Electrophotographic apparatus and process cartridge

Abstract

The invention relates to an electrophotographic apparatus and a process cartridge. Provided is an electrophotographic apparatus including: an electrophotographic photosensitive member; a charging unit that charges a surface of the electrophotographic photosensitive member; an exposure unit that irradiates the charged surface of the electrophotographic photosensitive member with light to form an electrostatic latent image on the surface of the electrophotographic photosensitive member; and a developing unit that includes a toner and develops the electrostatic latent image formed on the surface of the electrophotographic photosensitive member with the toner to form a toner image on the surface of the electrophotographic photosensitive member. The electrophotographic photosensitive member includes a single-layer photosensitive layer including a charge generating substance, a hole transporting substance, an electron transporting substance, and a binder resin. The photosensitive layer contains, as a binder resin, a polyarylate resin having a structural unit represented by formula (1) and a structural unit represented by formula (2). # imgabs0 #

Description

Technical Field

[0001] The present disclosure relates to an electrophotographic apparatus and a process cartridge using an electrophotographic photosensitive member and a toner. Background Art

[0002] In recent years, there has been a demand for electrophotographic apparatuses having a longer service life and higher image quality, and it is desired to provide an apparatus that outputs images with high quality stability when repeatedly used (after endurance).

[0003] An organic electrophotographic photosensitive member (hereinafter sometimes referred to simply as "electrophotographic photosensitive member" or "photosensitive member") containing an organic photoconductive substance (charge generating substance) is used as an electrophotographic photosensitive member mounted to an electrophotographic apparatus or a process cartridge. In recent electrophotographic apparatuses, in addition to the above-mentioned measures for extending the service life, it is also required to improve image quality by suppressing a decrease in transfer efficiency after durability, and to maintain high image quality from the initial stage to the post-durability stage.

[0004] At the same time, toners with a core-shell structure are sometimes used to improve the positive chargeability and charge stability of the toner in maintaining high image quality from the initial stage to the endurance stage. For example, in International Publication No. WO2015 / 129448, a toner using a melamine resin for the shell has been proposed. In addition, in Japanese Patent Application Laid-Open No. 2021-001970, a toner using a shell containing an oxazoline group has been proposed.

[0005] According to research conducted by the inventors of the present disclosure, for the purpose of suppressing a decrease in transfer efficiency after durability, in an image forming apparatus using a toner as described in International Publication No. WO2015 / 129448 or Japanese Patent Application Laid-Open No. 2021-001970, the transfer efficiency after durability decreases, so there is room for improvement. Summary of the invention

[0006] Therefore, an aspect of the present disclosure is to provide an excellent electrophotographic apparatus in which, in an electrophotographic apparatus using a toner having a core-shell structure, a decrease in transfer efficiency after endurance is suppressed and high image quality is maintained from an initial stage to a post-endurance stage.

[0007] The above aspects are achieved by the present disclosure described below. That is, the electronic photographic apparatus according to the present disclosure is an electronic photographic apparatus including: an electronic photographic photosensitive member; a charging unit configured to charge the surface of the electronic photographic photosensitive member; an exposure unit configured to irradiate the charged surface of the electronic photographic photosensitive member with light to form an electrostatic latent image on the surface of the electronic photographic photosensitive member; a developing unit including a toner and configured to develop the electrostatic latent image formed on the surface of the electronic photographic photosensitive member with the toner to form a toner image on the surface of the electronic photographic photosensitive member; and a transfer unit configured to transfer the toner image from the surface of the electronic photographic photosensitive member to a transfer target member. member), wherein the electrophotographic photosensitive member includes a single-layer type photosensitive layer including a charge generating substance, a hole transporting substance, an electron transporting substance and a binder resin, wherein the photosensitive layer includes a polyarylate resin having a structural unit represented by the following formula (1) and a structural unit represented by the following formula (2) as the binder resin, wherein the toner includes toner particles, wherein the toner particles include a core including the binder resin and a shell covering the surface of the core, and wherein the shell includes at least one resin selected from the group consisting of a melamine resin and a resin having a structural unit represented by the following formula (3):

[0008]

[0009] In formula (3), R 1 It represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms.

[0010] In addition, a process cartridge according to the present disclosure is a process cartridge comprising: an electrophotographic photosensitive member; and a developing unit comprising a toner and configured to form a toner image on a surface of the electrophotographic photosensitive member with the toner, the process cartridge integrally supporting the electrophotographic photosensitive member and the developing unit, and being detachably mounted to a main body of an electrophotographic apparatus, wherein the electrophotographic photosensitive member comprises a single-layer type photosensitive layer comprising a charge generating substance, a hole transporting substance, an electron transporting substance, and a binder resin, wherein the photosensitive layer comprises a polyarylate resin having a structural unit represented by the following formula (1) and a structural unit represented by the following formula (2) as a binder resin, wherein the toner comprises toner particles, wherein the toner particles comprise a core comprising the binder resin and a shell covering a surface of the core, and the shell comprises at least one resin selected from the group consisting of a melamine resin and a resin having a structural unit represented by the following formula (3):

[0011]

[0012] In formula (3), R 1It represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms.

[0013] Further features of the present disclosure will become apparent from the following description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a diagram for explaining one example of the layer configuration of the electrophotographic photosensitive member in the present disclosure.

[0015] Figure 2 is a diagram for explaining one example of the layer configuration of the electrophotographic photosensitive member in the present disclosure.

[0016] Figure 3 is a diagram for explaining one example of the layer configuration of the electrophotographic photosensitive member in the present disclosure.

[0017] Figure 4 It is a diagram for explaining an example of the configuration of the toner in the present disclosure.

[0018] Figure 5 is a diagram for explaining one example of a schematic configuration of an electrophotographic apparatus including the electrophotographic photosensitive member according to the present disclosure.

[0019] Figure 6 is a diagram for explaining one example of an apparatus for evaluating the chargeability of toner in the present disclosure. DETAILED DESCRIPTION

[0020] The present disclosure is described in detail below through exemplary embodiments.

[0021] It has been found that when a durability test is performed in an image forming device using a toner having a core-shell structure as described in International Publication No. WO2015 / 129448 or Japanese Patent Application Laid-Open No. 2021-001970, a reduction in transfer efficiency occurs. From the foregoing, it can be imagined that even a toner having a core-shell structure with improved positive chargeability and charging stability is subjected to stress caused by friction between the toner and the charging member along with durability, and the shell structure is partially peeled off, resulting in a reduction in the positive chargeability and charging stability of the toner. It is speculated that the reduction in the positive chargeability of the toner causes the toner to remain on the electrophotographic photosensitive member as a transfer residual toner when it is developed on the electrophotographic photosensitive member and transferred from it, resulting in a reduction in transfer efficiency.

[0022] Based on the above assumptions, the inventors of the present disclosure have conducted various studies on a method of maintaining high image quality from the initial stage to the post-durability stage by suppressing a decrease in transfer efficiency after durability in an electrophotographic apparatus using a toner having a core-shell structure. As a result, the inventors have achieved the configuration of the present disclosure.

[0023] The electrophotographic apparatus according to the present disclosure is an electrophotographic apparatus including: an electrophotographic photosensitive member; a charging unit configured to charge a surface of the electrophotographic photosensitive member; an exposure unit configured to irradiate the charged surface of the electrophotographic photosensitive member with light to form an electrostatic latent image on the surface of the electrophotographic photosensitive member; a developing unit including a toner and configured to develop the electrostatic latent image formed on the surface of the electrophotographic photosensitive member with the toner to form a toner image on the surface of the electrophotographic photosensitive member; and a transfer unit configured to transfer the toner image from the surface of the electrophotographic photosensitive member to the surface of the electrophotographic photosensitive member. surface onto a transfer target member, wherein the electrophotographic photosensitive member includes a single-layer type photosensitive layer including a charge generating substance, a hole transporting substance, an electron transporting substance and a binder resin, wherein the photosensitive layer includes a polyarylate resin having a structural unit represented by the following formula (1) and a structural unit represented by the following formula (2) as the binder resin, wherein the toner includes toner particles, wherein the toner particles include a core including the binder resin and a shell covering the surface of the core, and wherein the shell includes at least one resin selected from the group consisting of a melamine resin and a resin having a structural unit represented by the following formula (3):

[0024]

[0025] In formula (3), R 1 It represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms.

[0026] The electrophotographic apparatus according to the present disclosure is an electrophotographic apparatus including: an electrophotographic photosensitive member; a charging unit configured to charge a surface of the electrophotographic photosensitive member; an exposure unit configured to irradiate the charged surface of the electrophotographic photosensitive member with light to form an electrostatic latent image on the surface of the electrophotographic photosensitive member; a developing unit including a toner and configured to develop the electrostatic latent image formed on the surface of the electrophotographic photosensitive member with the toner to form a toner image on the surface of the electrophotographic photosensitive member; and a transfer unit configured to transfer the toner to the electrophotographic photosensitive member. An image is transferred from the surface of an electrophotographic photosensitive member onto a transfer target member, wherein the electrophotographic photosensitive member includes a single-layer type photosensitive layer containing a charge generating substance, a hole transporting substance, an electron transporting substance and a binder resin, wherein the photosensitive layer contains a polyarylate resin having a structural unit represented by the following formula (1) and a structural unit represented by the following formula (2) as the binder resin, wherein a toner contains toner particles, wherein surfaces of the toner particles contain at least one resin selected from the group consisting of a melamine resin and a resin having a structural unit represented by the following formula (3):

[0027]

[0028]

[0029] In formula (3), R 1 It represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms.

[0030] In the present disclosure, a toner includes toner particles. The toner particles include a core including a binder resin and a shell covering a surface of the core. The shell includes at least one resin selected from the group consisting of a melamine resin and a resin having a structural unit represented by formula (3).

[0031] In addition, the electrophotographic photosensitive member includes a single-layer photosensitive layer containing a charge generating substance, a hole transporting substance, an electron transporting substance and a binder resin. The photosensitive layer contains a polyarylate resin having a structural unit represented by formula (1) and a structural unit represented by formula (2) as a binder resin. It has been found that with this configuration, a decrease in transfer efficiency after durability is suppressed, and high image quality can be maintained from the initial stage to the post-durability stage.

[0032] The structural unit represented by formula (1) exhibits a structure having high electron accepting property. In addition, when the structural unit represented by formula (1) is bonded to the structural unit represented by formula (2), the resonance is stabilized and the electron accepting property becomes higher. It is believed that the electrophotographic photosensitive member containing the polyarylate resin having the structural unit represented by formula (1) and the structural unit represented by formula (2) improves the positive chargeability of the toner during toner development and transfer. That is, it is speculated that when the polyarylate resin having high electron accepting property is introduced, the electrophotographic photosensitive member is relatively negatively charged and the positive chargeability of the toner is relatively increased, thereby reducing the transfer residual toner.

[0033] [Electrophotographic photosensitive member]

[0034] The electrophotographic photosensitive member of the present disclosure includes at least a support and a photosensitive layer formed on the support.

[0035] The method for manufacturing an electrophotographic photosensitive member of the present disclosure is, for example, a method involving: preparing a coating liquid for each layer described later; applying the liquid in a desired layer order; and drying the liquid. In this case, examples of the method for applying the coating liquid include dip coating, spray coating, inkjet coating, roller coating, die coating, blade coating, curtain coating, wire rod coating, and ring coating. Among them, dip coating is preferred from the viewpoint of efficiency and productivity.

[0036] The details are described below.

[0037] (Single-layer type photosensitive member)

[0038] Reference Figures 1 to 3 A single-layer type photosensitive member as an example of the photosensitive member of this embodiment is described. Figures 1 to 3 Each is a partial cross-sectional view of a single-layer type photosensitive member. Figure 1 As shown, the single-layer photosensitive member 1 includes, for example, a conductive support 2 and a photosensitive layer 3. The photosensitive layer 3 included in the single-layer photosensitive member 1 is a single layer (single layer). The single-layer photosensitive layer 3 is a single-layer photosensitive layer 3s as a first photosensitive layer. Figure 2 As shown, the single-layer photosensitive member 1 may further include an undercoat layer 4 (intermediate layer) in addition to the conductive support 2 and the single-layer photosensitive layer 3s. The undercoat layer 4 is formed between the conductive support 2 and the single-layer photosensitive layer 3s. Figure 1 As shown in FIG. 1 , the single-layer photosensitive layer 3s can be directly formed on the conductive support 2. Alternatively, as shown in FIG. Figure 2 As shown, the single-layer photosensitive layer 3s can be formed on the conductive support 2 through the intervention of the undercoat layer 4. Figure 3 As shown in FIG. 1 , the single-layer photosensitive member 1 may further include a protective layer 5 in addition to the conductive support 2 and the single-layer photosensitive layer 3s. The protective layer 5 is formed on the single-layer photosensitive layer 3s. Figure 1 and Figure 2 As shown in FIGS. 1 and 1 , the single-layer photosensitive layer 3s is preferably formed as the outermost surface layer of the single-layer photosensitive member 1. When the single-layer photosensitive layer 3s containing a polyarylate resin (PAR) described later is formed as the outermost surface layer, it is easy to suppress a decrease in transfer efficiency after durability. Figure 3 As shown, the protective layer 5 can be formed as the outermost surface layer of the single-layer photosensitive member 1. The thickness of the single-layer photosensitive layer 3s is not particularly limited, but is preferably 5 μm or more and 100 μm or less, more preferably 10 μm or more and 50 μm or less. The single-layer photosensitive layer 3s as the first photosensitive layer contains a charge generating substance, a binder resin, an electron transporting substance, and a hole transporting substance.

[0039] <Support>

[0040] In the present disclosure, the electrophotographic photosensitive member includes a support. In the present disclosure, the support is preferably a conductive support having conductivity. In addition, examples of the shape of the support include cylindrical, belt-shaped, and sheet-shaped. Among these shapes, a support having a cylindrical shape is preferred. In addition, the surface of the support may be subjected to an electrochemical treatment such as anodizing, a sandblasting treatment, or a cutting treatment, for example.

[0041] Metal, resin, glass or the like is preferable as the material of the support.

[0042] Examples of the metal include aluminum, iron, nickel, copper, gold, stainless steel, and alloys thereof. Among these metals, an aluminum support using aluminum is preferred.

[0043] Furthermore, conductivity may be imparted to resin or glass through a process involving, for example, mixing or coating the resin or glass with a conductive material.

[0044] <Base Coating>

[0045] In the present disclosure, an undercoat layer may be disposed on the support. The undercoat layer may improve the interlayer adhesion function and thus impart a charge injection suppression function.

[0046] The primer layer preferably contains a resin. Alternatively, the primer layer can be formed as a cured film by polymerizing a composition containing a monomer having a polymerizable functional group.

[0047] Examples of the resin include polyester resins, polyarylate resins, polycarbonate resins, polyvinyl 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, polyamideimide resins, and cellulose resins.

[0048] Examples of the polymerizable functional group of the monomer having a polymerizable functional group include an isocyanate group, a blocked isocyanate group, a methylol group, an alkylated methylol group, an epoxy group, a metal alkoxide group, a hydroxyl group, an amino group, a carboxyl group, a thiol group, a carboxylic anhydride group, and a carbon-carbon double bond group.

[0049] In order to improve electrical characteristics, the undercoat layer may further contain an electron transporting substance, a metal oxide, a metal, a conductive polymer, etc. Among them, an electron transporting substance and a metal oxide are preferably used.

[0050] Examples of electron transporting substances include quinone compounds, imide compounds, benzimidazole compounds, cyclopentadiene compounds, fluorenone compounds, xanthone compounds, benzophenone compounds, cyanovinyl compounds, halogenated aryl compounds, silole compounds, and boron-containing compounds. An electron transporting substance having a polymerizable functional group can be used as the electron transporting substance, copolymerized with the above-mentioned monomer having a polymerizable functional group, thereby forming a primer layer as a cured film.

[0051] 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.

[0052] In addition, the undercoat layer may further contain additives.

[0053] The average thickness of the primer layer is preferably 0.1 μm or more and 50 μm or less, more preferably 0.2 μm or more and 40 μm or less, particularly preferably 0.3 μm or more and 30 μm or less.

[0054] The undercoat layer can be formed by: preparing an undercoat layer coating solution containing the above-mentioned materials and a solvent; forming a coating film of the coating solution; and drying and / or curing the coating film. Examples of the solvent used in the coating solution include alcohol solvents, ketone solvents, ether solvents, ester solvents, and aromatic hydrocarbon solvents.

[0055] <Single-layer photosensitive layer>

[0056] In the present disclosure, a single-layer type photosensitive layer is formed on a support or an undercoat layer formed on a support.

[0057] The single-layer type photosensitive layer in the present disclosure is formed so as to contain at least a binder resin, a charge generating substance, a hole transporting substance, and an electron transporting substance.

[0058] [Binder resin]

[0059] The binder resin used in the photosensitive layer contains a polyarylate resin having a structural unit represented by formula (1) and a structural unit represented by formula (2).

[0060]

[0061] The structural unit represented by formula (1) is a structure having high electron accepting property. In addition, when the structural unit represented by formula (1) is bonded to the structural unit represented by formula (2), the resonance is stabilized and the electron accepting property becomes higher. It is believed that the electrophotographic photosensitive member containing the polyarylate resin having the structural unit represented by formula (1) and the structural unit represented by formula (2) enhances the positive chargeability of the toner when the positively charged toner is developed on the electrophotographic photosensitive member and transferred to the transfer target member. It is presumed that, with this configuration, the electrophotographic photosensitive member is relatively negatively charged, and the positive chargeability of the toner is relatively increased, thereby reducing the transfer residual toner.

[0062] The polyarylate resin may further have a structural unit represented by the following formula (4) and a structural unit represented by the following formula (5) in addition to the structural unit represented by the formula (1) and the structural unit represented by the formula (2).

[0063]

[0064] When the polyarylate resin has the structural unit represented by formula (4) and the structural unit represented by formula (5), the solubility of the polyarylate resin in a solvent is improved, and thus a photosensitive layer can be satisfactorily formed.

[0065] When the ratio of the amount of substance of the structural unit represented by formula (1) relative to the total amount of substance of the structural unit represented by formula (1) and the structural unit represented by formula (4) in the polyarylate resin is represented by M1, from the viewpoint of suppressing the reduction of transfer efficiency, M1 is preferably greater than 0.30, and more preferably greater than 0.50.

[0066] When the ratio of the mass of the structural unit represented by formula (2) relative to the total mass of the structural unit represented by formula (2) and the structural unit represented by formula (5) in the polyarylate resin is represented by M2, M2 is preferably larger from the viewpoint of suppressing the reduction of the transfer efficiency. At the same time, from the viewpoint of solubility in a solvent, M2 is preferably less than 0.50. That is, M2 preferably satisfies 0<M2≤0.50. When the solubility in a solvent is improved, a photosensitive layer can be satisfactorily formed.

[0067] When the mass ratio of the structural unit represented by formula (4) relative to the total mass of the structural unit represented by formula (1) and the structural unit represented by formula (4) in the polyarylate resin is represented by M4, from the viewpoint of solubility in a solvent, M4 preferably satisfies 0.30≤M4≤0.70.

[0068] When the mass ratio of the structural unit represented by formula (5) relative to the total mass of the structural unit represented by formula (2) and the structural unit represented by formula (5) in the polyarylate resin is represented by M5, M5 is preferably 0.80 or less from the viewpoint of suppressing the reduction of transfer efficiency. In addition, M5 is preferably 0.50 or more from the viewpoint of solubility in a solvent.

[0069] In the polyarylate resin, the sum of the mass ratio of the structural unit represented by formula (1) and the mass ratio of the structural unit represented by formula (4) relative to the total mass of the structural units derived from dicarboxylic acid used to form the polyarylate resin is preferably 0.50 or more.

[0070] In the polyarylate resin, the sum of the mass ratio of the structural unit represented by formula (2) and the mass ratio of the structural unit represented by formula (5) relative to the total mass of the structural units derived from bisphenol used to form the polyarylate resin is preferably 0.50 or more.

[0071] The ratio of the amount of the structural unit represented by formula (1) to the total amount of the structural units derived from dicarboxylic acid used to form the polyarylate resin is more preferably 0.50 or more.

[0072] The photosensitive layer may contain resins other than the above-mentioned polyarylate resins to the extent that the effects of the present disclosure are not impaired. Examples of other resins include polycarbonate resins, styrene resins, and acrylic resins. The polyarylate resins may be, for example, random copolymers, alternating copolymers, periodic copolymers, or block copolymers.

[0073] The viscosity average molecular weight of the polyarylate resin (PAR) is preferably 10,000 or more, more preferably 30,000 or more, and even more preferably 50,000 or more. When the viscosity average molecular weight of the polyarylate resin (PAR) is 10,000 or more, the wear resistance of the photosensitive member is improved. At the same time, the viscosity average molecular weight of the polyarylate resin (PAR) is preferably 80,000 or less, and more preferably 70,000 or less. When the viscosity average molecular weight of the polyarylate resin (PAR) is 80,000 or less, the polyarylate resin (PAR) is easily dissolved in a solvent for forming a photosensitive layer.

[0074] In the present disclosure, the polyarylate resin is formed to have a structural unit represented by formula (2) as a bisphenol-derived repeating unit and a structural unit represented by formula (1) as a dicarboxylic acid-derived repeating unit. In addition, in the present disclosure, it is preferred that the polyarylate resin is formed to further have a structural unit represented by formula (5) as a bisphenol-derived repeating unit and a structural unit represented by formula (4) as a dicarboxylic acid-derived repeating unit. Examples of bisphenols used to form bisphenol-derived repeating units include compounds represented by formula (BP-2) and compounds represented by formula (BP-5) (hereinafter sometimes referred to as "compound (BP-2)" and "compound (BP-5)", respectively). Examples of dicarboxylic acids used to form dicarboxylic acid-derived repeating units include compounds represented by formula (DC-1) and compounds represented by formula (DC-4) (hereinafter sometimes referred to as "compound (DC-1)" and "compound (DC-4)", respectively). The bisphenol ratio in the resin (i.e., the content ratio of the structural unit represented by formula (2) and the structural unit represented by formula (5)) can be adjusted by changing the amounts of compound (BP-2) and compound (BP-5) added when producing the polyarylate resin (PAR). In addition, the amount of dicarboxylic acid in the resin, i.e., the dicarboxylic acid ratio (i.e., the content ratio of the structural unit represented by formula (1) and the structural unit represented by formula (4)) can be similarly adjusted by changing the amounts of compound (DC-1) and compound (DC-4) added during production.

[0075]

[0076] Bisphenols (e.g., compound (BP-2) and compound (BP-5)) can each be used by derivatization to aromatic diacetates. Dicarboxylic acids (e.g., compound (DC-1) and compound (DC-4)) can each be used by derivatization. Examples of derivatives of dicarboxylic acids include dicarboxylic acid dichlorides, dicarboxylic acid dimethyl esters, dicarboxylic acid diethyl esters, and dicarboxylic acid anhydrides. Dicarboxylic acid dichlorides are compounds obtained by replacing two "-C(=O)-OH" groups of dicarboxylic acids with "-C(=O)-Cl" groups.

[0077] In the polycondensation of bisphenol and dicarboxylic acid, one or both of a base and a catalyst may be added. An example of the base is sodium hydroxide. Examples of the catalyst include benzyltributylammonium chloride, ammonium chloride, ammonium bromide, quaternary ammonium salts, triethylamine, and trimethylamine.

[0078] The photosensitive layer may contain only the polyarylate resin (PAR) having the structural unit represented by formula (1) and the structural unit represented by formula (2) as a binder resin, and may also contain a binder resin other than the above (hereinafter sometimes referred to as "other binder resin" in the photosensitive layer). Examples of other binder resins in the photosensitive layer include: thermoplastic resins (more specifically, polyarylate resins other than the polyarylate resin (PAR) in the present disclosure, polycarbonate resins, styrene resins, styrene-butadiene copolymers, styrene-acrylonitrile copolymers, styrene-maleic acid copolymers, styrene-acrylic acid copolymers, acrylic copolymers, polyethylene resins, ethylene-vinyl acetate copolymers, chlorinated polyethylene resins, polyvinyl chloride resins, polypropylene resins, ionomers, vinyl chloride-vinyl acetate copolymers, polyester resins, alkyd resins, polyamide resins, polyurethane resins, polysulfone resins, diallyl phthalate resins, ketone resins, polyvinyl butyral resins, polyvinyl acetal resins, and polyether resins); thermosetting resins (more specifically, silicone resins, epoxy resins, phenolic resins, urea resins, melamine resins, and any other crosslinkable thermosetting resins); and photocurable resins (more specifically, epoxy-acrylic resins and urethane-acrylic copolymers). The binder resin in the photosensitive layer preferably contains 50% by mass or more of a polyarylate resin having a structural unit represented by formula (1) and a structural unit represented by formula (2).

[0079] The structure of the polyarylate resin disclosed in the present invention can be 1 H-NMR spectroscopy was used to determine the 1 H-NMR spectroscopy was performed using 1 H-nuclear magnetic resonance spectroscopy (proton NMR) is performed to analyze the components of the polymer components recovered from the photosensitive layer.

[0080] A specific analysis method of the polyarylate resin in the photosensitive layer when the photosensitive member is a cylindrical body is described below.

[0081] (Re-precipitation of resin in the photosensitive layer)

[0082] The photosensitive member was cut with a wire saw at a position 10 cm away from the end in the generatrix direction of the photosensitive member.

[0083] • Wipe the inner surface of the cut cylinder of 10 cm with lens cleaning paper impregnated with chloroform.

[0084] To wash off the photosensitive layer, immerse the 3 cm end of the cut cylinder in chloroform. (Put about 60 mL of chloroform in a 100 mL beaker and immerse the end for 5 minutes at room temperature.)

[0085] The chloroform solution from which the above-mentioned photosensitive layer was eluted was concentrated to 2 ml using a rotary evaporator to provide a concentrated solution, and the concentration was stopped.

[0086] 50 mL of a methanol / acetone mixed solution (volume ratio: 1:1) was prepared, and the entire amount of the concentrated solution was added dropwise thereto while stirring the mixed solution, thereby performing reprecipitation.

[0087] Suction filtration was performed using a funnel (funnel: SU-40, filter paper: No. 5C-40, manufactured by Kiriyama Glass Co.).

[0088] The residue on the filter paper was recovered with a spatula and dried in vacuo (70°C, 1 hour).

[0089] (NMR measurement)

[0090] To prepare a measurement sample, 20 mg of a sample was dissolved in 1 g of deuterated chloroform containing tetramethylsilane as a reference material, and the entire amount was transferred to an NMR tube.

[0091] (Deuterated chloroform: manufactured by Sigma-Aldrich Japan GK, Chloroform-d, model: 612200)

[0092] (NMR tube: manufactured by Norell, Inc., ST500-7, model: S3010)

[0093] NMR determination

[0094] Equipment: AVANCE 500 manufactured by Bruker

[0095] Conditions: Proton NMR, automatically determined by Icon-NMR

[0096] Scan times: 32 times

[0097] Reference peak: The peak of the methyl group of tetramethylsilane was set to 0 ppm.

[0098] [Charge generating material]

[0099] Examples of charge generating materials include phthalocyanine pigments, perylene pigments, disazo pigments, triazo pigments, dithioketopyrrolopyrrole pigments, metal-free naphthalocyanine pigments, metal naphthalocyanine pigments, squarylium pigments, indigo pigments, azulenium pigments, cyanine pigments, inorganic photoconductive materials (e.g., selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide, and amorphous silicon) powders, pyrylium pigments, anthraquinone pigments, triphenylmethane pigments, reduced pigments, toluidine pigments, pyrazoline pigments, and quinacridone pigments. The photosensitive layer may contain only one charge generating material, or may contain two or more charge generating materials.

[0100] Phthalocyanine pigments are pigments having a phthalocyanine structure. Examples of phthalocyanine pigments include metal-free phthalocyanine and metal phthalocyanine. Examples of metal phthalocyanine include oxytitanium phthalocyanine, hydroxygallium phthalocyanine and chlorogallium phthalocyanine. Metal phthalocyanine is preferably oxytitanium phthalocyanine. Oxytitanium phthalocyanine is a compound represented by the following formula (CGM-1).

[0101]

[0102] Phthalocyanine pigments may be crystalline or amorphous. Examples of crystals of metal-free phthalocyanine are X-type crystals of metal-free phthalocyanine (hereinafter sometimes referred to as "X-type metal-free phthalocyanine"). Examples of crystals of oxytitanium phthalocyanine include α-type crystals, β-type crystals, and Y-type crystals of oxytitanium phthalocyanine (hereinafter sometimes referred to as "α-type oxytitanium phthalocyanine", "β-type oxytitanium phthalocyanine", "Y-type oxytitanium phthalocyanine" respectively). For example, in digital optical electronic photographic equipment (for example, a laser beam printer or fax machine using a light source such as a semiconductor laser), it is preferred to use a photosensitive member having sensitivity in a wavelength region above 700nm. The charge generating substance is preferably a phthalocyanine pigment, more preferably a metal-free phthalocyanine or oxytitanium phthalocyanine, and even more preferably oxytitanium phthalocyanine, because each of these materials has a high quantum yield in a wavelength region above 700nm. Among them, Y-type oxytitanium phthalocyanine is particularly preferred.

[0103] Y-type oxytitanium phthalocyanine has a main peak at a Bragg angle (2θ±0.2°) of 27.2° in the CuKα characteristic X-ray diffraction spectrum. The main peak in the CuKα characteristic X-ray diffraction spectrum is a peak having the first or second maximum intensity within the range of the Bragg angle (2θ±0.2°) of 3° to 40°. Y-type oxytitanium phthalocyanine does not have a peak at 26.2° in the CuKα characteristic X-ray diffraction spectrum.

[0104] The CuKα characteristic X-ray diffraction spectrum can be measured, for example, by the following method. First, a sample is placed in a sample holder of an X-ray diffraction apparatus (e.g., "RINT (trademark) 1100" manufactured by Rigaku Corporation) and the CuKα characteristic X-ray wavelength is 0.0407 W. The X-ray diffraction spectrum is measured under the conditions of. The measurement range (2θ) is, for example, 3° or more and 40° or less (start angle: 3°, and stop angle: 40°), and the scanning speed is, for example, 10° / min. The main peak is determined from the obtained X-ray diffraction spectrum, and the Bragg angle of the main peak is read.

[0105] The content of the charge generating material is preferably 0.1 parts by mass or more and 50 parts by mass or less, and more preferably 0.5 parts by mass or more and 5 parts by mass or less, based on 100 parts by mass of the binder resin.

[0106] [Electron transport substances]

[0107] The electron transporting substance may include at least one compound selected from the group consisting of: a compound represented by the following formula (10); a compound represented by the following formula (11); a compound represented by the following formula (12); a compound represented by the following formula (13); a compound represented by the following formula (14); a compound represented by the following formula (15); and a compound represented by the following formula (16). It is believed that the introduction of the above-mentioned electron transporting substance into the photosensitive layer improves the compatibility between the binder resin in the present disclosure and the hole transporting substance described later, so as to improve the uniformity inside the photosensitive layer, thereby enhancing the effect of the present disclosure.

[0108]

[0109]

[0110] Q in formula (10) 1 and Q 2 , Q in formula (11) 11 , Q 12 and Q 13 , Q in formula (12) 21 , Q 22 , Q 23 and Q 24 , Q in formula (13) 31 and Q 32 , Q in formula (14) 41 , Q 42 , Q 43 and Q 44 , Q in formula (15) 51 , Q 52 , Q 53 , Q 54 , Q 55 and Q 56 And Q in formula (16) 61 and Q 62 Each independently represents a hydrogen atom, a halogen atom, a cyano group, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 14 carbon atoms which may be substituted with at least one substituent selected from the group consisting of an alkoxy group having 1 to 6 carbon atoms and a halogen atom. 1 and Y 2 Each independently represents an oxygen atom or a sulfur atom.

[0111] Preferably, Q in formula (10) 1 and Q 2, Q in formula (11) 11 To Q 13 , Q in formula (12) 21 To Q 24 , Q in formula (13) 31 and Q 32 , Q in formula (14) 41 To Q 44 , Q in formula (15) 51 To Q 56 And Q in formula (16) 61 and Q 62 Each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 14 carbon atoms which may be substituted with at least one substituent selected from the group consisting of an alkyl group having 1 to 6 carbon atoms and a halogen atom. Preferably, Y in formula (15) 1 and Y 2 Each represents an oxygen atom.

[0112] When Q in equation (10) 1 and Q 2 , Q in formula (11) 11 To Q 13 , Q in formula (12) 21 To Q 24 , Q in formula (13) 31 and Q 32 , Q in formula (14) 41 To Q 44 , Q in formula (15) 51 To Q 56 And Q in formula (16) 61 and Q 62 When each represents an alkyl group having 1 to 6 carbon atoms, each of these groups preferably represents an alkyl group having 1 to 5 carbon atoms, preferably a methyl group, an ethyl group, a propyl group, a butyl group or a pentyl group, and particularly preferably a methyl group, an isopropyl group, a tert-butyl group or a 1,1-dimethylpropyl group.

[0113] When Q in equation (10) 1 and Q 2 , Q in formula (11) 11 To Q 13 , Q in formula (12) 21 To Q 24 , Q in formula (13) 31 and Q 32 , Q in formula (14) 41 To Q 44 , Q in formula (15) 51 To Q 56 And Q in formula (16)61 and Q 62 When each represents an aryl group having 6 or more and 14 or less carbon atoms, each of these groups preferably represents an aryl group having 6 or more and 10 or less carbon atoms, more preferably a phenyl group. The aryl group having 6 or more and 14 or less carbon atoms may be substituted with at least one substituent selected from the group consisting of an alkyl group having 1 or more and 6 or less carbon atoms and a halogen atom. As a substituent, the alkyl group having 1 or more and 6 or less carbon atoms is preferably an alkyl group having 1 or more and 3 or less carbon atoms, more preferably a methyl group or an ethyl group. As a substituent, the halogen atom is preferably a fluorine atom, a chlorine atom or a bromine atom, particularly preferably a chlorine atom. When the aryl group having 6 or more and 14 or less carbon atoms is substituted with a substituent, the number of the substituents is preferably 1 or more and 5 or less, more preferably 1 or 2. The aryl group having 6 to 14 carbon atoms substituted with at least one substituent selected from the group consisting of an alkyl group having 1 to 6 carbon atoms and a halogen atom is preferably a chlorophenyl group, a dichlorophenyl group or an ethylmethylphenyl group, and more preferably a 4-chlorophenyl group, a 2,5-dichlorophenyl group or a 2-ethyl-6-methylphenyl group.

[0114] A suitable example of the compound represented by formula (10) is a compound represented by formula (E-4). A suitable example of the compound represented by formula (11) is a compound represented by formula (E-5). A suitable example of the compound represented by formula (12) is a compound represented by formula (E-7). A suitable example of the compound represented by formula (13) is a compound represented by formula (E-6). A suitable example of the compound represented by formula (14) is a compound represented by formula (E-8). A suitable example of the compound represented by formula (15) includes a compound represented by formula (E-2) and a compound represented by formula (E-3). A suitable example of the compound represented by formula (16) is a compound represented by formula (E-1). The compounds represented by formula (E-1) to formula (E-8) are sometimes referred to as "electron transport substance (E-1)" to "electron transport substance (E-8)" below, respectively.

[0115]

[0116]

[0117] The content of the electron transporting substance is preferably 5 parts by mass or more and 150 parts by mass or less, more preferably 10 parts by mass or more and 100 parts by mass or less, and still more preferably 30 parts by mass or more and 70 parts by mass or less, relative to 100 parts by mass of the binder resin. The photosensitive layer may contain only one electron transporting substance, or may contain two or more electron transporting substances.

[0118] [Hole transport substances]

[0119] It is preferred to use at least one compound selected from the group consisting of: a compound represented by the following formula (20); a compound represented by the following formula (21); a compound represented by the following formula (22); a compound represented by the following formula (23), and a compound represented by the following formula (24) as the hole transporting substance. It is believed that the introduction of the above-mentioned hole transporting substance into the photosensitive layer improves the compatibility between the binder resin and the electron transporting substance in the present disclosure to improve the uniformity of the photosensitive layer, thereby enhancing the effect of the present disclosure.

[0120]

[0121]

[0122] In formula (20), R 11 , R 12 , R 13 and R 14 Each independently represents an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms, a 1 、a 2 、a 3 and a 4 Each independently represents an integer greater than or equal to 0 and less than or equal to 5. In formula (20), when a 1 When the integer is 2 or more and 5 or less, a plurality of R 11 can represent groups that are the same or different from each other. 2 When the integer is 2 or more and 5 or less, a plurality of R 12 can represent groups that are the same or different from each other. 3 When the integer is 2 or more and 5 or less, a plurality of R 13 can represent groups that are the same or different from each other. 4 When the integer is 2 or more and 5 or less, a plurality of R 14 can represent groups that are the same as or different from each other. 11 , R 12 , R 13 and R 14 Each independently represents preferably an alkyl group having 1 to 3 carbon atoms, and more preferably a methyl group or an ethyl group. 1 、a 2 、a 3 and a 4 Each independently represents an integer of preferably 1 or more and 3 or less, and more preferably 1.

[0123] In formula (21), R 21 , R 22 and R 23 Each independently represents an alkyl group having 1 to 6 carbon atoms, R24 , R 25 and R 26 Each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, 1 , b 2 and b 3 Each independently represents 0 or 1. In formula (21), R 21 , R 22 and R 23 Each independently represents preferably an alkyl group having 1 to 3 carbon atoms, and more preferably a methyl group. 21 , R 22 and R 23 The respective bonding positions are preferably at the meta position relative to the bonding position of the vinyl group and the triphenylamine structure. 24 , R 25 and R 26 Each preferably represents a hydrogen atom. Preferably, b 1 , b 2 and b 3 All represent 0 or all represent 1.

[0124] In formula (22), R 31 , R 32 and R 33 Each independently represents an alkyl group having 1 to 6 carbon atoms, R 34 represents an alkyl group having 1 to 6 carbon atoms or a hydrogen atom, d 1 d 2 and d 3 Each independently represents an integer of 0 to 5. In formula (22), when d 1 When the integer is 2 or more and 5 or less, a plurality of R 31 can represent groups that are the same or different from each other. 2 When the integer is 2 or more and 5 or less, a plurality of R 32 can represent groups that are the same or different from each other. 3 When the integer is 2 or more and 5 or less, a plurality of R 33 can represent groups that are the same as or different from each other. 34 Preferably, it represents a hydrogen atom. 1 d 2 and d 3 Each preferably represents 0.

[0125] In formula (23), R 41 , R 42 , R 43 , R 44 , R 45 and R 46Each independently represents an alkyl group having 1 to 6 carbon atoms or a phenyl group, R 47 and R 48 Each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a phenyl group, e 1 、e 2 、e 3 and e 4 Each independently represents an integer of 0 to 5, e 5 and e 6 Each independently represents an integer of 0 to 4, e 7 and e 8 Each independently represents 0 or 1. In formula (23), when e 1 When the integer is 2 or more and 5 or less, a plurality of R 41 can represent groups that are the same or different from each other. 2 When the integer is 2 or more and 5 or less, a plurality of R 42 can represent groups that are the same or different from each other. 3 When the integer is 2 or more and 5 or less, a plurality of R 43 can represent groups that are the same or different from each other. 4 When the integer is 2 or more and 5 or less, a plurality of R 44 can represent groups that are the same or different from each other. 5 When the integer is 2 or more and 4 or less, a plurality of R 45 can represent groups that are the same or different from each other. 6 When the integer is 2 or more and 4 or less, a plurality of R 46 can represent groups that are the same as or different from each other. 41 To R 46 Each independently represents preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms, and still more preferably a methyl group or an ethyl group. 47 and R 48 Each preferably represents a hydrogen atom. Preferably, e 1 、e 2 、e 3 and e 4 Each independently represents an integer of 0 to 2. More preferably, e 1 and e 2 Each represents 0, e 3 and e 4 Each represents 2. 5 and e 6 Each preferably represents 0. Preferably, e 7 and e 8 All represent 0 or all represent 1.

[0126] In formula (24), R 50 and R 51 each independently represents an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a phenyl group, and R 52 , R 53 , R 54 , R 55 , R 56 , R 57 and R 58 each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a phenyl group which may be substituted with an alkyl group having 1 to 6 carbon atoms, 1 and f 2 Each independently represents an integer of 0 to 2, and f 3 and f 4 Each independently represents an integer greater than or equal to 0 and less than or equal to 5. In formula (24), when f 3 When the integer is 2 or more and 5 or less, a plurality of R 50 can represent groups that are the same or different from each other. 4 When the integer is 2 or more and 5 or less, a plurality of R 51 can represent groups that are the same as or different from each other. In formula (24), preferably, R 50 and R 51 Each independently represents an alkyl group having 1 to 6 carbon atoms. Preferably, R 52 and R 53 Each represents a hydrogen atom or a phenyl group which may be substituted by an alkyl group having 1 to 6 carbon atoms. 54 To R 58 Each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. 1 and f 2 All represent 0, all represent 1 or all represent 2. Preferably, f 3 and f 4 Each independently represents 0 or 1. 50 and R 51 When each represents an alkyl group having 1 to 6 carbon atoms, each of these groups preferably represents an alkyl group having 1 to 3 carbon atoms, and more preferably a methyl group. 52 and R 53When each represents a phenyl group which may be substituted by an alkyl group having 1 to 6 carbon atoms, each of these groups preferably represents a phenyl group or a phenyl group substituted by an alkyl group having 1 to 3 carbon atoms. The phenyl group substituted by an alkyl group having 1 to 3 carbon atoms is preferably a methylphenyl group, and more preferably a 4-methylphenyl group. 54 To R 58 When each represents an alkyl group having 1 to 6 carbon atoms, each of these groups preferably represents an alkyl group having 1 to 4 carbon atoms, and more preferably represents a methyl group, an ethyl group or an n-butyl group. 54 To R 58 When each represents an alkoxy group having 1 to 6 carbon atoms, these groups preferably represent an alkoxy group having 1 to 3 carbon atoms, and more preferably an ethoxy group.

[0127] Suitable examples of the compound represented by formula (20) are compounds represented by formula (H-11). Suitable examples of the compound represented by formula (21) include compounds represented by formula (H-7) and compounds represented by formula (H-8). Suitable examples of the compound represented by formula (22) are compounds represented by formula (H-6). Suitable examples of the compound represented by formula (23) include compounds represented by formula (H-9) and compounds represented by formula (H-10). Suitable examples of the compound represented by formula (24) include compounds represented by formula (H-1), compounds represented by formula (H-2), compounds represented by formula (H-3), compounds represented by formula (H-4) and compounds represented by formula (H-5). The compounds represented by formula (H-1) to formula (H-11) are sometimes referred to as "hole transport substances (H-1) to (H-11)" below.

[0128]

[0129]

[0130]

[0131]

[0132] The content of the hole transport substance is preferably 10 parts by mass or more and 200 parts by mass or less, more preferably 30 parts by mass or more and 120 parts by mass or less, and even more preferably 50 parts by mass or more and 90 parts by mass or less, relative to 100 parts by mass of the binder resin. The photosensitive layer may contain only one hole transport substance, or may contain two or more hole transport substances. In addition, the photosensitive layer may also contain a hole transport substance other than the compound represented by formula (20), formula (21), formula (22), formula (23) or formula (24) (hereinafter sometimes referred to as "other hole transport substances"). Examples of other hole transport substances include triphenylamine derivatives, diamine derivatives (e.g., N,N,N′,N′-tetraphenylbenzidine derivatives, N,N,N′,N′-tetraphenylphenylenediamine derivatives, N,N,N′,N′-tetraphenylnaphthalenediamine derivatives, N,N,N′,N′-tetraphenylphenanthrenediamine derivatives and di(aminophenylvinyl)benzene derivatives), oxadiazole compounds (e.g., 2,5-bis(4-methylaminophenyl)-1,3,4-oxadiazole), styryl compounds (e.g., 9-(4-diethylaminostyryl)anthracene), carbazole compounds (e.g., polyvinylcarbazole), organic polysilane compounds, pyrazoline compounds (e.g., 1-phenyl-3-(p-dimethylaminophenyl)pyrazoline), hydrazone compounds, indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds and triazole compounds.

[0133] [additive]

[0134] The photosensitive layer may contain additives as needed. Examples of additives include UV absorbers, antioxidants, free radical scavengers, singlet quenchers, softeners, surface modifiers, extenders, thickeners, waxes, donors, surfactants, plasticizers, sensitizers, and leveling agents. In particular, it is preferred to add a small amount of a compound represented by the following formula (30) (hereinafter sometimes referred to as "compound (T-1)").

[0135]

[0136] [Toner]

[0137] The toner of the present disclosure is characterized in that the toner includes toner particles, the toner particles include a core including a binder resin and a shell covering a surface of the core, and the shell includes at least one resin selected from the group consisting of a melamine resin and a resin having a structural unit represented by formula (3):

[0138]

[0139] In formula (3), R 1It represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms.

[0140] The toner in the present disclosure may be suitable for developing an electrostatic latent image. The toner in the present disclosure may be used as a single-component developer. The toner in the present disclosure may be used as a two-component developer by mixing with a carrier using a mixing device (e.g., a ball mill). When the toner is used as a single-component developer, the toner is positively charged by friction with a developing sleeve or a toner charging member in a developing device. An example of a toner charging member is a doctor blade. When the toner is used as a two-component developer, the toner is positively charged by friction with a carrier in a developing device.

[0141] [shell]

[0142] In the toner of the present disclosure, the shell covers the surface of the core.

[0143] The shell comprises at least one resin selected from the group consisting of melamine resins and resins having a structural unit represented by formula (3). 1 It represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms.

[0144] The resin for forming the shell may contain a thermosetting resin in order to improve strength. The resin for forming the shell preferably has sufficient positive chargeability.

[0145] In the toner of the present disclosure, it is preferred that the toner contains toner particles, and the surface of the toner particles contains at least one resin selected from the group consisting of a melamine resin and a resin having a structural unit represented by formula (3). For example, the shell preferably contains at least one resin selected from the group consisting of a melamine resin and a resin having a structural unit represented by formula (3).

[0146] Examples of thermosetting resins are thermosetting resins having positive chargeability or thermosetting resins having nitrogen atoms in the molecular skeleton. Examples of thermosetting resins having positive chargeability are thermosetting resins having amino groups (—NH 2) thermosetting resin. The example of the thermosetting resin with amino group includes melamine resin, derivative of melamine resin, guanamine resin, derivative of guanamine resin (such as benzoguanamine resin, acetylguanamine resin or spiroguanamine resin), sulfonamide resin, urea-formaldehyde resin, derivative of urea-formaldehyde resin (such as glyoxal resin) and aniline resin. In addition, the example of the thermosetting resin with nitrogen atom in the molecular skeleton is thermosetting polyimide resin (such as maleimide polymer, bismaleimide polymer, amino bismaleimide polymer or bismaleimide triazine copolymer). This type of thermosetting resin can be used alone or in combination. It is preferred to use melamine resin as thermosetting resin.

[0147] In order to improve strength, the resin used to form the shell may contain a resin having a structural unit represented by formula (3). It is known that the resin having a structural unit represented by formula (3) contains a non-ring-opened oxazoline group in the structure of formula (3) and has excellent positive charging properties.

[0148] In addition, the resin for forming the shell may include a resin having a structural unit represented by formula (3-B). In formula (3-B), R 2 represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, R 0 It indicates the bonding site with the atoms in the binder resin in the core.

[0149]

[0150] When R in formula (3) or formula (3-B) 1 or R 2 When representing an alkyl group having 1 to 10 carbon atoms, examples thereof include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, neopentyl, 1,2-dimethylpropyl, straight-chain or branched hexyl, straight-chain or branched heptyl, straight-chain or branched octyl, straight-chain or branched nonyl, and straight-chain or branched decyl. 1 Preferably, R represents a hydrogen atom, a methyl group, an ethyl group or an isopropyl group. 2 Preferably, it represents a hydrogen atom, a methyl group, an ethyl group or an isopropyl group. Preferably, the resin for forming the shell comprises 50% by mass or more of at least one resin selected from the group consisting of melamine resins and resins having a structural unit represented by formula (3). Here, an example of the resin having a structural unit represented by formula (3) is a copolymer of 2-vinyl-2-oxazoline and methyl methacrylate.

[0151] [Toner particles]

[0152] The toner particles include a core including a binder resin and a shell covering the surface of the core. In addition, the toner particles include toner base particles. Preferably, the toner particles further include an external additive attached to the surface of the toner base particles. The external additive includes external additive particles. Figure 4 It is a diagram for explaining an example of the cross-sectional structure of a toner particle in the toner of the present embodiment. Figure 4 The toner particles 20 shown include a toner base particle 10 and an external additive attached to the surface of the toner base particle 10. The toner base particle 10 includes a core 11 and a shell 12 covering the surface of the core 11. The shell 12 completely covers the surface of the core 11. The external additive includes an external additive particle 13. Figure 4 The structure of the toner particles in the toner is described. However, the toner particles in the toner of the present disclosure may have the same Figure 4 The toner particles 20 shown have different structures. For example, the shell may partially cover the surface of the core. In addition, the toner particles may not contain external additives.

[0153] The toner of the present disclosure is further described below.

[0154] [Toner base particles]

[0155] The toner base particle includes a core and a shell covering the surface of the core. From the viewpoint of obtaining a toner having further excellent heat-resistant storage stability while maintaining low-temperature fixability, the thickness of the shell is preferably 1 nm or more and 400 nm or less. The thickness of the shell can be measured by analyzing a transmission electron microscope (TEM) image of a cross section of a dyed toner particle using commercially available image analysis software (e.g., "WinROOF", manufactured by Mitani Corporation). When the thickness of the shell is uneven in one toner particle, the thickness of the shell is measured at each of four equidistant positions (specifically, four positions where two straight lines drawn approximately at the center of the cross section of the toner particle in a manner orthogonal to each other intersect the shell). The arithmetic mean of the four measured values ​​obtained can be defined as the evaluation value (shell thickness) of the toner particle. The area ratio of the region covered by the shell on the surface of the core (shell coverage) is preferably 90% or more and 100% or less, more preferably 95% or more and 100% or less. When the coverage of the shell is 90% or more, a toner having further excellent heat-resistant storage stability can be obtained. The coverage of the shell can be determined by analyzing a transmission electron microscope (TEM) image of a cross section of the toner particle using commercially available image analysis software (e.g., "WinROOF", manufactured by Mitani Corporation). Specifically, the coverage of the shell is obtained by measuring the ratio of the area covered by the shell to the surface area of ​​the core (the outline indicating the outer edge) in the TEM image of the cross section of the dyed toner particle. From the viewpoint of forming a satisfactory image, the volume median diameter (D50) of the toner base particles is preferably 4 μm or more and 9 μm or less.

[0156] [nuclear]

[0157] The core includes a binder resin. The binder resin in the core may include a polyester resin. In addition, the binder resin in the core may include a styrene-acrylic resin. As required, the core may further include an internal additive (e.g., at least one of a black colorant, other colorants, a release agent, or a charge control agent).

[0158] (Polyester resin)

[0159] The polyester resin is used as a binder resin of the toner of the present disclosure. The core contains, for example, a polyester resin as a main component.

[0160] The polyester resin is obtained by polycondensing one or more polyols and one or more polyvalent carboxylic acids. Examples of alcohols used to synthesize the polyester resin include diols (more specifically, diols and bisphenols) and trivalent or higher alcohols as described below. Examples of carboxylic acids used to synthesize the polyester resin include dicarboxylic acids and trivalent or higher carboxylic acids as described below. Polycarboxylic acid derivatives that can form ester bonds by polycondensation, such as polycarboxylic acid anhydrides or polycarboxylic acid halides, can be used instead of polycarboxylic acids.

[0161] The acid value of the polyester resin is preferably 10 mgKOH / g or more and 30 mgKOH / g or less, and more preferably 15 mgKOH / g or more and 25 mgKOH / g or less.

[0162] The acid value of the polyester resin can be measured by a method that complies with Japanese Industrial Standard (JIS) K0070-1992. The acid value of the polyester resin can be adjusted, for example, by changing the type or amount of the carboxylic acid used to synthesize the polyester resin. Specifically, the acid value of the synthesized polyester resin can be increased by using a carboxylic acid having multiple carboxyl groups in one molecule (e.g., a trivalent or higher carboxylic acid). In addition, the acid value of the polyester resin can be increased by increasing the amount of carboxylic acid added relative to the amount of alcohol added.

[0163] Suitable examples of glycols include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 2-butene-1,4-diol, 1,5-pentanediol, 2-pentene-1,5-diol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, dipropylene glycol, 1,4-benzenediol, polyethylene glycol, polypropylene glycol and polytetramethylene glycol.

[0164] Suitable examples of bisphenols include bisphenol A, hydrogenated bisphenol A, ethylene oxide adducts of bisphenol A, and propylene oxide adducts of bisphenol A.

[0165] Suitable examples of trivalent or higher alcohols include sorbitol, 1,2,3,6-hexanetetraol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, diglycerol, 2-methylglycerol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane and 1,3,5-trimethylolbenzene.

[0166] Suitable examples of dicarboxylic acids include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, adipic acid, sebacic acid, azelaic acid, malonic acid, succinic acid, alkylsuccinic acids (more specifically, such as n-butylsuccinic acid, isobutylsuccinic acid, n-octylsuccinic acid, n-dodecylsuccinic acid or isododecylsuccinic acid) and alkenylsuccinic acids (more specifically, such as n-butenylsuccinic acid, isobutenylsuccinic acid, n-octenylsuccinic acid, n-dodecenylsuccinic acid or isododecenylsuccinic acid).

[0167] Suitable examples of trivalent or higher carboxylic acids include 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxy-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, tetrakis(methylenecarboxy)methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid and EMPOL trimer acid.

[0168] In addition to the polyester resin, the core may also contain a binder resin other than the polyester resin (hereinafter, sometimes referred to as "other binder resins" in the core). The other binder resins in the core are preferably thermoplastic resins. The content ratio of the thermoplastic resin (other binder resins and polyester resins in the core as thermoplastic resins) is preferably 85% by mass or more relative to the total amount of the binder resins in the core (other binder resins and polyester resins in the core). Examples of other binder resins in the core as thermoplastic resins include styrene resins, acrylate resins, olefin resins (more specifically, such as polyethylene resins or polypropylene resins), vinyl resins (more specifically, such as vinyl chloride resins, polyvinyl alcohol, vinyl ether resins or N-vinyl resins), polyamide resins and polyurethane resins. In addition, copolymers of the above-mentioned resins, that is, copolymers obtained by introducing arbitrary repeating units into the above-mentioned resins (more specifically, such as styrene-acrylate resins or styrene-butadiene resins) can be used as other binder resins in the core as thermoplastic resins.

[0169] (Colorant)

[0170] The toner base particles may contain a colorant. Depending on the color of the toner, a known pigment or dye may be used as the colorant. In order to form a high-quality image by using the toner, the amount of the colorant is preferably 1 part by mass or more and 20 parts by mass or less, and more preferably 2 parts by mass or more and 10 parts by mass or less, relative to 100 parts by mass of the binder resin.

[0171] The toner base particles may contain a black colorant. An example of a black colorant is carbon black. In addition, the black colorant may be a colorant toned to black by using a yellow colorant, a magenta colorant, and a cyan colorant. The toner base particles may contain a colorant such as a yellow colorant, a magenta colorant, or a cyan colorant.

[0172] For example, as a yellow colorant, one or more compounds selected from the group consisting of condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and arylamide compounds can be used respectively. CI Pigment Yellow (3, 12, 13, 14, 15, 17, 62, 74, 83, 93, 94, 95, 97, 109, 110, 111, 120, 127, 128, 129, 147, 151, 154, 155, 168, 174, 175, 176, 180, 181, 191 or 194) classified by color index, naphthol yellow S, Hansa Yellow G or CI Vat Yellow can be suitably used as a yellow colorant.

[0173] As the magenta colorant, one or more compounds selected from the group consisting of condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinone compounds, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds can be used respectively. CI Pigment Red (2, 3, 5, 6, 7, 19, 23, 48:2, 48:3, 48:4, 57:1, 81:1, 122, 144, 146, 150, 166, 169, 177, 184, 185, 202, 206, 220, 221 or 254) classified by color index can be suitably used as the magenta colorant.

[0174] For example, as a cyan colorant, one or more compounds selected from the group consisting of: copper phthalocyanine compounds; anthraquinone compounds; and basic dye lake compounds can be used respectively. CI Pigment Blue (1, 7, 15, 15:1, 15:2, 15:3, 15:4, 60, 62 or 66), Phthalocyanine Blue, CI Vat Blue or CI Acid Blue classified by Color Index can be suitably used as a cyan colorant.

[0175] (Release Agent)

[0176] The core may contain a release agent. The release agent is used, for example, for the purpose of imparting heat offset resistance to the toner. When the core contains a release agent and a polyester resin, from the viewpoint of imparting more excellent heat offset resistance to the toner, the content of the release agent is preferably 1.0 parts by mass or more and 20.0 parts by mass or less relative to 100 parts by mass of the polyester resin. In addition, the content of the release agent is more preferably 5.0 parts by mass or more and 15.0 parts by mass or less relative to 100 parts by mass of the polyester resin.

[0177] For example, the following release agents can be appropriately used: aliphatic hydrocarbon waxes, such as low molecular weight polyethylene, low molecular weight polypropylene, polyolefin copolymers, polyolefin waxes, microcrystalline waxes, paraffin waxes and Fischer-Tropsch waxes; oxides of aliphatic hydrocarbon waxes, such as oxidized polyethylene waxes and block copolymers of oxidized polyethylene waxes; plant waxes, such as candelilla wax, carnauba wax, wood wax, jojoba wax and rice wax; animal waxes, such as beeswax, lanolin and spermaceti; mineral waxes, such as ozokerite, ceresin and vaseline; ester waxes each containing fatty acid esters as main components, such as montanic acid ester wax and castor wax; and partially or completely deoxidized waxes of fatty acid esters (e.g. deoxidized carnauba wax). Among them, ester waxes are preferably used as release agents. When the core contains a release agent and a polyester resin, a compatibilizer can be further added to the core to improve the compatibility between the polyester resin and the release agent.

[0178] (Charge Control Agent)

[0179] The core may contain a charge control agent. The charge control agent is used, for example, for the purpose of providing a colorant having excellent charging stability or excellent charging rise characteristics. The charging rise characteristics of the colorant are used as an indicator indicating whether the colorant can be charged to a predetermined charging level in a short time. Introducing a charge control agent having positive charging properties into the core can enhance the cationic nature of the core. When the core contains a charge control agent and a polyester resin, from the viewpoint of providing a colorant having excellent charging stability, the content of the charge control agent is preferably 0.1 parts by mass or more and 10.0 parts by mass or less relative to 100 parts by mass of the polyester resin.

[0180] [External additives]

[0181] The external additive particles are preferably inorganic particles. The inorganic particles are preferably silica particles or particles of metal oxides (more specifically, particles of aluminum oxide, titanium oxide, magnesium oxide, zinc oxide, strontium titanate or barium titanate), and more preferably silica particles, titanium oxide particles, strontium titanate particles or aluminum oxide particles. The content of the inorganic particles is preferably 0.01 parts by mass or more and 10 parts by mass or less, and more preferably 0.1 parts by mass or more and 5 parts by mass or less relative to 100 parts by mass of the toner base particles.

[0182] <Method for producing toner>

[0183] An example of a method for manufacturing a toner according to the present disclosure is described. The method for manufacturing a toner includes: a core preparation process of preparing a core; and a shell formation process of forming a shell on the surface of the core to provide a toner base particle. The method for manufacturing a toner may further include an external addition process of externally adding an external additive to the surface of the toner base particle after the shell formation process.

[0184] [Core preparation process]

[0185] The preparation method of the core is not particularly limited, and any known pulverization method or aggregation method can be used. Pulverization is preferred as the manufacturing method of the core. An example of the pulverization method is described below. First, a polyester resin, a black colorant and an internal additive added as needed are mixed. Subsequently, the resulting mixture is melt-kneaded with a melt-kneading device (for example, a single-screw or twin-screw extruder). Subsequently, the resulting melt-kneaded product is pulverized and classified. As a result, a core is obtained. An example of the aggregation method is described below. First, in an aqueous medium containing fine particles of each of a binder resin, a colorant and an internal additive to be added as needed to be used in the core, these fine particles are aggregated until the desired particle size is reached. As a result, aggregated particles containing a binder resin, etc. are formed. Subsequently, the resulting aggregated particles are heated so that the components in the aggregated particles are agglomerated with each other. As a result, a core is obtained.

[0186] [Shell Forming Process]

[0187] An example of a shell forming method is a method involving mixing a core and a shell forming solution in an aqueous medium. The shell forming solution contains a resin for forming a shell (shell forming resin). The shell forming resin is, for example, a melamine resin or a resin having a structural unit represented by formula (3). The shell forming resin is also used as a dispersant and can react with the core even in an aqueous medium that does not contain a dispersant (e.g., a surfactant) or an organic solvent. In addition, a surfactant or the like can be added as a dispersant. Preferably, a mixed solution of the core and shell forming solutions is heated. When the core and shell forming solutions are mixed, a shell is formed on the surface of the core, thereby providing a dispersion containing toner base particles. When the resulting dispersion is subjected to solid-liquid separation, washed and dried, toner base particles are obtained. Preferably, the dispersion (dispersion containing the core and shell forming solution) further contains an alkaline substance.

[0188] [External addition process]

[0189] In the external addition process, the external additive is attached to the surface of the toner base particles. As a result, toner particles containing the toner base particles and the external additive attached to the surface of the toner base particles are obtained. The method for attaching the external additive to the surface of the toner base particles is not particularly limited, and for example, a method involving stirring the toner base particles and the external additive using a mixer is used.

[0190] [Electronic photography equipment]

[0191] The present disclosure is described in detail below based on the illustrated embodiments.

[0192] refer to Figure 5 A tandem type color electrophotographic apparatus is described as an example. Figure 5 is a cross-sectional view for explaining one example of an electrophotographic apparatus. Figure 5 The illustrated electrophotographic apparatus 100 includes image forming units 40a, 40b, 40c and 40d, a transfer belt 50 and a fixing device 54. When no distinction is required, each image forming unit 40a, 40b, 40c, 40d is hereinafter referred to as an image forming unit 40. The image forming unit 40 includes an image bearing member 30, a charging device 42 as a charging unit, an exposure device 44 as an exposure unit, a developing device 46 as a developing unit, and a transfer device 48 as a transfer unit. The image bearing member 30 is a photosensitive member (specifically, a single-layer photosensitive member). In addition, a recording medium P is located at the lower part of the electrophotographic apparatus. The image bearing member 30 is arranged at the center position of the image forming unit 40. The image bearing member 30 is arranged to extend in the direction of the arrow ( Figure 5 The charging device 42, the exposure device 44, the developing device 46, and the transfer device 48 are arranged around the image bearing member 30 in the stated order from the upstream side in the rotation direction of the image bearing member 30.

[0193] A toner image of a plurality of colors (for example, four colors of black, cyan, magenta, and yellow) is sequentially superimposed on a recording medium P on a transfer belt 50 through each of the image forming units 40a to 40d. The charging device 42 charges the surface (for example, the peripheral surface) of the image bearing member 30 with positive polarity. When the image bearing member 30 is a single-layer type photosensitive member, the surface of the image bearing member 30 is charged with positive polarity. The charging device 42 is, for example, a charging roller. The exposure device 44 irradiates the charged surface of the image bearing member 30 with exposure light. That is, the exposure device 44 exposes the charged surface of the image bearing member 30. As a result, an electrostatic latent image is formed on the surface of the image bearing member 30. The electrostatic latent image is formed based on the image data input to the electrophotographic apparatus 100. The developing device 46 includes a toner and supplies the toner to the surface of the image bearing member 30, thereby developing the electrostatic latent image into a toner image. The developing device 46 (for example, the surface of the developing device 46, more specifically, the circumferential surface of the developing device 46) is in contact with the surface of the image bearing member 30. That is, the electrophotographic apparatus 100 adopts a contact developing system. The developing device 46 is, for example, a developing roller. When the developer is a single-component developer, the developing device 46 supplies a toner as a single-component developer to the electrostatic latent image formed on the image bearing member 30. When the developer is a two-component developer, the developing device 46 supplies a toner in the two-component developer and a toner in a carrier to the electrostatic latent image formed on the image bearing member 30. In this way, the image bearing member 30 carries the toner image. The transfer belt 50 conveys the recording medium P to a position between the image bearing member 30 and the transfer device 48. The transfer belt 50 is an endless belt. The transfer belt 50 is extended in the direction of the arrow ( Figure 5The transfer device 48 is configured in a rotatable manner (clockwise direction in the image). The transfer device 48 transfers the colorant image developed by the developing device 46 from the surface of the image bearing member 30 to the transfer target member. The transfer target member is the recording medium P. When the toner image is transferred, the image bearing member 30 is in contact with the recording medium P. That is, the electronic photographic apparatus 100 adopts a direct transfer system. The transfer device 48 is, for example, a transfer roller. The recording medium P having the toner image transferred thereto by the transfer device 48 is conveyed to the fixing device 54 by the transfer belt 50. The fixing device 54 is, for example, a heating roller and / or a pressure roller. The unfixed toner image transferred by the transfer device 48 is heated and / or pressurized by the fixing device 54. The toner image is fixed to the recording medium P by heating and / or pressurizing. As a result, an image is formed on the recording medium P. An example of an electronic photographic apparatus has been described above, but the electronic photographic apparatus is not limited to the electronic photographic apparatus 100 described above. The above-mentioned electronic photographic device 100 is a color electronic photographic device, but the electronic photographic device may also be a monochrome electronic photographic device. In this case, it is only necessary for the electronic photographic device to include, for example, only one image forming unit. In addition, the electronic photographic device 100 described above adopts a series system, but the electronic photographic device may also adopt, for example, a rotary system. The charging device 42 is described by taking a charging roller as an example, but the charging device may also be a charging device other than a charging roller (for example, a scorotron charger, a charging brush, or a corotron charger). The electronic photographic device 100 described above adopts a contact development system, but the electronic photographic device may also adopt a non-contact development system. The electronic photographic device 100 described above adopts a direct transfer system, but the electronic photographic device may also adopt an intermediate transfer system. When the electronic photographic device adopts an intermediate transfer system, the transfer target member corresponds to the intermediate transfer belt. The image forming unit 40 of the electronic photographic device described above does not include a cleaning member, but the image forming unit 40 may further include a cleaning member (for example, a cleaning blade). The image forming unit 40 described above does not include the charge eliminating device, but the image forming unit may further include the charge eliminating device.

[0194] [Processing cartridge]

[0195] A process cartridge according to the present disclosure is a process cartridge comprising: an electrophotographic photosensitive member; and a developing unit comprising a toner and configured to form a toner image on a surface of the electrophotographic photosensitive member with the toner, the process cartridge integrally supporting the electrophotographic photosensitive member and the developing unit and being detachably mounted to a main body of an electrophotographic apparatus, wherein the electrophotographic photosensitive member comprises a single-layer type photosensitive layer comprising a charge generating substance, a hole transporting substance, an electron transporting substance and a binder resin, wherein the photosensitive layer comprises a polyarylate resin having a structural unit represented by the following formula (1) and a structural unit represented by the following formula (2) as a binder resin, wherein the toner comprises toner particles, wherein the toner particles comprise a core comprising the binder resin and a shell covering a surface of the core, and wherein the shell comprises at least one resin selected from the group consisting of a melamine resin and a resin having a structural unit represented by the following formula (3):

[0196]

[0197] In formula (3), R 1 It represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms.

[0198] A process cartridge according to the present disclosure is a process cartridge comprising: an electrophotographic photosensitive member; and a developing unit comprising a toner and configured to form a toner image on a surface of the electrophotographic photosensitive member with the toner, the process cartridge integrally supporting the electrophotographic photosensitive member and the developing unit and being detachably mounted to a main body of an electrophotographic apparatus, wherein the electrophotographic photosensitive member comprises a single-layer type photosensitive layer comprising a charge generating substance, a hole transporting substance, an electron transporting substance and a binder resin, wherein the photosensitive layer comprises a polyarylate resin having a structural unit represented by the following formula (1) and a structural unit represented by the following formula (2) as a binder resin, wherein the toner comprises toner particles, wherein the surfaces of the toner particles comprise at least one resin selected from the group consisting of a melamine resin and a resin having a structural unit represented by the following formula (3):

[0199]

[0200] In formula (3), R 1 It represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms.

[0201] Continue to refer Figure 5, describes an example of a processing box according to an embodiment of the present disclosure. The processing box corresponds to each of the image forming units 40a to 40d. The processing box includes an image bearing member 30 and a developing device 46. The image bearing member 30 is a photosensitive member of the first embodiment. In addition to the image bearing member 30 and the developing device 46, the processing box may also include a charging device 42. The processing box may also include a cleaning member (not shown) and a charge eliminating device (not shown). The processing box is designed to be detachably mounted to the electronic photographic device 100. Therefore, the processing box is easy to handle, and when the sensitivity characteristics of the image bearing member 30, etc., are deteriorated, it can be easily and quickly replaced together with the image bearing member 30. Reference has been made above Figure 5 A process cartridge including a photosensitive member is described.

[0202] According to the present disclosure, it is possible to provide an excellent electrophotographic apparatus in which, in an electrophotographic apparatus using a toner having a core-shell structure, a decrease in transfer efficiency after durability is suppressed and high image quality is maintained from an initial stage to a post-durability stage.

[0203] [Example]

[0204] The present disclosure is described in more detail below by examples and comparative examples. Without departing from the scope of the subject matter of the present disclosure, the invention is by no means limited by the following examples. In the description of the following examples, unless otherwise stated, the term "part" is by mass.

[0205] <Production of polyarylate resin (PAR)>

[0206] [Synthesis of resin (PAR-1)]

[0207] A three-necked flask including a thermometer, a three-way stopcock and a dropping funnel was used as a reaction vessel. The following materials were charged into the reaction vessel.

[0208] ·Compound (BP-2) as a monomer (41.0 mmol)

[0209] · 2,6-Dimethylphenol (DMP) (0.625 mmol) as a terminal terminator

[0210] Sodium hydroxide (98 mmol)

[0211] Benzyltributylammonium chloride (0.384 mmol)

[0212] The air in the reaction vessel was replaced by argon. Water (300 mL) was added to the content of the reaction vessel. The content in the reaction vessel was stirred at 50° C. for 1 hour. The content in the reaction vessel was cooled to 10° C. to provide a basic aqueous solution A1.

[0213] Next, dicarboxylic acid dichloride (32.0 mmol) of the derivative of compound (DC-1) as a monomer was dissolved in chloroform (150 mL), thereby obtaining a chloroform solution B1.

[0214] Chloroform solution B1 was slowly dripped into alkaline aqueous solution A1 within 110 minutes by using a dropping funnel. While the temperature (liquid temperature) of the contents in the reaction vessel was adjusted to 15 ± 5 ° C, the contents in the reaction vessel were stirred for 4 hours to allow the polymerization reaction to proceed. The upper layer (water layer) of the contents in the reaction vessel was removed by decantation. Thus, an organic layer was obtained. Next, ion exchange water (400mL) was loaded into a conical flask. The obtained organic layer was further added to a conical flask. Chloroform (400mL) and acetic acid (2mL) were further added to a conical flask. The contents in the conical flask were stirred at room temperature (25 ° C) for 30 minutes. The upper layer (water layer) of the contents in the conical flask was removed by decantation. Thus, an organic layer was obtained. The obtained organic layer was washed with ion exchange water (1L) by using a separatory funnel. Washing with ion exchange water was repeated 5 times. Thus, a washed organic layer was obtained. Next, the washed organic layer was filtered to provide a filtrate. The obtained filtrate was slowly dripped into methanol (1L) to provide a precipitate. The precipitate was taken out by filtration. The precipitate thus taken out was vacuum dried at a temperature of 70° C. for 12 hours. As a result, a resin (PAR-1) having a viscosity average molecular weight of 35,000 was obtained.

[0215] [Synthesis of resin (PAR-7)]

[0216] A three-necked flask including a thermometer, a three-way stopcock and a dropping funnel was used as a reaction vessel. The following materials were charged into the reaction vessel.

[0217] ·Compound (BP-2) as a monomer (28.7 mmol)

[0218] ·Compound (BP-5) as a monomer (12.3 mmol)

[0219] · 2,6-Dimethylphenol (DMP) as a terminal terminator (0.413 mmol)

[0220] Sodium hydroxide (98 mmol)

[0221] Benzyltributylammonium chloride (0.384 mmol)

[0222] The air in the reaction vessel was replaced by argon. Water (300 mL) was added to the content of the reaction vessel. The content in the reaction vessel was stirred at 50° C. for 1 hour. The content in the reaction vessel was cooled to 10° C. to provide a basic aqueous solution A2.

[0223] Next, dicarboxylic acid dichloride (20.8 mmol) of the derivative of compound (DC-1) as a monomer and dicarboxylic acid dichloride (11.2 mmol) of the derivative of compound (DC-4) as a monomer were dissolved in chloroform (150 mL) to obtain a chloroform solution B2.

[0224] Chloroform solution B2 was slowly dripped into alkaline aqueous solution A2 within 110 minutes by using a dropping funnel. While the temperature (liquid temperature) of the contents in the reaction vessel was adjusted to 15 ± 5 ° C, the contents in the reaction vessel were stirred for 4 hours to allow the polymerization reaction to proceed. The upper layer (water layer) of the contents in the reaction vessel was removed by decantation. Thus, an organic layer was obtained. Next, ion exchange water (400mL) was loaded into a conical flask. The obtained organic layer was further added to a conical flask. Chloroform (400mL) and acetic acid (2mL) were further added to a conical flask. The contents in the conical flask were stirred at room temperature (25 ° C) for 30 minutes. The upper layer (water layer) of the contents in the conical flask was removed by decantation. Thus, an organic layer was obtained. The obtained organic layer was washed with ion exchange water (1L) by using a separatory funnel. Washing with ion exchange water was repeated 5 times. Thus, a water-washed organic layer was obtained. Next, the water-washed organic layer was filtered to provide a filtrate. The obtained filtrate was slowly dripped into methanol (1L) to provide a precipitate. The precipitate was taken out by filtration. The precipitate thus taken out was vacuum dried at a temperature of 70° C. for 12 hours. As a result, a resin (PAR-7) having a viscosity average molecular weight of 55,000 was obtained.

[0225] [Synthesis of resins (PAR-2) to (PAR-6) and (PAR-8) to (PAR-30)]

[0226] The synthesis was carried out by the same method as that of the resin (PAR-7) having a viscosity average molecular weight of 55,000 except that the ratio of bisphenol and dicarboxylic acid and the terminal terminator were changed. Thus, resins (PAR) having the viscosity average molecular weights shown in Table 1 were obtained. As the amount of the terminal terminator added became smaller, the viscosity average molecular weight of each resin (PAR) became higher.

[0227] Table 1

[0228]

[0229] The numerical values ​​of bisphenols in Table 1 each represent the ratio of the amount of each bisphenol to the total amount of two bisphenols in each of resins (PAR-1) to resins (PAR-30). In addition, the numerical values ​​of dicarboxylic acids each represent the ratio of the amount of each dicarboxylic acid to the total amount of two dicarboxylic acids. In addition, "PFH" represents 1H,1H-perfluoro-1-heptanol. In addition, the molecular weight represents the viscosity average molecular weight.

[0230] <Manufacture of Electrophotographic Photosensitive Member>

[0231] [Manufacture of Photosensitive Member 1]

[0232] Prepare the following materials.

[0233]

[0234] The above materials were mixed with a rod-shaped sonic oscillator for 20 minutes to provide a dispersion. The dispersion was filtered through a filter with an opening of 5 μm to provide a photosensitive layer coating liquid. The photosensitive layer coating liquid was applied to a conductive support (aluminum drum-shaped support) by dip coating (dip coating) and dried at 120° C. for 50 minutes with hot air. Thus, a photosensitive layer (thickness: 30 μm) was formed on the conductive support to provide a photosensitive member 1.

[0235] (Resin Component Analysis of Photosensitive Member 1)

[0236] By recovering the polymer component from the obtained photosensitive member in deuterated chloroform 1 H-NMR spectroscopy 1 H-NMR spectrum. 1 The H-NMR spectrum has peaks at 8.22±0.02ppm, 7.18±0.02ppm, 7.16±0.02ppm, 7.10±0.02ppm, 7.06±0.02ppm and 7.04±0.02ppm. Therefore, it was determined that the photosensitive member had a structural unit represented by formula (1) and a structural unit represented by formula (2). In addition, based on the integral ratio of the above peaks, the ratio of the amount of the structural unit represented by formula (1) and the structural unit represented by formula (2) was 1:1 as shown in Table 1.

[0237] [Manufacture of Photosensitive Members 2 to 32 and 34 to 36]

[0238] Photosensitive members 2 to 32 and 34 to 36 were respectively manufactured by the same method as the manufacture of the photosensitive member 1 except that the kinds of the charge generating substance, the additive, the hole transporting substance, the electron transporting substance and the binder resin were changed. The kinds of the charge generating substance, the additive, the hole transporting substance, the electron transporting substance and the binder resin used are shown in Table 2. The mass of each material used was the same as that in the photosensitive member 1. The manufacturing examples of the photosensitive members are shown in Table 2. In the table, "CGM", "HTM" and "ETM" respectively represent the charge generating substance, the hole transporting substance and the electron transporting substance, and the compound numbers are respectively shown.

[0239] (Resin Component Analysis of Photosensitive Member 21)

[0240] By recovering the polymer component from the obtained photosensitive member in deuterated chloroform1 H-NMR spectroscopy 1 H-NMR spectrum. 1 The H-NMR spectrum has peaks at 8.22±0.02ppm, 7.18±0.02ppm, 7.16±0.02ppm, 7.10±0.02ppm, 7.06±0.02ppm, 7.04±0.02ppm, 2.28±0.02ppm, 2.20±0.02ppm, 1.59±0.02ppm and 1.54±0.02ppm. Therefore, it is determined that the photosensitive member has a structural unit represented by formula (1), a structural unit represented by formula (2), a structural unit represented by formula (4) and a structural unit represented by formula (5). In addition, based on the integral ratio of the above peaks, the ratio of the amount of substance of the structural unit represented by formula (1), the structural unit represented by formula (2), the structural unit represented by formula (4) and the structural unit represented by formula (5) is shown in Table 1.

[0241] [Manufacturing of Photosensitive Member 33]

[0242] The photosensitive member 33 was produced by the same method as in the production of the photosensitive member 1 except that the kind of the binder resin was changed as described below.

[0243] · Polyarylate resin (PAR-30) as a binder resin 50.0 parts by mass

[0244] · Polyarylate resin (PAR-6) as a binder resin 50.0 parts by mass

[0245] Table 2

[0246]

[0247] <Manufacturing of Toner>

[0248] Toners (TA-1), (TB-1), (TM-1), and (TF-1) were obtained by the following method.

[0249] [Manufacturing of toner base particles]

[0250] First, polyester resin A for core is synthesized.

[0251] (Synthesis of Polyester Resin A)

[0252] A 5L four-necked flask including a thermometer (thermocouple), a nitrogen inlet pipe, a dehydration pipe, a rectifier and a stirring device (stirring blade) was used as a reaction vessel. The reaction vessel was placed in an oil bath. 1,200g of 1,2-propylene glycol, 1,700g of terephthalic acid and 3g of an esterification catalyst (tin (II) dioctoate) were loaded into the reaction vessel. Subsequently, the temperature in the reaction vessel was raised to 230°C by using an oil bath, and the contents in the reaction vessel were reacted (specifically, condensation reaction) for 15 hours under a nitrogen atmosphere and a temperature of 230°C. Subsequently, the pressure in the reaction vessel was reduced, and the contents in the reaction vessel were reacted under a reduced pressure atmosphere (pressure: 8.0kPa) and a temperature of 230°C until the Tm of the reaction product (polyester resin A) reached a predetermined temperature (90°C). As a result, a polyester resin A having a Tm of 90°C was obtained.

[0253] The acid value of the polyester resin A is measured by a method conforming to Japanese Industrial Standard (JIS) K0070-1992. The acid value of the polyester resin A is 20 mgKOH / g.

[0254] (Preparation of Core A)

[0255] Prepare the following materials.

[0256] Binder resin (polyester resin A) 80 parts by mass

[0257] Release agent ("NISSAN ELECTROL (trademark) WEP-3", manufactured by NOF Corporation, component: ester wax) 9 parts by mass

[0258] Black colorant ("MA-100", manufactured by Mitsubishi Chemical Corporation, component: acid carbon black) 9 parts by mass

[0259] The above materials were mixed for 4 minutes with an FM mixer ("FM-20B", manufactured by Nippon Coke & Engineering Co., Ltd.) at a rotation speed of 2,000 rpm. The resulting mixture was melt-kneaded using a twin-screw extruder ("PCM-30", manufactured by Ikegai Corp) at a melt-kneading temperature (cylinder temperature) of 100°C, a rotation speed of 150 rpm, and a processing speed of 100 g / min. The resulting melt-kneaded product was coarsely crushed to about 2 mm with a pulverizer ("Rotoplex (trademark)", manufactured by Hosokawa Micron Corporation). The resulting coarsely crushed product was crushed with a pulverizer ("Turbo Mill (RS type)", manufactured by Freund-Turbo Corporation). The crushing conditions of the coarsely crushed product were set to a mill speed of 12,000 rpm and a loading of 2 kg / hour. The obtained pulverized product was classified with an air classifier ("EJ-L3 model", manufactured by Nittetsu Mining Co., Ltd.) to provide a core A having a D50 of 6.7 μm. The core A had a Tm of 90°C and a Tg of 49°C.

[0260] (Preparation of Core B)

[0261] The core B was prepared by the same method as in the preparation of the core A, except that a styrene-acrylic resin ("CPR300", manufactured by Mitsui Chemicals, Inc.) was used as the binder resin.

[0262] (Formation of Shell of Toner (TA-1): Formation of Toner Base Particles Including a Shell Containing a Resin Having a Structural Unit Represented by Formula (3))

[0263] A three-necked flask of 1L volume including a thermometer and a stirring blade is placed in a water bath, and 300mL of ion exchange water is added to the flask. Afterwards, the temperature in the flask is maintained at 30°C by using a water bath. Subsequently, a shell-forming solution (EPOCROS (trademark) WS-300, manufactured by Nippon Shokubai Co., Ltd., solid content concentration: 10% by mass) containing a shell-forming resin (a resin having a structural unit represented by formula (3)) is added to the flask, and then the contents in the flask are fully stirred. "EPOCROS WS-300" comprises a copolymer of 2-vinyl-2-oxazoline and methyl methacrylate. In the manufacture of toner (TA-1), the addition amount of the shell-forming solution is set to 90g. The amount of the solid component (shell-forming resin) in the added shell-forming solution is 3 parts by mass relative to 100 parts by mass of toner. Subsequently, 300 g of the core (core A) was added to the flask, and the contents in the flask were stirred at 200 rpm for 1 hour. Thereafter, 300 mL of ion exchanged water was added to the flask. Subsequently, an aqueous ammonia solution having a concentration of 1% by mass was added to the flask.

[0264] In the manufacture of the base particles of the toner (TA-1), 0.1 mL of an aqueous ammonia solution is added. Subsequently, while stirring the contents in the flask at a rotation speed of 150 rpm, the temperature in the flask is raised to 60°C at a rate of 0.5°C / min. Subsequently, while maintaining the temperature at 60°C, the contents in the flask are stirred at a rotation speed of 100 rpm for 1 hour. Subsequently, a 1% by mass aqueous ammonia solution is added to the flask to adjust the pH of the contents in the flask to 7. Subsequently, the contents in the flask are cooled to room temperature (about 25°C) to provide a dispersion containing the base particles of the toner. The dispersion of the base particles of the toner obtained as described above is filtered (solid-liquid separation) with a Buchner funnel to provide wet cake-like base particles of the toner. Thereafter, the obtained wet cake-like base particles of the toner are redispersed in ion exchange water. This dispersion and filtration in ion exchange water is repeated 5 times to wash the base particles of the toner. Subsequently, at a hot air temperature of 45°C and a blower air volume of 2m 3 The washed toner base particles were dried with a continuous surface modifier ("COATMIZER (trademark)", manufactured by Freund Corporation) under the condition of 100 rpm / min. As a result, powder of toner base particles of Toner (TA-1) was obtained.

[0265] (Formation of Shell of Toner (TB-1): Formation of Toner Base Particles Including a Shell Containing a Resin Having a Structural Unit Represented by Formula (3))

[0266] Toner base particles of Toner (TB-1) were prepared by the same method as the toner base particles of Toner (TA-1) except that Core B was used.

[0267] (Formation of Shell of Toner (TM-1): Formation of Toner Base Particles Including Shell Containing Melamine Resin)

[0268] A three-necked flask of 1L capacity including a thermometer, a stirrer and a condenser was placed in a water bath at 30°C. 300mL of ion exchange water was charged into the flask, and hydrochloric acid was further added to the flask to adjust the pH to 4. 2mL of a hexamethylolmelamine precursor (an aqueous solution of an initial polymer of hexamethylolmelamine, "Mirbane (trademark) Resin SM-607", manufactured by Showa Denko KK, solid content concentration: 80% by mass) was added to the resulting acidic aqueous solution as a melamine resin precursor, mixed therewith and dissolved therein. 300g of the above-mentioned core (core A) was added to the resulting mixed solution so that the thickness of the shell became 6nm. The resulting mixture was stirred. Further, 300mL of ion exchange water was added thereto, and while stirring the mixture, the temperature in the flask was raised to 60°C at a heating rate of 5°C / min. Thereafter, the resultant was stirred at this temperature for 2 hours to form a shell on the surface of the core.

[0269] Next, the contents in the flask are cooled to 25°C, and then sodium hydroxide is added to neutralize the contents. After that, suction filtration is performed using a Buchner funnel to filter out the wet cake containing the toner base particles. In addition, the filtered wet cake containing the toner base particles is dispersed with ion exchange water. Thus, the toner base particles are washed. Then, the same washing of the toner base particles with ion exchange water is repeated 6 times. The washed wet cake containing the toner base particles is dispersed in an ethanol aqueous solution with a concentration of 50% by mass, and the mixture is heated to 45°C with a blower air volume of 2 m 3 / min, drying was performed with a fine particle surface modifier ("COATMIZER (trademark)", manufactured by Freund Corporation). As a result, powder of toner base particles of Toner (TM-1) was obtained.

[0270] (External addition)

[0271] 100 parts by mass of toner base particles of toner (TA-1), 1.0 parts by mass of dry silica particles ("AEROSIL (trademark) REA90", manufactured by Nippon Aerosil Co., Ltd., D50: 20 nm), and 0.5 parts by mass of conductive titanium oxide fine particles "EC-100J" (manufactured by Titan Kogyo Ltd.) were mixed using an FM mixer ("FM-10B", manufactured by Nippon Coke & Engineering Co., Ltd.) at a rotation speed of 3,000 rpm and a jacket temperature of 20°C. Thereafter, the resulting mixture was sieved through a 200-mesh (opening: 75 μm) sieve. As a result, a toner (toner (TA-1)) containing toner particles was obtained. In addition, toner (TB-1) and toner (TM-1) were also manufactured and obtained in the same manner.

[0272] (Manufacturing of toner (TF-1): shell-less toner)

[0273] Prepare the following materials.

[0274]

[0275] These materials were premixed with a Henschel mixer, and then the mixture was melt-kneaded with a twin-screw extruder. After the melt-kneaded product was cooled, the melt-kneaded product was pulverized and classified with a mechanical pulverizer (turbine mill) to provide toner particles having an average circularity of 0.955 and a volume average particle size of 7.2 μm. Next, 0.8 parts by weight of hydrophobic silica (product name "TG820F", manufactured by Cabot Corporation) was externally added to 100 parts by weight of the above toner particles, followed by mixing with a Henschel mixer, thereby providing a toner (TF-1).

[0276] (Synthesis of Polyester Resin B and Polyester Resin C in Toner (TF-1))

[0277] 2.2 mol of propylene oxide adduct of bisphenol A (2,000 g), 2.2 mol of ethylene oxide adduct of bisphenol A (800 g), terephthalic acid (500 g), n-dodecenylsuccinic acid (600 g), trimellitic anhydride (350 g) and dibutyltin oxide (4 g) were reacted at 220° C. for 8 hours under a nitrogen atmosphere, and then reacted under reduced pressure until a softening point of 155° C. was reached. Thus, polyester resin B was obtained. Separately, 2.2 mol of propylene oxide adduct of bisphenol A (2,800 g), terephthalic acid (400 g), fumaric acid (650 g) and dibutyltin oxide (4 g) were reacted at 220° C. for 8 hours under a nitrogen atmosphere, and then reacted under reduced pressure until a softening point of 90° C. was reached. Thus, polyester resin C was obtained.

[0278] (Manufacturing of Magnetic Powder in Toner (TF-1))

[0279] A caustic soda solution of 1.0 to 1.1 equivalents relative to iron ions is mixed into an aqueous solution of ferrous sulfate to prepare an aqueous solution containing ferrous hydroxide. While maintaining the pH of the aqueous solution at about 9, air is blown into the aqueous solution, and an oxidation reaction is carried out at 80°C to 90°C to prepare a slurry for generating seed crystals. Next, an aqueous solution of ferrous sulfate is added to the slurry in an amount of 0.9 to 1.2 equivalents relative to the initial amount of alkali (sodium component of caustic soda). Afterwards, the slurry is maintained at pH 8, and an oxidation reaction is carried out while air is blown into the slurry. The magnetic iron oxide particles generated after the oxidation reaction are washed, filtered and temporarily removed. At this time, a small amount of aqueous sample is collected and its water content is determined. Next, the aqueous sample is redispersed in another aqueous medium without drying, and the pH of the redispersed liquid is then adjusted to about 6. While the redispersed liquid is fully stirred, 1.0 parts by mass of a silane coupling agent [nC 10 H 21 Si(OCH 3 ) 3 ] (The amount of magnetic iron oxide is calculated as a value obtained by subtracting the water content from the water-containing sample.) Therefore, a coupling treatment is performed. The generated hydrophobic iron oxide particles are washed, filtered, and dried by a conventional method, and then the slightly agglomerated particles are crushed to provide a magnetic powder.

[0280] <Observation of the Presence or Absence of Shell in Toner Particles>

[0281] The presence or absence of the shell in the toner particles can be observed by observing the cross-sectional morphology of the toner particles. The specific method of observing the cross-sectional morphology of the toner particles is as follows.

[0282] First, the toner particles are fully dispersed in a photocurable epoxy resin, and then the epoxy resin is cured by irradiating ultraviolet light. The resulting cured product is cut with a microtome including a diamond blade to generate a flaky sample with a thickness of 100 nm. The sample is dyed with ruthenium tetroxide as required, and then a transmission electron microscope (TEM) (product name: electron microscope Tecnai TF20XT, manufactured by FEI Company Japan Ltd.) is used to observe the cross section of the toner under the condition that the accelerating voltage is 120 kV, thereby providing a TEM image.

[0283] In the above observation method, when the core part and the shell part are formed of different components, the contrast based on the difference in dyeing state or element mapping is observed. The observation magnification is set to 20,000 times.

[0284] Whether the resin in the shell is at least one resin selected from the group consisting of melamine resins and vinyl resins containing oxazoline groups can be identified using TOF-SIMS (TRIFT-IV, manufactured by ULVAC-PHI, Inc.).

[0285] The analysis conditions are as follows.

[0286] Sample Conditioning: Allow the toner to adhere to the indium sheet.

[0287] Sample pretreatment: None

[0288] Primary ion: Au +

[0289] Accelerating voltage: 30 kV

[0290] Charge Neutralization Mode: On

[0291] Assay mode: Positive

[0292] Grating size: 100μm

[0293] Integration time: 180 seconds

[0294] Through the above measurement, the content of melamine resin and oxazoline group in the resin contained in the shell on the colorant surface is calculated from the intensity of the secondary ion mass spectrum obtained under the above conditions (vertical axis: intensity, horizontal axis: mass number = m / z) by using a calibration curve created based on samples with known concentrations.

[0295] The results obtained by analyzing the obtained toner by the above-mentioned method are shown in Table 3.

[0296] Table 3

[0297] The presence or absence of a shell Structures included in the shell TA-1 exist A resin having a structural unit represented by formula (3) TB-1 exist A resin having a structural unit represented by formula (3) TM-1 exist Melamine resin TF-1 Does not exist -

[0298] [Preparation of two-component developer for evaluating positive chargeability]

[0299] 100 parts by mass of a developer carrier ("ECOSYS P5026cdw" carrier, manufactured by KYOCERA DocumentSolutions Japan Inc.) and 8 parts by mass of a toner to be evaluated (specifically, any one of toners (TA-1), (TB-1), (TM-1) or (TF-1)) were mixed with a drum mixer for 30 minutes. As a result, a two-component developer for evaluating positive chargeability was prepared.

[0300] <Example>

[0301] [evaluate]

[0302] The photosensitive member (single-layer photosensitive member) and the toner were evaluated for positive charging and transfer efficiency, respectively, by the following methods. The photosensitive member was mounted on an evaluation machine. A modified machine of an electrophotographic device ("ECOSYS P5026cdw", manufactured by KYOCERA Document Solutions Japan Inc.) was used as an evaluation machine. The evaluation machine includes a charging roller as a charging device. The charging polarity of the charging roller is positive polarity, and the applied voltage of the charging roller is a DC voltage. In addition, the evaluation machine adopts a two-component developing system and an intermediate transfer system. In addition, the evaluation machine includes a cleaning blade and a charge eliminating device.

[0303] [Evaluation of Positive Chargeability]

[0304] The toner on the photosensitive member is attracted and collected with a metal cylindrical tube and a cylindrical filter, and the triboelectric charge amount of the toner and the toner bearing amount are calculated. Figure 6 It means that the triboelectric charge amount of toner and the toner bearing amount on the photosensitive member are measured using a Faraday cage.

[0305] By using a Faraday cage 200 (the Faraday cage 200 includes an inner cylinder 201 and an outer cylinder 202 as inner and outer double cylinders in which metal cylinders with different axial diameters are coaxially arranged with each other and also includes a filter 203 for taking out the toner in the inner cylinder 201), the toner on the photosensitive member is attracted by air. In the Faraday cage 200, the inner cylinder 201 and the outer cylinder 202 are insulated from each other by an insulating member 204. When the toner is sucked into the filter, electrostatic induction is caused by the charge amount Q of the toner. When a charged body with the charge amount Q is placed in the inner cylinder, the situation becomes as if a metal cylinder with the charge amount Q exists by electrostatic induction. The induced charge amount is measured with an electrometer (Keithley 6517A, manufactured by Keithley Instruments, Inc.), and the charge amount per unit mass (Q / M) obtained by dividing the charge amount Q (mC) by the toner mass M (kg) in the inner cylinder is used as the friction charge amount of the toner.

[0306] In addition, the suction area S (cm 2 ), and the toner mass M is divided by the attraction area S (cm 2 ), thereby determining the toner carrying amount per unit area.

[0307] In the above-mentioned electrophotographic apparatus, before the toner layer formed on the photosensitive member is transferred onto the intermediate transfer member, the rotation of the photosensitive member is stopped, and the toner image on the photosensitive member is directly attracted with air to perform measurement.

[0308] Toner loading (mg / cm 2 )=M / S

[0309] Triboelectric charge of toner (mC / kg) = Q / M

[0310] In the above electrophotographic apparatus, the toner bearing amount on the photosensitive member was adjusted to 0.35 mg / cm 2 , and the toner is attracted and collected by the above-mentioned metal cylindrical tube and the cylindrical filter. At this time, the charge amount Q stored in the capacitor by the metal cylindrical tube and the mass M of the collected toner are measured, and the charge amount Q / M (mC / kg) per unit mass is calculated to determine the charge amount Q / M (mC / kg) per unit mass on the photosensitive member (initial evaluation).

[0311] After the above evaluation (initial evaluation), as a durability evaluation, a bar graph with an image rate of 0.1% was output on 30,000 A4 sheets using the above electrophotographic apparatus. The charge amount Q / M per unit mass on the photosensitive member was measured at the same DC voltage V as in the initial evaluation. DC The measurement was carried out under (post-durability evaluation).

[0312] [Transfer efficiency]

[0313] A bar graph with an image rate of 0.1% was output onto 5 sheets of A4 paper as an initial evaluation using the above-mentioned electrophotographic apparatus. After that, an evaluation image was formed on a photosensitive member and transferred onto an intermediate transfer member, and the evaluation machine was stopped before the evaluation image was transferred onto recording paper. The intermediate transfer member of the stopped evaluation machine was taken out. A transparent pressure-sensitive adhesive tape was attached to the transfer image to collect the toner, and the pressure-sensitive adhesive tape was attached to the recording paper together with the toner (evaluation of initial transfer efficiency).

[0314] A bar graph with an image rate of 0.1% was output onto 30,000 sheets of A4 paper as a durability evaluation. After that, the evaluation image was formed on the photosensitive member and transferred onto the intermediate transfer member, and the evaluation machine was stopped before the evaluation image was transferred onto the recording paper. The intermediate transfer member of the stopped evaluation machine was taken out. A transparent pressure-sensitive adhesive tape was attached to the transfer image to collect the toner, and the pressure-sensitive adhesive tape was attached to the recording paper together with the toner (evaluation of transfer efficiency after durability).

[0315] The density of the image is measured using an optical density system, and the density in the portion of the recording paper where only the pressure-sensitive adhesive tape is pasted is subtracted from the measured density to determine the transfer density A. In addition, the photosensitive member of the evaluation machine is taken out, and the transfer residual density B of the transfer residual toner is also measured by the same method. A transparent Superstick (manufactured by LINTEC Corporation) with weak pressure-sensitive adhesiveness is used as the pressure-sensitive adhesive tape, and an X-Rite color reflection densitometer (manufactured by X-Rite Inc.) is used as the optical densitometer. Then, the transfer efficiency is calculated by the following formula. The resulting transfer efficiency is evaluated according to the following evaluation criteria. The transfer efficiency is calculated as {transfer density A / (transfer density A+transfer residual density B)}×100.

[0316] Table 4 shows the evaluation results.

[0317] Table 4

[0318]

[0319] Table 4 (continued)

[0320]

[0321] In each of Examples 1 to 24 using the photosensitive member and the toner containing the polyarylate resin in the present disclosure, the reduction in transfer efficiency was suppressed, and the quality of the output image was maintained from the initial stage to the post-durability stage.

[0322] At the same time, in each comparative example, the reduction in transfer efficiency is large.

[0323] While the present disclosure has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments.The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims

1. An electronic photographic device comprising: Electrophotographic photosensitive member; a charging unit configured to charge a surface of the electrophotographic photosensitive member; an exposure unit configured to irradiate the charged surface of the electrophotographic photosensitive member with light to form an electrostatic latent image on the surface of the electrophotographic photosensitive member; a developing unit including a toner and configured to develop an electrostatic latent image formed on a surface of the electrophotographic photosensitive member with the toner to form a toner image on the surface of the electrophotographic photosensitive member; and a transfer unit configured to transfer the toner image from the surface of the electrophotographic photosensitive member to a transfer target member, wherein the electrophotographic photosensitive member comprises a single-layer type photosensitive layer comprising a charge generating substance, a hole transporting substance, an electron transporting substance and a binder resin, wherein the photosensitive layer comprises, as the binder resin, a polyarylate resin having a structural unit represented by formula (1) and a structural unit represented by formula (2), wherein the toner comprises toner particles, wherein the toner particles include a core containing a binder resin and a shell covering a surface of the core, and wherein the shell comprises at least one resin selected from the group consisting of melamine resins and resins having a structural unit represented by formula (3): In formula (3), R 1 It represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms.

2. The electrophotographic apparatus according to claim 1, wherein the polyarylate resin further has a structural unit represented by formula (4) and a structural unit represented by formula (5):

3. The electrophotographic apparatus according to claim 2, wherein: When the ratio of the amount of the structural unit represented by the formula (4) relative to the total amount of the structural unit represented by the formula (1) and the structural unit represented by the formula (4) in the polyarylate resin is represented by M4, M4 satisfies 0.30≤M4≤0.

70.

4. The electrophotographic apparatus according to claim 2, wherein: When the ratio of the amount of the structural unit represented by the formula (2) relative to the total amount of the structural unit represented by the formula (2) and the structural unit represented by the formula (5) in the polyarylate resin is represented by M2, M2 satisfies 0<M2≤0.

50.

5. The electrophotographic apparatus according to claim 1, wherein a ratio of the amount of the structural unit represented by the formula (1) relative to the total amount of the structural units derived from dicarboxylic acid used to form the polyarylate resin is 0.50 or more. 6 . The electrophotographic apparatus according to claim 1 , wherein a ratio of the polyarylate resin is 50% by mass or more relative to the total mass of the binder resin.

7. The electrophotographic apparatus according to claim 1, wherein the electron transport substance comprises at least one compound selected from the group consisting of a compound represented by formula (10), a compound represented by formula (11), a compound represented by formula (12), a compound represented by formula (13), a compound represented by formula (14), a compound represented by formula (15), and a compound represented by formula (16): Where Q in formula (10) 1 and Q 2 , Q in formula (11) 11 , Q 12 and Q 13 , Q in formula (12) 21 , Q 22 , Q 23 and Q 24 , Q in formula (13) 31 and Q 32 , Q in formula (14) 41 , Q 42 , Q 43 and Q 44 , Q in formula (15) 51 , Q 52 , Q 53 , Q 54 , Q 55 and Q 56 , and Q in formula (16) 61 and Q 62 Each independently represents a hydrogen atom, a halogen atom, a cyano group, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 14 carbon atoms which may be substituted with at least one substituent selected from the group consisting of an alkyl group having 1 to 6 carbon atoms and a halogen atom. In formula (15), Y 1 and Y 2 Each independently represents an oxygen atom or a sulfur atom.

8. The electrophotographic apparatus according to claim 1, wherein the electron transport substance comprises at least one compound selected from the group consisting of a compound represented by formula (E-1), a compound represented by formula (E-2), a compound represented by formula (E-3), a compound represented by formula (E-4), a compound represented by formula (E-5), a compound represented by formula (E-6), a compound represented by formula (E-7), and a compound represented by formula (E-8):

9. The electrophotographic apparatus according to claim 1, wherein the hole transporting substance comprises at least one compound selected from the group consisting of a compound represented by formula (20), a compound represented by formula (21), a compound represented by formula (22), a compound represented by formula (23), and a compound represented by formula (24): In formula (20), R 11 , R 12 , R 13 and R 14 Each independently represents an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms, and a1, a2, a3 and a4 each independently represent an integer of 0 to 5. In formula (21), R 21 , R 22 and R 23 Each independently represents an alkyl group having 1 to 6 carbon atoms, R 24 , R 25 and R 26 Each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, b1, b2 and b3 each independently represent 0 or 1; in formula (22), R 31 , R 32 and R 33 Each independently represents an alkyl group having 1 to 6 carbon atoms, R 34 represents an alkyl group having 1 to 6 carbon atoms or a hydrogen atom, d1, d2 and d3 each independently represent an integer of 0 to 5; in formula (23), R 41 , R 42 , R 43 , R 44 , R 45 and R 46 Each independently represents an alkyl group having 1 to 6 carbon atoms or a phenyl group, R 47 and R 48 Each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a phenyl group; e1, e2, e3, and e4 each independently represent an integer of 0 to 5; e5 and e6 each independently represent an integer of 0 to 4; and e7 and e8 each independently represent 0 or 1. In formula (24), R 50 and R 51 each independently represents an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a phenyl group, and R 52 , R 53 , R 54 , R 55 , R 56 , R 57 and R 58 Each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a phenyl group which may be substituted with an alkyl group having 1 to 6 carbon atoms, f1 and f2 each independently represent an integer of 0 to 2, and f3 and f4 each independently represent an integer of 0 to 5.

10. An electrophotographic apparatus according to claim 1, wherein the hole transporting substance comprises at least one compound selected from the group consisting of a compound represented by formula (H-1), a compound represented by formula (H-2), a compound represented by formula (H-3), a compound represented by formula (H-4), a compound represented by formula (H-5), a compound represented by formula (H-6), a compound represented by formula (H-7), a compound represented by formula (H-8), a compound represented by formula (H-9), a compound represented by formula (H-10), and a compound represented by formula (H-11):

11. The electrophotographic apparatus according to claim 1, wherein the charge generating substance comprises oxytitanium phthalocyanine.

12. The electrophotographic apparatus according to claim 1, wherein the photosensitive layer contains a compound represented by formula (30) as an additive: 13 . The electrophotographic apparatus according to claim 1 , wherein the binder resin in the core comprises a polyester resin. 14 . The electrophotographic apparatus according to claim 1 , wherein the binder resin in the core comprises a styrene-acrylic resin. 15 . The electrophotographic apparatus according to claim 1 , wherein the toner particles contain at least one particle selected from the group consisting of silica particles, titanium oxide particles, strontium titanate particles, and aluminum oxide particles as an external additive.

16. A process cartridge comprising: Electrophotographic photosensitive member; and a developing unit including a toner and configured to form a toner image on a surface of the electrophotographic photosensitive member with the toner, The process cartridge integrally supports the electrophotographic photosensitive member and the developing unit and is detachably mounted to a main body of the electrophotographic apparatus, wherein the electrophotographic photosensitive member comprises a single-layer type photosensitive layer comprising a charge generating substance, a hole transporting substance, an electron transporting substance and a binder resin, wherein the photosensitive layer comprises, as the binder resin, a polyarylate resin having a structural unit represented by formula (1) and a structural unit represented by formula (2), wherein the toner comprises toner particles, wherein the toner particles include a core containing a binder resin and a shell covering a surface of the core, and wherein the shell comprises at least one resin selected from the group consisting of melamine resins and resins having a structural unit represented by formula (3): In formula (3), R 1 It represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms.

17. An electrophotographic apparatus comprising: Electrophotographic photosensitive member; a charging unit configured to charge a surface of the electrophotographic photosensitive member; an exposure unit configured to irradiate the charged surface of the electrophotographic photosensitive member with light to form an electrostatic latent image on the surface of the electrophotographic photosensitive member; a developing unit including a toner and configured to develop an electrostatic latent image formed on a surface of the electrophotographic photosensitive member with the toner to form a toner image on the surface of the electrophotographic photosensitive member; and a transfer unit configured to transfer the toner image from the surface of the electrophotographic photosensitive member to a transfer target member, wherein the electrophotographic photosensitive member comprises a single-layer type photosensitive layer comprising a charge generating substance, a hole transporting substance, an electron transporting substance and a binder resin, wherein the photosensitive layer comprises, as the binder resin, a polyarylate resin having a structural unit represented by formula (1) and a structural unit represented by formula (2), wherein the toner comprises toner particles, and wherein the surface of the toner particles comprises at least one resin selected from the group consisting of melamine resins and resins having a structural unit represented by formula (3): In formula (3), R 1 It represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms.

18. A process cartridge comprising: Electrophotographic photosensitive member; and a developing unit including a toner and configured to form a toner image on a surface of the electrophotographic photosensitive member with the toner, The process cartridge integrally supports the electrophotographic photosensitive member and the developing unit and is detachably mounted to a main body of the electrophotographic apparatus, wherein the electrophotographic photosensitive member comprises a single-layer type photosensitive layer comprising a charge generating substance, a hole transporting substance, an electron transporting substance and a binder resin, wherein the photosensitive layer comprises, as the binder resin, a polyarylate resin having a structural unit represented by formula (1) and a structural unit represented by formula (2), wherein the toner comprises toner particles, and wherein the surface of the toner particles comprises at least one resin selected from the group consisting of melamine resins and resins having a structural unit represented by formula (3): In formula (3), R 1 It represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms.

Images