contains fluorine-containing resin particles, fluorine-based grafted polymers and at least one acidic compound selected from the group consisting of sulfonic acid compounds, carboxylic acid compounds having more than 2 and less than 4 carboxyl groups, phosphoric acid compounds and nitric acid compounds, and the content of the above-mentioned acidic compounds is more than 100 ppm and less than 10000 ppm relative to the outermost surface layer.

[0025] According to a fourteenth aspect of the present invention, there is provided a process cartridge that is detachably mounted in an image forming apparatus and includes the above-mentioned electrophotographic photoreceptor.

[0026] According to the 15th scheme of the present invention, there is provided an image forming device, which comprises: the above-mentioned electronic photographic photosensitive body; a charging mechanism for charging the surface of the above-mentioned electronic photographic photosensitive body; an electrostatic latent image forming mechanism for forming an electrostatic latent image on the charged surface of the above-mentioned electronic photographic photosensitive body; a developing mechanism for developing the electrostatic latent image formed on the surface of the above-mentioned electronic photographic photosensitive body using a developer containing a toner to form a toner image; and a transfer mechanism for transferring the above-mentioned toner image to the surface of a recording medium.

[0027] Effects of the Invention

[0028] According to each of the above-mentioned schemes 1, 4, 5, and 6, an electrophotographic photosensitive body is provided, which can suppress the increase of residual potential compared with the case where an electrophotographic photosensitive body having a conductive substrate and a photosensitive layer arranged on the above-mentioned conductive substrate and the outermost surface layer contains fluorine-containing resin particles and a fluorine-based grafted polymer, contains an acidic compound whose acid dissociation constant (pKa) in water at 25°C is greater than 3, or the case where the content of acidic compounds whose acid dissociation constant (pKa) in water at 25°C is less than 3 is less than 100 ppm relative to the outermost surface layer.

[0029] According to the second and third aspects, an electrophotographic photoreceptor is provided, wherein an increase in residual potential is suppressed compared to a case where the acid dissociation constant (pKa) of the acidic compound is less than -2.8 or greater than 2.5 (less than -2 or greater than 1.5).

[0030] According to the seventh aspect, there is provided an electrophotographic photoreceptor capable of suppressing an increase in residual potential compared with a case where the content of the acidic compound is less than 150 ppm with respect to the outermost surface layer.

[0031] According to each of the eighth, ninth and tenth embodiments, there is provided a fluorine-containing resin particle having a 6 The fluorine-containing resin particles of this embodiment can suppress the increase in residual potential compared to the case where the number of carboxyl groups per carbon atom is greater than 30 (or greater than 20) or the amount of the basic compound is greater than 3 ppm (or greater than 1.5 ppm).

[0032] According to each of the eleventh and twelfth aspects, there is provided a fluorine-containing resin particle having excellent charging properties compared with a case where the amount of the basic compound, the amine compound or the basic compound having a boiling point of 40° C. to 130° C., is greater than 3 ppm.

[0033] According to the above-mentioned scheme 13, an electrophotographic photosensitive body is provided, which can suppress the increase of residual potential compared with the case where the electrophotographic photosensitive body has a conductive substrate and a photosensitive layer arranged on the above-mentioned conductive substrate and the outermost surface layer contains fluorine-containing resin particles and a fluorine-based grafted polymer, and contains isophthalic acid with an acid dissociation constant (pKa) of 3.54 in water at 25°C.

[0034] According to each of the above-mentioned schemes 14 and 15, a processing box having an electrophotographic photosensitive body or an image forming device having the electrophotographic photosensitive body is provided. Compared with the case where an electrophotographic photosensitive body having a conductive substrate and a photosensitive layer provided on the above-mentioned conductive substrate and the outermost surface layer comprising fluorine-containing resin particles and a fluorine-based grafted polymer comprises an electrophotographic photosensitive body containing an acidic compound having an acid dissociation constant (pKa) greater than 3 in water at 25°C, a case where an electrophotographic photosensitive body having an acid dissociation constant (pKa) of 3 or less in water at 25°C and a content of an acidic compound having an acid dissociation constant (pKa) of 3 or less relative to the outermost surface layer is less than 100 ppm, or a case where an electrophotographic photosensitive body comprises isophthalic acid having an acid dissociation constant (pKa) of 3.54 in water at 25°C, the electrophotographic photosensitive body possessed by the above-mentioned scheme can suppress the increase in residual potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a schematic cross-sectional view showing an example of the layer structure of the electrophotographic photoreceptor according to the present embodiment.

[0036] Figure 2 This is a schematic structural diagram showing an example of the image forming apparatus according to the present embodiment.

[0037] Figure 3 This is a schematic structural diagram showing another example of the image forming apparatus according to the present embodiment. DETAILED DESCRIPTION

[0038] Hereinafter, an embodiment as an example of the present invention will be described in detail.

[0039] In addition, in the numerical range described in stages in the present specification, the upper limit value or the lower limit value described in a certain numerical range can be replaced with the upper limit value or the lower limit value of the numerical range described in another stage.

[0040] In addition, in the numerical range, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the value shown in the embodiment.

[0041] When two or more substances corresponding to each component are present in the composition, the amount of each component in the composition refers to the total amount of the two or more substances present in the composition unless otherwise specified.

[0042] The term "step" includes not only independent steps but also steps that cannot be clearly distinguished from other steps as long as the intended purpose of the step can be achieved.

[0043] <Electrophotographic Photoreceptor>

[0044] The electronic photographic photoreceptor of the first embodiment (hereinafter also referred to as the "photoreceptor of the first embodiment") has a conductive substrate and a photosensitive layer arranged on the above-mentioned conductive substrate, and the outermost surface layer contains fluorine-containing resin particles, fluorine-based grafted polymers and acidic compounds with an acid dissociation constant (pKa) of less than 3 in water at 25°C, and the content of the above-mentioned acidic compounds is greater than 100 ppm and less than 1.0% relative to the outermost surface layer.

[0045] The electronic photographic photoreceptor of the second embodiment (hereinafter also referred to as the "photoreceptor of the second embodiment") has a conductive substrate and a photosensitive layer arranged on the above-mentioned conductive substrate, and the outermost surface layer contains fluorine-containing resin particles, fluorine-based grafted polymers and at least one acidic compound selected from the group consisting of sulfonic acid compounds having a benzene ring, carboxylic acid compounds having 2 or more and 4 or less carboxyl groups, phosphoric acid compounds and nitric acid compounds, and the content of the above-mentioned acidic compounds is not less than 100 ppm and not more than 1.0% relative to the outermost surface layer.

[0046] The outermost layer may be a charge transport layer of a laminated photosensitive layer, a single-layer photosensitive layer, a surface protective layer, or the like.

[0047] The photoreceptors of the first and second embodiments can suppress the increase in residual potential by the above-mentioned configuration. The reason for this is presumably as follows.

[0048] "An acidic compound having an acid dissociation constant (pKa) of 3 or less" or "at least one acidic compound selected from the group consisting of a sulfonic acid compound having a benzene ring, a carboxylic acid compound having 2 or more and 4 or less carboxyl groups, a phosphoric acid compound, and a nitric acid compound" can both make the outermost surface layer have low resistance when mixed in the outermost surface layer.

[0049] Therefore, when these acidic compounds are contained in the outermost layer in a range of 100 ppm to 1.0%, the resistance can be appropriately reduced and an increase in residual potential can be suppressed.

[0050] The following describes in detail a photoreceptor that conforms to both the first embodiment and the second embodiment (hereinafter also referred to as "the photoreceptor of this embodiment"). An example of the photoreceptor of the present invention is a photoreceptor that conforms to either of the first and second embodiments.

[0051] The electrophotographic photoreceptor according to this embodiment will be described below with reference to the drawings.

[0052] Figure 1The electrophotographic photoreceptor 7 shown may have a structure in which an undercoat layer 1, a charge generating layer 2, and a charge transporting layer 3 are sequentially stacked on a conductive support 4. The charge generating layer 2 and the charge transporting layer 3 constitute a photosensitive layer 5.

[0053] It should be noted that the electrophotographic photoreceptor 7 may have a layer structure without providing the undercoat layer 1 .

[0054] The electrophotographic photoreceptor 7 may include a single-layer photosensitive layer integrating the functions of the charge generating layer 2 and the charge transporting layer 3. In the case of a photoreceptor including a single-layer photosensitive layer, the single-layer photosensitive layer constitutes the outermost layer.

[0055] The electrophotographic photoreceptor 7 may also be a photoreceptor having a surface protective layer on the charge transport layer 3 or on the single-layer photosensitive layer. In the case of a photoreceptor having a surface protective layer, the surface protective layer constitutes the outermost surface layer.

[0056] Hereinafter, each layer of the electrophotographic photoreceptor of this embodiment will be described in detail. Note that reference numerals will be omitted in the description.

[0057] (Outermost surface layer)

[0058] The outermost surface layer contains fluorine-containing resin particles, fluorine-based graft polymers and acidic compounds. The outermost surface layer contains additives according to the applied layer (charge transport layer of a laminated photosensitive layer, a single-layer photosensitive layer or a surface protective layer). It should be noted that the details of the applied layer are described below.

[0059] - Fluorine-containing resin particles -

[0060] Examples of the fluorine-containing resin particles include particles of a homopolymer of a fluoroolefin and particles of a copolymer of two or more fluoroolefins, that is, a copolymer of one or more fluoroolefins and a non-fluorine-containing monomer (that is, a monomer having no fluorine atom).

[0061] Examples of the fluoroolefin include perhaloolefins such as tetrafluoroethylene (TFE), perfluorovinyl ether, hexafluoropropylene (HFP), and chlorotrifluoroethylene (CTFE), and non-perfluoroolefins such as vinylidene fluoride (VdF), trifluoroethylene, and vinyl fluoride. Among these, VdF, TFE, CTFE, and HFP are preferred.

[0062] On the other hand, as non-fluorine-based monomers, for example, hydrocarbon olefins such as ethylene, propylene, and butene can be cited; alkyl vinyl ethers such as cyclohexyl vinyl ether (CHVE), ethyl vinyl ether (EVE), butyl vinyl ether, and methyl vinyl ether; alkenyl vinyl ethers such as polyoxyethylene allyl ether (POEAE) and ethyl allyl ether; organic silicon compounds having reactive α,β-unsaturated groups such as vinyl trimethoxysilane (VSi), vinyl triethoxysilane, and vinyl tri(methoxyethoxy)silane; acrylic acid esters such as methyl acrylate and ethyl acrylate; methacrylic acid esters such as methyl methacrylate and ethyl methacrylate; vinyl esters such as vinyl acetate, vinyl benzoate, and "VeoVA" (trade name, vinyl ester manufactured by Shell); etc. Among these, alkyl vinyl ethers, allyl vinyl ethers, vinyl esters, and organic silicon compounds having reactive α,β-unsaturated groups are preferred.

[0063] Among these, as fluorine-containing resin particles, particles with a high fluorination rate are preferred, and particles of polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymer (PFA), ethylene-tetrafluoroethylene copolymer (ETFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE) and the like are more preferred, and particles of PTFE, FEP, and PFA are particularly preferred.

[0064] The fluorine-containing resin particles are preferably 6 Particles having a carboxyl group number of 0 to 30 carbon atoms and a basic compound amount of 0 ppm to 3 ppm.

[0065] When the number of carboxyl groups and the amount of the basic compound in the fluorine-containing resin particles are within the above ranges, an increase in residual potential can be further suppressed.

[0066] Here, the fluorine-containing resin particles include particles obtained by irradiation with radiation (also referred to as "radiation-irradiated fluorine-containing resin particles" in this specification) and particles obtained by polymerization (also referred to as "polymerized fluorine-containing resin particles" in this specification).

[0067] The radiation-irradiated fluororesin particles (fluororesin particles obtained by irradiation) are fluororesin particles obtained by granulation by radiation polymerization, or fluororesin particles obtained by decomposing the polymerized fluororesin by irradiation to reduce the molecular weight and micronize the polymerized fluororesin.

[0068] The radiation-irradiated fluorine-containing resin particles generate a large amount of carboxylic acid by irradiation with radiation in the air, and therefore also contain a large amount of carboxyl groups.

[0069] On the other hand, polymerized fluorine-containing resin particles (fluorine-containing resin particles obtained by a polymerization method) refer to fluorine-containing resin particles which are granulated while being polymerized by a suspension polymerization method, an emulsion polymerization method or the like and which are not irradiated with radiation.

[0070] The polymerizable fluorine-containing resin particles are produced by polymerization in the presence of a basic compound and therefore contain the basic compound as a residue.

[0071] That is, conventional fluorine-containing resin particles contain a large amount of carboxyl groups or basic compounds.

[0072] When the fluorine-containing resin particles contain a large number of carboxyl groups, they exhibit ion conductivity and thus have a property of being difficult to be charged.

[0073] When a large amount of existing fluorine-containing resin particles containing a carboxyl group is contained in the outermost surface layer of an electrophotographic photoreceptor, the chargeability of the photoreceptor may be reduced under a high-temperature and high-humidity environment.

[0074] On the other hand, when the fluorine-containing resin particles contain a large amount of a basic compound, the basic compound exhibits a hole-trapping property and thus has a property of being difficult to be charged.

[0075] When the outermost surface layer of the electrophotographic photoreceptor contains a large amount of conventional fluorine-containing resin particles containing a basic compound, the residual potential may increase with time.

[0076] Therefore, by suppressing the amount of carboxyl groups and alkaline compounds in the fluorine-containing resin particles within the above range, the chargeability can be improved. It should be noted that when the number of carboxyl groups and the amount of alkaline compounds are suppressed within the above range, even if the number of carboxyl groups is slightly large, if the amount of alkaline compounds is large, the ion conductivity and hole-trapping properties offset each other, and there is a tendency for the chargeability to become better.

[0077] Therefore, when the outermost surface layer of the electrophotographic photoreceptor contains fluorine-containing resin particles having carboxyl groups and basic compounds in amounts within the above ranges, a decrease in chargeability and an increase in residual potential can be suppressed.

[0078] The number of carboxyl groups in the fluorine-containing resin particles is preferably 0 to 20 from the viewpoint of improving charging properties.

[0079] Here, the carboxyl group of the fluorine-containing resin particles is, for example, a carboxyl group derived from a terminal carboxylic acid contained in the fluorine-containing resin particles.

[0080] As methods for reducing the carboxyl group content of fluorine-containing resin particles, the following methods can be cited: 1) a method of not irradiating with radiation during the particle production process; 2) a method of irradiating with radiation in the absence of oxygen or under conditions of reduced oxygen concentration; and the like.

[0081] The carboxyl group content of the fluorine-containing resin particles is measured as described in Japanese Patent Application Laid-Open No. 4-20507 and the like, and is determined as follows.

[0082] The fluorine-containing resin particles were preformed using a press to produce a film with a thickness of about 0.1 mm. The produced film was subjected to infrared absorption spectrum measurement. The fluorine-containing resin particles whose carboxylic acid ends were completely fluorinated by contacting fluorine gas with the fluorine-containing resin particles were also subjected to infrared absorption spectrum measurement. The number of terminal carboxyl groups (per 10 6 carbon atoms) = (l×K) / t

[0083] l: absorbance

[0084] K: Correction coefficient

[0085] t: film thickness (mm)

[0086] The absorption wave number of carboxyl group is set at 3560 cm -1 , the correction factor is set to 440.

[0087] On the other hand, from the viewpoint of suppressing an increase in residual potential, the amount of the basic compound in the fluorine-containing resin particles is preferably from 0 ppm to 1.5 ppm, more preferably from 0 ppm to 1.2 ppm. It should be noted that ppm is a mass basis.

[0088] The basic compound of the fluorine-containing resin particles is, for example: 1) a basic compound derived from a polymerization initiator used when the fluorine-containing resin particles are polymerized and simultaneously granulated; 2) a basic compound used in the step of agglomeration after polymerization; and 3) a basic compound used as a dispersing aid to stabilize the dispersion after polymerization; etc.

[0089] Examples of the basic compound include amine compounds, hydroxides of alkali metals or alkaline earth metals, oxides of alkali metals or alkaline earth metals, acetates, and the like (for example, amine compounds are particularly useful).

[0090] Examples of the basic compound include basic compounds having a boiling point (boiling point at normal pressure (1 atm)) of 40°C to 130°C (preferably 50°C to 110°C, more preferably 60°C to 90°C).

[0091] Examples of the amine compound include primary amine compounds, secondary amine compounds, and tertiary amine compounds.

[0092] Examples of the primary amine compound include methylamine, ethylamine, propylamine, isopropylamine, n-butylamine, isobutylamine, tert-butylamine, hexylamine, 2-ethylhexylamine, sec-butylamine, allylamine, and methylhexylamine.

[0093] Examples of the secondary amine compound include dimethylamine, diethylamine, di-n-propylamine, diisopropylamine, di-n-butylamine, diisobutylamine, di-tert-butylamine, dihexylamine, di(2-ethylhexyl)amine, N-isopropyl-N-isobutylamine, di-sec-butylamine, diallylamine, N-methylhexylamine, 3-methylpyridine, 4-methylpyridine, 2,4-dimethylpiperidine, 2,6-dimethylpiperidine, 3,5-dimethylpiperidine, morpholine, and N-methylbenzylamine.

[0094] Examples of the tertiary amine compound include trimethylamine, triethylamine, tri-n-propylamine, triisopropylamine, tri-n-butylamine, triisobutylamine, tri-tert-butylamine, trihexylamine, tri(2-ethylhexyl)amine, N-methylmorpholine, N,N-dimethylallylamine, N-methyldiallylamine, triallylamine, N,N-dimethylallylamine, N,N,N',N'-tetramethyl-1,2-diaminoethane, N,N,N',N'-tetramethyl-1,3-diaminopropane, N,N,N',N'-tetraallyl-1,4-diaminobutane, N-methylpiperidine, pyridine, 4-ethylpyridine, N-propylamine, 2-Methyl-4-ethylpyridine, 2-methyl-5-ethylpyridine, N,N,N',N'-tetramethyl-1,6-hexanediamine, N-ethyl-3-hydroxypiperidine, 3-methyl-4-ethylpyridine, 3-ethyl-4-methylpyridine, 4-(5-nonyl)pyridine, imidazole, N-methylpiperazine, etc.

[0095] Examples of the hydroxide of an alkali metal or an alkaline earth metal include NaOH, KOH, Ca(OH) 2 , Mg(OH) 2 , and Ba(OH) 2 .

[0096] Examples of the oxide of an alkali metal or an alkaline earth metal include CaO and MgO.

[0097] Examples of acetates include zinc acetate and sodium acetate.

[0098] Methods for reducing the amount of alkaline compounds in fluorine-containing resin particles include: 1) washing the particles with water, organic solvents (alcohols such as methanol, ethanol, isopropanol, tetrahydrofuran, etc.) after the particles are manufactured; 2) heating the particles after they are manufactured (for example, heating to a temperature of 200°C to 250°C) to remove the alkaline compounds by decomposition or vaporization; and the like.

[0099] The amount of the basic compound in the fluorine-containing resin particles is measured as follows.

[0100] -Pre-treatment-

[0101] The outermost surface layer containing fluorine-containing resin particles is immersed in a solvent (e.g., tetrahydrofuran), and substances other than fluorine-containing resin particles and solvent-insoluble substances are dissolved in a solvent (e.g., tetrahydrofuran), and then added dropwise to pure water to filter out the precipitate. The solution containing perfluorooctanoic acid (PFOA) obtained at this time is captured. Further, the insoluble matter obtained by filtering is dissolved in a solvent, and then added dropwise to pure water to filter out the precipitate. This operation is repeated 5 times to obtain fluorine-containing resin particles as a measurement sample.

[0102] When a composition containing fluorine-containing resin particles is used as the measurement object, the composition is subjected to the same treatment as in the case of the outermost surface layer to obtain fluorine-containing resin particles as a measurement sample.

[0103] When the fluorine-containing resin particles themselves are the object of measurement, the fluorine-containing resin particles are subjected to the same treatment as in the case of measuring from the outermost surface layer to obtain fluorine-containing resin particles as measurement samples.

[0104] - Determination -

[0105] On the other hand, using a basic compound solution (methanol solvent) of known concentration, a calibration curve (calibration curve from 0 ppm to 100 ppm) is obtained from the basic compound concentration and peak area values ​​of the basic compound solution (methanol solvent) of known concentration by gas chromatography.

[0106] Thereafter, the measurement sample was measured by gas chromatography, and the amount of the basic compound in the fluorine-containing resin particles was calculated from the obtained peak area and the calibration curve. The measurement conditions were as follows.

[0107] -Measurement conditions-

[0108] Headspace sampler: (HP7694, manufactured by HP)

[0109] ·Measurement machine: Gas chromatograph (HP6890 series, manufactured by HP)

[0110] Detector: Flame ionization detector (FID)

[0111] Column: HP19091S-433, manufactured by HP)

[0112] Sample heating time: 10min

[0113] Split ratio: 300:1

[0114] Flow rate: 1.0ml / min

[0115] Column temperature setting: 60℃(3min), 60℃ / min, 200℃(1min)

[0116] The fluorine-containing resin particles are preferably polymerizable fluorine-containing resin particles. As described above, the polymerizable fluorine-containing resin particles are fluorine-containing resin particles that are polymerized and granulated by suspension polymerization, emulsion polymerization, etc., and are not irradiated with radiation.

[0117] Here, the production of fluorine-containing resin particles by suspension polymerization is, for example, a method in which monomers for forming fluorine-containing resins are suspended in a dispersion medium together with additives such as a polymerization initiator and a catalyst, and the polymer is granulated while polymerizing the monomers.

[0118] The production of fluorine-containing resin particles by emulsion polymerization is, for example, a method in which monomers for forming fluorine-containing resins are emulsified together with additives such as polymerization initiators and catalysts in a dispersion medium using a surfactant (i.e., an emulsifier), and then the polymer is granulated while the monomers are polymerized.

[0119] In particular, the fluorine-containing resin particles may be particles obtained without irradiation with radiation in the production step.

[0120] Among these, radiation-irradiated fluororesin particles obtained by irradiating fluororesin particles in the absence of oxygen or under conditions where the oxygen concentration is reduced may also be used.

[0121] The average particle size of the fluorine-containing resin particles is not particularly limited, and is preferably 0.2 μm to 4.5 μm, and more preferably 0.2 μm to 4 μm. Fluorine-containing resin particles (especially fluororesin particles such as PTFE particles) with an average particle size of 0.2 μm to 4.5 μm tend to contain a large amount of PFOA. Therefore, fluorine-containing resin particles with an average particle size of 0.2 μm to 4.5 μm have a tendency to have low chargeability. However, by suppressing the amount of PFOA within the above range, even fluorine-containing resin particles with an average particle size of 0.2 μm to 4.5 μm have high chargeability.

[0122] The average particle size of the fluorine-containing resin particles is a value measured by the following method.

[0123] The maximum diameter of the fluorine-containing resin particles (secondary particles formed by agglomeration of primary particles) is measured by SEM (scanning electron microscope) at a magnification of 5000 or more, and the measurement is performed on 50 particles and the average value obtained is used as the average particle size of the fluorine-containing resin particles. It should be noted that JSM-6700F manufactured by JEOL Ltd. is used as SEM, and secondary electron images with an acceleration voltage of 5 kV are observed.

[0124] From the viewpoint of dispersion stability, the specific surface area (BET specific surface area) of the fluorine-containing resin particles is preferably 5 m 2 / g above 15m 2 / g or less, more preferably 7m 2 / g above 13m 2 / g or less.

[0125] In addition, the specific surface area is a value measured by the nitrogen replacement method using a BET type specific surface area measuring instrument (manufactured by Shimadzu Corporation: FlowsoapII2300).

[0126] From the viewpoint of dispersion stability, the apparent density of the fluorine-containing resin particles is preferably from 0.2 g / ml to 0.5 g / ml, more preferably from 0.3 g / ml to 0.45 g / ml.

[0127] In addition, the apparent density is a value measured according to JIS K6891 (1995).

[0128] The melting temperature of the fluorine-containing resin particles is preferably 300°C or higher and 340°C or lower, more preferably 325°C or higher and 335°C or lower.

[0129] In addition, the melting temperature is a melting point measured according to JIS K6891 (1995).

[0130] -Fluorine-based graft polymers-

[0131] Fluorine-based graft polymers are dispersants containing fluorine.

[0132] Examples of the fluorine-based graft polymer include polymers obtained by homopolymerizing or copolymerizing a polymerizable compound having a fluoroalkyl group (hereinafter also referred to as "fluoroalkyl group-containing polymer").

[0133] Specific examples of the fluorine-based graft polymer include homopolymers of (meth)acrylates having a fluoroalkyl group, random or block copolymers of (meth)acrylates having a fluoroalkyl group and a monomer having no fluorine atom, etc. (Meth)acrylates refer to both acrylates and methacrylates.

[0134] Examples of the (meth)acrylate having a fluoroalkyl group include 2,2,2-trifluoroethyl (meth)acrylate and 2,2,3,3,3-pentafluoropropyl (meth)acrylate.

[0135] Examples of the monomer not having a fluorine atom include (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, isooctyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, methoxytriethylene glycol (meth)acrylate, 2-ethoxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, benzyl (meth)acrylate, ethyl carbitol (meth)acrylate, phenoxyethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, hydroxyethyl o-phenylphenol (meth)acrylate, and o-phenylphenol glycidyl ether (meth)acrylate.

[0136] In addition, as the fluorine-based graft polymer, specifically, block or branched polymers disclosed in US Pat. No. 5,637,142, Japanese Patent No. 4,251,662, etc. Further, as the fluorine-based graft polymer, specifically, fluorine-based surfactants can be mentioned.

[0137] Among these, as the fluorine-based graft polymer, a fluorinated alkyl-containing polymer having a structural unit represented by the following general formula (FA) is preferred, and a fluorinated alkyl-containing polymer having a structural unit represented by the following general formula (FA) and a structural unit represented by the following general formula (FB) is more preferred.

[0138] Next, the fluorinated alkyl group-containing polymer having a structural unit represented by the following general formula (FA) and a structural unit represented by the following general formula (FB) will be described.

[0139] [Chemistry 2]

[0140]

[0141] In the general formulas (FA) and (FB), R F1 , R F2 , R F3 and R F4 Each independently represents a hydrogen atom or an alkyl group.

[0142] X F1 It represents an alkylene chain, a halogen-substituted alkylene chain, -S-, -O-, -NH- or a single bond.

[0143] Y F1 represents an alkylene chain, a halogen-substituted alkylene chain, -(C fx H 2fx-1 (OH))- or single bond.

[0144] Q F1 It represents -O- or -NH-.

[0145] fl, fm and fn each independently represent an integer of 1 or more.

[0146] fp, fq, fr and fs each independently represent an integer of 0 or 1 or more.

[0147] ft represents an integer of 1-7.

[0148] fx represents an integer greater than or equal to 1.

[0149] In the general formulas (FA) and (FB), as R F1 , R F2 , R F3 and R F4 The group is preferably a hydrogen atom, a methyl group, an ethyl group, a propyl group, etc., more preferably a hydrogen atom, a methyl group, and further preferably a methyl group.

[0150] In the general formulas (FA) and (FB), as X F1 and Y F1 The alkylene chain (unsubstituted alkylene chain, halogen-substituted alkylene chain) is preferably a linear or branched alkylene chain having 1 to 10 carbon atoms.

[0151] Represents Y F1 -(C fx H 2fx-1 It is preferred that fx in (OH)- represents an integer of 1-10.

[0152] It is preferred that fp, fq, fr and fs each independently represent 0 or an integer of 1 to 10.

[0153] For example, fn is preferably 1 to 60.

[0154] Here, the ratio of the structural unit represented by the general formula (FA) to the structural unit represented by the general formula (FB) in the fluorine-based graft polymer, i.e., fl:fm, is preferably in the range of 1:9 to 9:1, and more preferably in the range of 3:7 to 7:3.

[0155] In the fluorine-based graft polymer, in addition to the structural unit represented by the general formula (FA) and the structural unit represented by the general formula (FB), the structural unit represented by the general formula (FC) may be further included. The content ratio of the structural unit represented by the general formula (FC) to the total of the structural units represented by the general formulas (FA) and (FB) (i.e., fl+fm) (fl+fm:fz) is preferably in the range of 10:0 to 7:3, and more preferably in the range of 9:1 to 7:3.

[0156] [Chemistry 3]

[0157]

[0158] In the general formula (FC), R F5 and R F6 Each independently represents a hydrogen atom or an alkyl group. fz represents an integer of 1 or greater.

[0159] In the general formula (FC), as R F5 and R F6 The group is preferably a hydrogen atom, a methyl group, an ethyl group, a propyl group, etc., more preferably a hydrogen atom, a methyl group, and further preferably a methyl group.

[0160] Examples of commercially available fluorine-based graft polymers include GF300 and GF400 (manufactured by Toagosei Co., Ltd.), Surflon series (manufactured by AGC Seimi Chemical Co., Ltd.), Ftergent series (manufactured by NOES Co., Ltd.), PF series (manufactured by Kitamura Chemical Co., Ltd.), MEGAFACE series (manufactured by DIC), and FC series (manufactured by 3M).

[0161] From the viewpoint of improving the dispersibility of the fluorine-containing resin particles, the weight average molecular weight Mw of the fluorine-based graft polymer is preferably from 20,000 to 200,000, more preferably from 50,000 to 200,000.

[0162] The weight average molecular weight of the fluorine-based graft polymer is a value measured by gel permeation chromatography (GPC). For molecular weight measurement by GPC, for example, a Tosoh GPC HLC-8120 is used as a measuring device, a Tosoh column TSKgel GMHHR-M + TSKgel GMHHR-M (7.8 mmI.D. 30 cm) is used, and a chloroform solvent is used for measurement, and a molecular weight calibration curve prepared using a monodisperse polystyrene standard sample is used to calculate based on the measurement result.

[0163] The content of the fluorine-based graft polymer is, for example, preferably from 0.5% by mass to 10% by mass, and more preferably from 1% by mass to 7% by mass, based on the fluorine-containing resin particles.

[0164] In addition, the fluorine-based graft polymer may be used alone or in combination of two or more.

[0165] -Acidic compounds-

[0166] The acidic compound is an acidic compound having an acid dissociation constant (pKa) of 3 or less in water at 25°C.

[0167] Here, the acid dissociation constant (pKa) refers to the first acid dissociation constant (pKa1).

[0168] From the viewpoint of suppressing an increase in residual potential, the acid dissociation constant (pKa) of the acidic compound is preferably -2.8 to 2.5, more preferably -2.1 to 2.5, further preferably -2 to 2.5, and most preferably 0.5 to 2.

[0169] The acidic compound may be any of an inorganic acid and an organic acid. The acidic compound may be used alone or in combination of two or more.

[0170] Examples of the inorganic acid include phosphoric acid compounds (having PO -3 Compounds with NO3 - Compounds containing radicals: such as nitric acid) etc.

[0171] Examples of the organic acid include sulfonic acid compounds and carboxylic acid compounds.

[0172] Sulfonic acid compounds are compounds with SOH3 - Examples of the sulfonic acid compound include sulfonic acid compounds having a benzene ring substituted with an alkyl group having 1 to 20 carbon atoms (preferably 1 to 12 carbon atoms) (such as toluenesulfonic acid, benzenesulfonic acid, dodecylbenzenesulfonic acid, 2,4-dimethylbenzenesulfonic acid, and hydroxybenzenesulfonic acid), alkylsulfonic acids having 1 to 6 carbon atoms (preferably 1 to 4 carbon atoms) (such as methylsulfonic acid, ethylsulfonic acid, propanesulfonic acid, and butanesulfonic acid), and hydrates thereof.

[0173] The carboxylic acid compound is a compound having a -COOH group. Examples of the carboxylic acid compound include oxalic acid, N,N-dimethylanthranilic acid, maleic acid, pyromellitic acid, acetoformic acid, tartaric acid, citric acid, trifluoroacetic acid, and phthalic acid.

[0174] That is, the acidic compound is preferably at least one selected from the group consisting of sulfonic acid compounds, carboxylic acid compounds, phosphoric acid compounds, and nitric acid compounds from the viewpoint of suppressing an increase in residual potential.

[0175] Among these, the acidic compound is more preferably at least one selected from the group consisting of sulfonic acid compounds and carboxylic acid compounds, and further preferably at least one selected from the group consisting of sulfonic acid compounds having a benzene ring and carboxylic acid compounds having 2 to 4 carboxyl groups.

[0176] The content of the acidic compound is 100 ppm to 5000 ppm relative to the outermost surface layer. From the perspective of suppressing the rise of residual potential, the content of the acidic compound is preferably 100 ppm to 5000 ppm, more preferably 150 ppm to 5000 ppm, and most preferably 200 ppm to 2000 ppm. It should be noted that ppm is a mass reference.

[0177] By including more than 100ppm of an acidic compound in the outermost surface layer, the residual potential rise can be suppressed. On the other hand, when a large amount of an acidic compound is included in the outermost surface layer, the charging property is reduced (specifically, dark decay increases and charge retention is reduced) due to the influence of humidity. Therefore, the content of the acidic compound is made less than 10000ppm.

[0178] (Conductive substrate)

[0179] As the conductive substrate, for example, metal plates, metal cylinders, and metal belts made of metals (aluminum, copper, zinc, chromium, nickel, molybdenum, vanadium, indium, gold, platinum, etc.) or alloys (stainless steel, etc.) can be cited. In addition, as the conductive substrate, for example, conductive compounds (such as conductive polymers, indium oxide, etc.), metals (such as aluminum, palladium, gold, etc.), or papers, resin films, and belts coated, vapor-deposited, or laminated with alloys can also be cited. Here, "conductive" means that the volume resistivity is less than 10 13 Ωcm.

[0180] When an electrophotographic photoreceptor is used in a laser printer, the surface of the conductive substrate is preferably roughened to a center line average roughness Ra of 0.04 μm or more and 0.5 μm or less in order to suppress interference fringes generated when irradiating laser. It should be noted that when non-interference light is used as a light source, roughening for preventing interference fringes is not particularly necessary, but since the roughening can suppress the occurrence of defects caused by the surface unevenness of the conductive substrate, it is suitable for further extending the life.

[0181] Examples of the roughening method include wet honing in which an abrasive is suspended in water and sprayed onto the conductive substrate; centerless grinding in which the conductive substrate is pressed against a rotating grindstone and continuously ground; and anodizing.

[0182] As a method for roughening the surface, there is also a method in which, instead of roughening the surface of the conductive substrate, conductive or semiconductive powder is dispersed in a resin to form a layer on the surface of the conductive substrate, and the surface is roughened using particles dispersed in the layer.

[0183] The roughening treatment by anodic oxidation is a roughening treatment in which an oxide film is formed on the surface of the conductive substrate by anodizing a conductive substrate made of metal (e.g., aluminum) as an anode in an electrolyte solution. As the electrolyte solution, for example, sulfuric acid solution, oxalic acid solution, etc. can be cited. However, the porous anodic oxide film formed by anodic oxidation is chemically active in its original state, easily contaminated, and the resistance change due to the environment is also large. Therefore, it is preferred that the porous anodic oxide film is subjected to the following sealing treatment: in pressurized steam or boiling water (metal salts such as nickel can also be added), the volume expansion caused by the hydration reaction is utilized to block the micropores of the oxide film, so that it becomes a more stable hydrated oxide.

[0184] The film thickness of the anodic oxide film is preferably, for example, 0.3 μm or more and 15 μm or less. When the film thickness is within the above range, the film tends to exhibit a barrier property against injection and tends to suppress an increase in residual potential due to repeated use.

[0185] The conductive substrate may be subjected to a treatment using an acidic treatment liquid or a boehmite treatment.

[0186] The treatment based on the acidic treatment solution is implemented, for example, as follows. First, an acidic treatment solution containing phosphoric acid, chromic acid and hydrofluoric acid is prepared. The mixing ratio of phosphoric acid, chromic acid and hydrofluoric acid in the acidic treatment solution can be, for example, a range of 10 mass % to 11 mass % for phosphoric acid, a range of 3 mass % to 5 mass % for chromic acid, and a range of 0.5 mass % to 2 mass % for hydrofluoric acid, and the overall concentration of these acids can be in the range of 13.5 mass % to 18 mass %. The treatment temperature is, for example, preferably 42° C. to 48° C. The film thickness of the coating is preferably 0.3 μm to 15 μm.

[0187] The boehmite treatment is carried out, for example, by immersing in pure water at 90°C to 100°C for 5 to 60 minutes or contacting with heated steam at 90°C to 120°C for 5 to 60 minutes. The film thickness of the coating is preferably 0.1 μm to 5 μm. It can also be further anodized using an electrolyte solution with low coating solubility such as adipic acid, boric acid, borate, phosphate, phthalate, maleate, benzoate, tartrate, citrate, etc.

[0188] (Base coating)

[0189] The undercoat layer is, for example, a layer containing inorganic particles and a binding resin.

[0190] Examples of inorganic particles include particles having a powder resistance (volume resistivity) of 10 2 Ωcm or more 10 11 Inorganic particles below Ωcm.

[0191] Among these, examples of the inorganic particles having the above resistance value include metal oxide particles such as tin oxide particles, titanium oxide particles, zinc oxide particles, and zirconium oxide particles, and zinc oxide particles are particularly preferred.

[0192] The specific surface area of ​​the inorganic particles based on the BET method can be, for example, 10 m 2 / g or above.

[0193] The volume average particle size of the inorganic particles can be, for example, 50 nm to 2000 nm (preferably 60 nm to 1000 nm).

[0194] The content of the inorganic particles is, for example, preferably from 10% by mass to 80% by mass, and more preferably from 40% by mass to 80% by mass, based on the binder resin.

[0195] The inorganic particles may be subjected to a surface treatment. Among the inorganic particles, two or more kinds of inorganic particles having different surface treatments or inorganic particles having different particle sizes may be mixed and used.

[0196] Examples of the surface treatment agent include silane coupling agents, titanate coupling agents, aluminum coupling agents, surfactants, etc. In particular, silane coupling agents are preferred, and silane coupling agents having an amino group are more preferred.

[0197] Examples of the silane coupling agent having an amino group include, but are not limited to, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, and N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane.

[0198] Silane coupling agents can be used in combination of two or more. For example, a silane coupling agent having an amino group can be used in combination with other silane coupling agents. As other silane coupling agents, for example, vinyl trimethoxysilane, 3-methacryloxypropyl-tris(2-methoxyethoxy)silane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyl triacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, etc. can be cited, but are not limited to these.

[0199] The surface treatment method using the surface treatment agent may be any method as long as it is a known method, and may be either a dry method or a wet method.

[0200] The treatment amount of the surface treatment agent is preferably, for example, 0.5% by mass or more and 10% by mass or less relative to the inorganic particles.

[0201] Here, from the viewpoint of long-term stability of electrical characteristics and high carrier blocking properties, the undercoat layer may contain an electron accepting compound (acceptor compound) together with the inorganic particles.

[0202] As electron accepting compounds, for example, there can be mentioned: quinone compounds such as chloranil and bromoaniline; tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone and 2,4,5,7-tetranitro-9-fluorenone; oxadiazole compounds such as 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole, 2,5-bis(4-naphthyl)-1,3,4-oxadiazole, and 2,5-bis(4-diethylaminophenyl)-1,3,4-oxadiazole; xanthone compounds; thiophene compounds; electron transporting substances such as diphenylquinone compounds such as 3,3',5,5'-tetra-tert-butyldiphenylquinone, and the like.

[0203] In particular, as the electron accepting compound, a compound having an anthraquinone structure is preferred. As the compound having an anthraquinone structure, for example, hydroxyanthraquinone compounds, aminoanthraquinone compounds, aminohydroxyanthraquinone compounds, etc. are preferred, and specifically, for example, anthraquinone, alizarin, quinizarin, anthraquinone, purpurin, etc. are preferred.

[0204] The electron accepting compound may be contained in the undercoat layer in a dispersed state together with the inorganic particles, or may be contained in the undercoat layer in a state of being attached to the surface of the inorganic particles.

[0205] Examples of a method for attaching the electron accepting compound to the surface of the inorganic particles include a dry method and a wet method.

[0206] The dry method is, for example, the following method: while the inorganic particles are stirred using a mixer with a large shear force, an electron accepting compound is directly added dropwise or an electron accepting compound dissolved in an organic solvent is added dropwise, and the electron accepting compound is sprayed together with dry air or nitrogen to attach the electron accepting compound to the surface of the inorganic particles. When the electron accepting compound is added dropwise or sprayed, it is preferably done at a temperature below the boiling point of the solvent. After the electron accepting compound is added dropwise or sprayed, it can be further calcined at more than 100°C. Regarding calcination, there is no particular restriction as long as the temperature and time are such that the electronic photographic properties can be obtained.

[0207] The wet method is, for example, the following method: while the inorganic particles are dispersed in a solvent by stirring, ultrasonic waves, a sand mill, an ultrafine grinder, a ball mill, etc., an electron accepting compound is added, and after stirring or dispersing, the solvent is removed so that the electron accepting compound is attached to the surface of the inorganic particles. The solvent removal method is, for example, filtering or distillation removal by distillation. After the solvent is removed, it can be further roasted at more than 100°C. Regarding roasting, there is no particular limitation as long as the temperature and time are such that the electronic photographic characteristics can be obtained. In the wet method, the water contained in the inorganic particles can be removed before the electron accepting compound is added. As examples thereof, a method of stirring and heating in a solvent and removing it at the same time and a method of removing it by azeotropy with a solvent can be cited.

[0208] The electron accepting compound may be attached before or after the inorganic particles are surface treated with a surface treatment agent, or the electron accepting compound may be attached and the surface treated with a surface treatment agent may be simultaneously performed.

[0209] The content of the electron accepting compound may be, for example, 0.01% by mass to 20% by mass, and preferably 0.01% by mass to 10% by mass, based on the inorganic particles.

[0210] Examples of the adhesive resin used in the primer layer include: acetal resins (e.g., polyvinyl butyral), polyvinyl alcohol resins, polyvinyl acetal resins, casein resins, polyamide resins, cellulose resins, gelatin, polyurethane resins, polyester resins, unsaturated polyester resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinyl acetate resins, vinyl chloride-vinyl acetate-maleic anhydride resins, silicone resins, silicone-modified alkyd resins, urea resins, phenol resins, phenol-formaldehyde resins, melamine resins, urethane resins, alkyd resins, epoxy resins and other known polymer compounds; zirconium chelate compounds; titanium chelate compounds; aluminum chelate compounds; titanium alkoxide compounds; organic titanium compounds; silane coupling agents and other known materials.

[0211] Examples of the binder resin used in the primer layer include a charge transporting resin having a charge transporting group, and a conductive resin (for example, polyaniline).

[0212] Among these, the binding resin for the primer layer is preferably a resin that is insoluble in the coating solvent of the upper layer, and is particularly preferably a thermosetting resin such as urea resin, phenol resin, phenol-formaldehyde resin, melamine resin, urethane resin, unsaturated polyester resin, alkyd resin, epoxy resin, or a resin obtained by reacting at least one resin selected from the group consisting of polyamide resin, polyester resin, polyether resin, methacrylic resin, acrylic resin, polyvinyl alcohol resin, and polyvinyl acetal resin with a curing agent.

[0213] When two or more of these adhesive resins are used in combination, the mixing ratio thereof is set as necessary.

[0214] The undercoat layer may contain various additives in order to improve electrical characteristics, improve environmental stability, and improve image quality.

[0215] As additives, there can be mentioned known materials such as polycyclic condensed pigments, azo pigments, etc., electron transport pigments, zirconium chelate compounds, titanium chelate compounds, aluminum chelate compounds, titanium alkoxide compounds, organic titanium compounds, silane coupling agents, etc. As mentioned above, silane coupling agents are used for surface treatment of inorganic particles, but can also be further added to the primer layer as an additive.

[0216] Examples of the silane coupling agent as an additive include vinyltrimethoxysilane, 3-methacryloxypropyl-tri(2-methoxyethoxy)silane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, and 3-chloropropyltrimethoxysilane.

[0217] Examples of the zirconium chelate compound include zirconium butoxide, zirconium ethyl acetoacetate, zirconium triethanolamine, zirconium acetylacetonate butoxide, zirconium ethyl acetoacetate butoxide, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octanoate, zirconium naphthenate, zirconium laurate, zirconium stearate, zirconium isostearate, zirconium methacrylate butoxide, zirconium stearate butoxide, and zirconium isostearate butoxide.

[0218] Examples of the titanium chelate compound include tetraisopropyl titanate, tetra-n-butyl titanate, butyl titanate dimer, tetra(2-ethylhexyl) titanate, titanium acetylacetonate, titanium polyacetylacetonate, titanium octylene glycollate, ammonium lactate titanium, lactate titanium, ethyl lactate titanium, triethanolamine titanium, and polyhydroxystearate titanium.

[0219] Examples of the aluminum chelate compound include aluminum isopropionate, monobutoxyaluminum diisopropionate, aluminum butyrate, aluminum diethylacetoacetate diisopropionate, and aluminum tris(ethylacetoacetate).

[0220] These additives may be used alone or in the form of a mixture or polycondensate of two or more compounds.

[0221] The Vickers hardness of the primer layer may be 35 or higher.

[0222] The surface roughness (ten-point average roughness) of the undercoat layer can be adjusted to 1 / (4n) to 1 / 2 of the wavelength λ of the exposure laser used (n is the refractive index of the upper layer) in order to suppress the moiré image.

[0223] In order to adjust the surface roughness, resin particles or the like may be added to the primer layer. Examples of the resin particles include silicone resin particles and cross-linked polymethyl methacrylate resin particles. In addition, in order to adjust the surface roughness, the surface of the primer layer may be ground. Examples of the grinding method include polishing, sandblasting, wet honing, grinding, and the like.

[0224] The formation of the undercoat layer is not particularly limited and can be formed by a known formation method. For example, the undercoat layer can be formed by forming a coating film of an undercoat layer-forming coating liquid prepared by adding the above components to a solvent, drying the coating film, and heating as necessary.

[0225] Examples of the solvent used for preparing the coating solution for forming the undercoat layer include known organic solvents such as alcohol solvents, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, ketone solvents, ketone alcohol solvents, ether solvents, and ester solvents.

[0226] Specific examples of these solvents include common organic solvents such as methanol, ethanol, n-propanol, isopropanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, dichloromethane, chloroform, chlorobenzene, and toluene.

[0227] Examples of the method for dispersing the inorganic particles when preparing the coating liquid for forming an undercoat layer include known methods such as a roll mill, a ball mill, a vibration ball mill, an attritor, a sand mill, a colloid mill, and a paint shaker.

[0228] Examples of a method for applying the coating liquid for forming an undercoat layer onto the conductive substrate include common methods such as blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating.

[0229] The film thickness of the primer layer is set, for example, preferably within the range of 15 μm or more, and more preferably within the range of 20 μm or more and 50 μm or less.

[0230] (Middle layer)

[0231] Although illustration is omitted, an intermediate layer may be further provided between the undercoat layer and the photosensitive layer.

[0232] The intermediate layer is, for example, a layer containing a resin. Examples of the resin used for the intermediate layer include acetal resins (e.g., polyvinyl butyral), polyvinyl alcohol resins, polyvinyl acetal resins, casein resins, polyamide resins, cellulose resins, gelatin, polyurethane resins, polyester resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinyl acetate resins, vinyl chloride-vinyl acetate-maleic anhydride resins, silicone resins, silicone-modified alkyd resins, phenol-formaldehyde resins, melamine resins and other polymer compounds.

[0233] The intermediate layer may be a layer containing an organic metal compound. Examples of the organic metal compound used for the intermediate layer include organic metal compounds containing metal atoms such as zirconium, titanium, aluminum, manganese, and silicon.

[0234] These compounds for the intermediate layer may be used alone or in the form of a mixture or polycondensate of two or more compounds.

[0235] Among these, the intermediate layer is preferably a layer containing an organic metal compound containing a zirconium atom or a silicon atom.

[0236] The formation of the intermediate layer is not particularly limited and can be performed by a known formation method, for example, by forming a coating film of an intermediate layer-forming coating liquid prepared by adding the above components to a solvent, drying the coating film, and heating as necessary to form the intermediate layer.

[0237] As a coating method for forming the intermediate layer, a common method such as a dip coating method, an extrusion coating method, a wire bar coating method, a spray coating method, a blade coating method, a knife coating method, a curtain coating method, etc. is used.

[0238] The film thickness of the intermediate layer is preferably set within a range of, for example, 0.1 μm or more and 3 μm or less. In addition, the intermediate layer may be used as a primer layer.

[0239] (Charge Generation Layer)

[0240] The charge generating layer is, for example, a layer containing a charge generating material and a binder resin. In addition, the charge generating layer may be a vapor-deposited layer of the charge generating material. The vapor-deposited layer of the charge generating material is suitable for the case where a non-interference light source such as an LED (Light Emitting Diode) or an organic EL (Electro-Luminescence) image array is used.

[0241] Examples of the charge generating material include azo pigments such as disazo and trisazo; condensed ring aromatic pigments such as dibromoanthanthrone; perylene pigments; pyrrolopyrrole pigments; phthalocyanine pigments; zinc oxide; and trigonal selenium.

[0242] Among these, in order to cope with laser exposure in the near-infrared region, metal phthalocyanine pigments or metal-free phthalocyanine pigments are preferably used as charge generating materials. Specifically, for example, hydroxygallium phthalocyanine disclosed in Japanese Patent Publication No. 5-263007, Japanese Patent Publication No. 5-279591, etc.; chlorogallium phthalocyanine disclosed in Japanese Patent Publication No. 5-98181, etc.; dichlorotin phthalocyanine disclosed in Japanese Patent Publication No. 5-140472, Japanese Patent Publication No. 5-140473, etc.; titanyl phthalocyanine disclosed in Japanese Patent Publication No. 4-189873, etc. are more preferred.

[0243] On the other hand, in order to cope with laser exposure in the near-ultraviolet region, preferred charge generating materials include condensed-ring aromatic pigments such as dibromoantanthrone; thioindigo pigments; tetraazaporphyrin compounds; zinc oxide; trigonal selenium; and disazo pigments disclosed in Japanese Patent Publication No. 2004-78147 and Japanese Patent Publication No. 2005-181992.

[0244] When using a non-interference light source such as an LED or an organic EL image array having a central wavelength of light emission between 450nm and 780nm, the above-mentioned charge generating material can also be used. However, from the aspect of resolution, when a photosensitive layer is used as a thin film of less than 20μm, the electric field intensity in the photosensitive layer increases, and it is easy to generate a charge reduction due to the injection of charges from the substrate, that is, to generate image defects called so-called black spots. This situation becomes significant when using a charge generating material that easily generates dark current in a p-type semiconductor, such as trigonal selenium and phthalocyanine pigments.

[0245] In contrast, when an n-type semiconductor such as a condensed aromatic pigment, perylene pigment, or azo pigment is used as a charge generating material, dark current is less likely to be generated, and image defects called black spots can be suppressed even when formed into a thin film. Examples of n-type charge generating materials include compounds (CG-1) to (CG-27) described in paragraphs

[0288] to

[0291] of Japanese Patent Application Laid-Open No. 2012-155282, but are not limited thereto.

[0246] The n-type was determined by using the polarity of the photocurrent flowing using the commonly used time-of-flight method, and the type in which electrons flow more easily as carriers than holes was determined as the n-type.

[0247] The binder resin used in the charge generating layer can be selected from a wide range of insulating resins. Alternatively, the binder resin can be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, polyvinylpyrene, and polysilane.

[0248] Examples of the adhesive resin include polyvinyl butyral resin, polyarylate resin (condensation product of bisphenol and aromatic dicarboxylic acid), polycarbonate resin, polyester resin, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyamide resin, acrylic resin, polyacrylamide resin, polyvinyl pyridine resin, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol resin, polyvinyl pyrrolidone resin, etc. Here, "insulating property" means that the volume resistivity is 10 13 Ωcm or more.

[0249] These adhesive resins may be used alone or in combination of two or more.

[0250] It should be noted that the mixing ratio of the charge generating material to the binder resin is preferably within a range of 10:1 to 1:10 in terms of mass ratio.

[0251] The charge generating layer may contain other known additives.

[0252] The formation of the charge generating layer is not particularly limited, and a known formation method can be used. For example, it can be performed as follows: a coating film of a coating liquid for forming a charge generating layer is formed by adding the above-mentioned components to a solvent, the coating film is dried, and heating is performed as needed to form the charge generating layer. The formation of the charge generating layer can also be performed by vapor deposition of the charge generating material. The formation of the charge generating layer by vapor deposition is particularly suitable for the case where a condensed aromatic pigment or a perylene pigment is used as the charge generating material.

[0253] Examples of the solvent used for preparing the charge generating layer-forming coating solution include methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, dichloromethane, chloroform, chlorobenzene, toluene, etc. These solvents may be used alone or in combination of two or more.

[0254] As a method for dispersing particles (e.g., charge generating materials) in a coating liquid for forming a charge generating layer, for example, a medium disperser such as a ball mill, a vibrating ball mill, an ultrafine grinder, a sand mill, a horizontal sand mill, etc.; a medium-free disperser such as a stirring, ultrasonic disperser, a roller mill, a high-pressure homogenizer, etc. As a high-pressure homogenizer, for example, a collision method in which the dispersion liquid is dispersed by liquid-liquid collision or liquid-wall collision under high pressure; a penetration method in which the dispersion liquid is dispersed by penetrating through a fine flow path under high pressure, etc. can be cited.

[0255] In the dispersion, it is effective that the average particle size of the charge generating material in the charge generating layer forming coating liquid is 0.5 μm or less, preferably 0.3 μm or less, and more preferably 0.15 μm or less.

[0256] Examples of a method for applying the charge generating layer-forming coating liquid onto the undercoat layer (or the intermediate layer) include common methods such as blade coating, wire rod coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating.

[0257] The film thickness of the charge generating layer is set, for example, preferably within the range of 0.1 μm to 5.0 μm, more preferably within the range of 0.2 μm to 2.0 μm.

[0258] (Charge Transport Layer)

[0259] The charge transport layer is, for example, a layer containing a charge transport material and a binder resin. The charge transport layer may also be a layer containing a polymer charge transport material.

[0260] As charge transport materials, there can be cited quinone compounds such as para-benzoquinone, chloranil, bromoquinone, anthraquinone, etc.; tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone; xanthone compounds; benzophenone compounds; cyanovinyl compounds; vinyl compounds and other electron transport compounds. As charge transport materials, there can also be cited hole transport compounds such as triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted vinyl compounds, isophenylethylene compounds, anthracene compounds, hydrazone compounds, etc. These charge transport materials can be used alone or in combination of two or more, but are not limited to these.

[0261] As the charge transport material, from the viewpoint of charge mobility, a triarylamine derivative represented by the following structural formula (a-1) and a benzidine derivative represented by the following structural formula (a-2) are preferred.

[0262] [Chemistry 4]

[0263]

[0264] In the structural formula (a-1), Ar T1 ,Ar T2 and Ar T3 Each independently represents a substituted or unsubstituted aryl group, -C6H4-C(R T4 )=C(R T5 )(R T6 ), or -C6H4-CH=CH-CH=C(R T7 )(R T8 ). T4 , R T5 , R T6 , R T7 and R T8 Each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group.

[0265] Examples of the substituents of the above groups include halogen atoms, alkyl groups having 1 to 5 carbon atoms, and alkoxy groups having 1 to 5 carbon atoms. Examples of the substituents of the above groups include substituted amino groups substituted with alkyl groups having 1 to 3 carbon atoms.

[0266] [Chemistry 5]

[0267]

[0268] In the structural formula (a-2), R T91 and R T92 Each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. T101 , R T102 , R T111 and R T112 Each independently represents a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an amino group substituted by an alkyl group having 1 to 2 carbon atoms, a substituted or unsubstituted aryl group, -C(R T12 )=C(R T13 )(R T14 ), or -CH=CH-CH=C(R T15 )(R T16 ), R T12 , R T13 , R T14, R T15 and R T16 Each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. Tm1, Tm2, ​​Tn1, and Tn2 each independently represent an integer of 0 or more and 2 or less.

[0269] Examples of the substituents of the above groups include halogen atoms, alkyl groups having 1 to 5 carbon atoms, and alkoxy groups having 1 to 5 carbon atoms. Examples of the substituents of the above groups include substituted amino groups substituted with alkyl groups having 1 to 3 carbon atoms.

[0270] Here, among the triarylamine derivatives represented by the structural formula (a-1) and the benzidine derivatives represented by the structural formula (a-2), the one having "-C6H4-CH=CH-CH=C(R T7 )(R T8 )" and triarylamine derivatives having "-CH=CH-CH=C(R T15 )(R T16 )" benzidine derivatives.

[0271] As the polymer charge transport material, known materials having charge transport properties such as poly-N-vinyl carbazole and polysilane are used. In particular, polyester-based polymer charge transport materials disclosed in Japanese Patent Publication No. 8-176293 and Japanese Patent Publication No. 8-208820 are particularly preferred. It should be noted that the polymer charge transport material can be used alone or in combination with a binder resin.

[0272] The adhesive resin for charge transport layer can include polycarbonate resin, polyester resin, polyarylate resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer, vinylidene chloride-acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone-modified alkyd resin, phenol-formaldehyde resin, styrene-modified alkyd resin, poly-N-vinyl carbazole, polysilane, etc. Among these, polycarbonate resin or polyarylate resin is preferred as the adhesive resin. These adhesive resins are used alone or in combination of two or more.

[0273] It should be noted that the mixing ratio of the charge transport material to the binder resin is preferably 10:1 to 1:5 in terms of mass ratio.

[0274] The charge transport layer may contain other known additives.

[0275] The charge transport layer can be formed by any known method without particular limitation. For example, the charge transport layer can be formed by forming a coating film of a charge transport layer-forming coating liquid prepared by adding the above components to a solvent, drying the coating film, and heating as necessary.

[0276] As the solvent for preparing the coating solution for forming the charge transport layer, there can be mentioned aromatic hydrocarbons such as benzene, toluene, xylene, and chlorobenzene; ketones such as acetone and 2-butanone; halogenated aliphatic hydrocarbons such as dichloromethane, chloroform, and vinyl chloride; cyclic or linear ethers such as tetrahydrofuran and diethyl ether, and other common organic solvents. These solvents can be used alone or in combination of two or more.

[0277] Examples of the coating method for coating the charge transport layer-forming coating liquid on the charge generating layer include common methods such as blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating.

[0278] The film thickness of the charge transport layer is set, for example, preferably within the range of 5 μm to 50 μm, more preferably within the range of 10 μm to 30 μm.

[0279] (Protective layer)

[0280] The protective layer is provided on the photosensitive layer as required. The protective layer is provided, for example, to prevent chemical changes in the photosensitive layer during charging or to further improve the mechanical strength of the photosensitive layer.

[0281] Therefore, the protective layer may be a layer composed of a cured film (crosslinked film). Examples of these layers include the layers described in the following 1) or 2).

[0282] 1) A layer consisting of a cured film of a composition comprising a reactive group-containing charge transport material having a reactive group and a charge transport skeleton in the same molecule (i.e., a layer comprising a polymer or a crosslinked body of the reactive group-containing charge transport material)

[0283] 2) A layer composed of a cured film of a composition comprising a non-reactive charge transport material and a reactive group-containing non-charge transport material having no charge transport skeleton but having a reactive group (i.e., a layer comprising a non-reactive charge transport material and a polymer or crosslinked body of the reactive group-containing non-charge transport material)

[0284] Examples of the reactive group of the reactive group-containing charge transport material include chain polymerizable groups, epoxy groups, -OH, -OR [wherein R represents an alkyl group], -NH2, -SH, -COOH, -SiR Q1 3-Qn (OR Q2 )Qn [Among them, R Q1 represents a hydrogen atom, an alkyl group, or a substituted or unsubstituted aryl group, R Q2 represents a hydrogen atom, an alkyl group, a trialkylsilyl group, Qn represents an integer of 1 to 3] and the like.

[0285] As a chain polymerizable group, there is no particular limitation as long as it is a functional group that can be subjected to free radical polymerization, and for example, it is a functional group having a group containing at least a carbon double bond. Specifically, there can be mentioned a group containing at least one selected from vinyl, vinyl ether, vinyl sulfide, styryl (vinyl phenyl), acryloyl, methacryloyl and their derivatives. Among them, for the reason of its excellent reactivity, as a chain polymerizable group, it is preferably a group containing at least one selected from vinyl, styryl (vinyl phenyl), acryloyl, methacryloyl and their derivatives.

[0286] The charge transport skeleton of the reactive group-containing charge transport material is not particularly limited as long as it is a known structure in an electrophotographic photoreceptor, and examples thereof include a structure in which the skeleton is derived from a nitrogen-containing hole transport compound such as a triarylamine compound, a benzidine compound, a hydrazone compound, and is conjugated with a nitrogen atom. Among these, a triarylamine skeleton is preferred.

[0287] The reactive group-containing charge transport material, the non-reactive charge transport material, and the reactive group-containing non-charge transport material having a reactive group and a charge transport skeleton may be selected from known materials.

[0288] The protective layer may contain other known additives.

[0289] The protective layer can be formed by any known method without particular limitation. For example, the protective layer can be formed by forming a coating film of a protective layer-forming coating liquid prepared by adding the above components to a solvent, drying the coating film, and performing a curing treatment such as heating as required.

[0290] Examples of the solvent used to prepare the protective layer-forming coating solution include aromatic solvents such as toluene and xylene; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester solvents such as ethyl acetate and butyl acetate; ether solvents such as tetrahydrofuran and dioxane; cellosolve solvents such as ethylene glycol monomethyl ether; alcohol solvents such as isopropyl alcohol and butanol, etc. These solvents may be used alone or in combination of two or more.

[0291] In addition, the coating liquid for forming a protective layer may be a solvent-free coating liquid.

[0292] Examples of a method for applying the protective layer-forming coating liquid onto a photosensitive layer (eg, charge transport layer) include common methods such as dip coating, extrusion coating, wire bar coating, spray coating, blade coating, knife coating, and curtain coating.

[0293] The film thickness of the protective layer is set, for example, preferably within the range of 1 μm to 20 μm, more preferably within the range of 2 μm to 10 μm.

[0294] (Single-layer photosensitive layer)

[0295] The single-layer photosensitive layer (charge generation / charge transport layer) is, for example, a layer containing a charge generation material and a charge transport material and, if necessary, a binding resin and other known additives. It should be noted that these materials are the same as those described for the charge generation layer and the charge transport layer.

[0296] Furthermore, in the monolayer photosensitive layer, the content of the charge generating material relative to the total solid content is preferably 0.1 mass % to 10 mass %, preferably 0.8 mass % to 5 mass %. In addition, in the monolayer photosensitive layer, the content of the charge transport material relative to the total solid content can be 5 mass % to 50 mass %.

[0297] The method for forming the single-layer photosensitive layer is the same as the method for forming the charge generating layer and the charge transporting layer.

[0298] The film thickness of the single-layer photosensitive layer is, for example, preferably 5 μm to 50 μm, and preferably 10 μm to 40 μm.

[0299] <Image Forming Apparatus (and Process Cartridge)>

[0300] The image forming apparatus of the present embodiment comprises: an electrophotographic photoreceptor; a charging mechanism for charging the surface of the electrophotographic photoreceptor; an electrostatic latent image forming mechanism for forming an electrostatic latent image on the surface of the charged electrophotographic photoreceptor; a developing mechanism for developing the electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing a toner to form a toner image; and a transfer mechanism for transferring the toner image to the surface of a recording medium. In addition, as the electrophotographic photoreceptor, the electrophotographic photoreceptor of the present embodiment described above is applied.

[0301] The image forming device of this embodiment can apply the following well-known image forming devices: a device equipped with a fixing mechanism for fixing the toner image transferred to the surface of a recording medium; a device for a direct transfer method for directly transferring the toner image formed on the surface of an electrophotographic photosensitive body to a recording medium; a device for an intermediate transfer method for transferring the toner image formed on the surface of an electrophotographic photosensitive body once to the surface of an intermediate transfer body, and then transferring the toner image transferred to the surface of the intermediate transfer body to the surface of a recording medium for a second time; a device equipped with a cleaning mechanism for cleaning the surface of the electrophotographic photosensitive body after the toner image is transferred but before charging; a device equipped with a de-staticizing mechanism for de-staticizing the surface of the electrophotographic photosensitive body by irradiating de-staticizing light to the surface of the electrophotographic photosensitive body after the toner image is transferred but before charging; a device equipped with an electrophotographic photosensitive body heating component for increasing the temperature of the electrophotographic photosensitive body and lowering the relative temperature; and the like.

[0302] In the case of an intermediate transfer type device, the transfer mechanism, for example, comprises an intermediate transfer body for transferring a toner image on a surface, a primary transfer mechanism for transferring a toner image formed on a surface of an electronic photographic photosensitive body to a surface of the intermediate transfer body, and a secondary transfer mechanism for secondary transferring the toner image transferred to the surface of the intermediate transfer body to a surface of a recording medium.

[0303] The image forming apparatus of the present embodiment may be any of a dry developing system image forming apparatus and a wet developing system (development system using a liquid developer) image forming apparatus.

[0304] It should be noted that, in the image forming apparatus of the present embodiment, for example, the portion having the electrophotographic photoreceptor may be a box structure (processing box) that can be loaded and unloaded relative to the image forming apparatus. As the processing box, for example, a processing box having the electrophotographic photoreceptor of the present embodiment is suitable for use. It should be noted that, in addition to the electrophotographic photoreceptor, the processing box may also have, for example, at least one selected from the group consisting of a charging mechanism, an electrostatic latent image forming mechanism, a developing mechanism, and a transfer mechanism.

[0305] An example of the image forming apparatus according to the present embodiment is shown below, but the present invention is not limited thereto. It should be noted that the main parts shown in the drawings will be described, and the description of other parts will be omitted.

[0306] Figure 2 This is a schematic structural diagram showing an example of the image forming apparatus according to the present embodiment.

[0307] like Figure 2As shown, the image forming apparatus 100 of the present embodiment includes: a process box 300 including an electrophotographic photoreceptor 7; an exposure device 9 (an example of an electrostatic latent image forming mechanism); a transfer device 40 (a primary transfer device); and an intermediate transfer body 50. It should be noted that in the image forming apparatus 100, the exposure device 9 is arranged at a position where the electrophotographic photoreceptor 7 can be exposed through the opening of the process box 300, and the transfer device 40 is arranged at a position opposite to the electrophotographic photoreceptor 7 across the intermediate transfer body 50, and the intermediate transfer body 50 is arranged so that a part of it contacts the electrophotographic photoreceptor 7. Although not shown in the figure, there is also a secondary transfer device for transferring the toner image transferred to the intermediate transfer body 50 to a recording medium (e.g., paper). It should be noted that the intermediate transfer body 50, the transfer device 40 (a primary transfer device), and the secondary transfer device (not shown) are equivalent to an example of a transfer mechanism.

[0308] Figure 2 The process box 300 in the embodiment integrally supports the electrophotographic photoreceptor 7, the charging device 8 (an example of a charging mechanism), the developing device 11 (an example of a developing mechanism), and the cleaning device 13 (an example of a cleaning mechanism) in a housing. The cleaning device 13 has a cleaning blade (an example of a cleaning member) 131, and the cleaning blade 131 is configured to contact the surface of the electrophotographic photoreceptor 7. It should be noted that the cleaning member may be a conductive or insulating fibrous member other than the cleaning blade 131, and may be used alone or in combination with the cleaning blade 131.

[0309] It should be noted that Figure 2 In the example, the image forming apparatus includes a fibrous member 132 (rolled) for supplying the lubricant 14 to the surface of the electrophotographic photoreceptor 7 and a fibrous member 133 (flat brush) for assisting cleaning, but these members are arranged as needed.

[0310] Next, each structure of the image forming apparatus according to this embodiment will be described.

[0311] -Charging device-

[0312] As the charging device 8, for example, a contact charger using a conductive or semi-conductive charging roller, a charging brush, a charging film, a charging rubber blade, a charging tube, etc. can be used. In addition, a non-contact roller charger, a scorotron charger using corona discharge, a corotron charger, or other known chargers can also be used.

[0313] -Exposure device-

[0314] As the exposure device 9, for example, there can be cited an optical device that uses semiconductor laser, LED light, liquid crystal shutter light and other light to expose the surface of the electrophotographic photoreceptor 7 according to a determined image. The wavelength of the light source is set to be within the spectral sensitivity area of ​​the electrophotographic photoreceptor. As the wavelength of the semiconductor laser, near-infrared with an oscillation wavelength near 780nm is the mainstream. However, it is not limited to this wavelength, and a laser with an oscillation wavelength of approximately 600nm or a laser with an oscillation wavelength of more than 400nm and less than 450nm as a blue laser can also be used. In addition, in order to form a color image, a surface-emitting laser source that can output a multi-beam type is also effective.

[0315] -Developing device-

[0316] As the developing device 11, for example, a common developing device that performs development in contact with or without contact with a developer can be cited. As the developing device 11, there is no particular limitation as long as it has the above-mentioned function, and it can be selected according to the purpose. For example, a known developer having a function of attaching a single-component developer or a two-component developer to the electrophotographic photoreceptor 7 using a brush, a roller, etc. can be cited. Among them, it is preferable to use a developing roller having a developer retained on the surface.

[0317] The developer used in the developing device 11 may be a one-component developer containing only a toner or a two-component developer containing a toner and a carrier. The developer may be magnetic or non-magnetic. These developers may be known developers.

[0318] -Cleaning device-

[0319] The cleaning device 13 is a cleaning blade type device including a cleaning blade 131 .

[0320] It should be noted that in addition to the cleaning blade method, a brush cleaning method and a simultaneous development and cleaning method may also be used.

[0321] -Transfer device-

[0322] Examples of the transfer device 40 include known transfer chargers such as a contact transfer charger using a belt, a roller, a film, a rubber blade, or the like, a scorotron transfer charger using corona discharge, and a corona transfer charger.

[0323] -Intermediate transfer body-

[0324] A belt-shaped transfer body (intermediate transfer belt) made of polyimide, polyamideimide, polycarbonate, polyarylate, polyester, rubber, etc. imparted with semiconductivity is used as the intermediate transfer body 50. In addition, a drum-shaped transfer body can be used as the intermediate transfer body in addition to a belt-shaped transfer body.

[0325] Figure 3 This is a schematic structural diagram showing another example of the image forming apparatus according to the present embodiment.

[0326] Figure 3 The image forming apparatus 120 shown is a multi-color image forming apparatus of a tandem type equipped with four process cartridges 300. In the image forming apparatus 120, the four process cartridges 300 are arranged in parallel on the intermediate transfer body 50, and one electrophotographic photoreceptor is used for each color. It should be noted that the image forming apparatus 120 has the same structure as the image forming apparatus 100 except that it is a tandem type.

[0327] Example

[0328] The following is an explanation of the embodiments of the present invention, but the present invention is not limited to the following embodiments. It should be noted that, unless otherwise stated, "parts" or "%" are based on mass.

[0329] <Production of fluorine-containing resin particles>

[0330] -Production of fluorine-containing resin particles (1)-

[0331] The fluorine-containing resin particles (1) were produced as follows.

[0332] 100 parts by mass of commercially available homopolytetrafluoroethylene fine powder (standard specific gravity 2.175 measured according to ASTM D 4895 (2004)) and 2.4 parts by mass of ethanol as an additive were placed in a barrier nylon bag, and the entire bag was purged with nitrogen. Then, 150 kGy of cobalt-60 gamma rays were irradiated at room temperature to obtain a low molecular weight polytetrafluoroethylene powder. The obtained powder was pulverized to obtain fluorine-containing resin particles (1).

[0333] -Production of fluorine-containing resin particles (2)-

[0334] 100 parts by mass of fluorine-containing resin particles (1) and 400 parts by mass of methanol were taken and washed for 20 minutes with a stirrer at 250 rpm while irradiating with ultrasonic waves, and the supernatant was filtered. This operation was repeated three times, and the filtrate was dried at 60 degrees for 17 hours under reduced pressure to produce fluorine-containing resin particles (2).

[0335] -Production of fluorine-containing resin particles (3)-

[0336] Fluorine-containing resin particles (3) were produced in the same manner as in the production of fluorine-containing resin particles (1), except that the entire bag was substituted with nitrogen so that the oxygen concentration became 8%.

[0337] -Production of fluorine-containing resin particles (4)-

[0338] Fluorine-containing resin particles (4) are produced in the same manner as in the production of the fluorine-containing resin particles (2), except that the fluorine-containing resin particles (3) are used in place of the fluorine-containing resin particles (1).

[0339] -Production of fluorine-containing resin particles (5)-

[0340] 3 liters of deionized water and 3.0 g of ammonium perfluorooctanoate were added to the autoclave, and 110 g of solid paraffin (manufactured by Nippon Oil Corporation) as an emulsion stabilizer was further added. The system was replaced with nitrogen three times and TFE (tetrafluoroethylene) twice. After removing oxygen, the internal pressure was set to 1.0 MPa using TFE, and the internal temperature was maintained at 70°C while stirring at 250 rpm. Next, 150 cc of ethane at normal pressure as a chain transfer agent and 20 ml of an aqueous solution containing 300 mg of ammonium persulfate as a polymerization initiator were added to the system to initiate the reaction. During the reaction, TFE was continuously supplied in such a manner that the temperature in the system was maintained at 70°C and the internal pressure of the autoclave was always maintained at 1.0 ± 0.05 MPa. After the initiator was added, when the TFE consumed by the reaction reached 1000 g, the supply of TFE and stirring were stopped to terminate the reaction. The particles were then separated by centrifugation, and 400 parts by mass of methanol were taken and washed for 10 minutes with a stirrer at 250 rpm while ultrasonic irradiation was performed, and the supernatant was filtered. This operation was repeated three times, and the filtrate was dried at 60 degrees for 17 hours under reduced pressure.

[0341] Through the above steps, fluorine-containing resin particles (5) are produced.

[0342] -Production of fluorine-containing resin particles (6)-

[0343] In the production of the fluorinated resin particles (5), fluorinated resin particles (6) were produced in the same manner as in the production of the fluorinated resin particles (5), except that 4.5 g of triethylamine was added after the reaction was completed.

[0344] -Production of fluorine-containing resin particles (C1)-

[0345] In the production of the fluorinated resin particles (1), fluorinated resin particles (C1) were produced in the same manner as in the production of the fluorinated resin particles (1), except that the radiation irradiation was carried out in air.

[0346] -Production of fluorine-containing resin particles (C2)-

[0347] Fluororesin particles (C2) are produced in the same manner as in the production of fluorine-containing resin particles (2), except that fluorine-containing resin particles (C1) are used in place of fluorine-containing resin particles (1).

[0348] -Production of fluorine-containing resin particles (C3)-

[0349] Fluorine-containing resin particles (C3) were produced in the same manner as in the production of fluorine-containing resin particles (6), except that the washing operation was performed once.

[0350] <Example 1>

[0351] -Production of photoreceptor-

[0352] Using the obtained fluorine-containing resin particles, a photoreceptor was produced as follows.

[0353] Zinc oxide (average particle size 70 nm: manufactured by TAYCA; specific surface area 15 m 2 / g) and 500 parts of tetrahydrofuran were stirred and mixed, and 1.4 parts of a silane coupling agent (KBE503: manufactured by Shin-Etsu Chemical Co., Ltd.) were added and stirred for 2 hours. Toluene was then distilled off by reduced pressure distillation, and the mixture was calcined at 120°C for 3 hours to obtain silane coupling agent surface-treated zinc oxide.

[0354] 110 parts of the surface-treated zinc oxide and 500 parts of tetrahydrofuran were stirred and mixed, and a solution prepared by dissolving 0.6 parts of alizarin in 50 parts of tetrahydrofuran was added, followed by stirring at 50° C. for 5 hours. The zinc oxide to which alizarin was imparted was then filtered out by vacuum filtration, and further dried under reduced pressure at 60° C. to obtain zinc oxide with alizarin.

[0355] 60 parts of the zinc oxide with alizarin, 13.5 parts of a curing agent (blocked isocyanate Sumidur 3175, manufactured by Sumitomo Bayer Urethane Co., Ltd.), 15 parts of a butyral resin (S-LECBM-1, manufactured by Sekisui Chemical Co., Ltd.), and 85 parts of methyl ethyl ketone were mixed to obtain a mixed solution. 38 parts of the mixed solution was mixed with 25 parts of methyl ethyl ketone and the mixture was stirred for 2 hours. The glass beads were dispersed using a sand mill for 2 hours to obtain a dispersion.

[0356] 0.005 parts of dioctyltin dilaurate and 30 parts of silicone resin particles (TOSPEARL 145, Momentive Performance Materials Japan) were added to the obtained dispersion as a catalyst to obtain a primer coating solution. The coating solution was applied to a cylindrical aluminum substrate by dip coating and dried and cured at 170°C for 30 minutes to obtain a primer layer with a thickness of 24 μm.

[0357] Next, 1 part of hydroxygallium phthalocyanine (which has strong diffraction peaks at Bragg angles (2θ±0.2°) of 7.5°, 9.9°, 12.5°, 16.3°, 18.6°, 25.1°, and 28.3° in its X-ray diffraction spectrum) was mixed with 1 part of polyvinyl butyral (S-LECBM-5, manufactured by Sekisui Chemical Co., Ltd.) and 80 parts of n-butyl acetate, and the mixture was dispersed together with glass beads using a paint shaker for 1 hour to prepare a coating liquid for a charge generation layer. The obtained coating liquid was dip-coated on the conductive support having the undercoat layer formed thereon, and dried by heating at 130°C for 10 minutes to form a charge generation layer having a film thickness of 0.15 μm.

[0358] 45 parts of a benzidine compound represented by the following formula (CTM1) as a charge transport material, 55 parts of a polymer compound (viscosity average molecular weight: 40,000) having a repeating unit represented by the following formula (PCZ1) as a binder resin, and 0.0111 parts (100 ppm) of dodecylbenzenesulfonic acid as an acidic compound (hereinafter, the acidic compound is mixed in the amounts shown in Table 1 (amount (ppm) relative to the solid content of the outermost surface layer)) are dissolved in 350 parts of toluene and 150 parts of tetrahydrofuran, 9.8 parts of fluorine-containing resin particles (1) and 1 part of a fluorine-containing dispersant GF400 (manufactured by Toagosei Co., Ltd.) are added, and the mixture is treated 5 times using a high-pressure homogenizer to prepare a coating liquid for a charge generating layer.

[0359] The obtained coating liquid was applied onto the charge generating layer by dip coating, and heated at 130° C. for 45 minutes to form a charge transporting layer having a film thickness of 31 μm.

[0360] [Chemistry 11]

[0361]

[0362] [Chemistry 12]

[0363]

[0364] Each photoreceptor is manufactured through the above steps.

[0365] <Examples 2 to 22, Comparative Examples 1 to 3>

[0366] A photoreceptor was prepared in the same manner as in Example 1 except that the type and amount of the acidic compound and the type of the fluorine-containing resin particles were changed.

[0367] <Evaluation>

[0368] (Various measurements)

[0369] With respect to the fluorine-containing resin particles, the following characteristics were measured according to the above-mentioned methods.

[0370] ·Carboxyl groups (represented as "COOH" in the table) relative to "per 10 6 The number of carbon atoms (a)

[0371] ·Amount of basic compounds (ppm)

[0372] (Actual machine evaluation)

[0373] -Evaluation Image Forming Device-

[0374] The obtained electrophotographic photoreceptor was installed in DocuCentre-VC7775 manufactured by Fuji Xerox Co., Ltd. A surface potential meter (Trek 334 manufactured by Trek Co., Ltd.) was used, and a surface potential probe was set at a position 1 mm from the surface of the photoreceptor in the region to be measured.

[0375] This apparatus was used as an image forming apparatus for evaluation.

[0376] -Evaluation of charging performance maintenance-

[0377] The charging properties of the obtained photoreceptor were evaluated as follows.

[0378] The surface potential after charging was set to -700 V using an evaluation image forming apparatus, and then 70,000 sheets of halftone images with an image density of 30% were output on A4 paper in a high temperature and high humidity environment (temperature 28°C, humidity 85% RH). The surface potential was then measured using a surface potentiometer and evaluated according to the following evaluation criteria.

[0379] 5: Surface potential is above -700V and less than -690V

[0380] 4: Surface potential is above -690V and less than -675V

[0381] 3: Surface potential is -675V or higher and less than -660V (a level that does not pose a practical problem)

[0382] 2: The surface potential is above -660V and less than -640V

[0383] 1: Surface potential is -640V or above

[0384] ―Evaluation of residual potential―

[0385] The residual potential of the obtained photoreceptor was evaluated as follows.

[0386] The surface potential after charging was set to -700 V using an evaluation image forming apparatus, and 70,000 sheets of a halftone image with an image density of 30% were output on A4 paper in a high temperature and high humidity environment (temperature 28°C, humidity 85% RH).

[0387] After that, the initial residual potential of the photoreceptor after discharge was measured with a surface potentiometer after 100 sheets were output, and the residual potential over time of the photoreceptor after discharge was measured after 70,000 sheets were output, and the difference (absolute value) was obtained and evaluated according to the following criteria.

[0388] 5: The difference in residual potential is less than 5V

[0389] 4: The difference in residual potential is greater than 5V and less than 10V

[0390] 3: The difference in residual potential is 10V or more and less than 20V (a level that is not a problem in practical use)

[0391] 2: The difference in residual potential is greater than 20V and less than 50V

[0392] 1: The difference in residual potential is more than 50V

[0393] -Evaluation of environmental changes-

[0394] The environmental changes of the obtained photoreceptor were evaluated as follows.

[0395] After the above-mentioned residual potential evaluation, the surface potential is set to -700 V in a low-temperature and low-humidity environment (temperature 15°C, humidity 10% RH), and the initial residual potential after outputting 100 sheets is measured. The difference (absolute value) between the initial residual potential and the high-temperature and high-humidity environment is determined and evaluated according to the following criteria.

[0396] 4: The difference in residual potential is less than 10V

[0397] 3: The difference in residual potential is 10V or more and less than 20V (a level that is not a problem in practical use)

[0398] 2: The difference in residual potential is greater than 20V and less than 50V

[0399] 1: The difference in residual potential is more than 50V

[0400] The details of Examples and Comparative Examples are listed in Tables 1 and 2 below.

[0401] It should be noted that the details of the abbreviations in Tables 1 and 2 are as follows.

[0402] NH3: Ammonia (boiling point = below room temperature 25°C)

[0403] TEA: triethylamine (boiling point 89 degrees)

[0404] DBS: Dodecylbenzenesulfonic acid

[0405] [Table 1]

[0406]

[0407] [Table 2]

[0408]

[0409] As can be seen from the above results, in the present example, the residual potential of the photoreceptor was evaluated to be better than that of the comparative example.

[0410] Furthermore, it was found that in this example, the evaluations of charging performance, environmental change, and charge retention were also good.

Claims

1. An electrophotographic photoreceptor, wherein: The electrophotographic photoreceptor comprises a conductive substrate and a photosensitive layer provided on the conductive substrate. The outermost surface layer of the electrophotographic photoreceptor contains fluorine-containing resin particles, a fluorine-based graft polymer, and an acidic compound having an acid dissociation constant (pKa) in water at 25° C. of not less than -2 and not more than 2.

65. The amount of the basic compound in the fluorine-containing resin particles is 0 ppm or more and 1.5 ppm or less, The content of the acidic compound is 100 ppm or more and 10000 ppm or less relative to the outermost surface layer. In the above-mentioned fluorine-containing resin particles, per 10 6 The number of carbon atoms is 0 or more and the number of carboxyl groups is 30 or less.

2. The electrophotographic photoreceptor according to claim 1, wherein The acid dissociation constant (pKa) of the acidic compound is -2 or more and 1.5 or less.

3. The electrophotographic photoreceptor according to claim 1 or 2, wherein The acidic compound is at least one selected from the group consisting of sulfonic acid compounds, carboxylic acid compounds, phosphoric acid compounds and nitric acid compounds.

4. The electrophotographic photoreceptor according to claim 1 or 2, wherein The acidic compound is at least one selected from the group consisting of sulfonic acid compounds and carboxylic acid compounds.

5. The electrophotographic photoreceptor according to claim 4, wherein The above-mentioned sulfonic acid compound is a sulfonic acid compound having a benzene ring, The carboxylic acid compound is a carboxylic acid compound having 2 or more and 4 or less carboxyl groups.

6. The electrophotographic photoreceptor according to claim 1 or 2, wherein The content of the acidic compound is 150 ppm to 5000 ppm with respect to the outermost surface layer.

7. The electrophotographic photoreceptor according to claim 1 or 2, wherein In the above-mentioned fluorine-containing resin particles, per 10 6 The number of carbon atoms is 0 or more and the number of carboxyl groups is 20 or less.

8. The electrophotographic photoreceptor according to claim 1 or 2, wherein The above-mentioned basic compound is an amine compound.

9. The electrophotographic photoreceptor according to claim 1 or 2, wherein The alkaline compound has a boiling point of 40° C. or higher and 130° C. or lower. 10 . A process cartridge that is detachably mounted in an image forming apparatus, comprising the electrophotographic photoreceptor according to claim 1 .

11. An image forming apparatus comprising: The electrophotographic photoreceptor according to any one of claims 1 to 9, A charging mechanism is used to charge the surface of the electrophotographic photoreceptor. The electrostatic latent image forming mechanism forms an electrostatic latent image on the charged surface of the electrophotographic photoreceptor. a developing mechanism for developing the electrostatic latent image formed on the surface of the electrophotographic photoreceptor using a developer containing a toner to form a toner image, and The transfer mechanism transfers the toner image to the surface of the recording medium.

Images