Electrophotographic photoreceptor, process cartridge, and image forming apparatus

Abstract

This invention provides an electrophotographic photosensitive material capable of suppressing image defects caused by fogging in an image forming apparatus using a non-magnetic, single-component, pulverized toner. The electrophotographic photosensitive material of this invention is used in an image forming apparatus using a non-magnetic, single-component, pulverized toner. The electrophotographic photosensitive material has a substrate disposed on a conductive substrate and a photosensitive layer on which a charge generation layer and a charge transport layer are sequentially stacked. The substrate comprises a thermosetting resin and titanium dioxide particles, wherein the thermosetting resin comprises an alkyd resin and a melamine resin. The charge transport layer comprises a binder resin and a hole transporter, wherein the binder resin comprises a polycarbonate resin or a polyaryl ester resin, and the hole transporter comprises a compound represented by general formula (1).

Description

Technical Field

[0001] The present invention relates to an electrophotographic photosensitive element, a processing cartridge, and an image forming apparatus for an image forming apparatus using a non-magnetic single-component pulverized toner. Background Technology

[0002] Generally, in image forming apparatuses, toners used to develop electrostatic latent images on the surface of a photoreceptor can be classified according to their composition as (1) magnetic two-component toners consisting of a magnetic toner and a carrier, (2) non-magnetic two-component toners consisting of a non-magnetic toner and a carrier, (3) non-magnetic one-component toners consisting of a non-magnetic toner, and (4) magnetic one-component toners consisting of a magnetic toner. Furthermore, toners can also be classified according to their manufacturing method as polymeric toners produced by polymerization and pulverized toners produced by pulverization.

[0003] In recent years, in the field of color printers for electrophotography, the development of image forming devices that use non-magnetic single-component pulverized toners has been underway, featuring small size, low cost, and maintenance-free operation.

[0004] However, in image forming apparatuses using non-magnetic, single-component, pulverized toners, the reduced charge of the toner leads to the adhesion of poorly charged toner to the blank background areas (i.e., unexposed areas) of the image, resulting in what is known as fogging and image quality degradation. In contrast, Japanese Patent Application Publication No. 2003-280256 describes a method for stabilizing the charge of toners by attaching fine inorganic particles to the surface of toner particles. Summary of the Invention

[0005] The problem the invention aims to solve

[0006] However, even with existing improved toners, the charge on the photoreceptor gradually decreases during continuous printing, making it easy for the toner to adhere to unexposed areas and cause fogging. Therefore, a method is needed to suppress image defects caused by fogging.

[0007] In view of the above problems, the object of the present invention is to provide an electrophotographic photosensitive material that can suppress image defects caused by fog in an image forming apparatus using a non-magnetic single-component pulverized toner.

[0008] An electrophotographic photosensitive material according to one embodiment of the present invention is used in an image forming apparatus that uses a non-magnetic single-component pulverized toner.

[0009] The aforementioned electrophotographic photosensitive material has a conductive substrate, a bottom layer disposed on the conductive substrate, and a photosensitive layer disposed on the bottom layer.

[0010] The aforementioned photosensitive layer includes a charge generation layer and a charge transport layer.

[0011] The aforementioned bottom layer contains thermosetting resin and titanium dioxide particles, wherein the thermosetting resin includes alkyd resin and melamine resin.

[0012] The charge transport layer comprises a binder resin and a hole transporter, wherein the binder resin comprises at least one of a polycarbonate resin and a polyarylate resin, and the hole transporter comprises a compound represented by the following general formula (1).

[0013] [Chemical Formula 1]

[0014]

[0015] In the formula, R 1 R 2 and R 3 Each of the following is independently an alkyl group having 1 or more and 8 or less carbon atoms, an alkoxy group having 1 or more and 8 or less carbon atoms, or a group represented by formula (I), formula (II) or formula (III) below.

[0016] R 1 R 2 and R 3 At least one of them is an alkyl group having 1 or more and 8 or less carbon atoms, or an alkoxy group having 1 or more and 8 or less carbon atoms, and a1, a2 and a3 each independently represent an integer having 0 or more and 5 or less.

[0017] [Chemical Formula 2]

[0018]

[0019] In formulas (I), (II), and (III) above, Rx is independently a hydrogen atom, an alkyl group having 1 or more but 8 or fewer carbon atoms, an alkoxy group having 1 or more but 8 or fewer carbon atoms, or a phenyl group that can be substituted by an alkyl group having 1 or more but 8 or fewer carbon atoms, and Ry is independently a phenyl group that can be substituted by an alkyl group having 1 or more but 8 or fewer carbon atoms, or a phenyl group that can be substituted by an alkoxy group having 1 or more but 8 or fewer carbon atoms.

[0020] In the electrophotographic photoreceptor of the present invention, by employing an underlayer having the specific components described above, the charge retention of the photoreceptor can be improved. Furthermore, in the charge transport layer, by selecting a specific triphenylamine derivative of the general formula (1) as a charge transport agent and combining it with the binder resin described above, the charge stability of the toner can be obtained. Specifically, there is a tendency for the triboelectric charge of the toner to be less than -15 μQ / g when the photoreceptor and toner of the present invention rub against each other, and the toner tends to become negatively charged. Through the combination of these components, that is, through the synergistic effect of the charge retention of the photoreceptor and the charge stability of the toner, image defects caused by fog can be more effectively suppressed.

[0021] The compound represented by the general formula (1) of the above-mentioned electrophotographic photosensitive material is selected from at least one of the compounds represented by formula (1-1), formula (1-2), and formula (1-3).

[0022] [Chemical Formula 3]

[0023]

[0024] In the above formula (1-1), R 11 R 12 and R 13 Each of these groups independently represents an alkyl group having 1 or more but less than 8 carbon atoms, or an alkoxy group having 1 or more but less than 8 carbon atoms; r1, r2, and r3 each independently represent an integer having 0 or more but less than 5.

[0025] In the above equation (1-2), R 20 R represents a hydrogen atom, an alkyl group having 1 or more but 8 or fewer carbon atoms, an alkoxy group having 1 or more but 8 or fewer carbon atoms, or a phenyl group that can be substituted by an alkyl group having 1 or more but 8 or fewer carbon atoms. 21 R 22 and R 23 Each of these characters independently represents an alkyl group having 1 or more but less than 8 carbon atoms, or an alkoxy group having 1 or more but less than 8 carbon atoms; f1, f2, and f3 each independently represent an integer having 0 or more but less than 5; f4 represents 0 or 1.

[0026] In the above equation (1-3), R 31 R 32 R 33 R 34 and R 35 Each of the following independently represents an alkyl group having 1 or more but less than 8 carbon atoms, or an alkoxy group having 1 or more but less than 8 carbon atoms. g1, g2, g3, g4, and g5 each independently represent an integer having 0 or more but less than 5.

[0027] The charge transport layer of the aforementioned electrophotographic photosensitive material can be the outermost layer.

[0028] The aforementioned electrophotographic photosensitive material can be exposed using a light-emitting diode (LED).

[0029] The aforementioned electrophotographic photosensitive material can be used in image forming apparatuses using a direct transfer method.

[0030] The processing box of one embodiment of the present invention may have the above-described electrophotographic photosensitive element.

[0031] An image forming apparatus according to one embodiment of the present invention includes: an image carrier; a charging device for charging the surface of the image carrier; an exposure device for exposing the charged surface of the image carrier to form an electrostatic latent image on the surface of the image carrier; a developing device for supplying toner to the surface of the image carrier and developing the electrostatic latent image as a toner image; and a transfer device for transferring the toner image from the image carrier to a transfer object; wherein the image carrier may be the aforementioned electrophotographic photosensitive material.

[0032] The developing apparatus described above includes a supply roller, a developing roller, and a limiting scraper. The supply roller supplies the toner, which is a non-magnetic single-component developer, to the developing roller. The developing roller holds a toner layer containing the toner on the surface of the developing roller. The limiting scraper limits the thickness of the toner layer held on the surface of the developing roller. The toner contained in the toner layer with its thickness limited is supplied from the surface of the developing roller to the electrostatic latent image, which can be developed as the toner image.

[0033] Invention Effects

[0034] The present invention provides an electrophotographic photosensitive element, processing cartridge, and image forming apparatus capable of suppressing image defects caused by fog in an image forming apparatus using a non-magnetic single-component pulverized toner. Attached Figure Description

[0035] Figure 1 This is a partial cross-sectional view of an electrophotographic photosensitive device, which is an example of an embodiment of the present invention.

[0036] Figure 2 A figure illustrating an example of an image forming apparatus according to a second embodiment of the present invention.

[0037] Figure 3 To show Figure 2 A diagram showing a portion of the structure of the developing apparatus.

[0038] Figure 4 A diagram showing the outline of a device for measuring the electric charge caused by friction. Detailed Implementation

[0039] The embodiments of the present invention will now be described in detail. However, the present invention is not limited to the configuration of the following embodiments, and appropriate modifications can be made to the configuration of the following embodiments within the scope of the technical concept of the present invention. Furthermore, "general formula" and "chemical formula" are both referred to as "formula". The phrase "each independent" in the description of a formula means that it can represent the same group or different groups.

[0040] Hereinafter, without any specific definition, alkyl with 1 or more and 8 or less carbon atoms, alkyl with 1 or more and 6 or less carbon atoms, alkyl with 1 or more and 4 or less carbon atoms, alkyl with 1 or more and 3 or less carbon atoms, alkoxy with 1 or more and 8 or less carbon atoms, alkoxy with 1 or more and 6 or less carbon atoms, and alkoxy with 1 or more and 3 or less carbon atoms shall each have the following meanings.

[0041] Alkyl groups having 1 or more but 8 or fewer carbon atoms, alkyl groups having 1 or more but 6 or fewer carbon atoms, alkyl groups having 1 or more but 4 or fewer carbon atoms, and alkyl groups having 1 or more but 3 or fewer carbon atoms are each linear or branched and unsubstituted. Examples of alkyl groups having 1 or more but 8 or fewer carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, neopentyl, 1,2-dimethylpropyl, hexyl, heptyl, or octyl. Examples of alkyl groups having 1 or more but 6 or fewer carbon atoms are examples of alkyl groups having 1 or more but 6 or fewer carbon atoms among the examples of alkyl groups having 1 or more but 8 or fewer carbon atoms. Alkyl groups having 1 or more but 4 or fewer carbon atoms are examples of alkyl groups having 1 or more but 4 or fewer carbon atoms among the examples of alkyl groups having 1 or more but 8 or fewer carbon atoms. Alkyl groups having 1 or more but 3 or fewer carbon atoms are examples of alkyl groups having 1 or more but 3 or fewer carbon atoms among the examples of alkyl groups having 1 or more but 8 or fewer carbon atoms.

[0042] Alkoxy groups having 1 or more but 8 or fewer carbon atoms and alkoxy groups having 1 or more but 6 or fewer carbon atoms are each either straight-chain or branched and unsubstituted. Examples of alkoxy groups having 1 or more but 8 or fewer carbon atoms include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, tert-butoxy, n-pentoxy, isopentoxy, neopentoxy, hexoxy, heptoxy, or octoxy. Examples of alkoxy groups having 1 or more but 6 or fewer carbon atoms are those with 1 or more but 6 or fewer carbon atoms among the examples of alkoxy groups having 1 or more but 8 or fewer carbon atoms.

[0043] <First Implementation Method: Electrophotographic Photoreceptor>

[0044] [The overall structure of an electrophotographic photosensitive element]

[0045] An electrophotographic photosensitive material according to one embodiment of the present invention is used in an image forming apparatus that uses a non-magnetic single-component pulverized toner. Figure 1 This is a partial cross-sectional view of the electrophotographic photoreceptor 1 (hereinafter sometimes referred to as photoreceptor 1) according to an embodiment of the present invention. Figure 1 As shown, the photoreceptor 1 has a conductive substrate 2, a bottom layer 3 disposed on the conductive substrate 2, and a photosensitive layer 4 disposed on the bottom layer 3. The photosensitive layer 4 includes a charge generating layer 4a and a charge transport layer 4b. The photoreceptor 1 of the present invention is typically as follows: Figure 1 As shown, no protective layer is provided on the photosensitive layer 4. In order to stabilize the charge of the toner, the toner is directly attached to the surface of the specific charge transport layer 4b, which is described in detail below. That is, the charge transport layer 4b is preferably located on the outermost layer.

[0046] The photoreceptor 1 of one embodiment of the present invention has characteristics in the structure of the bottom layer 3 and the charge transport layer 4b, and will therefore be described below.

[0047] The bottom layer 3 of the present invention is characterized by comprising a thermosetting resin and titanium dioxide, wherein the thermosetting resin includes alkyd resin and melamine resin. Typically, the bottom layer uses various resins, such as thermoplastic resins, as its main component, and further includes metal oxide particles, thereby providing an electrical blocking function that prevents charge injection from the conductive substrate 2. In the bottom layer 3 of the present invention, by using the aforementioned specific thermosetting resin, high charge retention is achieved. This suppresses the adhesion of toner to the unexposed areas of the photoreceptor, thereby suppressing the generation of fog.

[0048] Next, the charge transport layer 4b of the present invention is characterized in that it contains a binder resin and a hole transporter, wherein the binder resin comprises at least one of a polycarbonate resin and a polyarylate resin, and the hole transporter comprises a compound represented by the following general formula (1).

[0049] [Chemical Formula 4]

[0050]

[0051] In general formula (1), R 1 R 2 and R 3 Each is independently an alkyl group having 1 or more and 8 or less carbon atoms, an alkoxy group having 1 or more and 8 or less carbon atoms, or a group represented by formula (I), formula (II) or formula (III) below, R 1 R 2 and R 3 At least one of them is an alkyl group having 1 or more and 8 or less carbon atoms, or an alkoxy group having 1 or more and 8 or less carbon atoms. a1, a2 and a3 each independently represent an integer of 0 or more and 5 or less.

[0052] [Chemical Formula 5]

[0053]

[0054] In formulas (I), (II), and (III) above, Rx is independently a hydrogen atom, an alkyl group having 1 or more but 8 or fewer carbon atoms, an alkoxy group having 1 or more but 8 or fewer carbon atoms, or a phenyl group that can be substituted by an alkyl group having 1 or more but 8 or fewer carbon atoms; and Ry is independently a phenyl group that can be substituted by an alkyl group having 1 or more but 8 or fewer carbon atoms, or a phenyl group that can be substituted by an alkoxy group having 1 or more but 8 or fewer carbon atoms. Here, in formula (III), the two Rys can be the same or different.

[0055] In the charge transport layer 4b, the charge of the toner is stabilized by combining the aforementioned specific charge transport agent with the aforementioned binder resin. Specifically, there is a tendency for the triboelectric charge of the toner to be less than -15 μQ / g when the surface of the photosensitive layer 4 (typically the charge transport layer 4b) rubs against the toner, and the toner easily becomes negatively charged, thereby achieving the charge stability of the toner.

[0056] Furthermore, through the synergistic effect of combining the photosensitive layer 4 containing the aforementioned specific charge transport layer 4b with the specific bottom layer 3, namely through the synergistic effect of the high charge retention of the photosensitive material and the charge stability of the toner, even during continuous printing, the toner is difficult to adhere to the unexposed area and easily adheres to the exposed area, thereby more effectively reducing the generation of haze.

[0057] Furthermore, the pulverized toner used in this invention is an amorphous toner with a roundness of 0.90 or less. When such a pulverized toner is used in an image forming apparatus, the electrical properties deviate, the charge of the toner decreases, and fogging is easily generated. However, the electrophotographic photosensitive element 1 according to the present invention can effectively suppress the generation of fogging.

[0058] Furthermore, since the non-magnetic toner used in this invention cannot form a uniform toner layer on the developing roller by the magnetic force of a magnetic body, it needs to be brought into contact with a doctor blade (refer to the limiting doctor blade 400 described later) to form a thin toner layer of a certain thickness. Therefore, when using a non-magnetic toner, the friction between the doctor blade and the toner causes micro-pulverization, resulting in toner deterioration and a tendency for the toner's charge to decrease. However, according to the photoreceptor 1 of the present invention, the generation of fog can be suppressed more effectively.

[0059] According to the present invention, the electrophotographic photosensitive element 1 can suppress image defects caused by fog even in image forming apparatuses using non-magnetic single-component pulverized toners. Furthermore, particularly from the viewpoint of cost reduction, the electrophotographic photosensitive element 1 of the present invention is preferably exposed using a low-cost light-emitting diode (LED). Moreover, from the perspective of miniaturization and cost reduction, the photosensitive element 1 of one embodiment of the present invention is preferably used in an image forming apparatus employing a "direct transfer method" in which the toner image on the surface of the photosensitive element is directly transferred to the medium without passing through an intermediate transfer belt.

[0060] The detailed structure of the photoreceptor 1 according to one embodiment of the present invention will be described below.

[0061] [Detailed structure of an electrophotographic photosensitive element]

[0062] (Conductive substrate 2)

[0063] The conductive substrate 2 of the present invention is not particularly limited, and may be made of a material having conductivity at least on its surface. As an example of the conductive substrate 2, a conductive substrate 2 made of a conductive material may be given. As another example of the conductive substrate 2, a conductive substrate 2 coated with a conductive material may be given. Examples of conductive materials include aluminum, iron, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, and indium. Two or more conductive materials may be combined as an alloy (more specifically, aluminum alloy, stainless steel, or brass, etc.). From the perspective of good charge transfer from the photosensitive layer 4 to the conductive substrate 2, aluminum and aluminum alloys are preferred as conductive materials. The shape of the conductive substrate 2 can be appropriately selected to match the structure of the image forming apparatus. Examples of shapes for the conductive substrate 2 include sheet-like and drum-like shapes. Furthermore, the thickness of the conductive substrate 2 can be appropriately selected according to its shape.

[0064] (Bottom 3)

[0065] Thermosetting resins

[0066] From the perspective of electrical properties and film-forming properties, thermosetting resins containing alkyd resins and melamine resins are typically mixed resins in which melamine resin is used as a crosslinking agent in alkyd resins. The mixing mass ratio of alkyd resin to melamine resin (alkyd resin: melamine resin) can be appropriately selected according to the purpose.

[0067] Titanium oxide particles

[0068] The ratio of the mass of titanium dioxide particles contained in the bottom layer 3 to the mass of the thermosetting resin contained in the bottom layer 3 is, for example, 1 or more and 4 or less. The thickness of the bottom layer 3 is, for example, 0.1 μm or more and 5 μm or less.

[0069] Titanium oxide particles can be surface treated. Surface treatment of titanium oxide particles can be performed once or multiple times (e.g., twice). Examples of surface treatment agents used in the surface treatment of titanium oxide particles include alumina, silica, and organosilicon compounds (e.g., polysiloxanes, more specifically, methylhydropolysiloxanes).

[0070] In addition to titanium dioxide particles, other inorganic and organic particles may be included without impairing the effects of the present invention. For example, inorganic particles may include white pigments (more specifically, titanium dioxide particles, zinc oxide, zinc white, zinc sulfide, lead white, and zinc barium white, etc.) and extender pigments (more specifically, aluminum oxide, calcium carbonate, and barium sulfate, etc.). Furthermore, examples of organic particles include fluoropolymer particles, benzoguanamine resin particles, and styrene resin particles.

[0071] The number-average primary particle size of titanium oxide particles is preferably less than 100 nm, more preferably more than 1 nm and less than 50 nm.

[0072] (charge generation layer 4a)

[0073] The charge-generating layer 4a contains a charge-generating agent and has the function of generating charges when exposed to light. The charge-generating layer 4a may contain a matrix resin, additives, or free radical acceptor compounds as needed.

[0074] Examples of charge-generating agents include phthalocyanine pigments, perylene pigments, diazo pigments, triazo pigments, dithioketo-pyrrolopyrrole pigments, metal-free naphthalene phthalocyanine pigments, metal naphthalene phthalocyanine pigments, squaric acid cyanine pigments, indigo pigments, azurite pigments, cyanine pigments, powders of inorganic photoconductive materials (e.g., selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide, and amorphous silicon), pyrylium pigments, anthraquinone pigments, triphenylmethane pigments, threne pigments, toluidine pigments, pyrazoline pigments, and quinacridone pigments.

[0075] Phthalocyanine pigments have a phthalocyanine structure. Examples of phthalocyanine pigments include metallic phthalocyanines and metal-free phthalocyanines. Examples of metallic phthalocyanines include titanium dioxide phthalocyanine, hydroxygallium phthalocyanine, and gallium chloride phthalocyanine. Titanium dioxide phthalocyanine is preferred as a metallic phthalocyanine. Titanium dioxide phthalocyanine is represented by formula (CG-1). Metal-free phthalocyanines are represented by formula (CG-2).

[0076] [Chemical Formula 6]

[0077]

[0078] Phthalocyanine pigments can be crystalline or amorphous. Examples of crystalline metal-free phthalocyanines include, for example, type X crystalline metal-free phthalocyanine (hereinafter sometimes referred to as type X metal-free phthalocyanine). Examples of crystalline titanium phthalocyanines include, for example, type α, type β, and type Y crystalline titanium phthalocyanine (hereinafter sometimes referred to as type α, type β, and type Y titanium phthalocyanine, respectively).

[0079] For example, in electro-optical image forming apparatuses (e.g., laser beam printers or fax machines using light sources such as semiconductor lasers), a photoreceptor with sensitivity in the wavelength region above 700 nm is preferred. From the perspective of having a high quantum yield in the wavelength region above 700 nm, phthalocyanine pigments are preferred as charge generating agents, more preferably titanium dioxide phthalocyanine or metal-free phthalocyanine, and particularly preferably Y-type titanium dioxide phthalocyanine or X-type metal-free phthalocyanine.

[0080] In the characteristic X-ray diffraction (XRD) spectrum of CuKα, Y-type titanium phthalocyanine exhibits a main peak at, for example, a Bragg angle (2θ ± 0.2°) of 27.2°. The main peak in the characteristic XRD spectrum of CuKα is the first or second most intense peak within the range of Bragg angle (2θ ± 0.2°) between 3° and 40°. Y-type titanium phthalocyanine does not exhibit a peak at 26.2° in the characteristic XRD spectrum of CuKα.

[0081] The characteristic X-ray diffraction spectrum of CuKα can be determined, for example, by the following method. First, the sample (titanium phthalocyanine) is filled into the sample holder of an X-ray diffraction apparatus (e.g., RINT 1100 manufactured by Rigaku Corporation). The X-ray diffraction spectrum is measured under the following conditions: Cu X-ray tube bulb, tube voltage 40 kV, tube current 30 mA, and wavelength of CuKα characteristic X-rays 1.542 Å. The measurement range (2θ) is, for example, 3° or more and 40° or less (starting angle 3°, ending angle 40°), and the scanning speed is, for example, 10° / minute. The main peak is determined from the obtained X-ray diffraction spectrum, and the Bragg angle of the main peak is read.

[0082] · Matrix resin

[0083] The charge-generating layer may contain a matrix resin. Examples of the matrix resin contained in the charge-generating layer are not particularly limited and may be the same as those of the binder resin contained in the charge-transporting layer. However, in order to suitably form both the charge-generating layer and the charge-transporting layer, it is preferable to select a resin different from the resin used as the binder resin in the aforementioned examples of binder resins as the matrix resin.

[0084] ·additive

[0085] Examples of additives contained in the photosensitive layer include, for example, ultraviolet absorbers, antioxidants, free radical scavengers, singlet quenchers, softeners, surface modifiers, extenders, thickeners, dispersants, waxes, donors, surfactants, plasticizers, sensitizers, electron acceptor compounds, and leveling agents. Examples of leveling agents include, for example, silicone oil, and more specifically, dimethyl silicone oil.

[0086] The thickness of the charge generation layer 4a is not particularly limited, but is preferably 0.01 μm or more and 5 μm or less, more preferably 0.1 μm or more and 3 μm or less. Figure 1 In the example shown, the charge generation layer 4a is a single layer, but the charge generation layer 4a can also be multiple layers.

[0087] (charge transport layer 4b)

[0088] In addition to the binder resin and hole transport agent, the charge transport layer 4b may also contain additives and free radical acceptor compounds as needed. The matrix resin, additives, and free radical acceptor compounds can be the same as those described above.

[0089] · Adhesive resin

[0090] The binder resin comprises at least one of (1) polycarbonate resin (hereinafter also referred to as "PC resin") and (2) polyaryl ester resin (hereinafter also referred to as "PA resin") as a main component. That is, the binder resin may be contained as a homopolymer of PC resin, a homopolymer of PA resin, or a mixture of PC resin and PA resin. The binder resin of the present invention preferably comprises PC resin. By using at least one of PC resin and PA resin, the function of the aforementioned specific hole transporter can be maintained and a synergistic effect with the substrate can be achieved.

[0091] (1) PC resin

[0092] The PC resin is preferably a polycarbonate resin (PC1) containing at least one of the repeating units shown in the following formulas (20A) and (20B) (hereinafter also simply referred to as "repeating unit (20A)" and "repeating unit (20B)").

[0093] [Chemical Formula 7]

[0094]

[0095] In the above formula (20A), R 201 and R 202 Each of the above formulas (20B) independently represents an alkyl group having 1 or more hydrogen atoms and 4 or fewer carbon atoms. 203 and R 204Each of these groups independently represents an alkyl group having 1 or more hydrogen atoms and 4 or fewer carbon atoms, and X represents a divalent group as shown in formula (X1) or formula (X2).

[0096] R 201 and R 202 Each is preferably a hydrogen atom or a methyl group, more preferably a hydrogen atom. R 203 and R 204 Each of the groups independently represents an alkyl group having 1 or more but less than 4 carbon atoms, preferably a hydrogen atom or a methyl group, more preferably a hydrogen atom. From the viewpoint of more effectively suppressing fog, X is preferably a divalent group as shown in formula (X1).

[0097] [Chemical Formula 8]

[0098]

[0099] In the above formula (X1), t represents an integer greater than or equal to 1 and less than or equal to 3, and * represents a key. In the above formula (X2), R 205 and R 206 Each element independently represents an alkyl group having 1 or more hydrogen atoms and 4 or fewer carbon atoms; * indicates a bond. t is preferably 1.

[0100] In particular, from the viewpoint of abrasion resistance, PC resin preferably contains repeating units as shown in the following formula (20B-1) (hereinafter also referred to as "repeating unit (20B-1)").

[0101] [Chemical Formula 9]

[0102]

[0103] Furthermore, the terminal group preferably has a group represented by the following formula (T1). Hereinafter, this terminal group will also be simply referred to as the terminal group (T1).

[0104] [Chemical Formula 10]

[0105]

[0106] In general formula (T1), R 301 R 302 R 303 R 304 and R 305 Each of the following groups independently represents a hydrogen atom, an alkyl group with 1 or more but less than 20 carbon atoms, an alkoxy group with 1 or more but less than 20 carbon atoms, an alkoxycarbonyl group with 1 or more but less than 20 carbon atoms, or an aryl group with 6 or more but less than 14 carbon atoms. R 301 R 302 R 303 R 304 and R305 One or more of the above-mentioned alkyl group having 1 or more and 20 or less carbon atoms, alkoxy group having 1 or more and 20 or less carbon atoms, alkoxycarbonyl group having 1 or more and 20 or less carbon atoms, or aryl group having 6 or more and 14 or less carbon atoms.

[0107] Examples of alkyl groups having 1 or more but less than 20 carbon atoms include unsubstituted methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, neopentyl, 1,2-dimethylpropyl, hexyl, heptyl, or octyl, which can be linear or branched.

[0108] Examples of alkoxy groups with 1 or more but less than 20 carbon atoms include unsubstituted methoxy, ethoxy, propoxy, butoxy, pentoxy, hexoxy, heptoxy, octoxy, nonoxy, or decoxy groups, which can be linear or branched.

[0109] An alkoxy carbonyl group having 1 or more but less than 20 carbon atoms is either straight-chain or branched, and is formed by the bonding of an unsubstituted alkoxy group having 1 or more but less than 20 carbon atoms with a carbonyl group.

[0110] Aryl groups having 6 or more but 14 or fewer carbon atoms include, for example, unsubstituted aromatic monocyclic hydrocarbon groups having 6 or more but 14 or fewer carbon atoms, unsubstituted aromatic condensed bicyclic hydrocarbon groups having 6 or more but 14 or fewer carbon atoms, or unsubstituted aromatic condensed tricyclic hydrocarbon groups having 6 or more but 14 or fewer carbon atoms. Examples of aryl groups having 6 or more but 14 or fewer carbon atoms include phenyl, naphthyl, anthracene, or phenanthryl.

[0111] In general formula (T1), R 301 R 302 R 303 R 304 and R 305 Each of the components is preferably an alkyl group having 1 or more hydrogen atoms and 20 or fewer carbon atoms, and more preferably a tert-butyl group. Specifically, the terminal group is particularly preferably 4-(tert-butyl)phenyl.

[0112] In particular, the terminal group is especially preferably a group having the following formula (T2). Hereinafter, this terminal group will also be simply referred to as terminal group (T2).

[0113] [Chemical Formula 11]

[0114]

[0115] As a preferred polycarbonate resin (PC1), examples include polycarbonate resins having repeating units (20B-1) and terminal groups (T2), and polycarbonate resins comprising repeating units (20A-1), repeating units (20B-1), and terminal groups (T2). More preferably, the polycarbonate resin (PC1) is the polycarbonate resin shown in the following formula (PC1-1) (hereinafter also simply referred to as polycarbonate resin (PC1-1)), and even more preferably, the polycarbonate resin shown in the following formula (PC1-1-T) (hereinafter also simply referred to as polycarbonate resin (PC1-1-T)).

[0116] [Chemical Formula 12]

[0117]

[0118] In formulas (PC1-1) and (PC1-1-T), the lower right 'x' of the repeating unit (20B-1) represents the content (in mol%) of the repeating unit (20B-1) relative to the total number of repeating units (20A-1) and (20B-1) contained in the polycarbonate resin (PC1-1), and the lower right 'y' of the repeating unit (20A-1) represents the content (in mol%) of the repeating unit (20A-1) relative to the total number of repeating units (20A-1) and (20B-1) contained in the polycarbonate resin (PC1-1). The content (x) of the repeating unit (20B-1) is preferably greater than 0 mol%. The content (x) of the repeating unit (20B-1) is 80 mol% or more and 90 mol% or less, and the content (y) of the repeating unit (20A-1) is more preferably 10 mol% or more and 20 mol% or less.

[0119] Polycarbonate resin (PC1) can also have siloxane bonds "-Si-O-". An example of a polycarbonate resin (PC1) having siloxane bonds is a polycarbonate resin (PC1-S) having siloxane bonds "-Si-O-" in its main chain. Such a polycarbonate resin, for example, incorporates repeating units containing siloxane bonds in its main chain. As a polycarbonate resin having siloxane bonds in its main chain, it is preferable to have a polycarbonate resin having bonds represented by the formula "-Si(CH3)2-O-" in its main chain, more preferably a polycarbonate resin having repeating units represented by the formula (20C), further preferably a polycarbonate resin having repeating units represented by the formulas (20C), (20A-1), and (20B-1), and particularly preferably a polycarbonate resin having repeating units represented by the formulas (20C), (20A-1), and (20B-1) and terminal groups having groups represented by the formula (T1). As a repeating unit (20C), repeating unit (20C-1) is preferred. The terminal group (T1) is preferably the terminal group (T2).

[0120] [Chemical Formula 13]

[0121]

[0122] In equation (20C), Q 11 and Q 14 Each can be independently represented as an alkoxy group having 1 or more but 6 or fewer carbon atoms, or an alkyl group having 1 or more but 6 or fewer carbon atoms. Q 11 and Q 14 Preferably, it represents an alkoxy group having 1 or more and 6 or fewer carbon atoms; more preferably, it represents an alkoxy group having 1 or more and 3 or fewer carbon atoms; and even more preferably, it represents a methoxy group. In formula (20C), Q 12 and Q 13 Each of these can be used independently to represent an alkyldiyl group with 1 or more but less than 6 carbon atoms. Q 12 and Q 13 Preferably, it represents an alkyldiyl group with 2 or more and 4 or fewer carbon atoms, and more preferably, it represents a propanediyl group. In formulas (20C) and (20C-1), n ​​represents an integer of 30 or more and 60 or less.

[0123] In the polycarbonate resin (PC1-S), the content of the repeating unit shown in formula (20C) is preferably 0.05 mol% or more and 0.65 mol% or less relative to the total number of repeating units in the polycarbonate resin. The content of the repeating unit shown in formula (20A-1) is preferably 10 mol% or more and 20 mol% or less relative to the total number of repeating units in the polycarbonate resin. The content of the repeating unit shown in formula (20B-1) is preferably 80 mol% or more and 90 mol% or less relative to the total number of repeating units in the polycarbonate resin.

[0124] (2) PA resin

[0125] PA resin is not particularly limited, but is preferably composed of a polyarylate resin (PA1) containing repeating units (hereinafter also referred to as repeating units (40)) as shown in the following formula (40).

[0126] [Chemical Formula 14]

[0127]

[0128] In equation (40) above, R 401 Represents an alkyl group having 1 or more hydrogen atoms and 4 or fewer carbon atoms. R 402 and R 403 Each of these characters independently represents an alkyl group with 1 or more but less than 4 hydrogen atoms, and Y represents a single bond or an oxygen atom.

[0129] 2 Rs 401 They can be the same as each other or they can be different from each other. R402 and R 403 They can be the same or different, and they can also bond together to form a ring, becoming cycloalkane groups. R 401 Preferably, it represents a hydrogen atom or a methyl group.

[0130] (3) Other resins

[0131] To the extent that the effects of the present invention are not impaired, the binder resin may include resins other than PA resin and PC resin as needed. As for resins other than the aforementioned polycarbonate resin (PC1) and polyarylate resin (PA1), there are no particular limitations as long as they can be used as binder resins contained in the photosensitive layer of an electrophotographic photoreceptor. Specific examples include: styrene-based resins, styrene-butadiene copolymers, styrene-acrylonitrile copolymers, styrene-maleic acid copolymers, styrene-acrylic acid copolymers, acrylic copolymers, polyethylene resins, ethylene-ethyl acetate copolymers, chlorinated polyethylene resins, polyvinyl chloride resins, polypropylene resins, ionomers, vinyl chloride-ethyl acetate copolymers, alkyd resins, polyamide resins, polyurethane resins, diallyl phthalate resins, ketone resins, polyvinyl butyral resins, polyether resins, polyester resins, and other thermoplastic resins; silicone resins, epoxy resins, phenolic resins, urea resins, melamine resins, other crosslinked thermosetting resins, and other thermosetting resins; epoxy acrylate resins, urethane-acrylate copolymer resins, and other photocurable resins. These resins can be used in combination of two or more.

[0132] The content of polycarbonate resin (PC1) in the adhesive resin, which includes at least one of the repeating units (20A) and (20B) described above, is not particularly limited without prejudice to the purpose of the present invention. Preferably, the content of polycarbonate resin (PC1) in the adhesive resin, which includes at least one of the repeating units (20A) and (20B) described above, is 60% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more.

[0133] Similarly, the content of the polyarylate resin (PA1) containing the repeating unit (40) is not particularly limited without prejudice to the purpose of the present invention. The polyarylate resin (PA1) containing the repeating unit (40) in the binder resin is preferably 60% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more.

[0134] Furthermore, the total content of the above-mentioned polycarbonate resin (PC1) and polyarylate resin (PA1) in the binder resin may be 60% by mass or more, 80% by mass or more, or 90% by mass or more.

[0135] Cavitation delivery agent

[0136] From the viewpoint of obtaining better charge stability of the toner, the compound represented by the above general formula (1) contained in the hole transporter is preferably: in R 1 When a1 is a group represented by formula (I), formula (II), or formula (III), it represents the integer 1. 2 When a is a group represented by formula (I), formula (II), or formula (III), a2 represents the integer 1, in R 3 When a is a group represented by formula (I), formula (II) or formula (III), a3 represents the integer 1.

[0137] In addition, in general formula (1), when a1 represents an integer greater than 2 and less than 5, multiple R 1 They can represent the same group or different groups. When a2 represents an integer greater than 2 and less than 5, multiple R... 2 They can represent the same group or different groups. When a3 represents an integer greater than 2 and less than 5, multiple R... 3 They can represent the same group or different groups.

[0138] Furthermore, in the group Ry shown in formula (III) above, "a phenyl that can be substituted by an alkyl group having 1 or more but 8 or fewer carbon atoms" means that some or all of the hydrogen atoms of the phenyl group can be substituted by an alkyl group having 1 or more but 8 or fewer carbon atoms. Similarly, "a phenyl that can be substituted by an alkoxy group having 1 or more but 8 or fewer carbon atoms" means that some or all of the hydrogen atoms of the phenyl group can be substituted by an alkoxy group having 1 or more but 8 or fewer carbon atoms. That is, the phenyl group can be substituted by one or more substituents (C1 to C8 alkyl groups, C1 to C8 alkoxy groups).

[0139] From the viewpoint of obtaining a stable surface potential, the compound (triphenylamine derivative) represented by general formula (1) is preferably selected from at least one of the compounds represented by general formula (1-1), formula (1-2), and formula (1-3).

[0140] [Chemical Formula 15]

[0141]

[0142] In the above equation (1-1), R 11 R 12 and R 13 Each of them independently represents an alkyl group having 1 or more carbon atoms and 8 or less, or an alkoxy group having 1 or more carbon atoms and 8 or less, and r1, r2 and r3 each independently represent an integer having 0 or more carbon atoms and 5 or less.

[0143] In equation (1-1), when r1 represents an integer greater than 2 and less than 5, multiple R... 11They can represent the same group or different groups. When r2 represents an integer greater than 2 and less than 5, multiple R... 12 They can represent the same group or different groups. When r3 represents an integer greater than 2 and less than 5, multiple R... 13 They can represent the same group or different groups.

[0144] In equation (1-1), R 11 R 12 and R 13 Each of the following is preferably an alkyl group having 1 or more and 8 or less carbon atoms, more preferably an alkyl group having 1 or more and 6 or less carbon atoms, even more preferably an alkyl group having 1 or more and 3 or less carbon atoms, and particularly preferably a methyl group. r1, r2, and r3 are each preferably 0 or 1, more preferably 1.

[0145] In equation (1-2), R 20 R represents a hydrogen atom, an alkyl group having 1 or more but less than 8 carbon atoms, an alkoxy group having 1 or more but less than 8 carbon atoms, or a phenyl group that can be substituted by an alkyl group having 1 or more but less than 8 carbon atoms. 21 R 22 and R 23 Each of the following can be used to independently represent an alkyl group having 1 or more carbon atoms and 8 or less, or an alkoxy group having 1 or more carbon atoms and 8 or less. f1, f2, and f3 can each be used to independently represent an integer having 0 or more carbon atoms and 5 or less. f4 can represent 0 or 1.

[0146] In general formula (1-2), when f1 represents an integer greater than 2 and less than 5, multiple R 21 They can represent the same group or different groups. When f2 represents an integer greater than 2 and less than 5, multiple R... 22 They can represent the same group or different groups. When f3 represents an integer greater than 2 and less than 5, multiple R... 23 They can represent the same group or different groups.

[0147] In general formula (1-2), R 20 Preferably, it represents a phenyl group. R 21 R 22 and R 23 Each of the following is preferably an alkyl group having 1 or more and 8 or fewer carbon atoms, more preferably an alkyl group having 1 or more and 3 or fewer carbon atoms, and even more preferably a methyl group. f1 and f2 preferably represent 1. f3 preferably represents 0. As described above, f4 represents 0 or 1.

[0148] In the above equation (1-3), R 31 R32 R 33 R 34 and R 35 Each of the following independently represents an alkyl group having 1 or more but less than 8 carbon atoms, or an alkoxy group having 1 or more but less than 8 carbon atoms. g1, g2, g3, g4, and g5 each independently represent an integer having 0 or more but less than 5.

[0149] In general formula (1-3), when g1 represents an integer greater than 2 and less than 5, multiple R 31 They can represent the same group or different groups. When g2 represents an integer greater than 2 and less than 5, multiple R... 32 They can represent the same group or different groups. When g3 represents an integer greater than 2 and less than 5, multiple R... 33 They can represent the same group or different groups. When g4 represents an integer greater than 2 and less than 5, multiple R... 34 They can represent the same group or different groups. When g5 represents an integer greater than 2 and less than 5, multiple R... 35 They can represent the same group or different groups.

[0150] In general formula (1-3), R 31 R 32 R 33 R 34 and R 35 Each of the following is preferably an alkyl group having 1 or more and 8 or less carbon atoms, more preferably an alkyl group having 1 or more and 3 or less carbon atoms, and even more preferably a methyl group. g1, g2, g3, g4 and g5 preferably represent 1.

[0151] The hole delivery agent is preferably at least one compound (e.g., one compound) represented by chemical formulas (HTM-1) to (HTM-4). Hereinafter, the compounds represented by chemical formulas (HTM-1) to (HTM-4) will sometimes be referred to as hole delivery agents (HTM-1) to (HTM-4).

[0152] [Chemical Formula 16]

[0153]

[0154] The content of the cavitation delivery agent is preferably 10 parts by weight or more and 200 parts by weight or less relative to 100 parts by weight of the binder resin, more preferably 50 parts by weight or more and 100 parts by weight or less.

[0155] The content of the above general formula (1) relative to the total mass of the cavitation delivery agent is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 100% by mass.

[0156] The thickness of the charge transport layer 4b is not particularly limited, but is preferably 2 μm or more and 100 μm or less, more preferably 5 μm or more and 50 μm or less. Figure 1 In the example shown, the charge transport layer 4b is a single layer, but the charge transport layer 4b can be multiple layers.

[0157] <Second Embodiment: Image Forming Apparatus>

[0158] The image forming apparatus having the photoreceptor 1 of this embodiment will now be described. The image forming apparatus includes an image carrier (the photoreceptor 1 of this embodiment), a charging device, an exposure device, a developing device, and a transfer device. The charging device positively charges the surface of the photoreceptor. The exposure device exposes the charged surface of the photoreceptor to form an electrostatic latent image on the surface of the photoreceptor. The developing device supplies toner to the electrostatic latent image, allowing the electrostatic latent image to develop as a toner image. The transfer device transfers the toner image from the photoreceptor to a substrate to be transferred.

[0159] Hereinafter, as one embodiment of the image forming apparatus having the photoreceptor 1 of this embodiment, a color image forming apparatus in a series configuration and a direct transfer configuration will be described, and reference will be made to... Figure 2 Please provide an explanation.

[0160] The image forming apparatus 100 includes image forming units 40a, 40b, 40c and 40d, a transfer belt 50, and a fixing unit 52. Hereinafter, unless there is no need to distinguish them, the image forming units 40a, 40b, 40c and 40d will each be referred to as image forming unit 40.

[0161] The image forming unit 40 includes an image carrier 30 (photoreceptor 1), a charging device 42, an exposure device 44, a developing device 46, and a transfer device 48. The image carrier 30 is located at the center of the image forming unit 40. The image carrier 30 is configured to rotate in the direction of the arrow (counterclockwise). Around the image carrier 30, starting from the upstream side in the direction of rotation of the image carrier 30, the charging device 42, the exposure device 44, the developing device 46, and the transfer device 48 are arranged sequentially.

[0162] Furthermore, the image forming unit 40 may further include one or both of a cleaning section (not shown) and a static removal section (not shown). In the case where the image forming unit 40 includes both a cleaning section and a static removal section, the charging device 42, the exposure device 44, the developing device 46, the transfer device 48, the cleaning section, and the static removal section are sequentially arranged around the image carrier 30, starting from the upstream side in the rotation direction of the image carrier 30.

[0163] The charging device 42 charges the surface (peripheral surface) of the image carrier 30. The charging device 42 charges the image carrier 30 uniformly to a predetermined polarity by discharging. The charging device 42 is, for example, a charged roller.

[0164] The exposure apparatus 44 exposes the surface 30a (1a) of the charged image carrier 30 (photoreceptor 1). As a result, an electrostatic latent image is formed on the surface 30a of the image carrier 30. The electrostatic latent image is formed based on image data input to the image forming apparatus 100.

[0165] The developing apparatus 46 supplies toner to the electrostatic latent image formed on the surface 30a of the image carrier 30. Thus, the electrostatic latent image is developed as a toner image. The image carrier 30 is equivalent to an image carrier carrying the toner image. Details regarding the developing apparatus 46 will be described later.

[0166] The transfer device 48 transfers the toner image developed by the developing device 46 from the surface of the image carrier 30 to the recording medium P. During the transfer of the toner image from the image carrier 30 to the recording medium P, the image carrier 30 is in contact with the recording medium P. That is, the image forming apparatus 100 employs a so-called direct transfer method. Examples of transfer devices 48 include, for instance, transfer rollers.

[0167] Through each image forming unit 40a-40d, toner images of multiple colors (e.g., black, cyan, magenta, and yellow) are sequentially superimposed on the transfer belt 50. Then, the toner images of multiple colors superimposed on the transfer belt 50 are transferred to the recording medium P in one pass.

[0168] The image forming apparatus 100 may have a cleaning section (not shown). Examples of cleaning sections include a cleaning scraper or a cleaning roller.

[0169] The fixing unit 52 heats and / or pressurizes the unfixed toner image transferred to the recording medium P by the transfer device 48. The fixing unit 52 is, for example, a heating roller and / or a pressure roller. By heating and / or pressing the toner image, the toner image is fixed to the recording medium P. As a result, an image is formed on the recording medium P.

[0170] (Developing apparatus)

[0171] The developing apparatus 46 can employ a non-magnetic single-component developing method. This reduces wear on the charge-generating layer 4a of the photoreceptor 1. (Refer to the following...) Figure 3 The developing apparatus 46 employing a non-magnetic single-component developing method will be described. Figure 3 To show Figure 2 A diagram showing a portion of the structure of the developing apparatus 46.

[0172] The developing apparatus 46 includes a housing frame 210, a supply roller 220, a developing roller 230, and a limiting scraper 400. The axial direction of the supply roller 220 and the developing roller 230 is (within)... Figure 3 The length of the direction orthogonal to the paper surface is approximately the same as the length of the photoreceptor 1.

[0173] The housing frame 210 houses a non-magnetic single-component developer. This non-magnetic single-component developer is equivalent to a toner. The toner does not contain magnetic powder. The housing frame 210 also houses a supply roller 220, a developing roller 230, and a limiting scraper 400. The housing frame 210 has an opening 211 positioned opposite the photoreceptor 1. The opening 211 exposes a portion of the developing roller 230 to the outside of the housing frame 210.

[0174] The supply roller 220 is disposed inside the housing frame 210. The supply roller 220 is positioned opposite the developing roller 230. The supply roller 220 has a supply roller shaft component 221 and a roller portion 222. The supply roller shaft component 221 is arranged to extend along the rotation axis 223 of the supply roller 220. The supply roller shaft component 221 is rotatably supported by a shaft support portion (not shown) of the housing frame 210. The supply roller 220 is capable of rotating in the direction of the arrow (clockwise). The roller portion 222 is a cylindrical component mounted on the outside of the supply roller shaft component 221.

[0175] The supply roller 220 holds the toner, which is a non-magnetic single-component developer housed inside the housing frame 210, on its surface 220a (circumferential surface). Specifically, the roller portion 222 rotates integrally with the supply roller shaft component 221 as the supply roller shaft component 221 rotates. Furthermore, the roller portion 222 holds the toner housed in the housing frame 210 on its outer peripheral surface. The outer peripheral surface of the roller portion 222 corresponds to the surface 220a of the supply roller 220. The supply roller 220 supplies the toner held on its surface 220a to the developing roller 230.

[0176] The developing roller 230 is arranged opposite to the photoreceptor 1. The developing roller 230 is arranged opposite to the photoreceptor 1 via the opening 211 of the housing frame 210. In addition, the developing roller 230 is arranged opposite to the supply roller 220. The supply roller 220 is arranged opposite to the photoreceptor 1 via the developing roller 230.

[0177] The developing roller 230 includes a developing roller shaft component 231 and a roller portion 232. The developing roller shaft component 231 is arranged to extend along the rotation axis 233 of the developing roller 230. The developing roller shaft component 231 is rotatably supported by a shaft support portion (not shown) of a housing frame 210. The developing roller 230 is capable of rotating in the direction of the arrow (clockwise). The developing roller shaft component 231 has one or more magnet portions (not shown). By having the developing roller shaft component 231 have one or more magnet portions, a predetermined interval is provided between the limiting scraper 400 and the surface 230a of the developing roller 230. The roller portion 232 is a cylindrical component mounted on the outside of the developing roller shaft component 231. The roller portion 232 rotates integrally with the developing roller shaft component 231 as the developing roller shaft component 231 rotates.

[0178] The developing roller 230 receives toner from the supply roller 220. The toner supplied from the supply roller 220 is held as a toner layer TL on the surface 230a (circumferential surface) of the developing roller 230. The toner layer TL contains the toner supplied from the supply roller 220. The surface 230a of the developing roller 230 corresponds to the surface of the roller portion 232. For example, the toner is held on the surface 230a of the developing roller 230 by the mirror force of the developing roller 230.

[0179] The thickness of the toner layer TL maintained on the surface 230a of the developing roller 230 is limited by the limiting scraper 400. Limiting the thickness of the toner layer TL means uniformly adjusting the thickness of the toner layer TL to a specified value.

[0180] The restrictor blade 400 is plate-shaped. One end 401 of the restrictor blade 400 is fixed to the housing frame 210, and the other end 402 is a free end. The other end 402 (free end) is formed by bending the outer edge of the plate-shaped component constituting the restrictor blade 400 toward the side opposite to the developing roller 230.

[0181] The restrictor blade 400 is configured to abut (specifically, in surface contact) against the toner layer TL held on the surface 230a of the developing roller 230. A restrictor clamping portion N1 is formed between the restrictor blade 400 and the developing roller 230.

[0182] The developing roller shaft component 231 has one or more magnet portions. Furthermore, the retaining scraper 400 is magnetic. The retaining scraper 400 can be flexed and deformed so that its other end 402 side approaches the developing roller 230 side. Thus, through the force generated by the magnetic force from the magnet portions, the other end 402 (free end) of the retaining scraper 400 is forced toward the developing roller 230. Then, the retaining scraper 400 abuts against the toner layer TL held on the surface 230a of the developing roller 230 with a predetermined pressure. Thus, the thickness of the toner layer TL held on the surface 230a of the developing roller 230 can be limited (uniformly adjusted to a predetermined value).

[0183] The limiting scraper 400 can be flexed and deformed so that its other end 402 moves laterally away from the developing roller 230. As a result, the limiting scraper 400 can smoothly guide the toner supplied from the supply roller 220 to the developing roller 230 to the limiting clamping part N1.

[0184] The toner contained in the toner layer TL becomes kinetically charged through contact with the limiting scraper 400. The limiting scraper 400 limits the thickness of the toner layer TL while simultaneously charging the toner contained in the toner layer TL.

[0185] The photoreceptor 1, for example, has a cylindrical shape. The photoreceptor 1 can rotate in the direction of the arrow (counterclockwise) about its rotation axis 301. The rotation axis 301 of the photoreceptor 1 is... Figure 3 The paper surfaces are orthogonal.

[0186] After the thickness of the toner layer TL is limited by the scraper 400, the developing roller 230 supplies the toner contained in the toner layer TL held on its surface 230a to the electrostatic latent image formed on the surface 1a (peripheral surface) of the photoreceptor 1. Thus, the electrostatic latent image is developed as a toner image. To ensure that the toner effectively moves from the surface 230a of the developing roller 230 to the surface 1a of the photoreceptor 1, a developing bias voltage is preferably applied. The developing apparatus 46 employing a single-component developing method has been described above.

[0187] The above is for reference only. Figure 2 and Figure 3 An example of an image forming apparatus 100 having the photoreceptor 1 of this embodiment has been described. However, the image forming apparatus having the photoreceptor 1 of this embodiment is not limited to the image forming apparatus 100 described above. For example, the image forming apparatus may also be a monochrome image forming apparatus. In this case, the image forming apparatus may have only one image forming unit, for example. Furthermore, while the image forming apparatus 100 is a series-connected image forming apparatus, it may also be a rotating image forming apparatus, for example. Furthermore, while the image forming apparatus 100 is a direct transfer image forming apparatus, it may also be an intermediate transfer image forming apparatus, for example.

[0188] <Third Implementation Method: Processing Box>

[0189] Next, refer to Figure 2 An example of a processing cartridge having the photoreceptor 1 of this embodiment will be described. The processing cartridge is for image forming. The processing cartridge corresponds to each of the image forming units 40a to 40d. The processing cartridge has the photoreceptor 1 of this embodiment. In addition to the photoreceptor 1, the processing cartridge may further have at least one selected from the charging device 42, the exposure device 44, the developing device 46, and the transfer device 48. The processing cartridge may further have one or both of a cleaning section (not shown) and a static removal section (not shown). The processing cartridge may also employ a static removal-free method. The processing cartridge is designed to be freely detachable from the image forming apparatus 100. Therefore, the processing cartridge is easy to operate, and in the event of degradation of the sensitivity characteristics of the photoreceptor 1, etc., it can be easily and quickly replaced, including the photoreceptor 1. (See above for reference.) Figure 2 The processing box having the photoreceptor 1 of this embodiment has been described.

[0190] Example

[0191] The present invention will be further described in detail below using examples, but the present invention is not limited to the scope of the examples.

[0192] (Adhesive resin)

[0193] Prepare the following PC resins (R1) to (R4) as binder resins used in the charge transport layer.

[0194] • PC resin (R1): The polycarbonate resin (PC1-1-T) described in the embodiments, wherein the content (x) of the repeating unit (20B-1) is 100 mol% of the polycarbonate resin (R1).

[0195] • PC resin (R2): The polycarbonate resin (PC1-1-T) described in the embodiments, wherein the content (y) of the repeating unit (20A-1) and the content (x) of (20B-1) are both 50 mol% of polycarbonate resin.

[0196] • PC resin (R3): The polycarbonate resin (PC1-1-T) described in the embodiments, wherein the content (y) of the repeating unit (20A-1) is 40 mol% and the content (x) of the repeating unit (20B-1) is 60 mol%.

[0197] • PC resin (R4): The polycarbonate resin (PC1-S) described in the embodiments having siloxane bonds in its main chain, having repeating units (20A-1), (20B-1), and (20C-1) and terminal groups (T2).

[0198] [Chemical Formula 17]

[0199]

[0200] [Chemical Formula 18]

[0201]

[0202] (Cavitation delivery agent)

[0203] As hole transport agents used in the charge transport layer, the hole transport agents (HTM-1) to (HTM-4) used in the examples and the hole transport agents (HTM-5) to (HTM-8) used in the comparative examples are shown below.

[0204] [Chemical Formula 19]

[0205]

[0206] [The fabrication of an electrophotographic photosensitive material for evaluation]

[0207] The electrophotographic photosensitive materials of Examples 1-7 and Comparative Examples 1-5 were manufactured using the following methods. The structures of these electrophotographic photosensitive materials are shown in Table 1 described below.

[0208] (Example 1)

[0209] In Example 1, an electrophotographic photoreceptor consisting of a substrate (U1), PC resin (R1), and hole transport agent (HTM-1) was prepared by the following steps.

[0210] • Formation of the bottom layer (U1)

[0211] A mixture of 1.5 parts by weight of oil-free alkyd resin (manufactured by Dai Nippon Ink Chemical Co., Ltd.: Beckolite M6401), 1 part of melamine resin (manufactured by Dai Nippon Ink Chemical Co., Ltd.: SUPERBECKAMINE G-821), 5 parts by weight of titanium dioxide particles (manufactured by Ishihara Sangyo Co., Ltd.: TIPAQUE CR-EL), and 22.5 parts by weight of 2-butanone was placed into a ball mill and ball-milled for 48 hours using φ10mm alumina balls to prepare the undercoat solution.

[0212] The obtained substrate was filtered through a 5-micron filter and then coated onto a 30-mm diameter aluminum drum-shaped support as a conductive support using an dip-coating method. The substrate was then heat-treated at 150°C for 30 minutes to form a 2.0-μm thick substrate.

[0213] • Formation of the charge generation layer

[0214] Next, 2.3 parts by weight of Y-type titanium phthalocyanine, 1 part by weight of polyvinyl acetal resin (S-LEC BX-5 manufactured by Sekisui Chemicals Co., Ltd.) as the binder resin, 40 parts by weight of propylene glycol monomethyl ether as the dispersion medium, and 40 parts by weight of tetrahydrofuran were mixed and dispersed in a bead mill for 12 hours to prepare a coating solution for the charge generation layer. The obtained coating solution was filtered through a 3-micron filter and then applied to the substrate prepared above by dip coating. It was dried at 50°C for 5 minutes to form a charge generation layer with a film thickness of 0.3 μm.

[0215] • Formation of the charge transport layer

[0216] Next, 45 parts by weight of the compound represented by formula (HTM-1) as a hole transporter, 100 parts by weight of the polycarbonate resin represented by formula (R1) as a binder resin, 0.05 parts by weight of dimethyl silicone oil KF96-50CS as a leveling agent, 560 parts by weight of tetrahydrofuran as a solvent, and 140 parts by weight of toluene were mixed to prepare a coating liquid for the charge transport layer.

[0217] The prepared charge transport layer coating solution was applied to the charge generation layer in the same manner as the coating solution for the charge generation layer, and dried at 120°C for 40 minutes to form a charge transport layer with a film thickness of 25 μm, thus fabricating a stacked electrophotographic photosensitive material.

[0218] (Examples 2-4)

[0219] In Examples 2 to 4, the hole transport agent (HTM-1) in the coating solution for the charge transport layer in Example 1 was changed to hole transport agents (HTM-2), (HTM-3), and (HTM-4), respectively. Otherwise, the electrophotographic photoresist was fabricated in the same manner as in Example 1.

[0220] (Examples 5-7)

[0221] In Examples 5 to 7, the PC resin (R1) in the coating liquid for the charge transport layer in Example 1 was changed to PC resin (R2), (R3), and (R4), respectively. Otherwise, the electrophotographic photosensitive body was fabricated in the same manner as in Example 1.

[0222] (Comparative Examples 1-4)

[0223] In Comparative Examples 1 to 4, the hole transport agent (HTM-1) in the coating solution for the charge transport layer in Example 1 was changed to hole transport agents (HTM-5) to (HTM-8), respectively. Otherwise, the electrophotographic photoresist was made in the same manner as in Example 1.

[0224] (Comparative Example 5)

[0225] In Comparative Example 5, the bottom layer (U1) in Example 1 was changed to the bottom layer (U2), but the electrophotographic photosensitive material was fabricated in the same manner as in Example 1. The bottom layer (U2) was formed as shown below.

[0226] • Formation of the bottom layer (U2)

[0227] Two parts by weight of titanium dioxide (TAYCA SMT-A, number-average primary particle size 10 nm), which had been surface-treated with alumina and silica and then wet-dispersed with methylhydropolysiloxane, were dispersed in a bead mill for 5 hours to prepare a base coat. This base coat (U2) was then used to form the undercoat.

[0228] [Evaluation of Stacked Electrophotographic Photoresists]

[0229] For each type of stacked electrophotographic photosensitive material, the triboelectric charge, charge retention rate, and fog concentration of the toner were measured using the following methods to evaluate the triboelectric properties, charge retention, and fog characteristics of the toner. The evaluation results are shown in Table 1.

[0230] (1) Determination of the charge carried by friction of toner

[0231] The charge on the toner (friction charge) was measured when the photosensitive layer 4 was rubbed against the toner. Figure 4 An outline of the apparatus for measuring the triboelectric charge is shown. The triboelectric charge of the toner is measured by performing the following first, second, third, and fourth steps. Clamp 310 is used to measure the triboelectric charge of the toner.

[0232] like Figure 4 As shown, the fixture 310 includes a first unit 312, a rotating shaft 314, a rotation drive unit 316 (e.g., a motor), and a second unit 318. The rotation drive unit 316 rotates the rotating shaft 314. The rotating shaft 314 rotates about its rotation axis S. The first unit 312 rotates integrally with the rotating shaft 314 about the rotation axis S. The second unit 318 does not rotate but is fixed.

[0233] (First step)

[0234] In the first step, two photosensitive layers are prepared. Hereinafter, one of the photosensitive layers will be referred to as the first photosensitive layer 330, and the other as the second photosensitive layer 332. When fabricating the above-mentioned stacked photoreceptor, the prepared stacked photosensitive layer is coated with a coating solution onto a high-exposure projector sheet (hereinafter sometimes referred to as an OHP sheet) wound on an aluminum tube (diameter: 78 mm). The coating solution is dried at 120°C for 80 minutes. This produces a sheet for evaluating triboelectric properties, having a photosensitive layer with a film thickness of 30 μm. As a result, a first sheet having the first photosensitive layer 330 (film thickness L1: 30 μm) and the first OHP sheet 320, and a second sheet having the second photosensitive layer 332 (film thickness L2: 30 μm) and the second OHP sheet 322 are obtained. The dimensions of the first OHP sheet 320 and the second OHP sheet 322 are 5 cm in length and 5 cm in width, respectively. (In addition, the above-mentioned coating liquid for the laminated photosensitive layer is used as a general term for the coating liquid for the bottom layer, the coating liquid for the charge generation layer, and the coating liquid for the charge transport layer.)

[0235] (Second Step)

[0236] In the second step, 0.007g of toner is placed on the first photosensitive layer 330. Then, the second photosensitive layer 332 is placed on the toner layer 324. The specific sequence is as follows.

[0237] First, degraded toner is produced through continuous printing. This is done using a color printer (C844dnw, Oki Data Corporation). Cyan toner is filled into the printer's toner cartridge, and a laminated photosensitive element is mounted on the printer. Next, under normal temperature and humidity conditions (temperature 23°C and relative humidity 50% RH: hereinafter sometimes referred to as NN environment), image I (a pattern image with a print rate of 1%) is printed on 1000 sheets of paper to produce degraded toner.

[0238] Next, double-sided tape is used to bond the first OHP sheet 320 to the first unit 312, fixing the first sheet to the first unit 312. Double-sided tape is then used to bond the second OHP sheet 322 to the second unit 318, fixing the second sheet to the second unit 318. 0.007g of toner is uniformly applied to the first photosensitive layer 330 of the first sheet, forming a toner layer 324. The amount of toner is such that, during the 60-second rotation time in the third step, the toner can sufficiently and completely rub against the first photosensitive layer 330 and the second photosensitive layer 332, and that the toner can sufficiently and completely charge. The toner layer 324 is formed on the inner side of the first photosensitive layer 330, centered on the rotation axis S, by the rotation drive unit 316 in the third step, in a manner that prevents leakage between the first photosensitive layer 330 and the second photosensitive layer 332. Then, with the first photosensitive layer 330 and the second photosensitive layer 332 facing each other across the toner layer 324, the second photosensitive layer 332 is brought into contact with the toner layer 324, and placed on the toner layer 324. Thus, the first unit 312, the first OHP film 320, the first photosensitive layer 330, the toner layer 324, the second photosensitive layer 332, the second OHP film 322, and the second unit 318 are arranged sequentially from bottom to top. The centers of the first unit 312, the first OHP film 320, the first photosensitive layer 330, the toner layer 324, the second photosensitive layer 332, the second OHP film 322, and the second unit 318 are arranged via a rotation axis S.

[0239] (Step 3)

[0240] In the third step, under conditions of 23°C and 50% RH, with the second photosensitive layer 332 fixed, the first photosensitive layer 330 is rotated at 60 rpm for 60 seconds. Specifically, the rotation drive unit 316 is driven so that the rotation shaft 314, the first stage 312, the first OHP sheet 320, and the first photosensitive layer 330 rotate around the rotation shaft S at 60 rpm for 60 seconds. As a result, the toner is rubbed between the first photosensitive layer 330 and the second photosensitive layer 332, and the toner becomes charged.

[0241] (Fourth step)

[0242] In the fourth step, the charged toner from the third step is removed from fixture 310 and attracted using a charge measuring device (attraction-type small charge measuring device, Trek "MODEL 212HS"). The total charge Q (in μC) and mass M (in g) of the attracted toner are measured using the charge measuring device. The triboelectric charge (in μC / g) of the toner is calculated according to the formula "triboelectric charge = Q / M".

[0243] (Evaluation of triboelectricity)

[0244] The measured triboelectric charge of the toner is shown in Table 1. Furthermore, a larger absolute value of the negative triboelectric charge indicates that the toner is more likely to become negatively charged relative to the first photosensitive layer 330 and the second photosensitive layer 332. For cases where the triboelectric charge of the toner is a negative value with an absolute value larger than -15 μQ / g, the toner's charge stability was assessed.

[0245] (2) Determination of charge retention rate

[0246] The electrical characteristic testing machine from GENTEC was used as the evaluation machine for determining charge retention rate. Under high temperature and high humidity conditions (temperature 32 degrees Celsius, relative humidity 80% RH), the drum was charged to a surface potential of -600V. 0a The surface potential (V) was measured after 5 seconds. 0b Then, according to the formula "Charge retention rate (%) = (V)", 0b / V 0a )*100” calculates the charge retention rate.

[0247] (Evaluation of charge retention)

[0248] Electrophotographic photoresists with a charge retention rate of 93% or higher are considered to have achieved high charge retention among photoresists.

[0249] (3) Measurement of fog concentration

[0250] A color printer (C844dnw, Oki Data Corporation) was used as the evaluation machine for measuring fog concentration. Cyan toner was filled into the toner cartridge of the evaluation machine, and image I was printed on 2000 sheets of paper under HH (High-Hydrogen) conditions. After being placed in HH conditions for 12 hours, one sheet of white paper was printed, and the toner adhering to the unexposed drum surface was collected using a Scotch Mending Tape (manufactured by 3M). The concentration of the collected toner was measured using a fluorescence spectrophotometer and used as the fog concentration for fog evaluation.

[0251] (Fog Assessment)

[0252] Rating A (Excellent): Fog concentration below 1.40;

[0253] Rating B (Good): Fog concentration greater than 1.40 and less than 1.61;

[0254] Rating C (Poor): Fog concentration is above 1.61.

[0255] [Table 1]

[0256]

[0257] As shown in Table 1, the toner triboelectric charge of the electrophotographic photoresists in Examples 1 to 7 is all below -15 μQ / g, and the charge retention rate of the photoresist is as high as 93% or more. All of them are rated A in the fog evaluation.

[0258] On the other hand, as shown in Table 1, in the electrophotographic photosensitive materials of Comparative Examples 1 to 4, which used charge transport agents (HTM-5) to (HTM-8) different from the hole transport agent of the present invention but with the same bottom layer (U1) as the present invention, the charge retention rate was above 93%, but the toner triboelectric charge was a negative value with a smaller absolute value than -15 μQ / g, and the fog rating was B for all of them. In Comparative Example 5, which used a bottom layer (U2) that did not contain alkyd resin, melamine resin and titanium dioxide particles, the charge retention rate was as low as below 93%, and although the toner triboelectric charge was a negative value with a larger absolute value than -15 μQ / g, the fog rating was C.

[0259] Explanation of reference numerals in the attached figures

[0260] 1: Electrophotographic photosensitive material;

[0261] 2: Conductive substrate;

[0262] 3: Bottom layer;

[0263] 4: Photosensitive layer;

[0264] 4a: Charge generation layer;

[0265] 4b: Charge transport layer;

[0266] 30: Image carrier (electrophotographic photosensitive material);

[0267] 42: Electrically powered devices;

[0268] 44: Exposure apparatus;

[0269] 46: Developing apparatus;

[0270] 50: Transfer device;

[0271] 100: Image forming apparatus.

Claims

1. An electrophotographic photosensitive material used in an image forming apparatus employing a non-magnetic, single-component, pulverized toner. It has a conductive substrate, a bottom layer disposed on the conductive substrate, and a photosensitive layer disposed on the bottom layer. The photosensitive layer comprises a charge generation layer and a charge transport layer. The bottom layer contains thermosetting resin and titanium dioxide particles, wherein the thermosetting resin comprises alkyd resin and melamine resin. The charge transport layer comprises a binder resin and a hole transporter, the binder resin comprising at least one of a polycarbonate resin and a polyaryl ester resin, and the hole transporter comprising a compound represented by the following general formula (1). In the general formula (1), R 1 R 2 and R 3 Each is independently an alkyl group having 1 or more and 8 or less carbon atoms, an alkoxy group having 1 or more and 8 or less carbon atoms, or a group represented by formula (I), formula (II) or formula (III) below, R 1 R 2 and R 3 At least one of them is an alkyl group having 1 or more and 8 or less carbon atoms, or an alkoxy group having 1 or more and 8 or less carbon atoms, and a1, a2, and a3 each independently represent an integer of 0 or more and 5 or less. In formulas (I), (II), and (III), Rx is independently a hydrogen atom, an alkyl group having 1 or more but 8 or fewer carbon atoms, an alkoxy group having 1 or more but 8 or fewer carbon atoms, or a phenyl group that can be substituted by an alkyl group having 1 or more but 8 or fewer carbon atoms, and Ry is independently a phenyl group that can be substituted by an alkyl group having 1 or more but 8 or fewer carbon atoms, or a phenyl group that can be substituted by an alkoxy group having 1 or more but 8 or fewer carbon atoms.

2. The electrophotographic photosensitive material according to claim 1, characterized in that, The compound represented by general formula (1) is selected from at least one of the compounds represented by formulas (1-1), (1-2), and (1-3). In equation (1-1), R 11 R 12 and R 13 Each of these groups independently represents an alkyl group having 1 or more but less than 8 carbon atoms, or an alkoxy group having 1 or more but less than 8 carbon atoms; r1, r2, and r3 each independently represent an integer having 0 or more but less than 5. In equation (1-2), R 20 R represents a hydrogen atom, an alkyl group having 1 or more but 8 or fewer carbon atoms, an alkoxy group having 1 or more but 8 or fewer carbon atoms, or a phenyl group that can be substituted by an alkyl group having 1 or more but 8 or fewer carbon atoms. 21 R 22 and R 23 Each of these characters independently represents an alkyl group having 1 or more but less than 8 carbon atoms, or an alkoxy group having 1 or more but less than 8 carbon atoms; f1, f2, and f3 each independently represent an integer having 0 or more but less than 5; f4 represents 0 or 1. In the above formula (1-3), R 31 R 32 R 33 R 34 and R 35 Each of the following independently represents an alkyl group having 1 or more but less than 8 carbon atoms, or an alkoxy group having 1 or more but less than 8 carbon atoms. g1, g2, g3, g4 and g5 each independently represent an integer having 0 or more but less than 5.

3. The electrophotographic photosensitive material according to claim 1 or 2, characterized in that, The charge transport layer is the outermost layer.

4. The electrophotographic photosensitive material according to claim 1 or 2, characterized in that, The electrophotographic photosensitive element is exposed via a light-emitting diode (LED).

5. The electrophotographic photosensitive material according to claim 1 or 2, characterized in that, Image forming apparatus for direct transfer printing.

6. A processing box having the electrophotographic photosensitive element as described in claim 1 or 2.

7. An image forming apparatus comprising an image carrier, a charging device, an exposure device, a developing device, and a transfer device. The charging device charges the surface of the image carrier. The exposure device exposes the charged surface of the image carrier to form an electrostatic latent image on the surface of the image carrier. The developing apparatus supplies toner to the surface of the image carrier, causing the electrostatic latent image to develop as a toner image. The transfer device transfers the toner image from the image carrier to the object to be transferred. The image carrier is the electrophotographic photosensitive material as described in claim 1 or 2.

8. The image forming apparatus according to claim 7, characterized in that, The developing apparatus includes a supply roller, a developing roller, and a limiting scraper. The supply roller supplies the toner, which is a non-magnetic single-component developer, to the developing roller. The developing roller holds a toner layer containing the toner on its surface. The limiting scraper limits the thickness of the toner layer retained on the surface of the developing roller. The toner contained in the toner layer, whose thickness is limited, is supplied from the surface of the developing roller to the electrostatic latent image, which is developed as the toner image.

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