Process cartridge

Abstract

The present invention relates to a process cartridge. A process cartridge is provided which has excellent initial electrification elevation performance and excellent electrification uniformity of a halftone image for a long period of time from the start of use until durability. Specifically, a process cartridge is provided which includes: an electrophotographic photosensitive member; toner; and a developing unit, wherein the toner contains toner particles and an external additive A, and wherein the electrophotographic photosensitive member includes a conductive support, a photosensitive layer, and a surface protective layer, wherein the surface protective layer contains conductive particles.

Description

Technical Field

[0001] This invention relates to a processing box for copiers and printers that each use an electrophotographic system or an electrostatic recording system. Background Technology

[0002] In recent years, there has been a widespread demand for further increases in the processing speed and lifespan of electrophotographic image forming equipment.

[0003] In increasingly high-speed electrophotographic image forming equipment, the time for each step in electrophotographic processing, such as charging and development, is shortened. Therefore, in order to maintain the quality of electrophotographic images, it is necessary to develop technologies that can instantaneously charge the toner and stably maintain the toner charge over long periods of time in any operating environment.

[0004] In order to make the toner instantly charged, as described in Japanese Patent Application Publication No. 2001-125302, there are known techniques involving adding external additives with a certain resistance value to the toner.

[0005] Furthermore, as described in Japanese Patent Application Publication No. 2009-229495, there are known techniques that involve maintaining stable electrical properties by introducing titanium oxide particles containing niobium atoms into the protective layer of an electrophotographic photosensitive component.

[0006] In Japanese Patent Application Publication No. 2001-125302, although some effect on the charge-rising performance of toners has been found, it has been discovered that in further high-speed electrophotographic image forming apparatuses, the charge-rising performance is insufficient, and the density of solid images immediately after the apparatus is started is unsatisfactory. Furthermore, it has been recognized that in further high-speed electrophotographic image forming apparatuses, for processing cartridges used for extended periods, the density uniformity of halftone images is insufficient. The inventors speculate the reasons for these issues as follows.

[0007] Before the toner is developed from the developer carrier to the roller gap of the electrophotographic photosensitive element, the toner, to which an external additive with a certain resistance value is added, is rubbed and energized using a scraper or similar means. However, in increasingly high-speed electrophotographic image forming equipment, the time for rubbing to energize is insufficient, and in solid images that consume large amounts of toner, the energization is inadequate. This is one conceivable reason. Another conceivable reason is that the external additive is small and has a shape that easily embeds into the toner, resulting in localized charging of the embedded portion, making it difficult to maintain the effect over long-term use.

[0008] Furthermore, in Japanese Patent Application Publication No. 2009-229495, the electrophotographic image forming apparatus exhibits insufficient improvement in charge rise performance immediately upon startup and in the density uniformity of halftone images after long-term use. The inventors speculate the reasons for this as follows.

[0009] One possible reason is that, although the charge of the surface protective layer remains almost unchanged by introducing titanium oxide particles containing niobium atoms into the surface protective layer of the electrophotographic photosensitive component, there is no mechanism to impart a charge to the toner, and therefore, there is no effect on improving the charge of the toner. Summary of the Invention

[0010] Therefore, the object of the present invention is to provide a processing cartridge that, in a further high-speed electrophotographic image forming apparatus, exhibits excellent charge-up performance immediately after the apparatus is started and excellent halftone image density uniformity over a long period from the start of use of the processing cartridge until its full utilization. "Immediately after the electrophotographic image forming apparatus is started" is sometimes referred to as "initially" in the following text. Furthermore, "after the processing cartridge has been fully utilized" is sometimes referred to as "after its long service life" in the following text.

[0011] A processing cartridge is provided, detachable from the main body of an electrophotographic image forming apparatus. The processing cartridge includes: an electrophotographic photosensitive element; a toner; and a developing unit configured to contain the toner and supply it to the surface of the electrophotographic photosensitive element. The toner comprises toner particles and an external additive A, wherein the external additive A satisfies the following requirements (i) to (iii): (i) a major axis of 100 nm or more and 3,000 nm or less; (ii) an aspect ratio of 5.0 or more; and (iii) a resistivity of 1 × 10⁻⁶. 5 Ω·cm or more and 1×10 8 The resistivity is below Ω·cm, wherein when observed using a scanning electron microscope, the ratio of the number of toner particles with external additive A on its surface to the total number of toner particles is 30% or more, and wherein the electrophotographic photosensitive component includes a conductive support, a photosensitive layer formed on the conductive support, and a surface protective layer formed on the surface of the electrophotographic photosensitive component, wherein the surface protective layer contains conductive particles, wherein the content of conductive particles in the surface protective layer is 5% by volume or more and 70% by volume or less, and wherein the volume resistivity of the surface protective layer is 1.0 × 10⁻⁶. 9 Ω·cm or more and 1.0×10 14 Below Ω·cm.

[0012] Further features of the invention will become apparent from the following description of exemplary embodiments, with reference to the accompanying drawings. Attached Figure Description

[0013] Figure 1 This is an illustration of an example of a schematic structure of an electrophotographic photosensitive element.

[0014] Figure 2 This is an illustration of an example of a schematic structure of an electrophotographic image forming apparatus including a processing box equipped with an electrophotographic photosensitive element.

[0015] Figure 3 This is a STEM image of an example of niobium-containing titanium oxide particles used in an embodiment of the present invention.

[0016] Figure 4 This is a schematic diagram of an example of niobium-containing titanium oxide particles used in an embodiment of the present invention. Detailed Implementation

[0017] Unless otherwise stated, descriptions of numerical ranges such as "above XX and below YY" or "XX to YY" refer to a numerical range that includes the lower and upper limits as endpoints.

[0018] When describing a range of values ​​in stages, the upper and lower limits of each range can be combined arbitrarily.

[0019] The following describes the configuration of the processing box of the present invention.

[0020] The processing cartridge of the present invention is a detachable processing cartridge from the main body of an electrophotographic image forming apparatus. The processing cartridge includes: an electrophotographic photosensitive component; a toner; and a developing unit configured to contain the toner and supply it to the surface of the electrophotographic photosensitive component. The toner comprises toner particles and an external additive A, which satisfies the following requirements (i) to (iii): (i) a major axis of 100 nm or more and 3,000 nm or less; (ii) an aspect ratio of 5.0 or more; and (iii) a specific resistance of 1 × 10⁻⁶. 5 Ω·cm or more and 1×10 8 The resistivity is below Ω·cm, wherein when observed using a scanning electron microscope, the ratio of the number of toner particles with external additive A on its surface to the total number of toner particles is 30% or more, and wherein the electrophotographic photosensitive component includes a conductive support, a photosensitive layer formed on the conductive support, and a surface protective layer formed on the surface of the electrophotographic photosensitive component, wherein the surface protective layer contains conductive particles, wherein the content of conductive particles in the surface protective layer is 5% by volume or more and 70% by volume or less, and wherein the volume resistivity of the surface protective layer is 1.0 × 10⁻⁶. 9 Ω·cm or more and 1.0×10 14 Below Ω·cm.

[0021] In view of the above problems, the inventors have investigated a technique involving the injection and charging of toner from the electrophotographic photosensitive element while the toner enters the developing rollers from the developing rollers. Typically, toner is regulated by the developing rollers and becomes triboelectrically charged. The inventors believe that, in addition to triboelectric charging, injecting charge into the toner from the electrophotographic photosensitive element while it enters the developing rollers ensures stable toner charging properties even in high-speed electrophotographic image forming equipment, immediately after equipment startup.

[0022] Based on the above discussion, the inventors conducted research and found that when an external additive A with a deformed shape having a specific volume resistivity and a large surface area is disposed in the surface layer of each toner particle, charge is injected from the electrophotographic photosensitive component into the toner through the external additive A. Furthermore, it has been found that the following unexpected effect is also obtained: this charge injection property is maintained even after durability. This configuration can provide a processing cartridge with excellent charge rise performance immediately after the electrophotographic image forming device is started and excellent concentration uniformity over long-term use.

[0023] The electrophotographic photosensitive component of the present invention comprises, in sequence, a conductive support, a photosensitive layer and a surface protective layer formed on the conductive support.

[0024] The surface protective layer contains conductive particles, with a content of 5% to 70% by volume. Furthermore, the volume resistivity of the surface protective layer is 1.0 × 10⁻⁶. 9 Ω·cm or more and 1.0×10 14 Below Ω·cm. The volume resistivity was measured in an atmosphere at 23°C and 50% RH. When the volume resistivity falls within the above range, the volume resistivity remains relatively high despite the introduction of a large number of conductive particles into the surface protective layer. Therefore, charge can be injected into the toner through the conductive particles while ensuring charge retention.

[0025] From the viewpoint of ensuring that the charge injection properties are suitable for achieving a satisfactory concentration immediately upon startup of the electrophotographic image forming apparatus and for maintaining satisfactory concentration uniformity of the processing chamber over a long period from the start of use until full use, the proportion of conductive particles in the surface protective layer is more preferably 20% by volume or more and 70% by volume or less, and even more preferably 40% by volume or more and 70% by volume or less. Furthermore, from the same viewpoint, the volume resistivity of the surface protective layer is 1.0 × 10⁻⁶. 9 Ω·cm or more and 1.0×10 14 Below Ω·cm, preferably 1.0×10 10Ω·cm or more and 1.0×10 14 Below Ω·cm. The volume resistivity of the surface protective layer can be controlled, for example, based on the particle size of the conductive particles.

[0026] Examples of conductive particles included in the surface protective layer include particles of metal oxides such as titanium oxide, zinc oxide, tin oxide, or indium oxide. When metal oxides are used as conductive particles, they may be doped with elements such as niobium, phosphorus, or aluminum, or oxides thereof.

[0027] The conductive particles in the electrophotographic photosensitive component of the present invention are preferably titanium oxide particles. Titanium oxide particles are prepared using known techniques. For example, see Japanese Patent Application Publication No. H07-242422.

[0028] From the viewpoint of the moisture absorption and dispersibility of the particles, the particle size of the conductive particles, in terms of number average particle size, is preferably 5 nm or more and 300 nm or less, more preferably 40 nm or more and 300 nm or less, and even more preferably 100 nm or more and 250 nm or less.

[0029] The conductive particles are particularly preferred to be titanium oxide particles, each containing niobium and having a composition in which niobium is localized near the particle surface. This is because the localization of niobium near the surface enables efficient charge transfer. More specifically, in each titanium oxide particle, the concentration ratio calculated as "niobium atom concentration / titanium atom concentration" within 5% of the maximum diameter from the particle surface is at least 2.0 times that calculated as "niobium atom concentration / titanium atom concentration" at the center of the particle. When the concentration ratio within 5% of the maximum primary particle diameter from the surface is set to at least 2.0 times that at the center of the particle, charge can move easily within the surface protective layer, thus improving the performance of injecting charge from the electrophotographic photosensitive element into the toner. The niobium atom concentration and titanium atom concentration are obtained by scanning transmission electron microscopy (STEM) using an EDS analyzer (energy dispersive X-ray spectrometer). A STEM image of an example (X1) of the titanium oxide particles used in the embodiments of the present invention is shown below. Figure 3 In addition, Figure 3 STEM images are schematically shown in Figure 4 As described in detail below, the niobium-containing titanium oxide particles used in embodiments of the invention are produced by coating each niobium-containing titanium oxide particle, which serves as a core, with the niobium-containing titanium oxide, followed by firing the resulting product. Therefore, it is considered that the niobium-coated titanium oxide undergoes crystal growth as niobium-doped titanium oxide through so-called epitaxial growth along the crystal of the titanium oxide serving as the core. Figure 3As shown, the niobium-containing titanium oxide produced thus has a lower density near the surface 32 than at the particle center 31, exhibiting a core-shell morphology. Furthermore, in EDS analysis using STEM, X-rays penetrate the entire particle; therefore, as... Figure 4 As shown, compared to EDS analysis using X-rays 33 penetrating the particle center 31, EDS analysis using X-rays 34, used to analyze the interior of 5% of the primary particle size, is more significantly affected by the area near the surface 32. That is, in each of these niobium-containing titanium oxide particles as described above, the niobium / titanium atom concentration ratio in the interior of 5% of the maximum diameter from the particle surface is more than 2.0 times that in the particle center, and niobium atoms are localized near the surface. Analysis using a STEM with EDS involves observation with a transmission electron microscope and measurement of the niobium / titanium ratio using EDS. Furthermore, the niobium / titanium ratio can also be measured directly from the electrophotographic photosensitive element by slicing it using a slicer, Ar milling, or FIB, etc.

[0030] The titanium dioxide particles, each containing niobium atoms, are preferably anatase or rutile titanium dioxide particles, more preferably anatase titanium dioxide particles. When anatase titanium dioxide is used, charge movement within the surface protective layer is facilitated, thus charge injection becomes satisfactory. The conductive particles are more preferably anatase titanium dioxide particles, each having niobium atoms localized near the particle surface. When each anatase titanium dioxide particle serves as a core, and its surface is coated with titanium dioxide containing niobium atoms, charge can move easily within the surface protective layer, and the performance of injecting charge into the toner can be improved. Furthermore, the decrease in the volume resistivity of the surface protective layer can be suppressed.

[0031] In each conductive particle, to ensure uniform charging of the electrophotographic photosensitive component, the atomic concentration ratio of Nb atoms to Ti atoms within 5% of the maximum diameter from the surface is preferably 0.02 or more and 0.20 or less. Furthermore, the amount of niobium atoms relative to the mass of each titanium oxide particle is preferably 2.6% by mass or more and 10.0% by mass or less.

[0032] To make it difficult for the external additive A to embed into the toner and to have a large surface area, and to allow for efficient charging of the injection starting from the external additive, preferred examples of its shape are described below. That is, the external additive A preferably has a shape other than a sphere, and preferably has a shape that is longer in the direction of one axis (called the "major axis") in the three-dimensional structure. The shape of the cross-section obtained by cutting the external additive A perpendicular to its major axis is not limited and can be circular, quadrilateral, triangular, polygonal, or a combination thereof. Furthermore, the cross-sectional area of ​​the cross-section can be substantially the same or different along the entire major axis, and can take the following shapes: the cross-sectional area is smaller or larger at both ends relative to the major axis, or the cross-sectional area at one end is smaller than the cross-sectional area at the other end along the major axis. That is, examples of the shape of external additive A include: columnar (cylinder, square prism, triangular prism, or polygonal prism), columnar with a thick center, columnar with a thin center, or cone (cone, square pyramid, triangular pyramid, or polygonal pyramid) shapes; partial shapes obtained by cutting any of the above; needle-like (a column or cone whose major axis is sufficiently longer than its minor axis); rod-like; and mixtures thereof. The "major axis" of external additive A refers to the length of its major axis, and the "minor axis" refers to the equivalent diameter of the circle perpendicular to the major axis at the position of maximum cross-sectional area. The numbers are used as representative values ​​for both the major and minor axes.

[0033] The major diameter of the external additive A is 100 nm or more and 3,000 nm or less, preferably 500 nm or more and 2,000 nm or less, and more preferably 800 nm or more and 1,700 nm or less. When the major diameter of the external additive A falls within these ranges, the efficiency of injection charging from the electrophotographic photosensitive element is improved. Furthermore, the embedding of the external additive A into the toner particles is suppressed, thus improving the uniformity of the solid image during long-term use. The reason for the improved uniformity of the solid image is that the external additive A comes into contact with the electrophotographic photosensitive element momentarily before the toner is developed from the developer carrier to the gap on the electrophotographic photosensitive element, initiating injection charging of the toner from the contact point.

[0034] The aspect ratio of the external additive A, i.e., the ratio of major diameter to minor diameter, is 5.0 or more, preferably 6.0 or more, and more preferably 8.0 or more. When the aspect ratio of the external additive A falls within these ranges, the injection of toner from the electrophotographic photosensitive element is effectively charged, resulting in satisfactory solid concentration immediately after the electrophotographic image forming apparatus is started and satisfactory concentration uniformity during sufficient use. There is no particular upper limit to the aspect ratio, but from the viewpoint that particles with suitable particle sizes can be easily produced, it is preferably 20.0 or less, more preferably 16.0 or less.

[0035] The resistivity of external additive A is 1.0 × 10⁻⁶. 5Ω·cm or more and 1.0×10 8 Below Ω·cm, preferably 1.0×10 6 Ω·cm or higher and 5.0×10 7 Below Ω·cm. When the resistivity falls within these ranges, the injection of toner into a charged state is carried out effectively, and charge leakage is reduced. As a result, it is possible to simultaneously achieve charge rise performance immediately after startup of the electrophotographic image forming equipment and charge uniformity until durability.

[0036] In the toner, it can be confirmed that the number of toner particles containing external additive A on its surface is at least 30%, preferably at least 40%, and more preferably at least 50%. There is no particular upper limit to the above ratio, as long as it satisfies the purpose of injecting the toner into a charged state. However, from the viewpoint of preventing the toner from having an excessive negative charge, it is preferable to have 95% or less, more preferably 90% or less.

[0037] The presence of external additive A on the surface means that more than one particle of external additive A can be identified on the surface of the toner particles. The presence of external additive A on the surface can be confirmed by observing the toner using a scanning microscope.

[0038] There are no restrictions on the materials used for external additive A, as long as they meet the above-mentioned physical property range, but inorganic particles such as titanium dioxide particles or alumina particles are preferred.

[0039] External additive A preferably contains titanium oxide particles. When external additive A contains titanium oxide particles, the resistance value can be easily set to the desired range, and halftone unevenness after durability can be satisfactorily suppressed.

[0040] External additive A more preferably contains rutile titanium dioxide particles. When external additive A contains rutile titanium dioxide particles, the toner can be effectively charged without causing the charge injected from the surface of the electrophotographic photosensitive element to leak to the outside.

[0041] In this invention, the toner particles preferably contain boric acid. When each toner particle contains boric acid, the retention performance of the charge injected into the toner is improved, thereby improving image quality during full use.

[0042] Boric acid is preferably present near the surface of the toner. The presence of boric acid in the toner particles near the surface is determined using ATR-IR analysis of germanium. That is, detecting boric acid using ATR-IR analysis of germanium means that boric acid is present near the surface of the toner. When boric acid is present near the surface of the toner, the charge of the toner, which is injected with a charged electrode, is maintained, thus improving image quality during full use.

[0043] There are no particular limitations on the method of introducing boric acid into the toner particles. For example, boric acid can be introduced into the toner particles by internal addition or as an agglomerating agent in the aggregation process. When boric acid is added as an agglomerating agent, it can be easily introduced near the surface of each toner particle. Raw materials for boric acid include organic boric acid, borates, and borate esters. When toner particles are produced in an aqueous medium, from the viewpoint of reactivity and production stability, boric acid is preferably added as a borate. Specific examples include sodium tetraborate and ammonium borate. Borax is particularly preferred.

[0044] Borax is represented as the decahydrate of sodium tetraborate (Na₂B₄O₇) and transforms into boric acid in acidic aqueous solutions. Therefore, borax is preferred when used in acidic environments in aqueous media. Borax is preferably included in each toner particle at a concentration of 0.1% to 10% by mass.

[0045] The composition of the toner in this invention is described below.

[0046] <Adhesive Resin>

[0047] Each colorant particle contains a binder resin. The binder resin content is preferably 50% by mass or more of the total resin content in the colorant particles.

[0048] The adhesive resin only needs to contain resins with ester bonds, and there are no particular limitations; known resins can be used. Styrene-acrylic resins or polyester resins are preferred. Polyester resins are more preferred.

[0049] Polyester resins are synthesized by means of known methods, such as transesterification or polycondensation, from a combination of suitable materials selected from polycarboxylic acids, polyols, and hydroxycarboxylic acids. Polyester resins preferably comprise polycondensates of dicarboxylic acids and diols.

[0050] Polycarboxylic acids are compounds that contain two or more carboxyl groups in one molecule. Among these compounds, dicarboxylic acids, which contain two carboxyl groups in one molecule, are preferred.

[0051] Examples of dicarboxylic acids may include oxalic acid, succinic acid, glutaric acid, maleic acid, adipic acid, β-methyl adipic acid, azelaic acid, sebacic acid, nonanedicarboxylic acid, decanedicarboxylic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, fumaric acid, citralic acid, diethylene glycol, cyclohexane-3,5-diene-1,2-carboxylic acid, hexahydroterephthalic acid, malonic acid, pimecrolic acid, octanoic acid, phthalic acid, isophthalic acid, terephthalic acid, tetrachlorophthalic acid, chlorophthalic acid, nitrophthalic acid, p-carboxyphenylacetic acid, p-phenylene diacetic acid, m-phenylene diacetic acid, o-phenylene diacetic acid, diphenylacetic acid, diphenyl-p,p'-dicarboxylic acid, naphthalene-1,4-dicarboxylic acid, naphthalene-1,5-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, anthracene dicarboxylic acid, and cyclohexanedicarboxylic acid.

[0052] In addition to the dicarboxylic acids mentioned above, examples of polycarboxylic acids include trimellitic acid, pyromellitic acid, pyromellitic tetracarboxylic acid, naphthalene tricarboxylic acid, naphthalene tetracarboxylic acid, pyrene tricarboxylic acid, pyrene tetracarboxylic acid, itaconic acid, pentenic acid, n-dodecyl succinic acid, n-dodecenyl succinic acid, isododecyl succinic acid, isododecenyl succinic acid, n-octyl succinic acid, and n-octenyl succinic acid. These carboxylic acids can be used alone or in combination.

[0053] Polyols are compounds that contain two or more hydroxyl groups in one molecule. Among these compounds, diols are compounds that contain two hydroxyl groups in one molecule and are preferred.

[0054] Specific examples of diols may include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, and 1,14-tetradecanediol. Alcohols, 1,18-octadecanediol, 1,14-eicosenediol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, 1,4-cyclohexanediol, 1,4-cyclohexanediol, 1,4-butenediol, neopentyl glycol, polytetramethylenediol, hydrogenated bisphenol A, bisphenol A, bisphenol F, bisphenol S, and epoxide adducts of the above bisphenols (e.g., ethylene oxide, propylene oxide, and epoxide butane).

[0055] Preferably, alkylene glycols having 2 or more but less than 12 carbon atoms and alkylene glycols having 2 or more but less than 12 carbon atoms are used together; particularly preferred are alkylene glycols having 2 or more but less than 12 carbon atoms used in combination. An example of an alkylene glycol of bisphenol A is a compound represented by the following formula (A).

[0056]

[0057] In formula (A), R independently represents ethylidene or propylidene, x and y each represent integers greater than or equal to 0, and the average value of x+y is greater than or equal to 0 and less than 10.

[0058] The alkyl oxide adduct of bisphenol A is preferably a propylene oxide adduct and / or an ethylene oxide adduct. A propylene oxide adduct is more preferred. Furthermore, the average value of x+y is preferably 1 or more and 5 or less.

[0059] Alcohols with three or more components include, for example, glycerol, trimethylolethane, trimethylolpropane, pentaerythritol, hexamethylolmelamine, hexaethylolmelamine, tetramethylolbenzoguanamine, tetraethylolbenzoguanamine, sorbitol, triphenol (PA), phenolic varnish, cresol varnish, and epoxide adducts of the above-mentioned alcohols with three or more components. These alcohols can be used alone or in combination.

[0060] Examples of styrene-acrylic resins include homopolymers formed from any of the following polymerizable monomers, or copolymers obtained by combining two or more of them, and mixtures thereof.

[0061] Examples of styrene monomers include α-methylstyrene, β-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, p-n-butylstyrene, p-tert-butylstyrene, p-n-hexylstyrene, p-n-octylstyrene, p-n-nonylstyrene, p-n-decylstyrene, p-n-dodecylstyrene, p-methoxystyrene, and p-phenylstyrene.

[0062] Examples of (meth)acrylic acid monomers include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, n-pentyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, n-nonyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, dimethyl phosphate, ethyl methacrylate, diethyl phosphate, dibutyl phosphate, ethyl methacrylate, 2-benzoyloxyethyl methacrylate, methacrylonitrile, 2-hydroxyethyl methacrylate, methacrylic acid, and maleic acid.

[0063] Examples include vinyl ether monomers such as vinyl methyl ether and vinyl isobutyl ether; vinyl ketone monomers such as vinyl methyl ketone, vinyl ethyl ketone and vinyl isopropyl ketone; and polyolefin monomers such as ethylene, propylene and butadiene.

[0064] Multifunctional polymerizable monomers can be used as styrene-acrylic resins as needed. Examples of multifunctional polymerizable monomers include diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, 2,2'-bis(4-((meth)acryloyloxydiethoxy)phenyl)propane, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, divinylbenzene, divinylnaphthalene, and divinyl ether.

[0065] In addition, known chain transfer agents and polymerization inhibitors can be added to control the degree of polymerization.

[0066] Examples of polymerization initiators used to obtain styrene-acrylic resins include organic peroxide initiators and azo polymerization initiators.

[0067] Examples of organic peroxide initiators include benzoyl peroxide, lauroyl peroxide, di-α-cumyl peroxide, 2,5-dimethyl-2,5-bis(benzoyl peroxide)hexane, bis(4-tert-butylcyclohexyl)peroxide, 1,1-bis(tert-butyl peroxide)cyclododecane, tert-butyl maleate peroxide, bis(tert-butyl peroxide) isophthalate, methyl ethyl ketone peroxide, tert-butyl peroxide-2-ethylhexanoate, diisopropyl peroxide carbonate, cumene hydroperoxide, 2,4-dichlorobenzoyl peroxide, and tert-butyl perpentyl peroxide.

[0068] Examples of azo polymerization initiators include 2,2'-azobis-(2,4-dimethylvalerate), 2,2'-azobisisobutyronitrile, 1,1'-azobis(cyclohexane-1-carboxylonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvalerate, azobismethylbutyronitrile, and 2,2'-azobis-(methyl isobutyrate).

[0069] In addition, redox initiators obtained by combining oxidizing and reducing substances can also be used as polymerization initiators.

[0070] Examples of oxidizing substances include inorganic peroxides such as hydrogen peroxide and persulfates (sodium, potassium and ammonium salts), as well as oxidizing metal salts such as tetravalent cerium salts.

[0071] Examples of reducing substances include: reducing metal salts (ferrous, copper, and chromium salts); ammonia; amines such as lower amines (amines with one or more but less than six carbon atoms, such as methylamine and ethylamine) and hydroxylamine; reducing sulfur compounds such as sodium thiosulfate, sodium dithionite, sodium bisulfite, sodium sulfite, and sodium formaldehyde sulfoxylate; lower alcohols (each with one or more but less than six carbon atoms); ascorbic acid or its salts; and lower aldehydes (each with one or more but less than six carbon atoms).

[0072] The polymerization initiator is selected based on its 10-hour half-life temperature and can be used alone or as a mixture thereof. The amount of polymerization initiator added varies depending on the target degree of polymerization, but generally, 0.5 to 20.0 parts by weight of polymerization initiator is added relative to 100.0 parts by weight of polymerizable monomer.

[0073] <Mold Release Agent>

[0074] In this invention, known waxes can be used as release agents for colorants.

[0075] Specific examples include: petroleum-based waxes and their derivatives, represented by paraffin, microcrystalline wax, and petrolatum; lignite wax and its derivatives; hydrocarbon waxes and their derivatives produced by the Fischer-Tropsch process; polyolefin waxes and their derivatives, represented by polyethylene; and natural waxes and their derivatives, represented by carnauba wax and candelilla wax. The derivatives include oxides, as well as block copolymers or graft-modified products with vinyl monomers.

[0076] Examples also include: alcohols such as higher aliphatic alcohols; fatty acids such as stearic acid and palmitic acid, their amides, esters and ketones; hydrogenated castor oil and its derivatives; vegetable waxes; and animal waxes. These release agents can be used alone or in combination.

[0077] Polyolefins, hydrocarbon waxes produced by the Fischer-Tropsch process, or petroleum-based waxes are preferred, as the developability and transferability tend to be improved when using any of these waxes. Antioxidants can be added to these waxes within a range that does not affect the effectiveness of the invention.

[0078] Furthermore, from the viewpoint of phase separation or crystallization temperature relative to the binder resin, suitable examples of waxes may include, for example, benzyl ester of benzyl acid and dibenzyl sebacate, which are higher fatty acid esters.

[0079] Furthermore, when using a release agent, the content of the release agent is preferably 1.0 parts by weight or more and 30.0 parts by weight or less relative to 100.0 parts by weight of the adhesive resin.

[0080] The melting point of the release agent is preferably above 30°C and below 120°C, more preferably above 60°C and below 100°C.

[0081] When a release agent exhibiting the thermal properties described above is used, the release effect can be effectively achieved, thus ensuring a wider fixing area.

[0082] <Plasticizer>

[0083] In the colorant of the present invention, a crystalline plasticizer is preferably used to improve rapid melting. There are no particular limitations on the plasticizer; known plasticizers used in colorants as described below can be used.

[0084] Specific examples may include: esters of monohydric alcohols and aliphatic carboxylic acids, such as betaine, stearate, and palmitate; esters of monohydric carboxylic acids and aliphatic alcohols, such as ethylene glycol distearate, disabarate, and hexanediol distearate; esters of trihydric alcohols and aliphatic carboxylic acids, such as glyceryl trisabarate; esters of tetrahydric alcohols and aliphatic carboxylic acids, such as pentaerythritol tetrastearate and pentaerythritol tetrapalmitate; esters of hexahydric alcohols and aliphatic carboxylic acids, such as dipentaerythritol hexastearate and dipentaerythritol hexapalmitate; esters of polyhydric alcohols and aliphatic carboxylic acids, such as polyglycerol betaine; and natural ester waxes, such as carnauba wax and rice bran wax. These plasticizers can be used alone or in combination.

[0085] <Coloring agent>

[0086] The toner particles may each contain a colorant. Known pigments or dyes can be used as colorants. Pigments are preferred as colorants due to their excellent weather resistance.

[0087] Cyan colorants include, for example, copper phthalocyanine compounds and their derivatives, anthraquinone compounds, and basic dye lake compounds.

[0088] Specific examples include CI Pigment Blue 1, CI Pigment Blue 7, CI Pigment Blue 15, CI Pigment Blue 15:1, CI Pigment Blue 15:2, CI Pigment Blue 15:3, CI Pigment Blue 15:4, CI Pigment Blue 60, CI Pigment Blue 62, and CI Pigment Blue 66.

[0089] Magenta colorants include, for example, condensed azo compounds, pyrrolopyrrole dione compounds, anthraquinone compounds, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindole compounds, and perylene compounds.

[0090] Specific examples include CI Pigment Red 2, CI Pigment Red 3, CI Pigment Red 5, CI Pigment Red 6, CI Pigment Red 7, CI Pigment Violet 19, CI Pigment Red 23, CI Pigment Red 48:2, CI Pigment Red 48:3, CI Pigment Red 48:4, CI Pigment Red 57:1, CI Pigment Red 81:1, CI Pigment Red 122, CI Pigment Red 144, CI Pigment Red 146, CI Pigment Red 150, CI Pigment Red 166, CI Pigment Red 169, CI Pigment Red 177, CI Pigment Red 184, CI Pigment Red 185, CI Pigment Red 202, CI Pigment Red 206, CI Pigment Red 220, CI Pigment Red 221, CI Pigment Red 254, and CI Pigment Violet 19.

[0091] Yellow colorants include, for example, condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and allyl amide compounds.

[0092] Specific examples include CI Pigment Yellow 12, CI Pigment Yellow 13, CI Pigment Yellow 14, CI Pigment Yellow 15, CI Pigment Yellow 17, CI Pigment Yellow 62, CI Pigment Yellow 74, CI Pigment Yellow 83, CI Pigment Yellow 93, CI Pigment Yellow 94, CI Pigment Yellow 95, CI Pigment Yellow 97, CI Pigment Yellow 109, CI Pigment Yellow 110, CI Pigment Yellow 111, CI Pigment Yellow 120, CI Pigment Yellow 127, CI Pigment Yellow 128, CI Pigment Yellow 129, CI Pigment Yellow 147, CI Pigment Yellow 151, CI Pigment Yellow 154, CI Pigment Yellow 155, CI Pigment Yellow 168, CI Pigment Yellow 174, CI Pigment Yellow 175, CI Pigment Yellow 176, CI Pigment Yellow 180, CI Pigment Yellow 181, CI Pigment Yellow 185, CI Pigment Yellow 191; Pigment Yellow 194.

[0093] Black colorants are, for example, colorants made by mixing carbon black, as well as yellow, magenta, and cyan colorants to achieve a black color.

[0094] These colorants can be used alone or as a mixture thereof, and can be used individually in a solid solution state.

[0095] When using a colorant, it is preferable to use 1.0 parts by weight or more and 20.0 parts by weight or less of the colorant relative to 100.0 parts by weight of the adhesive resin.

[0096] <Charge control agents and charge control resins>

[0097] The toner particles may each contain a charge control agent or a charge control resin.

[0098] As charge control agents, known charge control agents can be used, and in particular, charge control agents with high triboelectric charging speed and the ability to stably maintain a certain amount of triboelectric charge are preferred. Furthermore, when producing toner particles by suspension polymerization, charge control agents with low polymerization inhibition and substantially free of substances dissolved in aqueous media are particularly preferred.

[0099] Examples of charge control agents that allow the toner to carry a negative charge include monoazo metal compounds, acetylacetone metal compounds, aromatic hydroxycarboxylic acid series, aromatic dicarboxylic acid series, hydroxycarboxylic acid series and dicarboxylic acid series metal compounds, aromatic hydroxycarboxylic acids, aromatic monocarboxylic acids and aromatic polycarboxylic acids, and their metal salts, acid anhydrides and esters, such as phenolic derivatives such as bisphenol, urea derivatives, metal-containing salicylic acid series compounds, metal-containing naphthoic acid series compounds, boron compounds, quaternary ammonium salts, calixarenes and charge control resins.

[0100] Examples of charge-controlled resins may include polymers and copolymers, each having a sulfonic acid, sulfonate, or sulfonate structure. Polymers having a sulfonic acid, sulfonate, or sulfonate structure are particularly preferred to be polymers containing, specifically, a copolymerization ratio of at least 2% by mass, and more preferably at least 5% by mass, an acrylamide monomer containing a sulfonic acid group or a methacrylamide monomer containing a sulfonic acid group.

[0101] The charge-controlled resin preferably has a glass transition temperature (Tg) of 35°C or higher and 90°C or lower, a peak molecular weight (Mp) of 10,000 or higher and 30,000 or lower, and a weight-average molecular weight (Mw) of 25,000 or higher and 50,000 or lower. When using such a charge-controlled resin, preferred triboelectric properties can be imparted without affecting the thermal properties required for the toner particles. Furthermore, the charge-controlled resin contains a sulfonic acid structure, thus improving, for example, the dispersibility of the charge-controlled resin itself in the polymerizable monomer composition, as well as the dispersibility of the colorant therein, resulting in further improvements in tinting strength, transparency, and triboelectric properties.

[0102] These charge control agents or charge control resins can be added individually or in combination.

[0103] When using a charge control agent or charge control resin, the amount added is preferably 0.01 parts by weight or more and 20.0 parts by weight or less, more preferably 0.5 parts by weight or more and 10.0 parts by weight or less, relative to 100.0 parts by weight of the binder resin.

[0104] <External Additives>

[0105] The colorant contains external additive A, and may contain other external additives.

[0106] The major diameter (maximum diameter) of external additive A is 100 nm or more and 3,000 nm or less, preferably 500 nm or more and 2,000 nm or less, more preferably 800 nm or more and 1,700 nm or less; the aspect ratio is 5.0 or more, preferably 6.0 or more, more preferably 8.0 or more; and the resistivity is 1.0 × 10⁻⁶. 5 Ω·cm or more and 1.0×10 8 Below Ω·cm, preferably 1.0×10 6 Ω·cm or higher and 5.0×10 7 Below Ω·cm. There are no restrictions on the material of the external additive A, as long as it meets the above-mentioned physical property range, but it is preferred to be, for example, inorganic particles such as titanium oxide particles or alumina particles.

[0107] External additive A preferably contains titanium oxide particles. When external additive A contains titanium oxide particles, the resistance value can be easily set to the desired range, and halftone unevenness after durability is satisfactorily suppressed.

[0108] External additive A more preferably contains rutile titanium dioxide particles. When external additive A contains rutile titanium dioxide particles, the toner can be effectively charged without leakage of charge injected from the surface of the electrophotographic photosensitive element to the outside.

[0109] External additive A can be produced by, for example, adding an aqueous solution of NaOH to metatitanic acid, heating, cooling, and neutralizing the mixture to produce fine-particle rutile titanium dioxide, and appropriately mixing, calcining, and washing the fine-particle rutile titanium dioxide in a ball mill or similar device.

[0110] In addition, the toner may contain additives other than external additive A, such as granular silica particles, vinyl resins, polyester resins, silicone resins, titanium dioxide particles, or alumina particles that do not have the above aspect ratio.

[0111] <Production Method of Toners>

[0112] There are no particular limitations on the production method of the colorant in this invention; known methods such as pulverization, suspension polymerization, dissolution-suspension polymerization, emulsion polymerization, or dispersion polymerization can be used. The colorant is preferably produced by emulsion polymerization. The emulsion polymerization method is described below.

[0113] Furthermore, the 50% particle size (D50) of the binder resin in the aqueous dispersion of the resin fine particles is preferably 0.05 μm or more and 1.0 μm or less, more preferably 0.05 μm or more and 0.4 μm or less. When the 50% particle size (D50) based on the volume distribution is adjusted to fall within the above range, toner particles with a size suitable for use as toner particles and a volume average particle size of 3 μm or more and 10 μm or less can be easily obtained.

[0114] The 50% particle size (D50) based on the volume distribution can be measured using a dynamic light scattering particle size analyzer, the Nantrac UPA-EX150 (manufactured by Nikkiso Co., Ltd.).

[0115] <Colorant Fine Particle Dispersion>

[0116] Use colorant fine particle dispersions as needed. Colorant fine particle dispersions can be prepared by any of the known methods given below, but are not limited to these techniques.

[0117] Colorant fine particle dispersions can be prepared by mixing colorants, aqueous media, and dispersants using any known mixer, such as a stirrer, emulsifier, or disperser. Known dispersants such as surfactants and polymeric dispersants can be used as the dispersants in this case.

[0118] Each of the surfactants and polymeric dispersants used as dispersants can be removed in the washing steps described later, but from the viewpoint of washing efficiency, surfactants are preferred as dispersants.

[0119] Examples of surfactants include: anionic surfactants such as sulfate ester surfactants, sulfonate surfactants, phosphate ester surfactants and soap surfactants; cationic surfactants such as amine salt and quaternary ammonium salt surfactants; and nonionic surfactants such as polyethylene glycol surfactants, alkylphenol ethylene oxide adduct surfactants and polyol surfactants.

[0120] Nonionic or anionic surfactants are preferred. Furthermore, nonionic and anionic surfactants can be used in combination. Surfactants can be used alone or in combination. When using surfactants, their concentration in aqueous media is preferably 0.5% by mass or more and 5% by mass or less.

[0121] There is no particular limitation on the content of colorant fine particles in the colorant fine particle dispersion, but it is preferably 1% by mass or more and 30% by mass or less relative to the total mass of the colorant fine particle dispersion.

[0122] Furthermore, from the viewpoint of the dispersibility of the colorant in the final toner, the dispersed particle size of the fine colorant particles in the aqueous dispersion of the colorant is preferably 0.5 μm or less based on the 50% particle size (D50) of the volume distribution. Moreover, for the same reason, the 90% particle size (D90) based on the volume distribution is preferably 2 μm or less. The dispersed particle size of the fine colorant particles dispersed in the aqueous medium can be measured using a dynamic light scattering type particle size analyzer (Nanotrac UPA-EX150, manufactured by Nikkiso Co., Ltd.).

[0123] Examples of known mixers used for dispersing colorants in aqueous media, such as agitators, emulsifiers, and dispersers, include ultrasonic homogenizers, jet mills, pressure homogenizers, colloid mills, ball mills, sand mills, and paint mixers. These mixers can be used individually or in combination.

[0124] <Mold Release Agent (Aliphatic Hydrocarbon Compound) Fine Particle Dispersion>

[0125] A fine particle dispersion of the release agent can be used as needed. The fine particle dispersion of the release agent can be prepared by any of the known methods given below, but is not limited to these techniques.

[0126] A fine-particle dispersion of a release agent can be prepared by adding the release agent to an aqueous medium containing a surfactant, heating the mixture to a temperature above the melting point of the release agent, dispersing the mixture into particles using a homogenizer or pressure-discharge disperser with strong shear application capability, and then cooling it to a temperature below the melting point. An example of a homogenizer is the "Clearmix W-Motion" manufactured by MTechnique Co., Ltd. Another example of a pressure-discharge disperser is the "Gaulin homogenizer" manufactured by Gaulin.

[0127] In the aqueous dispersion of the release agent, regarding the particle size of the fine particulate release agent dispersion, the 50% particle size (D50) based on the volume distribution is preferably 0.03 μm or more and 1.0 μm or less, more preferably 0.1 μm or more and 0.5 μm or less. Furthermore, it is preferable that there are no coarse particles larger than 1 μm.

[0128] When the particle size of the release agent fine particulate dispersion falls within the above-mentioned range, the release agent can exist as a fine dispersion in the toner. Therefore, the exudation effect during fixing can be maximized to provide satisfactory separation. The particle size of the release agent fine particulate dispersion in an aqueous medium can be measured using a dynamic light scattering particle size analyzer (Nanotrac UPA-EX150, manufactured by Nikkiso Co., Ltd.).

[0129] <Mixing Steps>

[0130] In the mixing step, a mixture is prepared by mixing a fine resin particle dispersion with at least one fine release agent particle dispersion or a fine colorant particle dispersion as needed. The mixing step can be performed using any known mixing equipment, such as a homogenizer and a mixer.

[0131] <Steps for forming aggregated particles (aggregation steps)>

[0132] In the aggregation step, for example, fine particles contained in the mixture prepared in the mixing step are aggregated to form aggregates, each having a target particle size. At this time, an agglomerating agent is added and mixed, and at least one of heating or mechanical power is applied as needed. Therefore, aggregates can be formed by agglomerating resin fine particles with at least one of release agent fine particles or colorant fine particles as needed.

[0133] Examples of agglomerating agents include organic agglomerating agents such as quaternary cationic surfactants and polyethyleneimine; and inorganic agglomerating agents such as inorganic metal salts such as sodium sulfate, sodium nitrate, sodium chloride, calcium chloride and calcium nitrate, inorganic ammonium salts such as ammonium sulfate, ammonium chloride and ammonium nitrate, and metal complexes with divalent or higher valence.

[0134] In addition, to lower the pH and thus induce soft aggregation, an acid can be added, such as sulfuric acid or nitric acid.

[0135] The agglomerating agent can be added in either the form of a dry powder or an aqueous solution dissolved in an aqueous medium, but in order to induce uniform aggregation, it is preferred to add it in the form of an aqueous solution.

[0136] The addition and mixing of the agglomerant are preferably carried out at a temperature below the glass transition temperature or melting point of the resin contained in the mixed liquid. When mixing is carried out under such temperature conditions, aggregation occurs in a relatively uniform manner. The mixing of the agglomerant into the mixed liquid can be carried out using any known mixing equipment, such as a homogenizer and a mixer. In the aggregation step, aggregates of the toner particle size are formed in the aqueous medium. The volume average particle size of the aggregates produced in the aggregation step is preferably 3 μm or more and 10 μm or less. The volume average particle size can be measured using a particle size distribution analyzer (Coulter Multisizer III, manufactured by Coulter) based on the Coulter method.

[0137] <Steps for obtaining a dispersion containing toner particles (fusion step)>

[0138] In the fusion step, firstly, the dispersion containing the aggregates obtained in the aggregation step is terminated by stirring, similar to that in the aggregation step.

[0139] Aggregation can be terminated by adding aggregation terminators that can adjust pH, such as alkalis, chelating compounds, or inorganic salt compounds like sodium chloride.

[0140] After the dispersion of aggregated particles in the dispersion becomes stable through the action of an aggregation terminator, the aggregated particles are fused by heating to a temperature above the glass transition temperature or melting point of the binder resin to adjust to the desired particle size. The 50% particle size (D50) based on the volume distribution of the toner particles is preferably 3 μm or more and 10 μm or less.

[0141] Cooling Steps

[0142] As needed, during the cooling step, the temperature of the dispersion containing toner particles obtained in the fusion step can be cooled to a temperature below at least one of the crystallization temperature or the glass transition temperature of the binder resin. When cooling to a temperature below at least one of the crystallization temperature or the glass transition temperature, the occurrence of depressions on the toner surface can be suppressed, and the shape factors SF1 and SF2 can be set to 125 or less. Specifically, the cooling rate during the cooling step is 0.5°C / second or more, preferably 2°C / second or more, and more preferably 4°C / second or more.

[0143] Post-processing steps

[0144] In the toner production method of this embodiment, post-processing steps such as washing, solid-liquid separation, or drying can be further performed. When performing post-processing steps, toner particles in a dry state are obtained, for example.

[0145] <External Addition Steps>

[0146] In the external addition step, the toner particles obtained in the drying step are subjected to external addition treatment. Specifically, under shear force applied in the dry state, the aforementioned external additive A is added, along with inorganic fine particles such as silica, or resin fine particles such as vinyl resins, polyester resins, or silicone resins, which may be used as other external additives as needed.

[0147] The following describes the structure of the electrophotographic photosensitive component in this invention.

[0148] The electrophotographic photosensitive component of this invention sequentially comprises a conductive support, a photosensitive layer formed on the conductive support, and a surface protective layer. Figure 1 As an example of an electrophotographic photosensitive component, an electrophotographic photosensitive component comprising a stacked photosensitive layer is shown. Figure 1 In the support 21, a base coating layer 22, a charge generation layer 23, a charge transport layer 24 and a surface protective layer 25 are stacked.

[0149] <Surface Protective Layer>

[0150] The surface protective layer may comprise: a polymer of a compound having polymerizable functional groups; and a resin. Examples of polymerizable functional groups or structures include isocyanate groups, terminal isocyanate groups, hydroxymethyl groups, alkylated hydroxymethyl groups, epoxy groups, metal alkoxide structures, hydroxyl groups, amino groups, carboxyl groups, thiol groups, carboxylic anhydride structures, carbon-carbon double bonds, alkoxysilyl groups, and silanol groups. Monomers with charge-transporting capabilities can be used as compounds having polymerizable functional groups. Compounds having polymerizable functional groups can possess both chain polymerizable functional groups and charge-transporting structures.

[0151] Examples of resins include polyester resins, acrylic resins, phenoxy resins, polycarbonate resins, polystyrene resins, phenolic resins, melamine resins, and epoxy resins. Polycarbonate resins, polyester resins, and acrylic resins are preferred. Furthermore, the surface protective layer can be formed into a cured film by polymerizing a composition containing monomers having polymerizable functional groups. The reaction in this case is, for example, thermal polymerization, photopolymerization, or radiation polymerization. Examples of polymerizable functional groups in monomers include acryloyl and methacryloyl groups. Materials with charge-transporting capabilities can be used as monomers having polymerizable functional groups.

[0152] The surface protective layer can be formed by preparing a coating solution containing conductive particles, the aforementioned materials, and a solvent, forming a coating film on a photosensitive layer, and then drying and / or curing the coating film. Examples of solvents used in this coating solution include alcohol-based solvents, ketone-based solvents, ether-based solvents, sulfoxide-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents.

[0153] The surface protective layer may contain additives such as antioxidants, UV absorbers, plasticizers, leveling agents, slip-improving agents, and abrasion resistance enhancers. Specific examples include hindered phenolic compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, siloxane-modified resins, silicone oils, fluoropolymer particles, polystyrene resin particles, polyethylene resin particles, silica particles, alumina particles, and boron nitride particles.

[0154] The average thickness of the surface protective layer is preferably 0.2 μm or more and 5 μm or less, more preferably 0.5 μm or more and 3 μm or less.

[0155] The titanium oxide particles containing niobium atoms, which serve as conductive particles in the surface protective layer, can be of various shapes, such as spherical, polyhedral, elliptical, flake-like, and needle-like. From the viewpoint of reducing image defects such as black spots, spherical, polyhedral, or elliptical particles are preferred. In this invention, the titanium oxide particles containing niobium atoms are preferably spherical or nearly spherical polyhedral.

[0156] The titanium dioxide particles each containing niobium atoms are preferably anatase or rutile titanium dioxide particles, more preferably titanium dioxide particles with anatase content close to 100%. When anatase titanium dioxide is used, charge movement in the surface protective layer is promoted, thus the injected charge becomes satisfactory. In one embodiment of the invention, the anatase titanium dioxide particles with anatase content close to 100% used can be produced by the known sulfuric acid process. That is, a hydrated titanium dioxide slurry is produced by heating and hydrolyzing a solution containing titanium sulfate and titanium oxysulfate, and the titanium dioxide slurry is dehydrated and calcined to obtain particles. In one embodiment of the invention, the anatase content of the anatase titanium dioxide used is preferably 90% or more and 100% or less. Furthermore, the intermediate layer of anatase titanium dioxide including niobium atoms within this range satisfactorily and stably achieves rectification and satisfactorily achieves the above-mentioned effects.

[0157] In this paper, "anatase strength" is a value determined by measuring the intensity IA of the strongest interference line of anatase (planar index: 101) and the intensity IR of the strongest interference line of rutile (planar index: 110) in powder X-ray diffraction of titanium oxide, and is obtained by the following equation.

[0158] Anatase content (%) = 100 / (1 + 1.265 × IR / IA)

[0159] To produce anatase content in the range of 90% to 100%, in the production of titanium oxide, a solution containing titanium sulfate and titanium oxysulfate, which are titanium compounds, is hydrolyzed by heating. According to this method, anatase-type titanium oxide with an anatase content close to 100% is obtained. Furthermore, neutralizing an aqueous solution of titanium tetrachloride with alkali yields anatase-type titanium oxide with high anatase content.

[0160] The conductive particles included in the surface protective layer of the electrophotographic photosensitive component of the present invention are more preferably anatase titanium oxide particles, each of which has niobium atoms localized near its surface. When each anatase titanium oxide particle serves as a core and its surface is coated with titanium oxide containing niobium atoms, charge can be readily injected from the charging component in contact with the surface of the conductive particles, and can also readily move within the surface protective layer. Furthermore, the decrease in resistivity that leads to image smearing is suppressed.

[0161] In this invention, the conductive particles contained in the surface protective layer of the electrophotographic photosensitive component preferably have a number-average particle size of 40 nm or more and 150 nm or less. When the number-average particle size of the conductive particles is less than 40 nm, the specific surface area of ​​the conductive particles increases, resulting in increased water adsorption near the conductive particles on the surface of the surface protective layer. Consequently, the surface resistance of the surface protective layer decreases, making image trailing more likely. When the number-average particle size is greater than 150 nm, the dispersion of the particles in the surface protective layer decreases, and the area of ​​the interface between the particles and the binder resin also decreases. Therefore, the resistance at the interface increases, thereby reducing the injected charge due to charge movement.

[0162] <Support Body>

[0163] In this invention, the support body is preferably a conductive support body with electrical conductivity. Furthermore, examples of the support body's shape include cylindrical, strip-shaped, and sheet-shaped. Cylindrical support bodies are preferred. Additionally, the surface of the support body can be subjected to electrochemical treatments such as anodizing, sandblasting, or cutting.

[0164] The preferred materials for the support structure are metal, resin, or glass.

[0165] Examples of metals include aluminum, iron, nickel, copper, gold, stainless steel, and their alloys. Among these, aluminum supports are preferred.

[0166] Furthermore, it is preferable to impart conductivity to the resin or glass by a process including, for example, mixing or coating the resin or glass with a conductive material.

[0167] <Conductive Layer>

[0168] In the electrophotographic photosensitive component used in this invention, a conductive layer can be provided on the support. The conductive layer can shield the surface of the support from damage and unevenness, and control the reflection of light on the surface of the support. The conductive layer preferably comprises conductive particles and resin.

[0169] The conductive particles contained in the conductive layer are made of materials such as metal oxides, metals, or carbon black.

[0170] Examples of metal oxides include zinc oxide, aluminum oxide, indium oxide, silicon oxide, zirconium oxide, tin oxide, titanium oxide, magnesium oxide, antimony oxide, and bismuth oxide. Examples of metals include aluminum, nickel, iron, nickel-chromium alloys, copper, zinc, and silver.

[0171] Preferably, metal oxides are used as conductive particles, and more preferably, titanium oxide, tin oxide and zinc oxide are used.

[0172] When metal oxides are used as conductive particles, the surface of the metal oxides can be treated with silane coupling agents, or the metal oxides can be doped with elements such as phosphorus or aluminum, or their oxides.

[0173] Furthermore, the conductive particles are titanium oxide particles, barium sulfate particles, or zinc oxide particles, and preferably particles having niobium atoms localized on or near their surface. Additionally, when metal oxides are used as conductive particles, their number-average particle size is preferably 1 nm or more and 500 nm or less, more preferably 3 nm or more and 400 nm or less.

[0174] Examples of resins include polyester resins, polycarbonate resins, polyvinyl acetal resins, acrylic resins, silicone resins, epoxy resins, melamine resins, polyurethane resins, phenolic resins, and alkyd resins.

[0175] In addition, the conductive layer may further contain masking agents such as silicone oil, resin particles, or titanium dioxide.

[0176] The conductive layer can be formed by preparing a coating liquid containing the above-mentioned materials and solvents, forming a coating film on a support, and drying the coating film. Examples of solvents used in the coating liquid include alcohol-based solvents, sulfoxide-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents. Dispersion methods for dispersing conductive particles in the coating liquid for the conductive layer include, for example, using a paint mixer, a sand mill, a ball mill, or a liquid impact type high-speed disperser.

[0177] When the electrophotographic photosensitive component includes a conductive layer, its average thickness is preferably 1 μm or more and 40 μm or less, and particularly preferably 3 μm or more and 30 μm or less.

[0178] <Undercoat>

[0179] In this invention, the primer layer can be applied to the support or the conductive layer. The primer layer improves the adhesion between layers, thereby providing charge injection suppression.

[0180] The primer layer preferably comprises a resin. Furthermore, the primer layer can be formed into a cured film by polymerizing a composition comprising monomers having polymerizable functional groups.

[0181] Examples of resins include polyester resins, polycarbonate resins, polyvinyl alcohol acetal resins, acrylic resins, epoxy resins, melamine resins, polyurethane resins, phenolic resins, polyvinylphenolic resins, alkyd resins, polyvinyl alcohol resins, polyethylene oxide resins, polypropylene oxide resins, polyamide resins, polyamic acid resins, polyimide resins, polyamide-imide resins, and cellulose resins.

[0182] Examples of polymerizable functional groups or structures of monomers include isocyanate groups, terminal isocyanate groups, hydroxymethyl groups, alkylated hydroxymethyl groups, epoxy groups, metal alkoxide structures, hydroxyl groups, amino groups, carboxyl groups, thiol groups, carboxylic anhydride structures, and carbon-carbon double bonds.

[0183] Furthermore, to improve electrical properties, the base coating may further include electron transport materials, metal oxides, metals, and conductive polymers. Among these, electron transport materials and metal oxides are preferred.

[0184] Examples of electron transport substances introduced into the primer layer include quinone compounds, imide compounds, benzimidazole compounds, cyclopentadienyl compounds, fluorenone compounds, xanthone compounds, benzophenone compounds, cyanovinyl compounds, halogenated aryl compounds, thiophene compounds, and boron-containing compounds. Electron transport substances having polymerizable functional groups can be used as electron transport substances and copolymerized with the aforementioned monomers having polymerizable functional groups to form a primer layer as a cured film.

[0185] Examples of metal oxides include indium tin oxide, tin oxide, indium oxide, titanium oxide, zinc oxide, aluminum oxide, and silicon dioxide. Examples of metals include gold, silver, and aluminum.

[0186] Metal oxide particles introduced into the base coating can be surface-treated with surface treatment agents such as silane coupling agents. Common methods for surface treatment of metal oxide particles include dry and wet methods.

[0187] The dry method involves adding an aqueous alcohol solution, an organic solvent solution, or an aqueous solution containing a surface treatment agent while stirring metal oxide particles in a mixer capable of high-speed stirring, such as a Henschel mixer, to uniformly disperse the mixture, and then drying the dispersion.

[0188] Furthermore, the wet process involves stirring the metal oxide particles and the surface treatment agent in a solvent, or dispersing the metal oxide particles and the surface treatment agent in the solvent using a sand mill or similar device employing glass beads. After dispersion, the solvent is removed by filtration or vacuum evaporation. After solvent removal, it is preferable to further bake at a temperature above 100°C.

[0189] The base coating may further contain additives, and may include, for example, powders of metals such as aluminum; conductive materials such as carbon black; charge transport materials; metal chelating compounds; or organometallic compounds.

[0190] Examples of charge-transporting substances introduced into the primer include quinone compounds, imide compounds, benzimidazole compounds, cyclopentadienyl compounds, fluorenone compounds, xanthone compounds, benzophenone compounds, cyanovinyl compounds, halogenated aryl compounds, thiophene compounds, and boron-containing compounds. Charge-transporting substances having polymerizable functional groups can be used as charge-transporting substances and copolymerized with the aforementioned monomers having polymerizable functional groups to form a primer as a cured film.

[0191] The primer layer can be formed by preparing a primer coating liquid containing the above-mentioned materials and solvents, forming its coating film on a support or conductive layer, and allowing the coating film to dry and / or cure.

[0192] Examples of solvents used in the coating liquid for the primer layer include organic solvents such as alcohols, sulfoxides, ketones, ethers, esters, aliphatic halogenated hydrocarbons, and aromatic compounds. In this invention, alcohol-based and ketone-based solvents are preferred.

[0193] Dispersion methods for preparing coating liquids for primer coatings include, for example, methods using homogenizers, ultrasonic dispersers, ball mills, sand mills, roller mills, vibratory mills, grinders, or liquid collision type high-speed dispersers.

[0194] When a base coating is applied, its average thickness is preferably 0.1 μm or more and 10 μm or less, more preferably 0.1 μm or more and 5 μm or less.

[0195] <Photosensitive layer>

[0196] The photosensitive layer of an electrophotographic photosensitive component is mainly divided into (1) a stacked photosensitive layer and (2) a single-layer photosensitive layer, and either (1) or (2) can be used. (1) A stacked photosensitive layer is a photosensitive layer that contains a charge-generating layer containing charge-generating material and a charge-transporting layer containing charge-transporting material. (2) A single-layer photosensitive layer is a photosensitive layer that contains both charge-generating material and charge-transporting material.

[0197] (1) Layered photosensitive layer

[0198] The stacked photosensitive layer has a charge generation layer and a charge transport layer.

[0199] (1-1) Charge generation layer

[0200] The charge-generating layer preferably comprises a charge-generating substance and a resin.

[0201] Examples of charge-generating substances include azo pigments, perylene pigments, polycyclic quinone pigments, indigo pigments, and phthalocyanine pigments. Among these, azo pigments and phthalocyanine pigments are preferred. Of the phthalocyanine pigments, titanium dioxide phthalocyanine pigments, gallium chloride phthalocyanine pigments, and hydroxy gallium phthalocyanine pigments are preferred.

[0202] The content of charge-generating material in the charge-generating layer is preferably 40% by mass or more and 85% by mass or less, more preferably 60% by mass or more and 80% by mass or less, relative to the total mass of the charge-generating layer.

[0203] Examples of resins include polyester resins, polycarbonate resins, polyvinyl acetal resins, polyvinyl butyral resins, acrylic resins, silicone resins, epoxy resins, melamine resins, polyurethane resins, phenolic resins, polyvinyl alcohol resins, cellulose resins, polystyrene resins, polyvinyl acetate resins, and polyvinyl chloride resins. Polyvinyl butyral resins are preferred among these.

[0204] Furthermore, the charge-generating layer may further contain additives such as antioxidants or UV absorbers. Specific examples include hindered phenolic compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, and benzophenone compounds.

[0205] The charge-generating layer can be formed by preparing a coating liquid containing the above-mentioned materials and solvents, forming a coating film on a lower layer such as a primer layer, and drying the coating film. Examples of solvents used in the coating liquid include alcohol solvents, sulfoxide solvents, ketone solvents, ether solvents, ester solvents, and aromatic hydrocarbon solvents.

[0206] The average thickness of the charge generation layer is preferably 0.1 μm or more and 1 μm or less, more preferably 0.15 μm or more and 0.4 μm or less.

[0207] (1-2) Charge transport layer

[0208] The charge transport layer preferably comprises a charge transport material and a resin.

[0209] Examples of charge-transporting substances introduced into the charge-transporting layer include polycyclic aromatic compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, enamine compounds, benzidine compounds, triarylamine compounds, and resins having groups derived from one of these substances. Among these, triarylamine compounds and benzidine compounds are preferred.

[0210] The content of charge transport material in the charge transport layer is preferably 25% by mass or more and 70% by mass or less, more preferably 30% by mass or more and 55% by mass or less, relative to the total mass of the charge transport layer.

[0211] Examples of resins include polyester resins, polycarbonate resins, acrylic resins, and polystyrene resins. Among these, polycarbonate resins and polyester resins are preferred. Polyaryl ester resins are particularly preferred as polyester resins.

[0212] The content ratio (mass ratio) between the charge transport material and the resin is preferably 4:10 to 20:10, more preferably 5:10 to 12:10.

[0213] In addition, the charge transport layer may contain additives such as antioxidants, UV absorbers, plasticizers, leveling agents, slip-improving agents, and abrasion resistance enhancers. Specific examples include hindered phenolic compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, siloxane-modified resins, silicone oils, fluoropolymer particles, polystyrene resin particles, polyethylene resin particles, silica particles, alumina particles, and boron nitride particles.

[0214] The charge transport layer can be formed by preparing a coating solution containing the above-described materials and solvents, forming a coating film on the charge generation layer, and drying the coating film. Examples of solvents used in the coating solution include alcohol-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents. Among these solvents, ether-based solvents or aromatic hydrocarbon-based solvents are preferred.

[0215] The average thickness of the charge transport layer is 3 μm or more and 50 μm or less, more preferably 5 μm or more and 40 μm or less, and particularly preferably 10 μm or more and 30 μm or less.

[0216] (2) Single-layer photosensitive layer

[0217] A single-layer photosensitive layer can be formed by preparing a coating solution for a photosensitive layer containing a charge-generating substance, a charge-transporting substance, a resin, and a solvent, forming its coating film on a lower layer such as a base layer, and drying the coating film. Examples of charge-generating substances, charge-transporting substances, and resins introduced into a single-layer photosensitive layer are the same as those in the section “(1) Laminated Photosensitive Layers”.

[0218] [Processing Box]

[0219] The processing cartridge of the present invention integrates the aforementioned electrophotographic photosensitive component and developing unit, and may further include a charging unit, a transfer unit, and a cleaning unit. Furthermore, the processing cartridge of the present invention is detachable from the main body of the electrophotographic image forming apparatus. "The main body of the electrophotographic image forming apparatus" refers to the portion of the electrophotographic image forming apparatus excluding the processing cartridge.

[0220] Furthermore, according to one embodiment of the present invention, an electrophotographic image forming apparatus including a processing cartridge is provided. The electrophotographic image forming apparatus has the features of including the aforementioned electrophotographic photosensitive element, charging unit, exposure unit, developing unit, and transfer unit.

[0221] Figure 2 The illustration shows an example of a schematic configuration of an electrophotographic image forming apparatus including a processing box with an electrophotographic photosensitive element.

[0222] A cylindrical (drum-shaped) electrophotographic photosensitive element 1 is driven to rotate about axis 2 at a predetermined circumferential speed (processing speed) in the direction indicated by the arrow. During rotation, the surface of the electrophotographic photosensitive element 1 is charged to a predetermined positive or negative potential via charging unit 3. Figure 2The diagram shows a roller charging system based on a roller-type charging member, but charging systems such as corona charging systems, proximity charging systems, or injection charging systems can also be used. Exposure light 4 from an exposure unit (not shown) irradiates the charged surface of the electrophotographic photosensitive member 1, thereby forming an electrostatic latent image corresponding to the target image information thereon. The exposure light 4 is light whose intensity has been modulated to a time-series electro-digital image signal corresponding to the information of the target image, and is emitted, for example, from an image exposure unit such as slit exposure or laser beam scanning exposure. Toner contained in the toner container in the developing unit 5 is supplied, causing the electrostatic latent image formed on the surface of the electrophotographic photosensitive member 1 to develop (positive development or reverse development), thereby forming a toner image on the surface of the electrophotographic photosensitive member 1. The toner image formed on the surface of the electrophotographic photosensitive member 1 is transferred to a transfer material 7 by a transfer unit 6. At this time, a bias voltage with a polarity opposite to the charge possessed by the toner is applied to the transfer unit 6 from a bias power supply (not shown). Additionally, when the transfer material 7 is paper, it is removed from the paper supply section (not shown) and supplied synchronously with the rotation of the electrophotographic photosensitive member 1 to the space between the electrophotographic photosensitive member 1 and the transfer unit 6. The transfer material 7, onto which the toner image has been transferred from the electrophotographic photosensitive member 1, is separated from the surface of the electrophotographic photosensitive member and conveyed to the fixing unit 8 for fixing the toner image, thereby printing it out of the exterior of the electrophotographic image forming apparatus as an image formation (printed or copied). The electrophotographic image forming apparatus may include a cleaning unit 9 for removing, for example, toner residues remaining on the surface of the electrophotographic photosensitive member after transfer. Furthermore, a so-called detergent-free system can be used, which is configured not to specifically include a cleaning unit 9, but instead uses a developing unit 5 or similar unit to remove residues. In this invention, multiple components selected from the electrophotographic photosensitive member 1, the charging unit 3, the developing unit 5, and the cleaning unit 9 can be housed in a container and integrally supported to form a processing cartridge. The processing cartridge is detachable from the main body of the electrophotographic image forming apparatus. For example, the processing cartridge is configured as follows: At least one selected from the charging unit 3, developing unit 5, and cleaning unit 9 is integrally supported with the electrophotographic photosensitive member 1 to form the cartridge. This cartridge can be used as a processing cartridge 11, and is detachable from the main body of the electrophotographic image forming apparatus by using a guide unit 12, such as a track, of the main body of the electrophotographic image forming apparatus. The electrophotographic image forming apparatus may include a static removal mechanism configured to perform static removal treatment on the surface of the electrophotographic photosensitive member 1 using pre-exposure light 10 from a pre-exposure unit (not shown). Furthermore, in order to detachably mount the processing cartridge 11 to the main body of the electrophotographic image forming apparatus, a guide unit 12, such as a track, may be provided. The electrophotographic image forming apparatus of the present invention may include the electrophotographic photosensitive member 1 and at least one unit selected from the group consisting of the charging unit 3, the exposure unit, the developing unit 5, and the transfer unit 6.

[0223] The processing box of the present invention can be used in, for example, laser beam printers, LED printers, copiers, fax machines and their multifunctional peripherals.

[0224] Next, preferred methods for measuring various physical properties of the external additive A, the surface protective layer of the photosensitive component, and the conductive particles contained in the surface protective layer are described. However, the following description is merely illustrative, and the measurement methods are not limited thereto.

[0225] <Methods for measuring the major diameter, minor diameter, and aspect ratio of external additive A>

[0226] The major diameter (maximum diameter) and aspect ratio of external additive A were measured using a scanning electron microscope (e.g., scanning electron microscope "S-4800" (product name; manufactured by Hitachi, Ltd.)). The toner with external additive A was observed at a maximum magnification of 50,000x, and the major and minor diameters of 100 random primary particles of external additive A were measured. The aspect ratio of external additive A was calculated using the following formula. The magnification was adjusted appropriately according to the size of external additive A.

[0227] The aspect ratio of external additive A = the major axis of external additive A ÷ the minor axis of external additive A

[0228] For both the major and minor diameters, the average value of the aforementioned 100 primary particles is taken as the representative value. Furthermore, the aspect ratio is obtained by dividing the average of the major diameters of the 100 primary particles by the average of their minor diameters.

[0229] <Method for measuring the proportion of toner particles with external additive A on their surface>

[0230] The proportion of toner particles having external additive A on their surface relative to the total toner particles was obtained by observing the toner using a scanning electron microscope (e.g., a scanning electron microscope "S-4800" (product name; manufactured by Hitachi, Ltd.)). To be able to observe 10 to 30 toner particles in one field of view, 50 toner particles were randomly observed in a field of view magnified to approximately 3,000x. The proportion was calculated using the following formula when the number of toner particles with more than one external additive A particle on their surface among the 50 toner particles was indicated by "X". The magnification was appropriately adjusted according to the size of the toner and the size of the external additive A.

[0231] Percentage (number of items %) = X / 50 × 100

[0232] <Calculation of the primary particle size of conductive particles>

[0233] First, the electrophotographic photosensitive element is completely immersed in methyl ethyl ketone (MEK) in a graduated cylinder and ultrasonically irradiated to peel off the resin layer. Then, the substrate of the electrophotographic photosensitive element is removed. Next, the insoluble matter (photosensitive layer and protective layer containing conductive particles) insoluble in MEK is filtered out, the filtration residue is recovered, and dried using a vacuum dryer. Further, the resulting solid is suspended in a 1:1 volume ratio of tetrahydrofuran (THF) / methyl acetal, the insoluble matter is filtered out, and the filtration residue is recovered and dried using a vacuum dryer. This operation yields a resin containing conductive particles and a protective layer. Further, the filtration residue is heated to 500°C in an electric furnace until the solid consists only of conductive particles, and the conductive particles are recovered. To ensure the required amount of conductive particles is measured, multiple electrophotographic photosensitive elements are treated similarly.

[0234] A portion of the recovered conductive particles was dispersed in isopropanol (IPA), and the dispersion was dropwise added onto a grid with a supporting film (manufactured by JEOL Ltd., CU150J). The conductive particles were then observed in STEM mode using a scanning transmission electron microscope (JEOL Ltd., JEM2800). To facilitate the calculation of the particle size, observations were performed at magnifications ranging from 500,000x to 1,200,000x, and STEM images of 100 conductive particles were captured. The following settings were used: accelerating voltage of 200kV, probe size of 1nm, and image size of 1,024×1,024 pixels. Using the obtained STEM images, the particle size was measured once using the image processing software "Image-Pro Plus" (manufactured by Media Cybernetics, Inc.). The measurement method is as follows: First, using the Straight Line tool in the toolbar, the scale bar displayed at the bottom of the STEM image was selected. When you select "Set Scale" from the "Analyze" menu in this state, a new window opens. In the "Distance in Pixels" field, enter the pixel distance of the selected line. In the "Known Distance" field, enter the scale value (e.g., 100), and in the "Unit of Measurement" field, enter the scale unit (e.g., nm). Then, click "OK." This completes the scale setting. Next, use the line tool to draw a line that matches the maximum diameter of the conductive particles and calculate the particle size. Perform this operation on 100 conductive particles and use the resulting values ​​(maximum diameter) as the primary particle size.

[0235] <Calculation of Niobium / Titanium Atom Concentration Ratio>

[0236] A 5 mm square sample slice was cut from the photosensitive element and then cut into 200 nm thick sections using an ultrasonic microtome (Leica, UC7) at a cutting speed of 0.6 mm / s to prepare thin-section samples. The thin-section samples were observed in STEM mode on a scanning transmission electron microscope (JEOL Ltd., JEM2800) connected to an EDS analyzer (energy dispersive X-ray spectrometer) at magnifications ranging from 500,000x to 1,200,000x.

[0237] From the observed cross-sections of conductive particles, cross-sections of conductive particles with a maximum diameter of approximately 0.9 to 1.1 times the previously calculated primary particle size were selected by visual observation. Subsequently, the elemental spectra of the selected conductive particle cross-sections were collected using an EDS analyzer to create EDS mapping images. Spectral collection and analysis were performed using an NSS (ThermoFisher Scientific) instrument. Collection conditions were set as follows: accelerating voltage 200 kV, a probe size of 1.0 nm or 1.5 nm appropriately selected to achieve a dead time of 15 to 30, mapping resolution of 256 × 256, and a frame count of 300. EDS mapping images of 100 conductive particle cross-sections were obtained.

[0238] The resulting EDS images were analyzed individually to calculate the ratios of niobium (atomic %) and titanium (atomic %) concentrations within the particle's center and within 5% of its maximum diameter measured from the particle's surface. Specifically, the analysis was performed as follows: First, the "Line Extraction" button on the NSS was pressed to draw a straight line parallel to the particle's maximum diameter, obtaining information on the atomic concentrations (atomic %) along this line extending from one surface, through the particle's interior, and to the other surface. Particles whose maximum diameter at this point fell within the range of less than 0.9 times or greater than 1.1 times the previously calculated primary particle diameter were excluded from subsequent analysis. (Only particles with maximum diameters greater than 0.9 times and less than 1.1 times the primary particle diameter were analyzed as follows). Next, the niobium (atomic %) concentrations within 5% of the particle's maximum diameter measured from the particle's surface were read from both sides of the particle's surface. Similarly, the titanium (atomic %) concentrations within 5% of the particle's maximum diameter measured from the particle's surface were obtained. Then, using these values, for each surface of the particles on both sides, the following formula is used to obtain the "concentration ratio between niobium and titanium atoms in the interior of the particle, measured from the surface of the particle at 5% of the maximum diameter".

[0239] (The concentration ratio between niobium and titanium atoms in the interior of 5% of the particle's maximum diameter, measured from the particle's surface) = (Niobium atom concentration (atomic %) in the interior of 5% of the particle's maximum diameter, measured from the particle's surface) / (Titanium atom concentration (atomic %) in the interior of 5% of the particle's maximum diameter, measured from the particle's surface)

[0240] Of the two concentration ratios obtained, the smaller concentration ratio is used as the "concentration ratio between niobium atoms and titanium atoms in 5% of the maximum diameter of the particle measured from the surface of the particle" in this invention.

[0241] In addition, the concentrations of niobium atoms (atomic %) and titanium atoms (atomic %) at locations on the aforementioned straight line that coincide with the midpoint of the maximum diameter are read. Using these values, the "concentration ratio between niobium atoms and titanium atoms at the center of the particle" is obtained from the following formula.

[0242] The concentration ratio of niobium atoms to titanium atoms in the center of the particle = (niobium atom concentration (atomic %) in the center of the particle) / (titanium atom concentration (atomic %) in the center of the particle).

[0243] The following formula is used to calculate the concentration ratio of niobium atoms to titanium atoms in the interior of the particle, which is 5% of the maximum diameter of the particle measured from the surface of the particle: niobium atom concentration / titanium atom concentration relative to the center of the particle.

[0244] (The ratio of niobium to titanium atoms within 5% of the particle's maximum diameter, measured from the particle's surface) / (The ratio of niobium to titanium atoms in the particle's center)

[0245] Next, four 5mm square sample pieces were cut from the photosensitive component, and the surface protective layer was reconstructed into a 2μm × 2μm × 2μm three-dimensional object using FIB-SEM Slice & View. Based on the contrast difference in the FIB-SEM Slice & View, the content of conductive particles in the total volume of the surface protective layer was calculated. In the following embodiments, the Slice & View conditions are as described below.

[0246] Sample preparation for analysis: FIB method

[0247] Processing and observation equipment: NVision 40 manufactured by SII / Zeiss

[0248] Slice spacing: 10nm

[0249] Observation conditions:

[0250] Accelerating voltage: 1.0kV

[0251] Sample tilt: 54°

[0252] WD: 5mm

[0253] Detector: BSE detector

[0254] Aperture: 60μm, high current

[0255] ABC: Open

[0256] Image resolution: 1.25nm / pixel

[0257] The analysis region was set to 2μm length × 2μm width. The information from each cross-section was integrated to determine the thickness of each 2μm length × 2μm width × 2μm thickness (8μm). 3 The sample volume V was measured. Furthermore, the ambient temperature was 23°C and the pressure was 1 × 10⁻⁶. -4 Pa. Alternatively, a Strata 400S (sample tilt: 52°) manufactured by FEI can be used as the processing and observation device. Furthermore, information for each cross-section is obtained through image analysis of the determined area of ​​the conductive particles. Image analysis is performed using image processing software (manufactured by MediaCybernetics, Image-Pro Plus).

[0258] Based on the obtained information, the volume in each of the four sample pieces was measured at 2μm×2μm×2μm (unit volume: 8μm). 3 The volume V of the conductive particles in the sample is then calculated. (V / μm) 3 / 8μm 3 ×100). The four sample pieces (Vμm) 3 / 8μm 3 The average value of (×100) is defined as the content of conductive particles in the surface protective layer relative to the total volume of the surface protective layer [vol%].

[0259] Furthermore, all four sample pieces are processed up to the boundary between the surface protective layer and the underlying layer to determine the thickness of the surface protective layer, which is used in the calculation of volume resistivity ρv in the following <Method for Measurement of Volume Resistivity of Protective Layer of Photosensitive Component>.

[0260] Measurement of volume resistivity of surface protective layer

[0261] The volume resistivity of the surface protective layer was measured using a picoampere (pA) meter. First, comb-shaped gold electrodes with an inter-electrode distance (d) of 180 μm and a length (L) of 5.9 cm were fabricated on a PET film via vapor deposition. A surface protective layer with a thickness (T1) of 2 μm was then formed on these electrodes. Next, the DC current (I) was measured when a DC voltage (V) of 100 V was applied between the comb-shaped electrodes at an environment of 23 °C and 50% RH. The volume resistivity A (temperature: 23 °C / humidity: 50% RH) was obtained using the following equation (7). Measurement results using this method are not documented in this paper.

[0262] Volume resistivity ρv (Ω·cm) = V(V) × T1(cm) × L(cm) / {I(A) × D(cm)} (7)

[0263] When the composition of the surface protective layer, including conductive particles and binder resin, is difficult to identify, the surface resistivity of the electrophotographic photosensitive component is measured and converted into volume resistivity. When measuring the volume resistivity of the surface protective layer in its coated state, rather than just the volume resistivity of the surface protective layer itself, it is desirable to measure the surface resistivity of the surface protective layer and then convert it into volume resistivity. With the photosensitive component coated, the surface resistivity ρs can be calculated from equation (8) by measuring the DC current while a constant DC voltage is applied, by depositing gold from vapor onto the surface protective layer to form a comb-shaped electrode. The results shown in the following examples are obtained using this measurement method.

[0264] ρv=ρs×t (8)

[0265] “t” represents the thickness of the charge injection layer.

[0266] This measurement involves measuring a minute current; therefore, it is preferable to use an instrument capable of measuring minute currents as the resistance measuring device. An example of a resistance measuring device is the PicoAmmeter 4140B manufactured by Hewlett-Packard. The comb electrode used and the applied voltage are appropriately selected based on the material and resistance value of the charge injection layer to obtain a suitable SN ratio.

[0267] In this invention, comb-shaped gold electrodes with an inter-electrode distance (D) of 120 μm and a length (L) of 2.0 cm are fabricated on the surface of an electrophotographic photosensitive component by vapor deposition. Next, the surface resistivity ρs is obtained by measuring the DC current (I) when a DC voltage (V) of 1,000 V is applied between the comb-shaped electrodes at an environment of 23°C and 50% RH (temperature: 23°C / humidity: 50% RH).

[0268] Furthermore, the thickness T1 (cm) of the surface protective layer was measured according to the above <Cross-sectional Analysis of the Surface Protective Layer of Electrophotographic Photosensitive Components>. The volume resistivity ρv (temperature: 23℃ / humidity: 50%RH) was obtained by multiplying the surface resistivity ρs by the thickness T1 in the above equation.

[0269] <Analytical Methods for Niobium Atom Content in Conductive Particles>

[0270] The niobium atom content in the conductive particles used in this invention is measured as follows.

[0271] The conductive particles recovered from the photosensitive element in the aforementioned section, <Calculation of Primary Particle Size of Conductive Particles>, were granulated using the pressing process described below to prepare a sample. Using the prepared sample, the niobium atom content of the conductive particles was quantified by X-ray fluorescence (XRF) analysis via the FP method.

[0272] Specifically, the quantification is performed in terms of niobium pentoxide, and then converted into the content of niobium atoms.

[0273] (i) Examples of equipment used

[0274] X-ray fluorescence analyzer 3080 (Rigaku Corporation)

[0275] (ii) Sample preparation

[0276] A sample compression molding machine (manufactured by MAEKAWA Testing Machine MFG. Co., LTD.) was used for sample preparation. 0.5g of conductive particles were placed in an aluminum ring (model: 3481E1) and granulated by pressing for 1 minute under a load setting of 5.0 tons.

[0277] (iii) Measurement conditions

[0278] Measured diameter: 10φ

[0279] Measurement of potential and voltage: 50kV, from 50mA to 70mA

[0280] 2θ angle: 25.12°

[0281] Crystallization plate: LiF

[0282] Measurement time: 60 seconds

[0283] <Powder X-ray Diffraction Measurement of Conductive Particles>

[0284] The following describes a method for determining whether the conductive particles used in the electrophotographic photosensitive component of the present invention contain anatase titanium dioxide or rutile titanium dioxide.

[0285] The pattern obtained by powder X-ray diffraction using CuKα X-rays was identified using the Inorganic Materials Database (AtomWorks) of the National Institute for Materials Science (NIMS) in Japan. The above-described (quantification of niobium atoms contained in the conductive particles) was used as an example for the conductive particles contained in the protective layer of the electrophotographic photosensitive component of the present invention.

[0286] Powder X-ray diffraction measurements can be performed under the following conditions.

[0287] Measurement equipment used: RINT-TTRII X-ray diffraction equipment (manufactured by Rigaku Corporation)

[0288] X-ray tube: Cu

[0289] Tube voltage: 50kV

[0290] Tube current: 300 mA

[0291] Scanning method: 2θ / θ scan

[0292] Scanning speed: 4.0° / min

[0293] Sampling interval: 0.02°

[0294] Starting angle (2θ): 5.0°

[0295] Termination angle (2θ): 40.0°

[0296] Attachment: Standard Sample Rack

[0297] Filter: Not used

[0298] Incident monochromator: using

[0299] Counting monochromator: Not in use

[0300] Diverging slit: Open

[0301] Longitudinal diverging slit: 10.00mm

[0302] Scattering slit: Open

[0303] Light receiving slit: Open

[0304] Flat panel monochromator: using

[0305] Counter: Blink Counter

[0306] Example

[0307] The present invention is described in more detail below with reference to embodiments and comparative examples. The present invention is by no means limited to the following embodiments, and various modifications can be made without departing from the spirit of the invention. In the following description of the embodiments, unless otherwise stated, "parts" simply refers to parts by mass.

[0308] <Production Example of Toner Granules 1>

[0309] Synthesis of Polyester Resin 1

[0310] • 9 moles of 2 mol bisphenol A-ethylene oxide adduct

[0311] • 95 moles of 2 mol bisphenol A-propylene oxide adduct

[0312] · 50 moles of terephthalic acid

[0313] • 30 moles of fumaric acid

[0314] • 25 moles of dodecenylsuccinic acid

[0315] The monomers were loaded into a flask equipped with a stirrer, nitrogen inlet, temperature sensor, and distillation column. The temperature was raised to 195°C over 1 hour to confirm that the reaction system was uniformly stirred. 1.0 part of distearate was added for every 100 parts of these monomers. Further, while distilling to remove the generated water, the temperature was raised from 195°C to 250°C over 5 hours, and a dehydration condensation reaction was carried out at 250°C for an additional 2 hours.

[0316] As a result, polyester resin 1 with a glass transition temperature of 60.2℃, an acid value of 16.8 mgKOH / g, a hydroxyl value of 28.2 mgKOH / g, a weight-average molecular weight of 11,200, and a number-average molecular weight of 4,100 was obtained.

[0317] Synthesis of Polyester Resin 2

[0318] • 48 moles of 2 mol bisphenol A-ethylene oxide adduct

[0319] • 48 moles of 2 mol bisphenol A-propylene oxide adduct

[0320] • 65 moles of terephthalic acid

[0321] • 30 moles of dodecenylsuccinic acid

[0322] The monomers were loaded into a flask equipped with a stirrer, nitrogen inlet, temperature sensor, and distillation column. The temperature was raised to 195°C over 1 hour to ensure uniform stirring of the reaction system. 0.7 parts of distearate were added per 100 parts of these monomers. Further, while distilling away the generated water, the temperature was raised from 195°C to 240°C over 5 hours, and a dehydration condensation reaction was carried out at 240°C for an additional 2 hours. Then, the temperature was lowered to 190°C, and 5 moles of trimellitic anhydride were gradually added, with the reaction continuing at 190°C for 1 hour.

[0323] As a result, polyester resin 2 with a glass transition temperature of 55.2℃, an acid value of 14.3 mgKOH / g, a hydroxyl value of 24.1 mgKOH / g, a weight-average molecular weight of 43,600, and a number-average molecular weight of 6,200 was obtained.

[0324] Preparation of Resin Particle Dispersion 1

[0325] • 100 parts polyester resin • 50 parts methyl ethyl ketone • 20 parts isopropanol

[0326] Methyl ethyl ketone and isopropanol were added to a container. Then, the above materials were slowly added, and the mixture was stirred until completely dissolved, thus obtaining a solution of polyester resin 1. The container containing the solution of polyester resin 1 was set to 65°C, and while stirring the contents, a total of 5 parts of a 10% ammonia solution were gradually added dropwise. Further, 230 parts of deionized water were slowly added dropwise at a rate of 10 mL / min to induce reverse emulsification. The solvent was then removed under reduced pressure using an evaporator. Thus, a resin particle dispersion 1 of polyester resin 1 was obtained. The volume average particle size of the resin particles was 135 nm. Furthermore, the solid content of the resin particles was adjusted to 20% using deionized water.

[0327] Preparation of Resin Particle Dispersion 2

[0328] • Polyester resin 2 100 parts

[0329] 50 parts of methyl ethyl ketone

[0330] • 20 parts isopropanol

[0331] Methyl ethyl ketone and isopropanol were added to a container. Then, the above materials were slowly added, and the mixture was stirred until completely dissolved, thus obtaining a solution of polyester resin 2. The container containing the solution of polyester resin 2 was set to 40°C, and while stirring the contents, a total of 3.5 parts of a 10% ammonia solution was gradually added dropwise. Further, 230 parts of deionized water were slowly added dropwise at a rate of 10 mL / min to induce reverse emulsification. The solvent was then removed under reduced pressure. Thus, a resin particle dispersion 2 of polyester resin 2 was obtained. The volume average particle size of the resin particles was 155 nm. Furthermore, the solid content of the resin particles was adjusted to 20% using deionized water.

[0332] Preparation of colorant particle dispersion

[0333] • Copper phthalocyanine (pigment blue 15:3) 45 parts

[0334] • 5 parts of ionic surfactant Neogen RK (manufactured by DKS Co. Ltd.)

[0335] • 190 portions of ion-exchanged water

[0336] The above materials were mixed and dispersed in a homogenizer for 10 minutes. Then, the mixture was further dispersed using an ulimizer at 250 MPa for 20 minutes to obtain a colorant particle dispersion with a volume average particle size of 120 nm and a solid content of 20%. An IKA-manufactured ULTRA-TURRAX was used as the homogenizer. A collision-type wet mill manufactured by SuginoMachine Limited was used as the ulimizer.

[0337] Preparation of release agent particle dispersion

[0338] • Release agent (hydrocarbon wax, melting point: 79℃) 15 parts

[0339] • 2 parts of ionic surfactant NEOGEN RK (manufactured by DKS Co. Ltd.)

[0340] • 240 portions of ion-exchanged water

[0341] The above material was heated to 100°C and fully dispersed using ULTRA-TURRAX T50 manufactured by IKA. Then, it was heated to 115°C and dispersed in a pressure-discharge Gaulin homogenizer for 1 hour to obtain a release agent particle dispersion with a volume average particle size of 160 nm and a solid content of 20%.

[0342] Production of Toner Granules 1

[0343] • 1,500 parts of resin particle dispersion

[0344] • 2,400 parts of resin particle dispersion

[0345] • 50 parts of colorant particle dispersion

[0346] • 80 parts of release agent granule dispersion

[0347] First, as a core formation step, the above materials were placed in a round-bottom flask made of stainless steel and mixed. Then, the contents were dispersed for 10 minutes at 5,000 rpm using a ULTRA-TURRAX T50 homogenizer (manufactured by IKA). The pH was adjusted to 3.0 by adding 1.0% aqueous nitric acid. The resulting mixture was then heated to 58°C in a heated water bath with a stirring blade, while the rotation speed of the stirring blade was adjusted appropriately to agitate the liquid. The volume average particle size of the formed aggregates was appropriately checked using a Coulter Multisizer III. At the point when aggregates (cores) with a volume average particle size of 5.0 μm were formed, as a shell formation step, the following materials were added, and the mixture was further stirred for 1 hour to form a shell.

[0348] • Resin particle dispersion 1 40 parts

[0349] · 300 portions of ion-exchanged water

[0350] • 19 parts of 10.0% (w / w) borax aqueous solution

[0351] (Borax; Sodium tetraborate decahydrate, manufactured by FUJIFILM Wako Pure Chemical Corporation)

[0352] Then, the pH was adjusted to 9.0 using a 5% sodium hydroxide aqueous solution, and the resulting mixture was heated to 89°C while continuously stirring.

[0353] At the point when the desired surface shape is obtained, heating is stopped, the product is cooled to 25°C, filtered, and subjected to solid-liquid separation, followed by washing with deionized water. After washing, the product is dried using a vacuum dryer to obtain toner particles 1. The obtained toner particles 1 have a boron-derived X-ray fluorescence intensity of 0.15 and a weight-average particle size of 6.5 μm.

[0354] Production of Toner Granules 2

[0355] • 1,500 parts of resin particle dispersion

[0356] • 2,400 parts of resin particle dispersion

[0357] • 50 parts of colorant particle dispersion

[0358] • 80 parts of release agent granule dispersion

[0359] First, as a core formation step, the above materials were placed in a round-bottom flask made of stainless steel and mixed. Then, the contents were dispersed for 10 minutes at 5,000 rpm using a ULTRA-TURRAX T50 homogenizer (manufactured by IKA). The pH was adjusted to 3.0 by adding 1.0% aqueous nitric acid. The resulting mixture was then heated to 58°C in a heated water bath with a stirring blade, while the rotation speed of the stirring blade was adjusted appropriately to agitate the liquid. The volume average particle size of the formed aggregates was appropriately checked using a Coulter Multisizer III. At the point when aggregates (cores) with a volume average particle size of 5.0 μm were formed, as a shell formation step, the following materials were added, and the mixture was further stirred for 1 hour to form a shell.

[0360] • Resin particle dispersion 1 40 parts

[0361] · 300 portions of ion-exchanged water

[0362] Then, the pH was adjusted to 9.0 using a 5% sodium hydroxide aqueous solution, and the resulting mixture was heated to 89°C while continuously stirring.

[0363] At the point when the desired surface shape is achieved, heating is stopped, the resulting material is cooled to 25°C, filtered, and subjected to solid-liquid separation, followed by washing with deionized water. After washing, the material is dried using a vacuum dryer to obtain toner particles 2. The weight-average particle size of the obtained toner particles 2 is 6.6 μm.

[0364] <Production Example of External Additive 1>

[0365] External additive 1, used as external additive A, is produced as follows. A 50% NaOH aqueous solution, in a molar amount of 4 times that of TiO2 (based on NaOH), is added to metatitanic acid obtained by the sulfuric acid method, and the mixture is heated at 95°C for 2 hours. After thorough washing, 31% HCl is added at an HCl / TiO2 ratio of 0.26, and the result is heated at its boiling point for 1 hour. After cooling, the result is neutralized to pH 7 with 1 mol / L NaOH, then washed and dried to obtain fine-grained rutile titanium dioxide. The specific surface area of ​​the obtained fine-grained rutile titanium dioxide is 115 g / m². 2100 parts of NaCl and 25 parts of Na₂P₂O₇·10H₂O were added to 100 parts of fine rutile titanium dioxide. The mixture was then thoroughly mixed in a vibratory ball mill for 1 hour, and subsequently calcined in an electric furnace at 850°C for 2 hours. The resulting calcined product was then placed in pure water and heated at 80°C for 6 hours, followed by washing to remove soluble salts. All particles obtained by drying were needle-shaped titanium dioxide fine particles, each with a minor diameter between 0.03 μm and 0.07 μm and a major diameter between 0.4 μm and 0.8 μm. The physical properties of the resulting external additive 1 are shown in Table 1.

[0366] <Production Examples of External Additives 2 to 14>

[0367] Except for the changes in conditions shown in Table 1, external additives 2 to 14, each used as external additive A, were obtained in the same manner as in the production example of external additive 1. The physical properties of the obtained external additives 2 to 14 are shown in Table 1. The processing agents shown in Table 1 were used as some of the external additives.

[0368] Table 1

[0369]

[0370] <Production Example of External Additive 15>

[0371] External additive 15, used as an external additive that does not fall within the category of external additive A, is produced by reacting a BET specific surface area of ​​170 m² with hexamethyldisilazane. 2 / g of basic material silica particles are obtained by hydrophobicating the silica particles.

[0372] <Production Example of Toner 1>

[0373] Toner granules 1,100.0 parts

[0374] External additive 1 0.60 parts

[0375] External additives 15 0.80 parts

[0376] The above materials were mixed at 3,000 rpm for 15 minutes using a Henschel mixer (manufactured by Nippon Coke & Engineering Co., Ltd.) to obtain toner 1. The toner was observed using a scanning electron microscope, and it was found that the proportion of toner particles confirming the presence of external additive A on its surface was over 70%.

[0377] <Production Examples of Toners 2 to 17>

[0378] Except for the changes in conditions shown in Table 2, toners 2 to 17 were obtained in the same manner as in the production example of toner 1. The proportion of toner particles on their surface, where external additives can be confirmed, is shown in Table 2.

[0379] Table 2

[0380]

[0381] <Production Examples of Anatase Titanium Oxide Particles 1 and 2, 5 and 6>

[0382] A hydrated titanium dioxide slurry was produced by hydrolyzing a solution containing titanium sulfate and titanium oxysulfate through heating. The titanium dioxide slurry was then dehydrated and calcined. This yielded anatase-type titanium dioxide particles 1, each with an anatase content approaching 100%. By controlling the concentration of the titanium oxysulfate solution in the above method, anatase-type titanium dioxide particles 2, 5, and 6, each with an anatase content approaching 100%, were produced. The physical properties of the obtained anatase-type titanium dioxide particles are shown in Table 3.

[0383] <Production Examples of Anatase Titanium Oxide Particles 3, 4, and 7>

[0384] Niobium sulfate (a water-soluble niobium compound) was added to a hydrated titanium dioxide slurry obtained by hydrolyzing an aqueous solution of titanium oxysulfate. The amount added was 10.0% by mass of niobium ions, relative to the amount of titanium (as titanium dioxide) in the slurry.

[0385] A hydrated titanium dioxide slurry was produced by hydrolyzing an aqueous solution of titanium dioxide containing niobium sulfate at a ratio of 10.0% by mass (based on niobium ions). Next, the hydrated titanium dioxide slurry containing niobium ions was dehydrated and calcined at a firing temperature of 1,000°C. Thus, anatase-type titanium dioxide particles 3, each containing niobium atoms, were obtained.

[0386] By controlling the amount of niobium sulfate added in the above method, anatase titanium dioxide particles 4 and 7, each containing niobium atoms, were obtained. The physical properties of the obtained anatase titanium dioxide particles are shown in Table 3.

[0387] <Production Examples of Conductive Particles 1, 2, 3, and 5>

[0388] Niobium hydroxide (V) is dissolved in concentrated sulfuric acid, and the solution is mixed with an aqueous solution of titanium sulfate to prepare an acidic mixture of niobium and titanium salts (hereinafter referred to as "titanium-niobium mixture").

[0389] Weigh 100 parts of anatase titanium dioxide particles 1 and disperse them in water as core particles to obtain a suspension. While stirring, heat 1,000 parts of the aqueous suspension to 670°C.

[0390] While maintaining the pH at 2.5, a titanium-niobium mixture containing 337 g / kg Ti and 10.3 g / kg Nb, along with an aqueous sodium hydroxide solution, was added relative to the weight of the anatase titanium oxide particles 1. Furthermore, a titanium-niobate solution (with a niobium / titanium atom weight ratio of 1.0 / 20.0) was prepared by mixing a niobium solution obtained by dissolving 3 parts of niobium pentachloride (NbCl5) in 100 parts of 11.4 mol / L hydrochloric acid with 200 parts of a titanium sulfate solution containing 12.0 parts of titanium. The titanium-niobate solution and the 10.7 mol / L sodium hydroxide solution were simultaneously added dropwise (in parallel) to the above aqueous suspension over 3 hours to bring the pH of the aqueous suspension to 2 to 3. After the addition was complete, the suspension was filtered, washed, and dried at 110°C for 8 hours. The dried product and organic matter were calcined at 725°C for 1 hour in a nitrogen atmosphere to obtain titanium oxide particles containing niobium atoms with their respective niobium atoms localized near their surfaces.

[0391] Next, prepare the following materials.

[0392] • 1,100.0 parts of titanium dioxide particles containing niobium atoms

[0393] • Surface treatment agent 1 6.0 parts

[0394] • Toluene 200.0 parts

[0395] Surface treatment agent 1 is a product manufactured by Shin-Etsu Chemical Co., Ltd. under the trade name KBM-3033, represented by the following formula (S-1).

[0396]

[0397] The above materials were mixed and stirred for 4 hours, then filtered and washed, followed by further heating at 130°C for 3 hours. This yielded conductive particles 1.

[0398] Conductive particles 2, 3, and 5 were obtained by controlling the amount of niobium pentachloride in the manner described above to achieve the weight ratio of niobium atoms to titanium oxide shown in Table 3. The surface physical properties and particle size of the obtained conductive particles are shown in Table 3.

[0399] (Production example of conductive particle 4)

[0400] 100 g of spherical anatase titanium dioxide particles 4 with a number-average particle size of 190 nm were dispersed in water to obtain 1 L of aqueous suspension, which was heated to 60 °C. Simultaneously (in parallel) dropwise (by mixing 600 ml of a titanium sulfate solution containing 33.7 g of titanium) and a 10.7 mol / L sodium hydroxide solution were added to adjust the pH of the suspension to 2-3. After the addition was complete, the suspension was filtered, washed, and dried at 110 °C for 8 hours. The dried product was then heated at 800 °C for 1 hour in atmospheric atmosphere. Thus, conductive particles 4 made of titanium dioxide with niobium atoms localized near their surface were obtained.

[0401] (Production example of conductive particle 6)

[0402] Approximately spherical anatase titanium oxide particles 6 with a number-average particle size of 170 nm were used as conductive particles 6. The physical properties of conductive particles 6 are shown in Table 3.

[0403] (Production example of conductive particle 7)

[0404] Prepare the following materials.

[0405] Tin oxide particles (product name: S-2000, manufactured by Mitsubishi Materials Corporation): 100.0 parts

[0406] • Surface treatment agent 2: 20.0 parts

[0407] Toluene: 200.0 parts

[0408] Surface treatment agent 2 is a product manufactured by Shin-Etsu Chemical Co., Ltd. under the trade name KBM-3033, represented by the following formula (S-2).

[0409]

[0410] These materials were mixed and stirred for 4 hours, then filtered and washed, followed by further heat treatment at 130°C for 3 hours. This process resulted in surface treatment to obtain conductive particles 7.

[0411] (Production example of conductive particles 8)

[0412] Except for changing the tin oxide particles to tin oxide particles with a number average particle size of 20 nm, conductive particles 8 are obtained in the same manner as conductive particles 7.

[0413] (Production example of conductive particle 9)

[0414] Nearly spherical anatase titanium dioxide particles 7 with a number-average particle size of 6 nm and a niobium atom content of 0.5% by mass were used as conductive particles 9.

[0415] Table 3

[0416]

[0417] In the table, A represents the concentration ratio of niobium atoms to titanium atoms in the interior of the particle, measured at 5% of the particle's maximum diameter from the particle's surface, and B represents the concentration ratio of niobium atoms to titanium atoms in the center of the particle.

[0418] <Production Example of Electrophotographic Photosensitive Component 1>

[0419] An aluminum cylinder (JIS-A3003, aluminum alloy) with a diameter of 24 mm and a length of 257.5 mm is used as the support (conductive support).

[0420] (Example 1 of conductive layer production)

[0421] Next, prepare the following materials.

[0422] • Titanium oxide (TiO2) particles coated with oxygen-deficient tin oxide (SnO2) (average primary particle size: 230 nm) 214 parts

[0423] • Phenolic resin (product name: PLYOPHEN J-325, manufactured by Dainippon Ink and Chemicals, Inc., resin solids content: 60% by weight) 132 parts

[0424] · 98 parts of 1-methoxy-2-propanol

[0425] The materials were placed in a sand mill using 450 parts each of glass beads with a diameter of 0.8 mm and dispersed at 2,000 rpm for 4.5 hours and with cooling water at a preset temperature of 18°C ​​to prepare a dispersion. The glass beads were removed from the dispersion using a sieve (pore size: 150 μm). Silicone resin particles (product name: TOSPEARL 120, manufactured by MomentivePerformance Materials, average particle size: 2 μm) were added to the resulting dispersion as a surface roughening material. The amount of silicone resin particles added was set to 10% by mass relative to the total mass of metal oxide particles and binder material in the dispersion after glass bead removal. Furthermore, silicone oil (product name: SH28PA, manufactured by Dow Corning Toray Co., Ltd.) was added to the dispersion as a leveling agent at 0.01% by mass relative to the total mass of metal oxide particles and binder material.

[0426] Next, a mixed solvent of methanol and 1-methoxy-2-propanol (mass ratio: 1:1) was added to the dispersion, such that the total mass of the metal oxide particles, binder, and surface roughness-contributing material in the dispersion (i.e., the mass of the solid component) relative to the mass of the dispersion became 67% by mass. The mixture was then stirred to prepare a coating solution for the conductive layer. The coating solution for the conductive layer was applied to the support by dip coating, and the resulting material was heated at 140°C for 1 hour to form a conductive layer with a thickness of 30 μm.

[0427] (Example 1 of primer coating production)

[0428] Next, prepare the following materials.

[0429] • 3.0 parts of the compound represented by the following formula E-1, which is used as an electron transport substance.

[0430] • Capped isocyanate (product name: DURANATE SBB-70P, manufactured by Asahi Kasei Chemicals Corporation) 6.5 parts

[0431] • Styrene-acrylic resin (trade name: UC-3920, manufactured by Toagosei Co., Ltd.) 0.4 parts

[0432] • 1.8 parts of silica slurry (product name: IPA-ST-UP, manufactured by Nissan Chemical Industries, solid content: 15% by mass, viscosity: 9 mPa·s)

[0433] · 48 parts of 1-butanol

[0434] · 24 parts acetone

[0435] The electron transport substance (E-1) is represented by the following formula.

[0436]

[0437] The above materials are mixed and dissolved to prepare a base coat coating solution. The base coat coating solution is applied to the conductive layer by dip coating, and the resulting mixture is heated at 170°C for 30 minutes to form a base coat with a thickness of 0.7 μm.

[0438] Next, 10 parts of hydroxygallium phthalocyanine with peaks at 7.5° and 28.4° in the characteristic X-ray diffraction pattern obtained by CuKα and 5 parts of polyvinyl butyral resin (product name: S-LEC BX-1, manufactured by Sekisui Chemical Co., Ltd.) were prepared. These materials were added to 200 parts of cyclohexanone, and the mixture was dispersed for 6 hours using a sand mill with glass beads of 0.9 mm in diameter.

[0439] The resulting mixture was diluted by adding 50 parts cyclohexanone and 350 parts ethyl acetate to obtain a coating solution for the charge generation layer. The resulting coating solution was applied to the primer layer by dip coating and then dried at 95°C for 10 minutes to form a charge generation layer with a thickness of 0.20 μm.

[0440] Powder X-ray diffraction measurements were performed under the following conditions.

[0441] Measurement equipment used: RINT-TTRII X-ray diffraction equipment manufactured by Rigaku Corporation.

[0442] X-ray tube: Cu

[0443] Tube voltage: 50kV

[0444] Tube current: 300 mA

[0445] Scanning method: 2θ / θ scan

[0446] Scanning speed: 4.0° / min

[0447] Sampling interval: 0.02°

[0448] Starting angle (2θ): 5.0°

[0449] Termination angle (2θ): 40.0°

[0450] Attachment: Standard Sample Rack

[0451] Filter: Not used

[0452] Incident monochromator: using

[0453] Counting monochromator: Not in use

[0454] Diverging slit: Open

[0455] Longitudinal diverging slit: 10.00mm

[0456] Scattering slit: Open

[0457] Light receiving slit: Open

[0458] Flat panel monochromator: using

[0459] Counter: Blink Counter

[0460] (Example 1 of photosensitive layer production)

[0461] Next, prepare the following materials.

[0462] • 6.0 parts of charge-transporting substance (hole-transporting substance) represented by the following formula (C-1).

[0463] • 3.0 parts of charge-transporting substance (hole-transporting substance) represented by the following formula (C-2).

[0464] • 1.0 part of charge-transporting substance (hole-transporting substance) represented by the following formula (C-3).

[0465] • Polycarbonate (Product name: Iupilon Z400, manufactured by Mitsubishi Engineering-Plastics Corporation) 10.0 parts

[0466] • 0.02 parts of polycarbonate resin having copolymer units of formula (C-4) and formula (C-5) (x / y=0.95 / 0.05, viscosity-average molecular weight=20,000)

[0467] These materials were dissolved in a mixed solvent of 25 parts o-xylene / 25 parts methyl benzoate / 25 parts dimethoxymethane to prepare a coating solution for the charge transport layer. The coating solution for the charge transport layer was applied to the charge generation layer by dip coating to form a coating film, and the coating film was dried at 120°C for 30 minutes to form a charge transport layer with a thickness of 12 μm.

[0468]

[0469]

[0470]

[0471]

[0472]

[0473] (Example 1 of surface protective layer production)

[0474] Next, prepare the following materials.

[0475] • Conductive particles 1 76.0 parts

[0476] • 76.0 parts of a compound represented by the following formula (O-1) used as an adhesive resin.

[0477] 1-Propanol (1-PA) 100.0 parts

[0478] Cyclohexane (CH) 100.0 parts

[0479] The above materials are mixed and stirred for 6 hours to prepare coating liquid 1 for surface protective layer.

[0480]

[0481] A protective coating was applied to the charge transport layer using coating solution 1 via dip coating to form a film. The resulting film was dried at 50°C for 6 minutes. Then, under a nitrogen atmosphere, with an accelerating voltage of 70 kV and a beam current of 5.0 mA, the film was irradiated with an electron beam for 1.6 seconds while the support (irradiation target) rotated at 300 rpm. The electron beam dose at the location of the protective coating on the support was 15 kGy. Subsequently, the temperature of the film was raised to 117°C under a nitrogen atmosphere. The oxygen concentration during the period from electron beam irradiation to the subsequent heat treatment was 10 ppm.

[0482] Next, the coating is allowed to cool naturally in air until its temperature reaches 25°C, and then heat-treated for 1 hour at a temperature of 120°C to form a surface protective layer with a thickness of 2 μm. This produces an electrophotographic photosensitive component 1 comprising a surface protective layer containing conductive particles 1. The physical properties of the surface protective layer of the photosensitive component are shown in Table 4.

[0483] (Production examples of electrophotographic photosensitive components 2 to 4 and 6 to 15)

[0484] Except for the changes shown in Table 4 made in the production example of electrophotographic photosensitive element 1, electrophotographic photosensitive elements 2 to 4 and 6 to 15 are produced in the same manner as in Example 1. The physical properties of the surface protective layer of the photosensitive element are shown in Table 4.

[0485] (Production example of electrophotographic photosensitive component 5)

[0486] Except for the changes described below (production example of surface protective layer), the electrophotographic photosensitive element 5 is obtained in the same manner as the production example of the electrophotographic photosensitive element 1.

[0487] The coating liquid for preparing the surface protective layer is described below.

[0488] First, prepare the following materials.

[0489] • Conductive particles 9: 10 parts • Compound represented by the following formula (H-7) 10 parts

[0490] • Polymerization initiator (1-hydroxycyclohexyl(phenyl)methyl ketone) 1 part

[0491] These materials were mixed into 40 parts of n-propanol, and the mixture was dispersed in a sand mill for 2 hours to produce a coating liquid for the protective layer.

[0492] Except for using the coating liquid for the protective layer, the electrophotographic photosensitive element 5 is manufactured in the same manner as the electrophotographic photosensitive element 1. The physical properties of the electrophotographic photosensitive element 5 are shown in Table 4.

[0493]

[0494] Table 4

[0495]

[0496] <Example 1>

[0497] The following practical evaluation was conducted using toner 1 and electrophotographic photosensitive element 1. The evaluation results are shown in Table 5.

[0498] For the practical evaluation, a modified version of the commercially available Canon Inc. laser beam printer "LBP 7600C" was used. The modifications were as follows: the gears and software of the evaluation unit were changed to set the developing roller rotation speed to twice the circumferential speed of the drum, and the processing speed was doubled. Additionally, the pre-exposure unit in the laser beam printer was removed. This modification, as described above, resulted in a more stringent mode for evaluating changes in image density.

[0499] Next, the electrophotographic image forming equipment and the unused electrophotographic photosensitive component 1 are placed in an environment with a temperature of 23.0°C and a humidity of 50%RH for more than 24 hours. Then, 70g of toner 1 and the electrophotographic photosensitive component 1 are installed into the box of the electrophotographic image forming equipment.

[0500] The paper used is LETTER size Business 4200 (manufactured by Xerox Corporation, 75g / m²). 2 It has a 50 mm blank space on its left and right sides respectively.

[0501] Evaluation of the immediate charge rise performance of the electrophotographic image forming equipment after startup.

[0502] The modified machine was placed in an environment of 23°C and 50% RH to output 10 solid images in monochrome. For the 2nd and 10th images respectively, concentration measurements were performed at 20 arbitrary sites, and the concentration of the solid image was calculated from the average of the 20 sites. The concentration was measured using an X-Rite color reflectance density meter (manufactured by X-Rite, Inc., X-Rite 500 series). The concentration difference between the resulting solid images on the 2nd and 10th images was defined as the initial charge rise performance, and evaluated using the following evaluation criteria. The evaluation results are shown in Table 5.

[0503] (Evaluation Criteria)

[0504] A: Initial charge rise performance is less than 0.04.

[0505] B: The initial charge rise performance is above 0.04 and less than 0.07.

[0506] C: Initial charge rise performance is above 0.07 and less than 0.10.

[0507] D: Initial charge rise performance is above 0.10.

[0508] Evaluation of initial concentration uniformity and post-durability concentration uniformity

[0509] The modified machine was placed in an environment of 23°C and 50% RH. As described above, a text image with a 1% print percentage was output on one sheet, followed by a halftone (40H) image. Subsequently, text images with a 1% print percentage were output on 10,000 sheets, along with halftone (40H) images. For these halftone images, density uniformity was evaluated based on the following criteria: "40H image" is a halftone image obtained by representing 256 gray levels in hexadecimal, where 00H represents pure white (non-image) and FFH represents pure black (full-surface image).

[0510] To evaluate concentration uniformity, concentration measurements were taken at 20 locations, and the concentration difference between the maximum and minimum values ​​was defined as concentration uniformity. Concentration was measured using an X-Rite color reflectance aluminometer (manufactured by X-Rite, Inc., X-Rite 500 series), and initial concentration uniformity and subsequent uniformity after durability were evaluated using the 2nd and 10,000th sheets, respectively, according to the following evaluation criteria. The evaluation results are shown in Table 5.

[0511] (Evaluation Criteria)

[0512] A: Concentration uniformity is less than 0.04.

[0513] B: Concentration uniformity is above 0.04 and below 0.07.

[0514] C: Concentration uniformity is above 0.07 and below 0.10.

[0515] D: Concentration uniformity is above 0.10.

[0516] <Examples 2 to 23 and Comparative Examples 1 to 8>

[0517] Except for changing the toner and electrophotographic photosensitive component to the combinations shown in Table 5, the evaluation was conducted in the same manner as in Example 1. The evaluation results of Examples 2 to 23 and Comparative Examples 1 to 8 are shown in Table 5.

[0518] Table 5

[0519]

[0520] The processing cartridge of the present invention exhibits excellent toner charge rise performance immediately upon startup of the electrophotographic image forming apparatus, and excellent charge stability over a long period from the initial use of the processing cartridge until its durability. In other words, it can provide a processing cartridge that achieves both: satisfactory solid images immediately upon startup of the electrophotographic image forming apparatus; and halftones with excellent density uniformity over a long period.

[0521] While the invention has been described with reference to exemplary embodiments, it should be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the appended claims should be accorded the broadest interpretation to cover all such modifications and equivalent structures and functions.

Claims

1. A processing box, characterized in that, It is detachable from the main body of the electrophotographic image forming device. The processing box includes: Electrophotographic photosensitive components; Toners; and A developing unit configured to contain the toner and supply the toner to the surface of the electrophotographic photosensitive element. The toner comprises toner particles and external additive A. The external additive A meets the following requirements (i) to (iii): (i) The major axis is 100 nm or more and 3,000 nm or less; (ii) The aspect ratio is 5.0 or higher; and (iii) The resistivity is 1×10 5 Ω·cm or more and 1×10 8 Below Ω·cm, When observed using a scanning electron microscope, the ratio of the number of toner particles with external additive A on its surface to the total number of toner particles was more than 30%. The electrophotographic photosensitive component includes a conductive support, a photosensitive layer formed on the conductive support, and a surface protective layer formed on the surface of the electrophotographic photosensitive component. The surface protective layer contains conductive particles. The content of the conductive particles in the surface protective layer is more than 5% by volume and less than 70% by volume, and The volume resistivity of the surface protective layer is 1.0 × 10⁻⁶. 9 Ω·cm or more and 1.0×10 14 Below Ω·cm, The conductive particles mentioned above are titanium oxide particles, each containing niobium atoms. In each of the titanium oxide particles containing niobium atoms, the concentration ratio calculated as niobium atom concentration / titanium atom concentration in the interior of 5% of the maximum diameter of the particle measured from the surface of the particle is more than 2.0 times that calculated as niobium atom concentration / titanium atom concentration in the center of the particle.

2. The processing box according to claim 1, wherein the external additive A is titanium dioxide particles.

3. The processing box according to claim 1, wherein the external additive A is rutile titanium dioxide particles.

4. The processing box according to claim 1, wherein each of the toner particles comprises boric acid.

5. The processing box according to claim 1, wherein each of the titanium oxide particles containing niobium atoms contains 2.6% by mass and less than 10.0% by mass of niobium atoms.

6. The processing box according to any one of claims 1 to 5, The proportion of conductive particles in the surface protective layer is 40% by volume or more and 70% by volume or less, and The volume resistivity of the surface protective layer is 1.0 × 10⁻⁶. 10 Ω·cm or more and 1.0×10 14 Below Ω·cm.

Images