Image forming apparatus

Abstract

To provide an image forming apparatus that excels in suppressing wear of the photoreceptor and suppressing contamination of the charged component. [Solution] An image forming apparatus comprising a charging device having a charging member for charging the surface of an electrophotographic photoreceptor and a cleaning member, wherein the electrophotographic photoreceptor has a conductive substrate and a photosensitive layer, the outermost layer of the electrophotographic photoreceptor contains a charge transport material and a polyarylate resin having dicarboxylic acid units represented by the following formula (A) and diol units represented by formula (B), and the cleaning member has a core metal and a foamed elastic layer helically provided on the outer circumferential surface of the core metal, and the ratio T / W of the thickness T of the foamed elastic layer to the width W of the foamed elastic layer is 0.6 or more and 1.2 or less. JPEG2026084599000056.jpg3381

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus. [Background technology]

[0002] Patent Document 1 discloses an image forming apparatus comprising: charging a latent image holder using a charging member that contacts and rotates with the latent image carrier; exposing the charged latent image holder to form an electrostatic latent image; developing the electrostatic latent image with toner carried on a toner carrier to form a toner image; transferring the toner image formed on the latent image holder onto a transfer material using a transfer member that contacts and rotates with the latent image holder; recovering the remaining toner on the latent image carrier after transfer using a cleaning means; and fixing the toner image on the transfer material after transfer using a fixing means, wherein the charging member has a material with high release properties on its surface, and the transfer member is made of foam and has a skin layer on its surface.

[0003] Patent Document 2 discloses a charging device comprising a charging member and a cleaning member having a core body and an elastic layer containing silicone oil and arranged spirally on the outer circumferential surface of the core body, wherein after bringing the elastic layer of the cleaning member and the charging member in their initial state into contact for 24 hours, the surface of the charging member is analyzed by X-ray photoelectron spectroscopy and the maximum value obtained for the Si atoms constituting the siloxane skeleton in the contact area, which is the region that was in contact with the elastic layer, and the maximum value for the Si atoms constituting the siloxane skeleton in the non-contact area, which is the region that was not in contact with the elastic layer, relative to the total number of atoms, is 6 atomic percent or less.

[0004] Patent Document 3 discloses a positively charged multilayer electrophotographic photoreceptor in which a charge transport layer consisting of at least a hole transport material and a binder resin and a charge generation / transport layer consisting of at least a charge generation material, an electron transport material, a hole transport material, and a binder resin are sequentially laminated on a conductive substrate, wherein the binder resin in the charge transport layer contains a polyarylate resin, the thickness of the charge transport layer is 10 to 40 μm, and the thickness of the charge generation / transport layer is 3 to 20 μm. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2005-309039 [Patent Document 2] Japanese Patent Publication No. 2012-78518 [Patent Document 3] Japanese Patent Publication No. 2014-146001 [Overview of the project] [Problems that the invention aims to solve]

[0006] The object of the present invention is to provide an image forming apparatus that exhibits superior wear suppression of the photoreceptor and contamination suppression of the charged member compared to a case where the outermost surface layer of the electrophotographic photoreceptor does not contain a charge transport material and a polyarylate resin having dicarboxylic acid units represented by formula (A) and diol units represented by formula (B) below, or a case where the cleaning member has a core metal and a foamed elastic layer helically provided on the outer peripheral surface of the core metal, and the ratio T / W of the thickness T of the foamed elastic layer to the width W of the foamed elastic layer is less than 0.6 or greater than 1.2. [Means for solving the problem]

[0007] Means for solving the aforementioned problem include the following embodiments. <1> An image forming apparatus including an electrophotographic photosensitive member, a charging member for charging the surface of the electrophotographic photosensitive member, and a cleaning member arranged in contact with the charging member, wherein the electrophotographic photosensitive member has a conductive substrate and a photosensitive layer disposed on the conductive substrate, and the outermost surface layer of the electrophotographic photosensitive member contains a charge transport material and a polyarylate resin having a dicarboxylic acid unit represented by the following formula (A) and a diol unit represented by the following formula (B), the cleaning member has a core metal and a foamed elastic layer provided spirally on the outer peripheral surface of the core metal, and the value of the ratio T / W of the thickness T to the width W of the foamed elastic layer is 0.6 or more and 1.2 or less.

[0008]

Chemical formula

[0009] In formula (A), Ar A1 and Ar A2 are each independently an aromatic ring which may have a substituent, L A is a single bond or a divalent linking group, and n A1 is 0, 1 or 2. In formula (B), Ar B1 and Ar B2 are each independently an aromatic ring which may have a substituent, L B is a single bond, an oxygen atom, a sulfur atom or -C(Rb 1 )(Rb 2 )-, and n B1 is 0, 1 or 2. Rb 1 and Rb 2 are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 12 carbon atoms or an aralkyl group having 7 to 20 carbon atoms, and Rb 1 and Rb 2 may combine to form a cyclic alkyl group.

[0010] <2> The image forming apparatus according to <1>, wherein the covering area ratio A of the foamed elastic layer provided on the cleaning member is 20 area% or more and 60 area% or less. <3> The surface roughness Rz of the charging member is 5 μm or more and 10 μm or less. <1> or <2> The image forming apparatus described above. <4> The outermost layer of the electrophotographic photoreceptor further comprises a polycarbonate resin. <1> ~ <3> An image forming apparatus as described in any one of the following. <5> The mass ratio of the polyarylate resin to the polycarbonate resin in the outermost layer of the electrophotographic photoreceptor is 3:7 to 7:3. <4> The image forming apparatus described above. <6> The dicarboxylic acid unit represented by formula (A) includes at least one selected from the group consisting of the dicarboxylic acid unit represented by formula (A1) (A1), the dicarboxylic acid unit represented by formula (A2) (A2), the dicarboxylic acid unit represented by formula (A3) (A3), the dicarboxylic acid unit represented by formula (A4) (A4), and the dicarboxylic acid unit represented by formula (A5) (A5). <1> ~ <5> An image forming apparatus as described in any one of the following.

[0011] [ka]

[0012] In equation (A1), n 101 n is an integer between 0 and 4, and 101 Individual Ra 101 Each of these is independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. In equation (A2), n 201 and n 202 Each of these is an independent integer between 0 and 4, and n 201 Individual Ra 201 and n 202 Individual Ra 202 Each of these is independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. In equation (A3), n 301 and n 302 Each of these is an independent integer between 0 and 4, and n 301 Individual Ra 301 and n302 Individual Ra 302 Each of these is independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. In equation (A4), n 401 n is an integer between 0 and 6, and 401 Individual Ra 401 Each of these is independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. In equation (A5), n 501 , n 502 and n 503 Each of these is an independent integer between 0 and 4, and n 501 Individual Ra 501 , n 502 Individual Ra 502 and n 503 Individual Ra 503 Each of these is independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

[0013] <7> The diol unit represented by formula (B) includes at least one selected from the group consisting of the following: diol unit represented by formula (B1) (B1), diol unit represented by formula (B2) (B2), diol unit represented by formula (B3) (B3), diol unit represented by formula (B4) (B4), diol unit represented by formula (B5) (B5), diol unit represented by formula (B6) (B6), diol unit represented by formula (B7) (B7), and diol unit represented by formula (B8) (B8). <1> ~ <6> An image forming apparatus as described in any one of the following.

[0014] [ka]

[0015] [ka]

[0016] In equation (B1), Rb 101 Rb is a branched alkyl group having 4 to 20 carbon atoms. 201 Rb is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. 401 , Rb 501 , Rb 801 and Rb 901 Each of these is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. In equation (B2), Rb 102 Rb is a linear alkyl group having 4 to 20 carbon atoms. 202 Rb is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. 402 , Rb 502 , Rb 802 and Rb 902 Each of these is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. In equation (B3), Rb 113 and Rb 213 Each of these is independently a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom, d is an integer between 7 and 15, and Rb 403 , Rb 503 , Rb 803 and Rb 903 Each of these is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. In equation (B4), Rb 104 and Rb 204 Each is independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and Rb 404 , Rb 504 , Rb 804 and Rb 904 Each of these is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. In equation (B5), Ar 105 Rb is an aryl group having 6 to 12 carbon atoms or an aralkyl group having 7 to 20 carbon atoms. 205Rb is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. 405 , Rb 505 , Rb 805 and Rb 905 Each of these is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. In equation (B6), Rb 116 and Rb 216 Each of these is independently a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom, e is an integer between 4 and 6, and Rb 406 , Rb 506 , Rb 806 and Rb 906 Each of these is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. In equation (B7), Rb 407 , Rb 507 , Rb 807 and Rb 907 Each of these is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. In equation (B8), Rb 408 , Rb 508 , Rb 808 and Rb 908 Each of these is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. <8> The polyarylate resin and the polycarbonate resin each have a constituent unit containing biphenyl represented by the following formula (BP), <1> ~ <7> An electrophotographic photoreceptor as described in any one of the following.

[0017] [ka]

[0018] In equation (BP), j is an integer between 0 and 4, and j R 1Each is independently either a methyl group or an ethyl group, k is an integer between 0 and 4, and there are k R 2 These are independently either a methyl group or an ethyl group. [Effects of the Invention]

[0019] <1> According to the present invention, an image forming apparatus is provided that is superior in terms of suppressing wear of the photoreceptor and suppressing contamination of the charged member compared to a case in which the outermost surface layer of the electrophotographic photoreceptor does not contain a charge transport material and a polyarylate resin having dicarboxylic acid units represented by the following formula (A) and diol units represented by formula (B), or a case in which the cleaning member has a core metal and a foamed elastic layer helically provided on the outer peripheral surface of the core metal, and the ratio T / W of the thickness T of the foamed elastic layer to the width W of the foamed elastic layer is less than 0.6 or greater than 1.2. <2> According to the invention, an image forming apparatus is provided that is superior in its ability to suppress contamination of the charged member compared to cases where the coverage area ratio A of the foamed elastic layer provided on the cleaning member is less than 20 area% or more than 60 area%. <3> According to the invention, an image forming apparatus is provided that exhibits superior contamination suppression of the charged member compared to cases where the surface roughness Rz of the charged member is less than 5 μm or greater than 10 μm. <4> According to the invention, an image forming apparatus is provided that is superior in terms of suppressing wear of the photoreceptor and suppressing contamination of the charged member compared to the case in which the outermost surface layer of the electrophotographic photoreceptor contains only polyarylate resin. <5> According to the invention, an image forming apparatus is provided that exhibits superior wear suppression of the photoreceptor and contamination suppression of the charged member compared to cases where the mass ratio of the polyarylate resin to the polycarbonate resin in the outermost surface layer of the electrophotographic photoreceptor is less than 3:7 or greater than 7:3. <6> According to the invention relating to the present invention, compared to the case in which the dicarboxylic acid unit represented by formula (A) does not include at least one selected from the group consisting of the dicarboxylic acid unit represented by formula (A1) (A1), the dicarboxylic acid unit represented by formula (A2) (A2), the dicarboxylic acid unit represented by formula (A3) (A3), the dicarboxylic acid unit represented by formula (A4) (A4), and the dicarboxylic acid unit represented by formula (A5) (A5), an image forming apparatus is provided that is superior in terms of suppressing wear of the photoreceptor and suppressing contamination of the charged member. <7> According to the invention relating to the present invention, compared to the case in which the diol unit represented by formula (B) does not include at least one selected from the group consisting of the diol unit represented by formula (B1) (B1), the diol unit represented by formula (B2) (B2), the diol unit represented by formula (B3) (B3), the diol unit represented by formula (B4) (B4), the diol unit represented by formula (B5) (B5), the diol unit represented by formula (B6) (B6), the diol unit represented by formula (B7) (B7), and the diol unit represented by formula (B8) (B8), an image forming apparatus is provided that is superior in terms of suppressing wear of the photoreceptor and suppressing contamination of the charged member. <8> According to the invention, an image forming apparatus is provided that is superior in suppressing wear of the photoreceptor compared to a case in which the polyarylate resin and the polycarbonate resin do not each have a constituent unit containing biphenyl represented by the following formula (BP). [Brief explanation of the drawing]

[0020] [Figure 1] This is an enlarged cross-sectional view showing a foamed elastic layer in an example of a cleaning member used in this embodiment. [Figure 2] This is a side view showing a schematic configuration of an example of a charging device used in this embodiment. [Figure 3] This is a front view showing a schematic configuration of an example of a charging device used in this embodiment. [Figure 4] This is a schematic side view showing an example of a charging member cleaning member used in the charging device used in this embodiment. [Figure 5] This is a partial cross-sectional view showing an example of the layer structure of an electrophotographic photoreceptor. [Figure 6] This is a partial cross-sectional view showing another example of the layer structure of an electrophotographic photoreceptor. [Figure 7] This is a schematic diagram showing an example of an image forming apparatus according to this embodiment. [Figure 8] This is a schematic diagram showing another example of the image forming apparatus according to this embodiment. [Modes for carrying out the invention]

[0021] The following describes in detail an embodiment that is an example of the present invention. In this specification, numerical ranges indicated using "~" represent a range that includes the numbers before and after "~" as the minimum and maximum values, respectively. In numerical ranges described stepwise within this specification, the upper or lower limit of one numerical range may be replaced with the upper or lower limit of another numerical range described stepwise. Furthermore, in numerical ranges described within this specification, the upper or lower limit of that range may be replaced with the values ​​shown in the examples. In this specification, the term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes, provided that their objective is achieved. When embodiments are described herein with reference to the drawings, the configuration of such embodiments is not limited to that shown in the drawings. Furthermore, the sizes of the components in each figure are conceptual, and the relative relationships between the components are not limited thereto. In this specification, each component may contain multiple types of the corresponding substance. In this embodiment, when referring to the amount of each component in the composition, if there are multiple types of the substance corresponding to each component in the composition, unless otherwise specified, it refers to the total amount of those multiple types of substances present in the composition. In this specification, each component may contain multiple types of particles. When multiple types of particles corresponding to each component are present in a composition, the particle size of each component refers to the value for a mixture of such multiple types of particles present in the composition, unless otherwise specified. In this specification, unless otherwise specified, the alkyl group and alkylene group include all of linear, branched and cyclic ones. In this specification, organic groups, aromatic rings, linking groups, alkyl groups, alkylene groups, aryl groups, aralkyl groups, alkoxy groups, aryloxy groups and the like may have hydrogen atoms in the groups substituted by halogen atoms. When a compound is represented by a structural formula in this specification, it may be represented by a structural formula in which the symbols (C and H) representing carbon atoms and hydrogen atoms in a hydrocarbon group and / or hydrocarbon chain are omitted. In this specification, the "constitutional unit" of a copolymer or resin is synonymous with a monomer unit. In this specification, ppm is an abbreviation of parts per million and is based on mass.

[0022] (Image forming apparatus) The image forming apparatus according to this embodiment includes a charging device having an electrophotographic photoreceptor, a charging member for charging the surface of the electrophotographic photoreceptor, and a cleaning member disposed in contact with the charging member. The electrophotographic photoreceptor has a conductive substrate and a photosensitive layer disposed on the conductive substrate, and the outermost surface layer of the electrophotographic photoreceptor contains a charge transport material and a polyarylate resin having a dicarboxylic acid unit represented by the following formula (A) and a diol unit represented by formula (B). The cleaning member has a core bar and a foamed elastic layer spirally provided on the outer peripheral surface of the core bar, and the value of the ratio T / W of the thickness T to the width W of the foamed elastic layer is 0.6 or more and 1.2 or less.

[0023]

Chemical formula

[0024] In formula (A), Ar A1 and Ar A2 are each independently an aromatic ring which may have a substituent, and L A is a single bond or a divalent linking group, and n A1 is 0, 1 or 2. In formula (B), ArB1 and Ar B2 are each independently an aromatic ring which may have a substituent, and L B is a single bond, an oxygen atom, a sulfur atom or -C(Rb 1 )(Rb 2 )-, and n B1 is 0, 1 or 2. Rb 1 and Rb 2 are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 12 carbon atoms or an aralkyl group having 7 to 20 carbon atoms, and Rb 1 and Rb 2 may combine with each other to form a cyclic alkyl group.

[0025] In a conventional image forming apparatus, when contaminants on a charging member are continuously pressed by a cleaning member, the adhesion of dirt (filming) progresses. Further, in a conventional image forming apparatus, much wear of a photoreceptor occurred. The electrophotographic photoreceptor according to the present embodiment has a polyarylate resin in which the outermost surface layer of the electrophotographic photoreceptor contains a charge transport material and a dicarboxylic acid unit represented by the following formula (A) and a diol unit represented by formula (B), and the cleaning member has a core metal and a foamed elastic layer provided spirally on the outer peripheral surface of the core metal, and the mechanism by which the value of the ratio T / W of the thickness T to the width W of the foamed elastic layer is 0.6 or more and 1.2 or less is estimated as follows. The polyarylate resin suppresses wear of the photoreceptor, and by using the cleaning member, contact pressure occurs in both continuous and intermittent portions, the contaminant removability is excellent, filming can be suppressed, and the contamination suppressibility of the charging member is excellent.

[0026] 〔Charging device〕 The image forming apparatus according to the present embodiment includes a charging device having a charging member that charges the surface of an electrophotographic photoreceptor and a cleaning member that is disposed in contact with the charging member, the cleaning member having a core metal and a foamed elastic layer provided spirally on the outer peripheral surface of the core metal, and the value of the ratio T / W of the thickness T to the width W of the foamed elastic layer being 0.6 or more and 1.2 or less.

[0027] <T / W value of foamed elastic layer> The ratio T / W of the thickness T of the foamed elastic layer to the width W of the foamed elastic layer is preferably 0.6 or more and 1.2 or less, and from the viewpoint of suppressing contamination of the charged member, it is preferably 0.60 or more and 1.05 or less, more preferably 0.70 or more and 0.95 or less, and particularly preferably 0.75 or more and 0.90 or less. The thickness T of the foamed elastic layer is the thickness of the smallest portion of the foamed elastic layer. Furthermore, as will be described later, when foamed elastic layers are provided in a double helix, triple helix, or the like, it is preferable that each of the two or more helical foamed elastic layers satisfies the T / W value. The width W of the foamed elastic layer is the width of each helical foamed elastic layer. Figure 1 is an enlarged cross-sectional view showing a foamed elastic layer in an example of a cleaning member used in this embodiment. In the cleaning member shown in Figure 1, three or more divided foamed elastic layers 104 are wound around a core metal 102 in a bundled state via a notch 110. As described above, each divided foamed elastic layer 104 (104A, 104B) has protrusions on both edges in the width direction that protrude radially outward from the core body. In the cleaning member shown in Figure 1, it is preferable that the thickness T and width W of each foamed elastic layer, i.e., both T1 / W3 and T2 / W4 in Figure 1, satisfy the T / W value.

[0028] The width W of the foamed elastic layer is preferably 1.0 mm or more and 5.0 mm or less, more preferably 1.5 mm or more and 4.0 mm or less, and particularly preferably 2.0 mm or more and 4.0 mm or less, from the viewpoint of suppressing contamination of the charged member. The thickness T of the foamed elastic layer is preferably 1.5 mm or more and 7.0 mm or less, more preferably 2.0 mm or more and 6.0 mm or less, even more preferably 2.5 mm or more and 4.5 mm or less, and particularly preferably 2.5 mm or more and 4.0 mm or less, from the viewpoint of suppressing contamination of the charged member.

[0029] In this embodiment, the thickness and width of the foamed elastic layer are measured using a laser displacement meter or calipers.

[0030] <Coverage area ratio of foamed elastic layer A> The coverage area ratio A of the foamed elastic layer provided on the cleaning member is preferably 10% to 70% of the area, more preferably 20% to 60% of the area, and particularly preferably 30% to 60% of the area, from the viewpoint of suppressing contamination of the charged member. The coverage area ratio A of the foamed elastic layer represents the proportion of the area covered by the foamed elastic layer relative to the entire circumferential surface of the core metal. In other words, it can also be expressed as the helical width R1 of the foamed elastic layer 20 / [helical width R1 of the foamed elastic layer 20 + helical pitch R2 of the foamed elastic layer 20] in Figure 4.

[0031] <Surface roughness Rz of charged material> From the viewpoint of suppressing contamination of the charged member, the surface roughness Rz is preferably 3 μm or more and 12 μm or less, preferably 5 μm or more and 10 μm or less, and particularly preferably 5 μm or more and 7 μm or less. The surface roughness Rz of the charged material is measured using a Surfcom roughness meter (manufactured by Tokyo Seimitsu Co., Ltd.).

[0032] <Number of windings of foamed elastic layer> The foamed elastic layer may be in the form of a single helix, double helix, triple helix, or the like. From the viewpoint of suppressing contamination of the charged member, the number of windings of the foamed elastic layer on the core metal is preferably 1 to 5, more preferably 1 to 3, even more preferably 2 or 3, and particularly preferably 3.

[0033] The shapes of the charging member and cleaning member according to this embodiment are not particularly limited as long as the above conditions are met. The following description will explain a charging roll and a cleaning member according to this embodiment as examples of charging members. Of course, the constituent materials of each layer of the charging member or cleaning member can be used similarly for charging members or cleaning members of other shapes.

[0034] Figure 2 is a side view showing a schematic configuration of an example of a charging device according to this embodiment. Figure 3 is a front view showing a schematic configuration of an example of a charging device according to this embodiment. Figure 4 is a schematic side view showing an example of a cleaning member used in the charging device according to this embodiment.

[0035] The charging device 1A shown in Figures 2 and 3 is a charging member for charging the surface of an image holder provided in an image forming apparatus, and comprises a charging roll 10 which is a cylindrical charging member that rotates around its axis, and a cleaning roll 12 which is a cleaning member that contacts the charging roll 10 and cleans the surface of the charging roll 10. The electrostatic roll 10 comprises, for example, a conductive core 14 and an electrostatic layer 16 formed on the outer circumference of the conductive core 14. The electrostatic layer 16 has, for example, a conductive elastic layer, and a surface layer or the like is formed as needed. As shown in Figure 4, the cleaning roll 12 is a roll-shaped member comprising a core metal 18 and a foamed elastic layer 20 formed on the outer circumference of the core metal 18, the foamed elastic layer 20 being arranged spirally on the surface of the core metal 18. Specifically, the foamed elastic layer 20 is arranged, for example, from one end of the core metal 18 to the other, wound spirally around the core metal 18 with the core metal 18's axis as the helical axis, at intervals.

[0036] As shown in Figure 3, in the charging device 1A, the charging roll 10 is pressed against the surface of the photoreceptor 24, which is the image holder, by elastic members such as coil springs 26 installed at both ends of the conductive core 14, and moves along with the photoreceptor 24. On the other hand, the cleaning roll 12 is held by a bearing 28 at the bearing distance between the conductive core 14 of the charging roll 10 and the core metal 18 of the cleaning roll 12, and the cleaning roll 12 contacts and moves along with the charging roll 10 with a predetermined nip amount. Note that the charging roll 10 and the cleaning roll 12 may be driven along with the photoreceptor 24 and the charging roll 10 respectively, or they may be driven separately.

[0037] <Cleaning materials> The following describes the layers and other components that make up the cleaning member, such as the cleaning roll 12. The configuration of the cleaning member is not particularly limited as long as it has a cleaning function for charged members such as the charged roll and satisfies the above requirements, but it is preferable that it is configured so as not to cause scratches, contamination, etc. on the surface of the charged roll that appear as image quality.

[0038] Examples of materials used for the core metal 18 of the roll-shaped cleaning roll 12 include metals such as free-cutting steel and stainless steel, and resins such as polyacetal (POM). The material and surface treatment method of the core metal 18 are selected according to the application, such as sliding properties. In particular, if the core metal 18 is made of metal, plating may be performed from the viewpoint of rust prevention. If the core metal 18 is made of a resin or other material that does not have conductivity, it may be made conductive by processing with general treatments such as plating, or it may be used as is. The outer diameter of the core metal 18 can be, for example, in the range of φ3 mm to φ6 mm.

[0039] The foamed elastic layer 20 on the core metal 18 may be a single layer or a laminated structure of two or more layers. The foamed elastic layer 20 may contain foam, or it may be a two-layer structure consisting of a solid layer and a foamed layer. By configuring the foamed elastic layer 20 so that the surface of the charged member is cleaned, the function of a cleaning roll can be obtained.

[0040] The material constituting the foamed elastic layer 20 may be a foaming resin such as polyurethane, polyethylene, polyamide, or polypropylene, or a material made by mixing one or more types of rubber materials such as silicone rubber, fluororubber, urethane rubber, ethylene-propylene-diene rubber (EPDM), nitrile rubber (NBR), chloroprene rubber (CR), chlorinated polyisoprene rubber, isoprene rubber, acrylonitrile-butadiene rubber, styrene-butadiene rubber, hydrogenated polybutadiene rubber, or butyl rubber. These may also be supplemented with foaming aids, foam stabilizers, catalysts, curing agents, plasticizers, vulcanization accelerators, and other auxiliary agents as needed.

[0041] As for the material constituting the foamed elastic layer 20, among the above materials, a material having air bubbles (so-called foam) is particularly desirable from the viewpoint of ease of foreign matter removal. In particular, to prevent damage to the surface of the charged member due to friction, and to prevent tearing or damage over a long period of time, it is preferable to use foamed polyurethane which is resistant to tearing and stretching. While there are no particular restrictions on the polyurethane, examples include those obtained by the reaction of polyols such as polyester polyols, polyether polyols, and acrylic polyols with isocyanates such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4-diphenylmethane diisocyanate, tolidine diisocyanate, and 1,6-hexamethylene diisocyanate. Chain extenders such as 1,4-butanediol and trimethylolpropane may also be mixed in. Foaming may be induced using foaming agents such as water or azo compounds such as azodicarbonamide and azobisisobutyronitrile. Furthermore, foaming aids such as foam stabilizers and catalysts may be added as needed. Furthermore, among the foamed polyurethanes mentioned above, polyether-based polyurethanes (ether-based foamed polyurethanes) that use polyether polyol as a raw material for urethane are particularly good. Compared to polyester-based polyurethanes, they are less susceptible to hydrolysis, and therefore have good storage properties under high temperature and high humidity conditions (for example, 45°C and 95% humidity).

[0042] Examples of foam stabilizers include silicone-based foam stabilizers such as the silicone-based oils mentioned above. In particular, since silicone oil is often used as a foam stabilizer when manufacturing polyether-based polyurethane, when polyether-based polyurethane is used as the material for the elastic layer 20, the foamed elastic layer 20 often contains silicone oil.

[0043] The foamed elastic layer 20 is arranged in a spiral shape as shown in Figure 4. Specifically, for example, a spiral shape with a spiral angle θ of 10° to 65° (preferably 20° to 50°) is used.

[0044] The helical angle θ mentioned above refers to the angle (acute angle) at which the longitudinal direction P (helical direction) of the foamed elastic layer 20 intersects with the axial direction Q (core axis direction) of the core metal 18. The spiral width R1 refers to the length of the core metal 18 in the foamed elastic layer 20 along the axial direction Q (core axis direction). The helical pitch R2 refers to the length between adjacent foamed elastic layers 20 along the axial direction Q (core axis direction) of the core metal 18 in the foamed elastic layer 20. Furthermore, the foamed elastic layer 20 refers to a layer made of a material that returns to its original shape even when deformed by an external force of 100 Pa.

[0045] <Electrified material> Next, we will describe the charging roll 10, which is a charging component. However, it is not limited to the following configuration as long as it has predetermined charging performance to charge the image holder, which is the object to be charged.

[0046] The electrostatic roll 10 is composed of, for example, a conductive core 14 and an electrostatic layer 16 including an elastic layer or a resin layer. The electrostatic layer 16 may consist of, for example, a single layer of elastic material, or it may be a laminated structure consisting of multiple different layers having several functions. Furthermore, it may be a material on which a surface treatment has been applied to the elastic layer. Here, "conductive" refers to a volume resistivity at 20°C: 1 × 10⁻⁶ 7 This means that the value is less than or equal to Ωcm. The same applies to subsequent values.

[0047] Examples of materials used for the conductive core 14 include metals such as free-cutting steel and stainless steel, and the material and surface treatment method may be selected as appropriate depending on the application, such as sliding properties. From the viewpoint of rust prevention, the conductive core 14 may be plated. If the material of the conductive core 14 is not conductive, it may be made conductive by processing it with a general treatment such as plating, or it may be used as is.

[0048] To obtain predetermined charging performance, the elastic layer may be a conductive elastic layer. Examples of conductive elastic layers include those composed of an elastic material such as elastic rubber, a conductive material such as carbon black or an ionic conductive agent to adjust the resistance of the conductive elastic layer, and, if necessary, additives such as softeners, plasticizers, hardeners, vulcanizing agents, vulcanization accelerators, antioxidants, silica, and fillers such as calcium carbonate. The conductive elastic layer is formed, for example, by coating the circumferential surface of the conductive core 14 with a mixture of the above materials. As a conductive agent for the purpose of adjusting the resistance value, a material dispersed in the matrix material that conducts electricity using at least one of electrons and ions as a charge carrier, such as carbon black or an ionic conductive agent, may be used. Furthermore, the elastic material may be a foam.

[0049] The elastic material constituting the conductive elastic layer is formed, for example, by dispersing a conductive agent in a rubber material. Examples of rubber materials include isoprene rubber, chloroprene rubber, epichlorohydrin rubber, butyl rubber, urethane rubber, silicone rubber, fluororubber, styrene-butadiene rubber, butadiene rubber, nitrile rubber, ethylene propylene rubber, epichlorohydrin-ethylene oxide copolymer rubber, epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer rubber, ethylene-propylene-diene terpolymer rubber (EPDM), acrylonitrile-butadiene copolymer rubber, natural rubber, and mixtures thereof. Among these, silicone rubber, ethylene propylene rubber, epichlorohydrin-ethylene oxide copolymer rubber, epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer rubber, acrylonitrile-butadiene copolymer rubber, and mixtures thereof are preferably used. These rubber materials may be foamed or non-foamed.

[0050] Examples of conductive agents include electronic conductive agents and ionic conductive agents. Examples of electronic conductive agents include carbon black such as Ketjenblack and acetylene black; pyrolytic carbon and graphite; various conductive metals or alloys such as aluminum, copper, nickel, and stainless steel; various conductive metal oxides such as tin oxide, indium oxide, titanium oxide, tin oxide-antimony oxide solid solution, and tin oxide-indium oxide solid solution; and fine powders of insulating materials whose surfaces have been treated to make them conductive. Examples of ionic conductive agents include perchlorates and chlorates such as tetraethylammonium and lauryltrimethylammonium; and perchlorates and chlorates of alkali metals such as lithium and magnesium, and alkaline earth metals.

[0051] These conductive agents may be used individually or in combination of two or more. There are no particular restrictions on the amount added, but in the case of the electronic conductive agent, for example, the range is 1 to 60 parts by mass per 100 parts by mass of rubber material, while in the case of the ionic conductive agent, for example, the range is 0.1 to 5.0 parts by mass per 100 parts by mass of rubber material.

[0052] The surface of the electrostatic roll 10 may have a surface layer formed on it to prevent contamination by foreign substances such as toner. The material of the surface layer may be any of resins and rubbers, and is not particularly limited. Examples of resins and rubbers include polyester, polyimide, copolymer nylon, silicone resin, acrylic resin, polyvinyl butyral, ethylene tetrafluoroethylene copolymer, melamine resin, fluororubber, epoxy resin, polycarbonate, polyvinyl alcohol, cellulose, polyvinylidene chloride, polyvinyl chloride, polyethylene, ethylene vinyl acetate copolymer, and the like.

[0053] Of these, polyvinylidene fluoride, tetrafluoroethylene copolymer, polyester, polyimide, and copolymerized nylon are preferably used from the viewpoint of suppressing the contamination of toner additives. Copolymerized nylon contains one or more of 610 nylon, 11 nylon, and 12 nylon as polymerization units, and other polymerization units included in this copolymer include 6 nylon and 66 nylon. Here, it is preferable that the proportion of polymerization units such as 610 nylon, 11 nylon, and 12 nylon in the copolymer is 10% or more by mass ratio.

[0054] The above-mentioned resin or rubber may be used alone, mixed with two or more other types, or mixed with other resins. Furthermore, the number-average molecular weight of the resin or rubber is preferably in the range of 1,000 to 100,000, and more preferably in the range of 10,000 to 50,000.

[0055] Furthermore, the surface layer may contain a conductive material to adjust its resistance. The conductive material is preferably one with a particle size of 3 μm or less.

[0056] Furthermore, as a conductive agent for adjusting the resistance value, a material that conducts electricity using at least one of electrons or ions as a charge carrier may be dispersed in the matrix material, such as carbon black or conductive metal oxide particles, or an ionic conductive agent.

[0057] Examples of carbon blacks used as conductive agents include, for example, Degussa's "Special Black 350," "Special Black 100," "Special Black 250," "Special Black 5," "Special Black 4," "Special Black 4A," "Special Black 550," "Special Black 6," "Color Black FW200," "Color Black FW2," and "Color Black FW2V," as well as Cabot's "MONARCH 1000," "MONARCH 1300," "MONARCH 1400," "MOGUL-L," and "REGAL 400R," all of which have a pH of 4.0 or lower.

[0058] Examples of conductive metal oxide particles used to adjust the above-mentioned resistance include conductive particles such as tin oxide, antimony-doped tin oxide, zinc oxide, anatase-type titanium oxide, and ITO. Any conductive agent that uses electrons as charge carriers may be used, and there are no particular limitations. These may be used alone or in combination of two or more types. In addition, any particle size is acceptable as long as it does not hinder the effects of this embodiment, but from the viewpoint of resistance adjustment and strength, tin oxide, antimony-doped tin oxide, and anatase-type titanium oxide are preferred, and tin oxide and antimony-doped tin oxide are more preferred.

[0059] Furthermore, the surface layer is preferably composed of a fluorine-based or silicone-based resin, and in particular, a fluorine-modified acrylate polymer. Particles may also be added to the surface layer. This makes the surface layer hydrophobic, preventing foreign matter from adhering to the charging roll 10. Additionally, insulating particles such as alumina or silica may be added to create an uneven surface on the charging roll, reducing the stress during friction with the photoreceptor drum and improving the mutual wear resistance between the charging roll and the image holder. Here, "insulating" refers to a volume resistivity at 20°C: 1 × 10⁻⁶. 13 This means that the value is greater than or equal to Ωcm. The same applies to subsequent values.

[0060] The outer diameter of the charging roll 10 is preferably 8 mm to 16 mm. From the viewpoint of miniaturizing the image forming apparatus, a diameter of 14 mm or less is preferable. If the diameter is 8 mm or less, the number of times the external additive comes into contact with each point on the circumferential surface of the charging roll increases, and the number of discharges also increases, which may be disadvantageous for maintaining charging performance. The outer diameter can be measured using commercially available calipers or laser-type outer diameter measuring devices.

[0061] The microhardness of the electrostatic roll 10 is preferably between 45° and 60°. If it is harder than 60°, it becomes difficult to ensure contact with the image holder even when a cleaning member is attached, which may result in uneven image density. If it is softer than 45°, contact with the image holder can be ensured even without a cleaning member. However, methods to lower the hardness include increasing the amount of plasticizer added or using a low-hardness material such as silicone rubber. In the former case, the plasticizer may bleed, causing problems such as image quality degradation, and in the latter case, it may result in a significant increase in cost. Furthermore, the microhardness of the charged roll 10 can be measured using the MD-1 hardness tester manufactured by Polymer Instruments Co., Ltd.

[0062] The above describes a charging roll as an example of a charging device, but the device is not limited to a roll-shaped charging device; for example, a brush-shaped, belt-shaped, or blade-shaped charging device may also be used.

[0063] [Electrophotographic photoreceptor] The image forming apparatus according to this embodiment comprises an electrophotographic photoreceptor (hereinafter also referred to as "photoreceptor"), wherein the electrophotographic photoreceptor has a conductive substrate and a photosensitive layer disposed on the conductive substrate, and the outermost surface layer of the electrophotographic photoreceptor contains a charge transport material and a polyarylate resin having dicarboxylic acid units represented by the following formula (A) and diol units represented by formula (B).

[0064] Figure 5 is a schematic partial cross-sectional view showing an example of the layer structure of a photoreceptor according to this embodiment. The photoreceptor 10A shown in Figure 5 has a stacked photoreceptor layer. The photoreceptor 10A has a structure in which a base layer 2, a charge generation layer 3, and a charge transport layer 4 are stacked in this order on a conductive substrate 1, and the charge generation layer 3 and the charge transport layer 4 constitute the photoreceptor layer 5 (a so-called functionally separated photoreceptor layer). The photoreceptor 10A may have an intermediate layer (not shown) between the base layer 2 and the charge generation layer 3. The base layer 2 may or may not be present.

[0065] Figure 6 is a schematic partial cross-sectional view showing another example of the layer configuration of a photoreceptor according to this embodiment. The photoreceptor 10B shown in Figure 6 has a single-layer photosensitive layer. The photoreceptor 10B has a structure in which an undercoat layer 2 and a photosensitive layer 5 are stacked in that order on a conductive substrate 1. The photoreceptor 10B may have an intermediate layer (not shown) between the undercoat layer 2 and the photosensitive layer 5. The undercoat layer 2 may or may not be present.

[0066] <Top surface layer> The outermost layer of the photoreceptor comprises a charge transport material and a polyarylate resin having dicarboxylic acid units represented by formula (A) and diol units represented by formula (B).

[0067] The charge transport material included in the outermost layer is the same compound as the charge transport material included in the charge transport layer described later, and the preferred compound is also the same.

[0068] The polyarylate resin contained in the outermost layer includes a polyarylate resin having dicarboxylic acid units represented by formula (A) and diol units represented by formula (B) below. In this disclosure, the polyarylate resin is referred to as polyarylate resin (PA).

[0069] The dicarboxylic acid unit (A) is a constituent unit represented by the following formula (A).

[0070] [ka]

[0071] In equation (A), Ar A1 and Ar A2 Each of these is an aromatic ring which may independently have substituents, L A is a single bond or a divalent linking group, n A1 It is 0, 1, or 2.

[0072] Ar A1 The aromatic ring may be monocyclic or polycyclic. Examples of aromatic rings include benzene rings, naphthalene rings, anthracene rings, and phenanthrene rings, with benzene rings and naphthalene rings being preferred.

[0073] Ar A1 The hydrogen atoms on the aromatic ring may be substituted with alkyl groups, aryl groups, aralkyl groups, alkoxy groups, aryloxy groups, halogen atoms, etc. A1 When the aromatic ring is substituted, preferred substituents are alkyl groups having 1 to 10 carbon atoms, aryl groups having 6 to 12 carbon atoms, and alkoxy groups having 1 to 6 carbon atoms.

[0074] Ar A2 The aromatic ring may be monocyclic or polycyclic. Examples of aromatic rings include benzene rings, naphthalene rings, anthracene rings, and phenanthrene rings, with benzene rings and naphthalene rings being preferred.

[0075] Ar A2 The hydrogen atoms on the aromatic ring may be substituted with alkyl groups, aryl groups, aralkyl groups, alkoxy groups, aryloxy groups, halogen atoms, etc. A2 When the aromatic ring is substituted, preferred substituents are alkyl groups having 1 to 10 carbon atoms, aryl groups having 6 to 12 carbon atoms, and alkoxy groups having 1 to 6 carbon atoms.

[0076] L A When it is a divalent linking group, the divalent linking group can be, for example, an oxygen atom, a sulfur atom, -C(Ra 1 )(Ra 2 )- is one example. Here, Ra 1and Ra 2 Each of these is independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms, Ra 1 and Ra 2 These may be bonded together to form a cyclic alkyl group.

[0077] Ra 1 and Ra 2 The alkyl group having 1 to 10 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group is preferably 1 to 6, more preferably 1 to 4, and even more preferably 1 or 2.

[0078] Ra 1 and Ra 2 The aryl group having 6 to 12 carbon atoms may be monocyclic or polycyclic. The number of carbon atoms in the aryl group is preferably 6 to 10, and more preferably 6.

[0079] Ra 1 and Ra 2 The alkyl group in the aralkyl group having 7 to 20 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the aralkyl group having 7 to 20 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. Ra 1 and Ra 2 The aryl group in the aralkyl group having 7 to 20 carbon atoms may be monocyclic or polycyclic. The number of carbon atoms in the aryl group is preferably 6 to 10, and more preferably 6.

[0080] The dicarboxylic acid unit (A) preferably includes at least one selected from the group consisting of dicarboxylic acid unit (A1) represented by formula (A1), dicarboxylic acid unit (A2) represented by formula (A2), dicarboxylic acid unit (A3) represented by formula (A3), dicarboxylic acid unit (A4) represented by formula (A4), and dicarboxylic acid unit (A5) represented by formula (A5). More preferably, the dicarboxylic acid unit (A) includes at least one selected from the group consisting of dicarboxylic acid unit (A2), dicarboxylic acid unit (A3), and dicarboxylic acid unit (A4), and even more preferably includes dicarboxylic acid unit (A2).

[0081] [ka]

[0082] In equation (A1), n 101 n is an integer between 0 and 4, and 101 Individual Ra 101 Each of these is independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. n 101 It is preferably 0, 1, or 2, more preferably 0 or 1, and even more preferably 0.

[0083] [ka]

[0084] In equation (A2), n 201 and n 202 Each of these is an independent integer between 0 and 4, and n 201 Individual Ra 201 and n 202 Individual Ra 202 Each of these is independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. n 201is preferably 0, 1 or 2, more preferably 0 or 1, and still more preferably 0. n 202 is preferably 0, 1 or 2, more preferably 0 or 1, and still more preferably 0.

[0085]

Chemical formula

[0086] In formula (A3), n 301 and n 302 are each independently an integer of 0 or more and 4 or less, and n 301 number of Ra 301 and n 302 number of Ra 302 are each independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. n 301 is preferably 0, 1 or 2, more preferably 0 or 1, and still more preferably 0. n 302 is preferably 0, 1 or 2, more preferably 0 or 1, and still more preferably 0.

[0087]

Chemical formula

[0088] In formula (A4), n 401 is an integer of 0 or more and 6 or less, and n 401 number of Ra 401 are each independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. n 401 is preferably an integer of 0 or more and 4 or less, more preferably 0, 1 or 2, and still more preferably 0. is still more preferably.

[0089] [ka]

[0090] In equation (A5), n 501 , n 502 and n 503 Each of these is an independent integer between 0 and 4, and n 501 Individual Ra 501 , n 502 Individual Ra 502 and n 503 Individual Ra 503 Each of these is independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. n 501 It is preferably 0, 1, or 2, more preferably 0 or 1, and even more preferably 0. n 502 It is preferably 0, 1, or 2, more preferably 0 or 1, and even more preferably 0. n 503 It is preferably 0, 1, or 2, more preferably 0 or 1, and even more preferably 0.

[0091] Ra in equation (A1) 101 Ra in equation (A2) 201 and Ra 202 Ra of formula (A3) 301 and Ra 302 Ra of formula (A4) 401 Also, Ra in formula (A5) 501 Ra 502 and Ra 503 Since the specific form and preferred form are the same, hereinafter, Ra 101 Ra 201 Ra 202 Ra 301 Ra 302 Ra 401 Ra 501 Ra 502 and Ra 503 We will refer to them collectively as "Ra" and explain them accordingly.

[0092] The alkyl group having 1 to 10 carbon atoms related to Ra may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group is preferably 1 to 6, more preferably 1 to 4, and even more preferably 1 or 2. Examples of linear alkyl groups having 1 to 10 carbon atoms include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, and n-decyl groups. Examples of branched alkyl groups having 3 to 10 carbon atoms include isopropyl group, isobutyl group, sec-butyl group, tert-butyl group, isopentyl group, neopentyl group, tert-pentyl group, isohexyl group, sec-hexyl group, tert-hexyl group, isoheptyl group, sec-heptyl group, tert-heptyl group, isooctyl group, sec-octyl group, tert-octyl group, isononyl group, sec-nonyl group, tert-nonyl group, isodecyl group, sec-decyl group, tert-decyl group, and the like. Examples of cyclic alkyl groups having 3 to 10 carbon atoms include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, and cyclodecyl groups, as well as polycyclic alkyl groups (e.g., bicyclic, tricyclic, spirocyclic) formed by linking these monocyclic alkyl groups.

[0093] The aryl group with 6 to 12 carbon atoms related to Ra may be monocyclic or polycyclic. The number of carbon atoms in the aryl group is preferably 6 to 10, and more preferably 6. Examples of aryl groups having 6 to 12 carbon atoms include phenyl, biphenyl, 1-naphthyl, and 2-naphthyl groups.

[0094] The alkyl group in the alkoxy group having 1 to 6 carbon atoms related to Ra may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having 1 to 6 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. Examples of linear alkoxy groups having 1 to 6 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an n-pentyloxy group, and an n-hexyloxy group. Examples of branched alkoxy groups having 3 to 6 carbon atoms include an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, an isopentyloxy group, a neopentyloxy group, a tert-pentyloxy group, an isohexyloxy group, a sec-hexyloxy group, a tert-hexyloxy group, and the like. Examples of cyclic alkoxy groups having 3 to 6 carbon atoms include a cyclopropoxy group, a cyclobutoxy group, a cyclopentyloxy group, a cyclohexyloxy group, and the like.

[0095] Specific examples of the dicarboxylic acid unit (A1) are shown below as the dicarboxylic acid units (A1-1) to (A1-9). The dicarboxylic acid unit (A1) is not necessarily limited thereto.

[0096]

Chemical formula

[0097] Specific examples of the dicarboxylic acid unit (A2) are shown below as the dicarboxylic acid units (A2-1) to (A2-3). The dicarboxylic acid unit (A2) is not necessarily limited thereto.

[0098]

Chemical formula

[0099] Specific examples of the dicarboxylic acid unit (A3) are shown below as the dicarboxylic acid units (A3-1) to (A3-2). The dicarboxylic acid unit (A3) is not necessarily limited thereto.

[0100]

Chemical formula

[0101] Below are examples of dicarboxylic acid units (A4-1) to (A4-3). Dicarboxylic acid units (A4) are not limited to these examples.

[0102] [ka]

[0103] Below are examples of dicarboxylic acid units (A5), specifically (A5-1) to (A5-4). Dicarboxylic acid units (A5) are not limited to these examples.

[0104] [ka]

[0105] The dicarboxylic acid unit (A) preferably includes at least one selected from the group consisting of (A1-1), (A1-7), (A2-3), (A3-2), and (A4-3) as described above, more preferably includes at least one selected from the group consisting of (A2-3), (A3-2), and (A4-3), and even more preferably includes at least (A2-3).

[0106] The polyarylate resin (PA) may contain one or more dicarboxylic acid units (A).

[0107] The mass percentage of dicarboxylic acid units (A) in the polyarylate resin (PA) is preferably 15% by mass or more and 60% by mass or less. When the mass percentage of dicarboxylic acid units (A) is 15% by mass or more, the wear resistance of the outermost layer is good. From this viewpoint, the mass percentage of dicarboxylic acid units (A) is more preferably 20% by mass or more, and even more preferably 25% by mass or more. When the mass percentage of dicarboxylic acid units (A) is 60% by mass or less, peeling of the outermost layer can be suppressed. From this viewpoint, the mass percentage of dicarboxylic acid units (A) is more preferably 55% by mass or less, and even more preferably 50% by mass or less.

[0108] Polyarylate resin (PA) may contain dicarboxylic acid units other than dicarboxylic acid unit (A). Examples of other dicarboxylic acid units include aliphatic dicarboxylic acid units (e.g., oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, alkenylsuccinic acid, adipic acid, sebacic acid), alicyclic dicarboxylic acid units (e.g., cyclohexanedicarboxylic acid), and lower alkyl ester units thereof (e.g., having 1 to 5 carbon atoms). The polyarylate resin (PA) may contain one or more of these dicarboxylic acid units.

[0109] The diol unit (B) is a constituent unit represented by the following formula (B).

[0110] [ka]

[0111] In equation (B), Ar B1 and Ar B2 Each of these is an aromatic ring which may independently have substituents, L B is a single bond, oxygen atom, sulfur atom or -C(Rb 1 )(Rb 2 )- and n B1 Rb is 0, 1, or 2. 1 and Rb 2 Each of these is independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms, and Rb 1 and Rb 2 These may be bonded together to form a cyclic alkyl group.

[0112] Ar B1 The aromatic ring may be monocyclic or polycyclic. Examples of aromatic rings include benzene rings, naphthalene rings, anthracene rings, and phenanthrene rings, with benzene rings and naphthalene rings being preferred.

[0113] Ar B1 The hydrogen atoms on the aromatic ring may be substituted with alkyl groups, aryl groups, aralkyl groups, alkoxy groups, aryloxy groups, halogen atoms, etc. B1 When the aromatic ring is substituted, preferred substituents are alkyl groups having 1 to 10 carbon atoms, aryl groups having 6 to 12 carbon atoms, and alkoxy groups having 1 to 6 carbon atoms.

[0114] Ar B2 The aromatic ring may be monocyclic or polycyclic. Examples of aromatic rings include benzene rings, naphthalene rings, anthracene rings, and phenanthrene rings, with benzene rings and naphthalene rings being preferred.

[0115] Ar B2 The hydrogen atoms on the aromatic ring may be substituted with alkyl groups, aryl groups, aralkyl groups, alkoxy groups, aryloxy groups, halogen atoms, etc. B2 When the aromatic ring is substituted, preferred substituents are alkyl groups having 1 to 10 carbon atoms, aryl groups having 6 to 12 carbon atoms, and alkoxy groups having 1 to 6 carbon atoms.

[0116] Rb 1 and Rb 2 The alkyl group having 1 to 20 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group is preferably 1 to 18, more preferably 1 to 14, and even more preferably 1 to 10.

[0117] Rb 1 and Rb 2 The aryl group having 6 to 12 carbon atoms may be monocyclic or polycyclic. The number of carbon atoms in the aryl group is preferably 6 to 10, and more preferably 6.

[0118] Rb 1 and Rb 2The alkyl group in the aralkyl group having 7 to 20 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the aralkyl group having 7 to 20 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. Rb 1 and Rb 2 The aryl group in the aralkyl group having 7 to 20 carbon atoms may be monocyclic or polycyclic. The number of carbon atoms in the aryl group is preferably 6 to 10, and more preferably 6.

[0119] The diol unit (B) preferably includes at least one selected from the group consisting of the diol unit (B1) represented by formula (B1), the diol unit (B2) represented by formula (B2), the diol unit (B3) represented by formula (B3), the diol unit (B4) represented by formula (B4), the diol unit (B5) represented by formula (B5), the diol unit (B6) represented by formula (B6), the diol unit (B7) represented by formula (B7), and the diol unit (B8) represented by formula (B8).

[0120] The diol unit (B) more preferably includes at least one selected from the group consisting of the diol unit (B1) represented by the following formula (B1), the diol unit (B2) represented by the formula (B2), the diol unit (B4) represented by the formula (B4), the diol unit (B5) represented by the formula (B5), and the diol unit (B6) represented by the formula (B6). It is even more preferable to include at least one selected from the group consisting of a diol unit represented by the following formula (B1), a diol unit represented by the following formula (B2), a diol unit represented by the following formula (B5), and a diol unit represented by the following formula (B6): It is even more preferable to include at least one selected from the group consisting of a diol unit represented by the following formula (B1), a diol unit represented by the following formula (B2), and a diol unit represented by the following formula (B6): It is most preferable that the material contains at least one selected from the group consisting of a diol unit (B1) represented by the following formula (B1) and a diol unit (B2) represented by the following formula (B2).

[0121] [ka]

[0122] In equation (B1), Rb 101 Rb is a branched alkyl group having 4 to 20 carbon atoms. 201 Rb is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. 401 , Rb 501 , Rb 801 and Rb 901 Each of these is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0123] Rb 101 The number of carbon atoms in the branched alkyl group having 4 to 20 carbon atoms is preferably 4 to 16, more preferably 4 to 12, and even more preferably 4 to 8. 101 Specific examples include isobutyl group, sec-butyl group, tert-butyl group, isopentyl group, neopentyl group, tert-pentyl group, isohexyl group, sec-hexyl group, tert-hexyl group, isoheptyl group, sec-heptyl group, tert-heptyl group, isooctyl group, sec-octyl group, tert-octyl group, isononyl group, sec-nonyl group, tert-nonyl group, isodecyl group, sec-decyl group, tert-decyl group, isododecyl group, sec-dodecyl group, tert-dodecyl group, tert-tetradecyl group, tert-pentadecyl group, and the like.

[0124] [ka]

[0125] In equation (B2), Rb 102Rb is a linear alkyl group having 4 to 20 carbon atoms. 202 Rb is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. 402 , Rb 502 , Rb 802 and Rb 902 Each of these is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0126] Rb 102 The number of carbon atoms in the linear alkyl group having 4 to 20 carbon atoms is preferably 4 to 16, more preferably 4 to 12, and even more preferably 4 to 8. 102 Specific examples include n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, tridecyl group, n-tetradecyl group, n-pentadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group, n-icosyl group, and the like.

[0127] [ka]

[0128] In equation (B3), Rb 113 and Rb 213 Each of these is independently a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom, d is an integer between 7 and 15, and Rb 403 , Rb 503 , Rb 803 and Rb 903 Each of these is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0129] Rb 113 and Rb 213 The number of carbon atoms in the linear alkyl group having 1 to 3 carbon atoms is preferably 1 or 2, and more preferably 1. Specific examples of this group include a methyl group, an ethyl group, and an n-propyl group. Rb 113 and Rb 213 The alkyl group in the alkoxy group having 1 to 4 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having 1 to 4 carbon atoms is preferably 1 to 3, more preferably 1 or 2, and even more preferably 1. Specific examples of the group include methoxy, ethoxy, n-propoxy, n-butoxy, isopropoxy, isobutoxy, sec-butoxy, tert-butoxy, cyclopropoxy, and cyclobutoxy groups. Rb 113 and Rb 213 Examples of halogen atoms involved include fluorine, chlorine, bromine, and iodine atoms.

[0130] [ka]

[0131] In equation (B4), Rb 104 and Rb 204 Each is independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and Rb 404 , Rb 504 , Rb 804 and Rb 904 Each of these is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0132] Rb 104 The alkyl group having 1 to 3 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group is preferably 1 or 2, and more preferably 1. Rb 104 Specific examples include methyl groups, ethyl groups, n-propyl groups, isopropyl groups, and cyclopropyl groups.

[0133] [ka]

[0134] In equation (B5), Ar 105 Rb is an aryl group having 6 to 12 carbon atoms or an aralkyl group having 7 to 20 carbon atoms. 205 Rb is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. 405 , Rb 505 , Rb 805 and Rb 905 Each of these is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0135] Ar 105 The aryl group having 6 to 12 carbon atoms may be monocyclic or polycyclic. The number of carbon atoms in the aryl group is preferably 6 to 10, and more preferably 6. Ar 105 The alkyl group in the aralkyl group having 7 to 20 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the aralkyl group having 7 to 20 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. 105 The aryl group in the aralkyl group having 7 to 20 carbon atoms may be monocyclic or polycyclic. The number of carbon atoms in the aryl group is preferably 6 to 10, and more preferably 6. Examples of aralkyl groups having 7 to 20 carbon atoms include benzyl group, phenylethyl group, phenylpropyl group, 4-phenylbutyl group, phenylpentyl group, phenylhexyl group, phenylheptyl group, phenyloctyl group, phenylnonyl group, naphthylmethyl group, naphthylethyl group, anthranylmethyl group, and phenylcyclopentylmethyl group.

[0136] [ka]

[0137] In equation (B6), Rb 116 and Rb 216 Each of these is independently a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom, e is an integer between 4 and 6, and Rb406 , Rb 506 , Rb 806 and Rb 906 Each of these is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0138] Rb 116 and Rb 216 The number of carbon atoms in the linear alkyl group having 1 to 3 carbon atoms is preferably 1 or 2, and more preferably 1. Specific examples of this group include a methyl group, an ethyl group, and an n-propyl group. Rb 116 and Rb 216 The alkyl group in the alkoxy group having 1 to 4 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having 1 to 4 carbon atoms is preferably 1 to 3, more preferably 1 or 2, and even more preferably 1. Specific examples of the group include methoxy, ethoxy, n-propoxy, n-butoxy, isopropoxy, isobutoxy, sec-butoxy, tert-butoxy, cyclopropoxy, and cyclobutoxy groups. Rb 116 and Rb 216 Examples of halogen atoms involved include fluorine, chlorine, bromine, and iodine atoms.

[0139] [ka]

[0140] In equation (B7), Rb 407 , Rb 507 , Rb 807 and Rb 907 Each of these is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0141] [ka]

[0142] In equation (B8), Rb 408 , Rb 508 , Rb 808 and Rb 908 Each of these is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[0143] Rb of equation (B1) 201 Rb of formula (B2) 202 Rb in formula (B4) 204 and Rb of formula (B5) 205 Since the specific form and preferred form are the same, hereinafter referred to as Rb 201 , Rb 202 , Rb 204 and Rb 205 to "Rb 200 They explain it collectively as "[...]."

[0144] Rb 200 The alkyl group having 1 to 3 carbon atoms may be linear, branched, or cyclic. The alkyl group preferably has 1 or 2 carbon atoms, and more preferably 1 carbon atom. Examples of alkyl groups having 1 to 3 carbon atoms include methyl, ethyl, n-propyl, isopropyl, and cyclopropyl groups.

[0145] Rb of equation (B1) 401 Rb of formula (B2) 402 Rb of formula (B3) 403 Rb in formula (B4) 404 Rb in formula (B5) 405 Rb in formula (B6) 406 Rb in equation (B7) 407 and Rb of formula (B8) 408 Since the specific form and preferred form are the same, hereinafter referred to as Rb 401 , Rb 402 , Rb 403 , Rb 404 , Rb 405 , Rb 406 , Rb 407 and Rb 408 to "Rb 400 They explain it collectively as "[...]."

[0146] Rb 400 The alkyl group having 1 to 4 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group is preferably 1 to 3, more preferably 1 or 2, and even more preferably 1. Examples of linear alkyl groups having 1 to 4 carbon atoms include methyl, ethyl, n-propyl, and n-butyl groups. Examples of branched alkyl groups having 3 or 4 carbon atoms include isopropyl, isobutyl, sec-butyl, and tert-butyl groups. Examples of cyclic alkyl groups having 3 or 4 carbon atoms include the cyclopropyl group and the cyclobutyl group.

[0147] Rb 400 The alkyl group in the alkoxy group having 1 to 6 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having 1 to 6 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. Examples of linear alkoxy groups having 1 to 6 carbon atoms include methoxy, ethoxy, n-propoxy, n-butoxy, n-pentyloxy, and n-hexyloxy groups. Examples of branched alkoxy groups having 3 to 6 carbon atoms include isopropoxy group, isobutoxy group, sec-butoxy group, tert-butoxy group, isopentyloxy group, neopentyloxy group, tert-pentyloxy group, isohexyloxy group, sec-hexyloxy group, and tert-hexyloxy group. Examples of cyclic alkoxy groups having 3 to 6 carbon atoms include cyclopropoxy, cyclobutoxy, cyclopentyloxy, and cyclohexyloxy groups.

[0148] Rb 400 Examples of halogen atoms involved include fluorine, chlorine, bromine, and iodine atoms.

[0149] Rb of equation (B1) 501 Rb of formula (B2) 502Rb of formula (B3) 503 Rb in formula (B4) 504 Rb in formula (B5) 505 Rb in formula (B6) 506 Rb in equation (B7) 507 and Rb of formula (B8) 508 Since the specific form and preferred form are the same, hereinafter referred to as Rb 501 , Rb 502 , Rb 503 , Rb 504 , Rb 505 , Rb 506 , Rb 507 and Rb 508 to "Rb 500 They explain it collectively as "[...]."

[0150] Rb 500 The alkyl group having 1 to 4 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group is preferably 1 to 3, more preferably 1 or 2, and even more preferably 1. Examples of linear alkyl groups having 1 to 4 carbon atoms include methyl, ethyl, n-propyl, and n-butyl groups. Examples of branched alkyl groups having 3 or 4 carbon atoms include isopropyl, isobutyl, sec-butyl, and tert-butyl groups. Examples of cyclic alkyl groups having 3 or 4 carbon atoms include the cyclopropyl group and the cyclobutyl group.

[0151] Rb 500 The alkyl group in the alkoxy group having 1 to 6 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having 1 to 6 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. Examples of linear alkoxy groups having 1 to 6 carbon atoms include methoxy, ethoxy, n-propoxy, n-butoxy, n-pentyloxy, and n-hexyloxy groups. Examples of branched alkoxy groups having 3 to 6 carbon atoms include isopropoxy group, isobutoxy group, sec-butoxy group, tert-butoxy group, isopentyloxy group, neopentyloxy group, tert-pentyloxy group, isohexyloxy group, sec-hexyloxy group, and tert-hexyloxy group. Examples of cyclic alkoxy groups having 3 to 6 carbon atoms include cyclopropoxy, cyclobutoxy, cyclopentyloxy, and cyclohexyloxy groups.

[0152] Rb 500 Examples of halogen atoms involved include fluorine, chlorine, bromine, and iodine atoms.

[0153] Rb of equation (B1) 801 Rb of formula (B2) 802 Rb of formula (B3) 803 Rb in formula (B4) 804 Rb in formula (B5) 805 Rb in formula (B6) 806 Rb in equation (B7) 807 and Rb of formula (B8) 808 Since the specific form and preferred form are the same, hereinafter referred to as Rb 801 , Rb 802 , Rb 803 , Rb 804 , Rb 805 , Rb 806 , Rb 807 and Rb 808 to "Rb 800 They explain it collectively as "[...]."

[0154] Rb 800 The alkyl group having 1 to 4 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group is preferably 1 to 3, more preferably 1 or 2, and even more preferably 1. Examples of linear alkyl groups having 1 to 4 carbon atoms include methyl, ethyl, n-propyl, and n-butyl groups. Examples of branched alkyl groups having 3 or 4 carbon atoms include isopropyl, isobutyl, sec-butyl, and tert-butyl groups. Examples of cyclic alkyl groups having 3 or 4 carbon atoms include the cyclopropyl group and the cyclobutyl group.

[0155] Rb 800 The alkyl group in the alkoxy group having 1 to 6 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having 1 to 6 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. Examples of linear alkoxy groups having 1 to 6 carbon atoms include methoxy, ethoxy, n-propoxy, n-butoxy, n-pentyloxy, and n-hexyloxy groups. Examples of branched alkoxy groups having 3 to 6 carbon atoms include isopropoxy group, isobutoxy group, sec-butoxy group, tert-butoxy group, isopentyloxy group, neopentyloxy group, tert-pentyloxy group, isohexyloxy group, sec-hexyloxy group, and tert-hexyloxy group. Examples of cyclic alkoxy groups having 3 to 6 carbon atoms include cyclopropoxy, cyclobutoxy, cyclopentyloxy, and cyclohexyloxy groups.

[0156] Rb 800 Examples of halogen atoms involved include fluorine, chlorine, bromine, and iodine atoms.

[0157] Rb of equation (B1) 901 Rb of formula (B2) 902 Rb of formula (B3) 903 Rb in formula (B4) 904 Rb in formula (B5) 905 Rb in formula (B6) 906 Rb in equation (B7) 907 and Rb of formula (B8) 908 Since the specific form and preferred form are the same, hereinafter referred to as Rb 901 , Rb 902 , Rb 903 , Rb 904 , Rb 905 , Rb 906 , Rb907 and Rb 908 to "Rb 900 They explain it collectively as "[...]."

[0158] Rb 900 The alkyl group having 1 to 4 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group is preferably 1 to 3, more preferably 1 or 2, and even more preferably 1. Examples of linear alkyl groups having 1 to 4 carbon atoms include methyl, ethyl, n-propyl, and n-butyl groups. Examples of branched alkyl groups having 3 or 4 carbon atoms include isopropyl, isobutyl, sec-butyl, and tert-butyl groups. Examples of cyclic alkyl groups having 3 or 4 carbon atoms include the cyclopropyl group and the cyclobutyl group.

[0159] Rb 900 The alkyl group in the alkoxy group having 1 to 6 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having 1 to 6 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. Examples of linear alkoxy groups having 1 to 6 carbon atoms include methoxy, ethoxy, n-propoxy, n-butoxy, n-pentyloxy, and n-hexyloxy groups. Examples of branched alkoxy groups having 3 to 6 carbon atoms include isopropoxy group, isobutoxy group, sec-butoxy group, tert-butoxy group, isopentyloxy group, neopentyloxy group, tert-pentyloxy group, isohexyloxy group, sec-hexyloxy group, and tert-hexyloxy group. Examples of cyclic alkoxy groups having 3 to 6 carbon atoms include cyclopropoxy, cyclobutoxy, cyclopentyloxy, and cyclohexyloxy groups.

[0160] Rb 900 Examples of halogen atoms involved include fluorine, chlorine, bromine, and iodine atoms.

[0161] The following are specific examples of diol units (B1), specifically (B1-1) to (B1-6). Diol units (B1) are not limited to these examples.

[0162] [ka]

[0163] The following are specific examples of diol units (B2), specifically (B2-1) to (B2-11). Diol units (B2) are not limited to these examples.

[0164] [ka]

[0165] The following are specific examples of diol units (B3), namely (B3-1) to (B3-4). Diol units (B3) are not limited to these examples.

[0166] [ka]

[0167] The following are examples of diol units (B4-1) to (B4-7). Diol units (B4) are not limited to these examples.

[0168] [ka]

[0169] The following are examples of diol units (B5-1) to (B5-6). Diol units (B5) are not limited to these examples.

[0170] [ka]

[0171] The following are specific examples of diol units (B6), namely (B6-1) to (B6-4). Diol units (B6) are not limited to these examples.

[0172] [ka]

[0173] The following are examples of diol units (B7-1) to (B7-3). Diol units (B7) are not limited to these examples.

[0174] [ka]

[0175] The following are specific examples of diol units (B8), namely (B8-1) to (B8-3). Diol units (B8) are not limited to these examples.

[0176] [ka]

[0177] The diol units (B) contained in the polyarylate resin (PA) may be one type or two or more types.

[0178] The mass percentage of diol units (B) in the polyarylate resin (PA) is preferably 25% by mass or more and 80% by mass or less. When the mass percentage of diol units (B) is 25% by mass or more, peeling of the outermost layer can be suppressed. From this viewpoint, a mass percentage of diol units (B) of 30% by mass or more is more preferable, and 35% by mass or more is even more preferable. When the mass percentage of diol units (B) is 80% by mass or less, it is possible to maintain solubility in the coating solution for forming the outermost layer and improve wear resistance. From this viewpoint, the mass percentage of diol units (B) is more preferably 75% by mass or less, and even more preferably 70% by mass or less.

[0179] Polyarylate resin (PA) may contain other diol units besides diol unit (B). Examples of other diol units include aliphatic diol units (e.g., ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol) and alicyclic diol units (e.g., cyclohexanediol, cyclohexanedimethanol, hydrogenated bisphenol A). The polyarylate resin (PA) may contain one or more of these diol units.

[0180] The ends of the polyarylate resin (PA) may be sealed or modified with end-capping agents or molecular weight modifiers used during manufacturing. Examples of end-capping agents or molecular weight modifiers include monohydric phenols, monohydric acid chlorides, monohydric alcohols, and monohydric carboxylic acids. Examples of monohydric phenols include phenol, o-cresol, m-cresol, p-cresol, o-ethylphenol, m-ethylphenol, p-ethylphenol, o-propylphenol, m-propylphenol, p-propylphenol, o-tert-butylphenol, m-tert-butylphenol, p-tert-butylphenol, pentylphenol, hexylphenol, octylphenol, nonylphenol, 2,6-dimethylphenol derivatives, 2-methylphenol derivatives, o-phenylphenol, m Examples include -phenylphenol, p-phenylphenol, o-methoxyphenol, m-methoxyphenol, p-methoxyphenol, 2,3,5-trimethylphenol, 2,3,6-trimethylphenol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, 3,5-xylenol, 2-phenyl-2-(4-hydroxyphenyl)propane, 2-phenyl-2-(2-hydroxyphenyl)propane, and 2-phenyl-2-(3-hydroxyphenyl)propane. Examples of monovalent acid chlorides include monofunctional acid halides such as benzoyl chloride, benzoic acid chloride, methanesulfonyl chloride, phenylchloroformate, acetate chloride, butyrate chloride, octic acid chloride, benzenesulfonyl chloride, benzenesulfinyl chloride, sulfinyl chloride, benzenephosphonyl chloride, and their substituted derivatives. Examples of monohydric alcohols include methanol, ethanol, n-propanol, isopropanol, n-butanol, 2-butanol, pentanol, hexanol, dodecyl alcohol, stearyl alcohol, benzyl alcohol, and phenethyl alcohol. Examples of monocarboxylic acids include acetic acid, propionic acid, octanoic acid, cyclohexanecarboxylic acid, benzoic acid, toluic acid, phenylacetic acid, p-tert-butylbenzoic acid, and p-methoxyphenylacetic acid.

[0181] The weight-average molecular weight of the polyarylate resin (PA) is preferably 30,000 to 300,000, more preferably 40,000 to 250,000, and even more preferably 50,000 to 200,000. The molecular weight of polyarylate resin (PA) is the molecular weight in polystyrene equivalent, measured by GPC (gel permeation chromatography). Tetrahydrofuran is used as the eluent in GPC.

[0182] Polyarylate resins (PA) can be obtained by polycondensation of monomers that give dicarboxylic acid units (A) and monomers that give diol units (B), along with other monomers as needed, using conventional methods. Methods for the polycondensation of monomers include interfacial polymerization, solution polymerization, and melt polymerization. Interfacial polymerization is a polymerization method that obtains polyester by mixing a divalent carboxylic acid halide dissolved in an organic solvent immiscible with water with a divalent alcohol dissolved in an alkaline aqueous solution. Literature on interfacial polymerization includes WMERECKSON, J. Poly. Sci., XL399, 1959, and Japanese Patent Publication No. 40-1959. Because interfacial polymerization is faster than solution polymerization, it can suppress the hydrolysis of divalent carboxylic acid halides, resulting in the acquisition of high molecular weight polyarylate resins (PA).

[0183] Other resins that can be included in the outermost layer include polyarylate resins other than polyarylate resin (PA), polycarbonate resins, polyester resins other than polyarylate resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinylidene chloride resins, polystyrene resins, polyvinyl acetate resins, styrene-butadiene copolymers, vinylidene chloride-acrylonitrile copolymers, vinyl chloride-vinyl acetate copolymers, vinyl chloride-vinyl acetate-maleic anhydride copolymers, silicone resins, silicone alkyd resins, phenol-formaldehyde resins, styrene-alkyd resins, poly-N-vinylcarbazole, polysilanes, etc. Two or more resins can be used in any combination from these resins.

[0184] From the viewpoint of abrasion resistance of the outermost layer, it is preferable that the resin included in the outermost layer contains polyarylate resin and polycarbonate resin. The form containing polyarylate resin and polycarbonate resin is also preferable from the viewpoint of forming a fine phase separation structure in the outermost layer.

[0185] The proportion of polyarylate resin in the total amount of polyarylate resin and polycarbonate resin contained in the outermost layer of the photoreceptor is preferably 20% by mass or more and 80% by mass or less, more preferably 25% by mass or more and 75% by mass or less, and even more preferably 30% by mass or more and 70% by mass or less, from the viewpoint of forming a fine phase separation structure in the outermost layer.

[0186] Polyarylate resins improve the abrasion resistance of the outermost layer because the resin molecules are bound together by intermolecular forces through the stacking of aromatic rings. A polycondensate of bisphenols and aromatic divalent carboxylic acids is preferred as the polyarylate resin. A preferred form of polyarylate resin is the polyarylate resin (PA) described later.

[0187] As the polycarbonate resin, a polycarbonate resin having continuous structural units with aromatic rings is preferred. In this polycarbonate resin, the resin molecules are bound together by intermolecular forces due to the stacking of aromatic rings, improving the abrasion resistance of the outermost layer. A preferred form of the polycarbonate resin is specifically the polycarbonate resin disclosed in Japanese Patent Application Publication No. 2023-121553. A more preferred form of the polycarbonate resin is the polycarbonate resin used in the examples described later.

[0188] As for the combination of polyarylate resin and polycarbonate resin, a combination of resins in which both have a structural unit containing biphenyl represented by the following formula (BP) is preferred.

[0189] [ka]

[0190] In equation (BP), j is an integer between 0 and 4, and j R 1 Each is independently either a methyl group or an ethyl group, k is an integer between 0 and 4, and there are k R 2 These are independently either a methyl group or an ethyl group.

[0191] The biphenyl represented by formula (BP) may be the entire structure or a part of the structure obtained by removing the ester bond (-C(=O)O-) or carbonate bond (-OC(=O)O-) from the constituent unit containing the biphenyl represented by formula (BP). In other words, the right and left ends of the biphenyl represented by formula (BP) may be independently directly bonded to an ester bond or a carbonate bond, or they may be bonded to an ester bond or a carbonate bond via other atoms or groups of atoms.

[0192] j is an integer between 0 and 4, preferably between 0 and 3, more preferably between 0 and 2, even more preferably 0 or 1, and particularly preferably 0. If j is an integer greater than or equal to 1, then j R 1 Each of these is independently a methyl group or an ethyl group, and a methyl group is preferred.

[0193] k is an integer between 0 and 4, preferably between 0 and 3, more preferably between 0 and 2, even more preferably 0 or 1, and particularly preferably 0. If k is an integer greater than or equal to 1, then k R 2 Each of these is independently a methyl group or an ethyl group, and a methyl group is preferred.

[0194] The biphenyl represented by formula (BP) is preferably 4,4'-biphenyl in terms of its linkage position in the main chain.

[0195] As for the combination of polyarylate resin and polycarbonate resin, a combination of a polyarylate resin having at least one of dicarboxylic acid units (A2-3) and diol units (B7-1) and a polycarbonate resin having constituent units (Cb7-1) is particularly preferred.

[0196] [ka]

[0197] The outermost layer preferably further contains a phenolic compound. Examples of phenolic compounds included in the outermost layer include phenol, cresol, catechol, resorcinol, hydroquinone, naphthol, and bisphenol (bisphenol A, AP, AF, B, BP, C, C2, E, F, G, M, S, P, PH, TMC, Z). A single phenolic compound may be used, or two or more may be used in combination.

[0198] Hindered phenol compounds are also included as phenolic compounds in the outermost layer. From the viewpoint of suppressing oxidative degradation of the outermost layer, it is preferable that the phenolic compounds in the outermost layer include hindered phenol compounds. Hindered phenol compounds are generally compounds in which at least one of the ortho positions of the hydroxyl group of phenol is substituted with a bulky group, and are known to exhibit an antioxidant effect on the composition.

[0199] Examples of hindered phenol compounds include the following: • Alkylated monophenol compounds and their derivatives: e.g., 2,6-di-t-butyl-4-methylphenol, 2,6-di-t-butyl-4-ethylphenol, octyl-3,5-di-t-butyl-4-hydroxyhydrocinnamate • Alkylated hydroquinone compounds and their derivatives: e.g., 2,5-di-t-butylhydroquinone, 2,5-di-t-amylhydroquinone • Alkylthiomethylphenol compounds and their derivatives: For example, 2,4-dioctylthiomethyl-6-t-butylphenol, 2,4-dioctylthiomethyl-6-methylphenol, 2,4-dioctylthiomethyl-6-ethylphenol, 2,6-didodecylthiomethyl-4-nonylphenol • Alkylidenebisphenol compounds and their derivatives: e.g., 4,4'-Butylidenebis(6-t-butyl-3-methylphenol), 2,2'-Methylenebis(6-t-butyl-4-methylphenol), 2,2'-Methylenebis(6-t-butyl-4-ethylphenol), 2-t-butyl-6-(3-t-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate, 3,9-bis[2-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane

[0200] Commercially available hindered phenol compounds include ADEKA Corporation's "ADEKA Stab AO-80," "ADEKA Stab AO-60," "ADEKA Stab AO-50," "ADEKA Stab AO-40," "ADEKA Stab AO-30," "ADEKA Stab AO-20," and "ADEKA Stab AO-330," BASF Japan Ltd.'s "Irganox 1010," "Irganox 245," "Irganox 1076," and "Irganox 1520," and Sumitomo Chemical Co., Ltd.'s "Sumilizer GA-80," "Sumilizer GM," and "Sumilizer GS."

[0201] Hindered phenol compounds may be used individually or in combination of two or more.

[0202] The content of phenolic compounds in the outermost layer is preferably 0.1% to 20% by mass, more preferably 0.5% to 10% by mass, and even more preferably 1% to 5% by mass, based on the total mass of the outermost layer, from the viewpoint of promoting phase separation of two or more types of resins during the formation of the outermost layer and forming a fine phase separation structure in the outermost layer.

[0203] The outermost surface layer of the photoreceptor preferably contains 5% by mass or less of fluororesin particles, preferably 1% by mass or less, and more preferably 0% by mass (i.e., it does not contain fluororesin particles). Given the high likelihood of increased regulations on the manufacture and use of organofluorine compounds in the future, the above-mentioned range for the content of fluororesin particles is preferable.

[0204] The thickness of the outermost layer should be set according to the function of that layer. When the charge transport layer is the outermost layer, the thickness of the outermost layer is preferably 5 μm or more and 50 μm or less, more preferably 8 μm or more and 45 μm or less, and even more preferably 10 μm or more and 40 μm or less. When a single-layer photosensitive layer is the outermost layer, the thickness of the outermost layer is preferably 5 μm or more and 50 μm or less, more preferably 8 μm or more and 45 μm or less, and even more preferably 10 μm or more and 40 μm or less.

[0205] The method for forming the outermost layer is the same as the method for forming the charge transport layer and the single-layer photosensitive layer, which will be described later.

[0206] The following provides a detailed explanation of each layer of the photoreceptor.

[0207] <Conductive substrate> Examples of conductive substrates include metal plates, metal drums, and metal belts containing metals (aluminum, copper, zinc, chromium, nickel, molybdenum, vanadium, indium, gold, platinum, etc.) or alloys (stainless steel, etc.). Other examples of conductive substrates include paper, resin films, and belts coated, vapor-deposited, or laminated with conductive compounds (e.g., conductive polymers, indium oxide, etc.), metals (e.g., aluminum, palladium, gold, etc.) or alloys. Here, "conductive" refers to a volume resistivity of 1 × 10⁻⁶. 13 This refers to a value less than Ω·cm.

[0208] When an electrophotographic photoreceptor is used in a laser printer, the surface of the conductive substrate is preferably roughened to a center-line average roughness Ra of 0.04 μm to 0.5 μm in order to suppress interference fringes that occur when irradiated with laser light. When non-interfering light is used as the light source, roughening to prevent interference fringes is not particularly necessary, but it is suitable for a longer lifespan because it suppresses the occurrence of defects due to surface irregularities of the conductive substrate.

[0209] Methods for roughening a surface include, for example, wet honing, which involves suspending an abrasive in water and spraying it onto a conductive substrate; centerless grinding, which involves pressing a conductive substrate against a rotating grinding wheel and continuously grinding it; and anodizing.

[0210] One method for roughening the surface is to disperse conductive or semiconductive powder in a resin without roughening the surface of the conductive substrate, to form a layer on the surface of the conductive substrate, and then roughen the surface with the particles dispersed in that layer.

[0211] Anodizing roughening treatment involves forming an oxide film on the surface of a conductive substrate (e.g., aluminum) by anodizing it in an electrolyte solution. Examples of electrolyte solutions include sulfuric acid solution and oxalic acid solution. However, the porous anodic oxide film formed by anodizing is chemically active, easily contaminated, and exhibits large resistance fluctuations depending on the environment. Therefore, it is preferable to perform a sealing treatment on the porous anodic oxide film to block the micropores of the oxide film by volume expansion due to a hydration reaction using pressurized steam or boiling water (metal salts such as nickel may be added), thereby converting it into a more stable hydrated oxide.

[0212] The thickness of the anodic oxide film is preferably, for example, 0.3 μm to 15 μm. When the film thickness is within this range, it tends to exhibit barrier properties against injection and tends to suppress the increase in residual potential due to repeated use.

[0213] The conductive substrate may be treated with an acidic treatment solution or with boehmite. Treatment with an acidic solution is carried out, for example, as follows: First, an acidic solution containing phosphoric acid, chromic acid, and hydrofluoric acid is prepared. The mixing ratio of phosphoric acid, chromic acid, and hydrofluoric acid in the acidic solution is, for example, in the range of 10% to 11% by mass for phosphoric acid, 3% to 5% by mass for chromic acid, and 0.5% to 2% by mass for hydrofluoric acid, and the total concentration of these acids is preferably in the range of 13.5% to 18% by mass. The treatment temperature is preferably, for example, 42°C to 48°C. The film thickness is preferably 0.3 μm to 15 μm.

[0214] The boehmite treatment is carried out, for example, by immersing the material in pure water at 90°C to 100°C for 5 to 60 minutes, or by contacting it with heated steam at 90°C to 120°C for 5 to 60 minutes. The film thickness is preferably 0.1 μm to 5 μm. This can be further treated with anodic oxidation using an electrolyte solution with low film solubility, such as adipic acid, boric acid, borate, phosphate, phthalate, maleate, benzoate, tartrate, or citrate.

[0215] <Sublayer> The undercoat layer is, for example, a layer containing inorganic particles and a binder resin.

[0216] As for inorganic particles, for example, powder resistance (volume resistivity) 1 × 10 2 Ω cm or more 1×10 11 Examples include inorganic particles with a size of Ω·cm or less. Among these, suitable inorganic particles having the above-mentioned resistance values ​​include metal oxide particles such as tin oxide particles, titanium oxide particles, zinc oxide particles, and zirconium oxide particles, with zinc oxide particles being particularly preferred.

[0217] The specific surface area of ​​inorganic particles using the BET method is, for example, 10 m². 2 A value of 1g or more is preferable. The volume-average particle size of the inorganic particles is preferably between 50 nm and 2000 nm (preferably between 60 nm and 1000 nm).

[0218] The inorganic particle content is preferably 10% by mass or more and 80% by mass or less relative to the binder resin, and more preferably 40% by mass or more and 80% by mass or less.

[0219] The inorganic particles may be surface-treated. Two or more types of inorganic particles with different surface treatments or particle sizes may be mixed and used.

[0220] Examples of surface treatment agents include silane coupling agents, titanate-based coupling agents, aluminum-based coupling agents, and surfactants. Silane coupling agents are particularly preferred, and silane coupling agents having an amino group are more preferred.

[0221] Examples of silane coupling agents having an amino group include, but are not limited to, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, and N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane.

[0222] Silane coupling agents may be used in combination of two or more types. For example, a silane coupling agent having an amino group may be used in combination with another silane coupling agent. Examples of other silane coupling agents include, but are not limited to, vinyltrimethoxysilane, 3-methacrylateoxypropyl-tris(2-methoxyethoxy)silane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, and 3-chloropropyltrimethoxysilane.

[0223] The surface treatment method using the surface treatment agent may be any known method, and may be either a dry or wet method.

[0224] The amount of surface treatment agent applied is preferably, for example, 0.5% by mass or more and 10% by mass or less relative to the inorganic particles.

[0225] In this case, it is preferable for the underlayer to contain electron-accepting compounds (acceptor compounds) along with inorganic particles, from the viewpoint of improving the long-term stability of electrical properties and carrier blocking ability.

[0226] Examples of electron-accepting compounds include electron-transporting substances such as: compounds having an anthraquinone structure; quinone compounds such as chloranil and bromoanil; tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone and 2,4,5,7-tetranitro-9-fluorenone; oxadiazole compounds such as 2-(4-biphenyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole, 2,5-bis(4-naphthyl)-1,3,4-oxadiazole, and 2,5-bis(4-diethylaminophenyl)-1,3,4-oxadiazole; xanthone compounds; thiophene compounds; diphenoquinone compounds such as 3,3',5,5'-tetra-t-butyldiphenoquinone; and benzophenone compounds such as 4-hydroxybenzophenone and 2,3,4-trihydroxybenzophenone. In particular, compounds having an anthraquinone structure are preferred as electron-accepting compounds. Examples of compounds having an anthraquinone structure include hydroxyanthraquinone compounds, aminoanthraquinone compounds, and aminohydroxyanthraquinone compounds. Specifically, examples of preferred compounds include anthraquinone, alizarin, quinizarin, anthralphine, purpurin, 4-ethoxy-1,2-hydroxy-9,10-anthraquinone, and their derivatives.

[0227] The electron-accepting compound may be dispersed in the underlayer together with inorganic particles, or it may be present attached to the surface of the inorganic particles.

[0228] Methods for attaching electron-accepting compounds to the surface of inorganic particles include, for example, dry methods or wet methods.

[0229] The dry method involves, for example, adding an electron-accepting compound, either directly or dissolved in an organic solvent, dropwise while stirring inorganic particles with a mixer that has a high shear force, or spraying it with dry air or nitrogen gas, to adhere the electron-accepting compound to the surface of the inorganic particles. When adding or spraying the electron-accepting compound, it is preferable to do so at a temperature below the boiling point of the solvent. After adding or spraying the electron-accepting compound, further baking at 100°C or higher may be performed. The baking temperature and time are not particularly limited as long as electrophotographic characteristics can be obtained.

[0230] The wet method involves dispersing inorganic particles in a solvent using, for example, a stirrer, ultrasonic disperser, sand mill, attritor, or ball mill, while adding an electron-accepting compound. After stirring or dispersion, the solvent is removed, and the electron-accepting compound adheres to the surface of the inorganic particles. Solvent removal methods include, for example, filtration or distillation. After solvent removal, further baking at 100°C or higher may be performed. The baking temperature and time are not particularly limited as long as electrophotographic characteristics can be obtained. In the wet method, the water content of the inorganic particles may be removed before adding the electron-accepting compound. Examples of this include removing water while stirring and heating in the solvent, or removing water by azeotrope with the solvent.

[0231] The electron-accepting compound may be applied before or after surface treatment with a surface treatment agent to the inorganic particles, or it may be applied simultaneously with the surface treatment with the surface treatment agent.

[0232] The content of the electron-accepting compound is preferably, for example, 0.01% by mass or more and 20% by mass or less relative to the inorganic particles, and more preferably 0.01% by mass or more and 10% by mass or less.

[0233] Examples of known polymer compounds used as the binder resin for the undercoat include acetal resin (e.g., polyvinyl butyral), polyvinyl alcohol resin, polyvinyl acetal resin, casein resin, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, unsaturated polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, urea resin, phenol resin, phenol-formaldehyde resin, melamine resin, urethane resin, alkyd resin, epoxy resin, zirconium chelate compounds, titanium chelate compounds, aluminum chelate compounds, titanium alkoxide compounds, organic titanium compounds, and silane coupling agents. Examples of binder resins used in the undercoat include charge-transporting resins having charge-transporting groups, conductive resins (e.g., polyaniline), and the like.

[0234] Among these, a resin insoluble in the coating solvent of the upper layer is preferred as the binder resin used for the undercoat layer. In particular, a resin obtained by the reaction of a curing agent with at least one resin selected from the group consisting of thermosetting resins such as urea resin, phenol resin, phenol-formaldehyde resin, melamine resin, urethane resin, unsaturated polyester resin, alkyd resin, and epoxy resin is preferred. When using two or more of these binder resins in combination, the mixing ratio is set as needed.

[0235] The undercoat may contain various additives to improve electrical properties, environmental stability, and image quality. Examples of known additives include electron-transporting pigments such as polycyclic condensation and azo pigments, zirconium chelate compounds, titanium chelate compounds, aluminum chelate compounds, titanium alkoxide compounds, organic titanium compounds, and silane coupling agents. As mentioned above, silane coupling agents are used for surface treatment of inorganic particles, but they may also be added to the undercoat as additives.

[0236] Examples of silane coupling agents used as additives include vinyltrimethoxysilane, 3-methacrylateoxypropyl-tris(2-methoxyethoxy)silane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, and 3-chloropropyltrimethoxysilane.

[0237] Examples of zirconium chelate compounds include zirconium butoxide, ethyl zirconium acetate, zirconium triethanolamine, acetylacetonate zirconium butoxide, ethyl acetate zirconium butoxide, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octanoate, zirconium naphthenate, zirconium laurate, zirconium stearate, zirconium isostearate, methacrylate zirconium butoxide, stearate zirconium butoxide, and isostearate zirconium butoxide.

[0238] Examples of titanium chelate compounds include tetraisopropyl titanate, tetran-butyl titanate, butyl titanate dimer, tetra(2-ethylhexyl) titanate, titanium acetylacetonate, polytitanium acetylacetonate, titanium octylene glycolate, titanium lactate ammonium salt, titanium lactate, titanium lactate ethyl ester, titanium triethanolamine, and polyhydroxytitanium stearate.

[0239] Examples of aluminum chelating compounds include aluminum isopropylate, monobutoxyaluminum diisopropylate, aluminum butyrate, diethylacetoacetate aluminum diisopropylate, and aluminum tris(ethylacetoacetate).

[0240] These additives may be used individually or as a mixture or polycondensate of multiple compounds.

[0241] The underlayer should ideally have a Vickers hardness of 35 or higher. The surface roughness (ten-point average roughness) of the undercoat layer should be adjusted to between 1 / (4n) (where n is the refractive index of the upper layer) and 1 / 2 of the exposure laser wavelength λ used, in order to suppress moiré patterns. Resin particles may be added to the undercoat to adjust the surface roughness. Examples of resin particles include silicone resin particles and cross-linked polymethyl methacrylate resin particles. The surface of the undercoat may also be polished to adjust the surface roughness. Polishing methods include buffing, sandblasting, wet honing, and grinding.

[0242] The formation of the undercoat is not particularly limited, and known formation methods can be used. For example, it can be carried out by forming a coating film of an undercoat-forming solution obtained by adding the above components to a solvent, drying the coating film, and heating it if necessary.

[0243] Solvents for preparing the coating solution for forming the undercoat include known organic solvents such as alcohol-based solvents, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, ketone-based solvents, ketone alcohol-based solvents, ether-based solvents, and ester-based solvents. Specific examples of these solvents include common organic solvents such as methanol, ethanol, n-propanol, iso-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, and toluene.

[0244] Known methods for dispersing inorganic particles when preparing a coating solution for forming an undercoat include, for example, roll mills, ball mills, vibrating ball mills, attritors, sand mills, colloid mills, and paint shakers.

[0245] Conventional methods for applying the undercoating solution onto a conductive substrate include, for example, the blade coating method, wire bar coating method, spray coating method, immersion coating method, bead coating method, air knife coating method, and curtain coating method.

[0246] The thickness of the undercoat layer is preferably set to a range of 15 μm or more, and more preferably within the range of 20 μm to 50 μm.

[0247] <Middle class> The intermediate layer is, for example, a layer containing a resin. Examples of resins used in the intermediate layer include polymer compounds such as acetal resin (e.g., polyvinyl butyral), polyvinyl alcohol resin, polyvinyl acetal resin, casein resin, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, and melamine resin. The intermediate layer may contain an organometallic compound. Examples of organometallic compounds used in the intermediate layer include those containing metal atoms such as zirconium, titanium, aluminum, manganese, and silicon. The compounds used in these intermediate layers may be used individually, as a mixture of multiple compounds, or as polycondensates.

[0248] Among these, the intermediate layer is preferably a layer containing an organometallic compound that contains zirconium atoms or silicon atoms.

[0249] The formation of the intermediate layer is not particularly limited, and known formation methods can be used. For example, it can be carried out by forming a coating film of an intermediate layer-forming coating solution obtained by adding the above components to a solvent, drying the coating film, and heating it if necessary. Conventional methods such as immersion coating, push-up coating, wire bar coating, spray coating, blade coating, air knife coating, and curtain coating are used to form the intermediate layer.

[0250] The thickness of the intermediate layer is preferably set in the range of 0.1 μm to 3 μm. The intermediate layer may also be used as a base layer.

[0251] <Charge generation layer> The charge generation layer is, for example, a layer containing a charge generation material and a binder resin. Alternatively, the charge generation layer may be a vapor-deposited layer of the charge generation material. A vapor-deposited layer of the charge generation material is suitable when using non-coherent light sources such as LEDs (Light Emitting Diodes) or organic EL (Electro-Luminescence) image arrays.

[0252] Examples of charge-generating materials include azo pigments such as bisazo and trisazo; fused aromatic pigments such as dibromoanthonthrone; perylene pigments; pyrrolopyrrole pigments; phthalocyanine pigments; zinc oxide; and trigonal selenium.

[0253] Among these, in order to accommodate laser exposure in the near-infrared region, it is preferable to use a metal phthalocyanine pigment or a metal-free phthalocyanine pigment as the charge generating material. Specifically, for example, hydroxygallium phthalocyanine; chlorogallium phthalocyanine; dichlorotin phthalocyanine; and titanyl phthalocyanine are more preferable.

[0254] On the other hand, to accommodate laser exposure in the near-ultraviolet region, preferred charge-generating materials include fused aromatic pigments such as dibromoanthoten; thioindigo pigments; porphyrazine compounds; zinc oxide; trigonal selenium; and bisazo pigments.

[0255] The above charge generating material may also be used when using non-coherent light sources such as LEDs and organic EL image arrays, which have a central emission wavelength between 450 nm and 780 nm.

[0256] When n-type semiconductors such as fused aromatic pigments, perylene pigments, and azo pigments are used as charge-generating materials, dark currents are less likely to be generated, and image defects called black spots can be suppressed even in thin films. The n-type is determined using the commonly used time-of-flight method, which is determined by the polarity of the photocurrent that flows, and materials that readily carry electrons as carriers rather than holes are classified as n-type.

[0257] The binder resin used in the charge generation layer can be selected from a wide range of insulating resins, or it may be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, polyvinylpyrene, and polysilane. Examples of binder resins include polyvinyl butyral resin, polyarylate resin (such as polycondensates of bisphenols and aromatic divalent carboxylic acids), polycarbonate resin, polyester resin, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyamide resin, acrylic resin, polyacrylamide resin, polyvinylpyridine resin, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol resin, and polyvinylpyrrolidone resin. Here, "insulating properties" refer to a volume resistivity of 1 × 10⁻⁶. 13This refers to a density of Ω·cm or greater. These binder resins can be used individually or in mixtures of two or more types.

[0258] The mixing ratio of the charge-generating material to the binder resin is preferably within the range of 10:1 to 1:10 by mass ratio.

[0259] The charge generation layer may also contain other known additives.

[0260] The formation of the charge generation layer is not particularly limited, and known formation methods can be used. For example, it can be carried out by forming a coating film of a coating solution for forming a charge generation layer by adding the above components to a solvent, drying the coating film, and heating it as necessary. The charge generation layer may also be formed by vapor deposition of a charge generation material. Formation of the charge generation layer by vapor deposition is particularly suitable when using fused ring aromatic pigments or perylene pigments as the charge generation material.

[0261] Solvents for preparing the coating solution for forming the charge generation layer include methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, and toluene. These solvents may be used individually or in mixtures of two or more.

[0262] Methods for dispersing particles (e.g., charge-generating material) in a coating solution for forming a charge-generating layer include, for example, media dispersers such as ball mills, vibrating ball mills, attritors, sand mills, and horizontal sand mills, as well as media-less dispersers such as stirrers, ultrasonic dispersers, roll mills, and high-pressure homogenizers. Examples of high-pressure homogenizers include collision methods, in which the dispersion is dispersed by liquid-liquid collisions or liquid-wall collisions under high pressure, and penetration methods, in which the dispersion is dispersed by penetrating fine channels under high pressure. During dispersion, it is effective to set the average particle size of the charge-generating material in the coating solution for forming the charge-generating layer to 0.5 μm or less, preferably 0.3 μm or less, and more preferably 0.15 μm or less.

[0263] Conventional methods for applying the charge-generating layer forming solution onto the undercoat (or intermediate layer) include, for example, the blade coating method, wire bar coating method, spray coating method, immersion coating method, bead coating method, air knife coating method, and curtain coating method.

[0264] The thickness of the charge generation layer is preferably set within the range of 0.1 μm to 5.0 μm, and more preferably within the range of 0.2 μm to 2.0 μm.

[0265] <Charge transport layer> The charge transport layer is, for example, a layer containing a binder resin and a charge transport material. The charge transport layer may also be a layer containing a polymer charge transport material.

[0266] Examples of charge transport materials include quinone compounds such as p-benzoquinone, chloranil, bromanil, and anthraquinone; tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone; xanthone compounds; benzophenone compounds; cyanovinyl compounds; and ethylene compounds, which are electron transport compounds. Other examples of charge transport materials include hole transport compounds such as triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted ethylene compounds, stilbene compounds, anthracene compounds, and hydrazone compounds. These charge transport materials may be used individually or in combination of two or more, but are not limited to these.

[0267] As charge transport materials, from the viewpoint of charge mobility, the triarylamine derivative shown in the following structural formula (a-1) and the benzidine derivative shown in the following structural formula (a-2) are preferred.

[0268] [ka]

[0269] In structural formula (a-1), Ar T1 Ar T2, and Ar T3 Each is independently a substituted or unsubstituted aryl group, -C6H4-C(R T4 )=C(R T5 )(R T6 ), or -C6H4-CH=CH-CH=C(R T7 )(R T8 ) indicates R T4 , R T5 , R T6 , R T7 , and R T8 Each of these independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. Substituents for each of the above groups include halogen atoms, alkyl groups having 1 to 5 carbon atoms, and alkoxy groups having 1 to 5 carbon atoms. Furthermore, substituted amino groups substituted with alkyl groups having 1 to 3 carbon atoms are also examples of substituents for each of the above groups.

[0270] [ka]

[0271] In structural formula (a-2), R T91 and R T92 Each of these independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. T101 , R T102 , R T111 and R T112 Each of these independently consists of a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an amino group substituted with an alkyl group having 1 to 2 carbon atoms, a substituted or unsubstituted aryl group, and -C(R T12 )=C(R T13 )(R T14 ), or -CH=CH-CH=C(R T15 )(R T16 ) shows R T12 , R T13 , R T14 , R T15 and R T16Each of these independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. Tm1, Tm2, ​​Tn1, and Tn2 each independently represent an integer between 0 and 2. Substituents for each of the above groups include halogen atoms, alkyl groups having 1 to 5 carbon atoms, and alkoxy groups having 1 to 5 carbon atoms. Furthermore, substituted amino groups substituted with alkyl groups having 1 to 3 carbon atoms are also examples of substituents for each of the above groups.

[0272] Among the triarylamine derivatives represented by structural formula (a-1) and the benzidine derivatives represented by structural formula (a-2), in particular, "-C6H4-CH=CH-CH=C(R T7 )(R T8 Triarylamine derivatives having ")" and "-CH=CH-CH=C(R T15 )(R T16 A benzidine derivative having ) is preferred from the viewpoint of charge mobility.

[0273] As polymer charge transport materials, known charge transport materials such as poly-N-vinylcarbazole and polysilane can be used. Polyester-based polymer charge transport materials are particularly preferred. Polymer charge transport materials may be used alone or in combination with a binder resin.

[0274] Examples of binder resins used in the charge transport layer include polycarbonate resin, polyester resin, polyarylate resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer, vinylidene chloride-acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin, poly-N-vinylcarbazole, and polysilane. Among these, polycarbonate resin or polyarylate resin is preferred as the binder resin. These binder resins can be used individually or in combination of two or more. The preferred mixing ratio of the charge transport material to the binder resin is between 10:1 and 1:5 by mass.

[0275] When the charge transport layer is the outermost layer of the photoreceptor, the charge transport layer contains at least two types of resins. When the charge transport layer is the outermost layer of the photoreceptor, it is preferable that the charge transport layer contains at least one of a polyarylate resin and a polycarbonate resin, and more preferably contains both a polyarylate resin and a polycarbonate resin. As for the combination of polyarylate resin and polycarbonate resin, a combination of resins in which both have a constituent unit containing biphenyl represented by formula (BP) is preferred. As the polyarylate resin, polyarylate resin (PA) is preferred.

[0276] When the charge transport layer is the outermost layer of the photoreceptor, the charge transport layer contains a phenol compound. The preferred form of the phenol compound is as described above.

[0277] The charge transport layer may also contain other known additives.

[0278] The formation of the charge transport layer is not particularly limited, and known formation methods can be used. For example, it can be carried out by forming a coating film of a charge transport layer forming solution obtained by adding the above components to a solvent, drying the coating film, and heating it if necessary.

[0279] Suitable solvents for preparing the coating solution for forming the charge transport layer include common organic solvents such as aromatic hydrocarbons like benzene, toluene, xylene, and chlorobenzene; ketones like acetone and 2-butanone; halogenated aliphatic hydrocarbons like methylene chloride, chloroform, and ethylene chloride; and cyclic or linear ethers like tetrahydrofuran and ethyl ether. These solvents can be used individually or in mixtures of two or more.

[0280] Conventional methods for applying a charge transport layer forming coating solution onto a charge generation layer include blade coating, wire bar coating, spray coating, immersion coating, bead coating, air knife coating, and curtain coating.

[0281] The thickness of the charge transport layer is preferably set within the range of 5 μm to 50 μm, more preferably 8 μm to 45 μm, and even more preferably 10 μm to 40 μm.

[0282] <Single-layer photosensitive layer> A single-layer photosensitive layer (charge generation / charge transport layer) is, for example, a layer comprising a charge generation material, a charge transport material, and optionally a binder resin and other known additives. These materials are the same as those described for the charge generation layer and the charge transport layer. In the single-layer photosensitive layer, the content of the charge-generating material is preferably 0.1% to 10% by mass, and more preferably 0.8% to 5% by mass, relative to the total solid content. Furthermore, in the single-layer photosensitive layer, the content of the charge-transporting material is preferably 5% to 50% by mass, relative to the total solid content. The method for forming a single-layer photosensitive layer is the same as the method for forming a charge generation layer or a charge transport layer. The thickness of the single-layer photosensitive layer is preferably, for example, 5 μm to 50 μm, more preferably 8 μm to 45 μm, and even more preferably 10 μm to 40 μm.

[0283] When the single-layer photosensitive layer is the outermost layer of the photoreceptor, the single-layer photosensitive layer contains at least two types of resins. When the single-layer photosensitive layer is the outermost layer of the photoreceptor, it is preferable that the single-layer photosensitive layer contains at least one of a polyarylate resin and a polycarbonate resin, and more preferably contains both a polyarylate resin and a polycarbonate resin. As for the combination of polyarylate resin and polycarbonate resin, a combination of resins in which both have a constituent unit containing biphenyl represented by formula (BP) is preferred. As the polyarylate resin, polyarylate resin (PA) is preferred.

[0284] When the single-layer photosensitive layer is the outermost layer of the photoreceptor, the single-layer photosensitive layer contains a phenolic compound. The preferred form of the phenolic compound is as described above.

[0285] The image forming apparatus according to this embodiment includes known image forming apparatuses such as: an apparatus equipped with a fixing device for fixing a toner image transferred to the surface of a recording medium; a direct transfer apparatus for directly transferring a toner image formed on the surface of an electrophotographic photoreceptor to a recording medium; an intermediate transfer apparatus for first transferring a toner image formed on the surface of an electrophotographic photoreceptor to the surface of an intermediate transfer body, and secondarily transferring the toner image transferred to the surface of the intermediate transfer body to the surface of a recording medium; an apparatus equipped with a static elimination device for irradiating the surface of the electrophotographic photoreceptor with static elimination light to eliminate static charge after the transfer of the toner image and before charging; and an apparatus equipped with an electrophotographic photoreceptor heating member for raising the temperature of the electrophotographic photoreceptor and reducing the relative temperature.

[0286] In the case of an intermediate transfer method apparatus, the transfer apparatus may be configured to include, for example, an intermediate transfer body on which a toner image is transferred; a primary transfer apparatus that first transfers the toner image formed on the surface of an electrophotographic photoreceptor to the surface of the intermediate transfer body; and a secondary transfer apparatus that secondarily transfers the toner image transferred to the surface of the intermediate transfer body to the surface of a recording medium.

[0287] The image forming apparatus according to this embodiment may be either a dry developing type image forming apparatus or a wet developing type image forming apparatus (a developing method using a liquid developer).

[0288] In the image forming apparatus according to this embodiment, for example, the portion comprising the electrophotographic photoreceptor may be a cartridge structure (process cartridge) that can be attached to and detached from the image forming apparatus. As the process cartridge, for example, a process cartridge comprising the electrophotographic photoreceptor according to this embodiment is preferably used. In addition to the electrophotographic photoreceptor, the process cartridge may also include at least one selected from the group consisting of, for example, a charging device, an electrostatic latent image forming device, a developing device, and a transfer device.

[0289] The following is an example of an image forming apparatus according to this embodiment, but it is not limited to this example. The main parts shown in the figure will be described, and the descriptions of other parts will be omitted.

[0290] Figure 7 is a schematic diagram showing an example of an image forming apparatus according to this embodiment. As shown in Figure 7, the image forming apparatus 100 according to this embodiment includes a process cartridge 300 equipped with an electrophotographic photoreceptor 7, an exposure device 9 (an example of an electrostatic latent image forming apparatus), a transfer device 40 (a primary transfer device), and an intermediate transfer body 50. In the image forming apparatus 100, the exposure device 9 is positioned to expose the electrophotographic photoreceptor 7 from the opening of the process cartridge 300, and the transfer device 40 is positioned opposite the electrophotographic photoreceptor 7 via the intermediate transfer body 50, with a portion of the intermediate transfer body 50 in contact with the electrophotographic photoreceptor 7. Although not shown, the apparatus also includes a secondary transfer device that transfers the toner image transferred to the intermediate transfer body 50 to a recording medium (e.g., paper). The intermediate transfer body 50, the transfer device 40 (primary transfer device), and the secondary transfer device (not shown) are examples of transfer devices.

[0291] In Figure 7, the process cartridge 300 integrally supports an electrophotographic photoreceptor 7, a charging device 8 (an example of a charging device), a developing device 11 (an example of a developing device), and a cleaning device 13 (an example of a cleaning device) within a housing. The cleaning device 13 has a cleaning blade (an example of a cleaning member) 131, which is positioned to contact the surface of the electrophotographic photoreceptor 7. The cleaning member may be a conductive or insulating fibrous member, rather than a cleaning blade 131, and may be used alone or in combination with the cleaning blade 131.

[0292] Figure 7 shows an example of an image forming apparatus that includes a fibrous member 132 (roll-shaped) for supplying lubricant 14 to the surface of the electrophotographic photoreceptor 7, and a fibrous member 133 (flat brush-shaped) for assisting cleaning. These can be arranged as needed.

[0293] The following describes the various components of the image forming apparatus according to this embodiment.

[0294] -Charging device- The charging device 8 is the charging device described above.

[0295] -Exposure equipment- Examples of exposure devices 9 include optical equipment that exposes the surface of an electrophotographic photoreceptor 7 to a predetermined image using light such as semiconductor laser light, LED light, or liquid crystal shutter light. The wavelength of the light source is within the spectral sensitivity range of the electrophotographic photoreceptor. As for the wavelength of the semiconductor laser, near-infrared lasers with an oscillation wavelength of around 780 nm are the mainstream. However, the wavelength is not limited to this, and lasers with oscillation wavelengths in the 600 nm range or blue lasers with oscillation wavelengths between 400 nm and 450 nm may also be used. Furthermore, for color image formation, surface-emitting laser light sources capable of outputting multiple beams are also effective.

[0296] -Developing equipment- Examples of developing devices 11 include general developing devices that develop by contacting or not contacting the developing agent. There are no particular restrictions on the developing device 11 as long as it has the above-described functions, and it can be selected according to the purpose. For example, known developing devices that have the function of applying a one-component or two-component developing agent to the electrophotographic photoreceptor 7 using a brush, roller, etc. Among these, those that use a developing roller that holds the developing agent on its surface are preferred.

[0297] The developer used in the developing device 11 may be a one-component developer consisting of toner alone, or a two-component developer containing toner and a carrier. Furthermore, the developer may be magnetic or non-magnetic. Known developers can be used.

[0298] -Cleaning device- The cleaning device 13 uses a cleaning blade system equipped with a cleaning blade 131. In addition to the cleaning blade system, a fur brush cleaning system or a developing and cleaning system may also be used.

[0299] -Transfer device- Examples of the transfer device 40 include contact-type transfer chargers using belts, rollers, films, rubber blades, etc., and transfer chargers that are known themselves, such as scorotron transfer chargers and corotron transfer chargers that utilize corona discharge.

[0300] -Intermediate Transcript- As the intermediate transfer body 50, a belt-shaped material (intermediate transfer belt) containing semiconducting polyimide, polyamide-imide, polycarbonate, polyarylate, polyester, rubber, etc. is used. In addition to the belt shape, the intermediate transfer body may also be in the form of a drum.

[0301] Figure 8 is a schematic diagram showing another example of an image forming apparatus according to this embodiment. The image forming apparatus 120 shown in Figure 8 is a tandem-type multi-color image forming apparatus equipped with four process cartridges 300. In the image forming apparatus 120, the four process cartridges 300 are arranged in parallel on the intermediate transfer body 50, and one electrophotographic photoreceptor is used for each color. The image forming apparatus 120 has the same configuration as the image forming apparatus 100, except that it is a tandem type. [Examples]

[0302] The embodiments of the invention will be described in detail below with reference to examples, but the embodiments of the invention are not limited to these examples. In the following explanation, unless otherwise specified, "parts" and "%" refer to mass. In the following descriptions, synthesis, processing, and manufacturing were carried out at room temperature (25°C ± 3°C) unless otherwise specified.

[0303] <Synthesis of polyarylate resin> Polyarylate resins (1-1) to (1-6) were prepared. Table 1 shows the units and composition of the polyarylate resins. Table 1 shows the "constituent units:composition ratio" (e.g., A2-3:50). The composition ratio is expressed in mol% for dicarboxylic acid units and diol units, respectively. A2-3 and others listed in Table 1 are specific examples of the dicarboxylic acid unit (A) described above. Table 1 shows examples of B1-4, etc., which are specific examples of the diol unit (B) described above.

[0304] (Example 1) <Manufacturing of photoreceptors with stacked photosensitive layers> -Formation of the lower layer- An aluminum cylindrical tube was prepared as the conductive substrate.

[0305] 3.5 parts of butyral resin (product name: S-Rec BM-1, Sekisui Chemical Co., Ltd.) and 41 parts of methyl ethyl ketone were mixed and dissolved. 10 parts of a curing agent (blocked isocyanate, product name: Sumijule 3175, Sumitomo Bayer Urethane Co., Ltd.), 45.5 parts of zinc oxide (product name: SMZ-017N, Teika Co., Ltd.) surface-treated with a silane coupling agent (product name: KBM603, Shin-Etsu Chemical Co., Ltd.), and 0.27 parts of 4-ethoxy-1,2-hydroxy-9,10-anthraquinone were added and stirred. The mixture was then dispersed for 2 hours using 1 mm diameter glass beads in a sand mill. Furthermore, 0.01 parts of dioctyl tin dilaurate and 2 parts of silicone resin particles (product name: Tospearl 145, GE Toshiba Silicone Co., Ltd.) were added and stirred to obtain a coating solution for forming the undercoat layer. A coating solution for forming the undercoat layer was applied to the outer surface of the conductive substrate by immersion coating, and drying and curing was performed at 170°C for 40 minutes to form an undercoat layer with a thickness of 20 μm.

[0306] -Formation of a charge generation layer- A mixture consisting of 15 parts of hydroxygallium phthalocyanine as a charge-generating material (having diffraction peaks at Bragg angles (2θ±0.2°) of at least 7.5°, 9.9°, 12.5°, 16.3°, 18.6°, 25.1°, and 28.3° in its X-ray diffraction spectrum using Cukα characteristic X-rays), 10 parts of vinyl chloride / vinyl acetate copolymer resin (product name: VMCH, manufactured by Nippon Unicar Co., Ltd.) as a binder resin, and 200 parts of n-butyl acetate was dispersed for 4 hours using glass beads with a diameter of 1 mm in a sand mill. 175 parts of n-butyl acetate and 180 parts of methyl ethyl ketone were added to the dispersion and stirred to obtain a coating solution for forming the charge-generating layer. The coating solution for forming the charge-generating layer was immersed and coated onto the undercoat, and dried at room temperature (25℃±3℃) to form a charge-generating layer with an average thickness of 0.18 μm.

[0307] -Formation of a charge transport layer- A coating solution for forming a charge transport layer was obtained by dissolving 42 parts of polyarylate resin (1-1) as a binder resin, 18 parts of polycarbonate resin PC-1, and 40 parts of CTM-1 as a charge transport material in 270 parts of tetrahydrofuran and 30 parts of toluene. The coating solution for forming a charge transport layer was applied to the charge generating layer by immersion, and dried at 145°C for 30 minutes to form a charge transport layer. The average thickness As of the charge transport layer is shown in Table 1. Polycarbonate resin PC-1 is a resin consisting of the following repeating structural units. The numbers accompanying the structural units represent the molar ratio.

[0308] [ka]

[0309] [ka]

[0310] -Creation of cleaning rolls- A 2.5mm thick sheet of polyurethane foam (EP-70; manufactured by Inoac Corporation) was cut into strips 3.0mm wide. Double-sided tape (manufactured by Nitto Denko Corporation, No. 5605) with a thickness of 0.05mm was applied to the entire surface of each strip to obtain strips with double-sided tape attached.

[0311] The resulting strip with double-sided tape attached was placed on a horizontal surface with the release paper attached to the double-sided tape facing downwards. Then, the longitudinal end of the strip was compressed from above with heated stainless steel so that the thickness of a 1 mm length from the longitudinal end of the strip was 15% of the thickness of the rest of the strip.

[0312] The three strips of double-sided tape that were obtained were placed on a horizontal surface with the release paper attached to the double-sided tape facing upwards, and were wrapped around a metal core (material: SUM24EZ, outer diameter: φ5.0 mm) while applying tension so that the spiral angle θ was 25° and the total length of the strips stretched in the range of 0% to 5%.

[0313] Through the above process, a cleaning roll having a foamed elastic layer wound spirally around the outer surface of the core metal was obtained.

[0314] <Fabrication of electrostatic rolls> -Formation of the elastic layer- The following mixture was kneaded in an open roll and coated onto the outer surface of a 9 mm diameter conductive core made of SUS416 in a cylindrical shape to a thickness of 1.5 mm. This was then placed in a cylindrical mold with an inner diameter of 12.0 mm and vulcanized at 170°C for 30 minutes. After being removed from the mold, it was polished. This resulted in obtaining a cylindrical conductive elastic layer.

[0315] • Rubber material (epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer rubber, GECHRON3106, manufactured by Nippon Zeon Co., Ltd.): 100 parts by mass • Conductive agent (carbon black, manufactured by Asahi Thermal and Asahi Carbon Co., Ltd.): 25 parts by mass • Conductive agent (Ketjenblack EC, manufactured by Lion Corporation): 8 parts by mass • Ionic conductive agent (lithium perchlorate): 1 part by mass • Vulcanizing agent (sulfur, 200 mesh, manufactured by Tsurumi Chemical Industries, Ltd.): 1 part by mass • Vulcanization accelerator (Noxellar DM, manufactured by Ouchi Shinko Chemical Industry Co., Ltd.): 2.0 parts by mass • Vulcanization accelerator (Noxellar TT, manufactured by Ouchi Shinko Chemical Industry Co., Ltd.): 0.5 parts by mass

[0316] -Formation of the surface layer- The following mixture was dispersed in a bead mill, the resulting dispersion was diluted with methanol, and then immersed and coated onto the surface (outer surface) of a conductive elastic layer. After this, it was heated and dried at 140°C for 15 minutes. This resulted in a charged roll having a surface layer with a thickness of 4 μm.

[0317] • Polymer material (copolymer nylon, Amilan CM8000, manufactured by Toray Industries, Inc.): 100 parts by mass • Conductive agent (antimond-doped tin oxide, SN-100P, manufactured by Ishihara Sangyo Co., Ltd.): 30 parts by mass • Solvent (methanol): 500 parts by mass • Solvent (butanol): 240 parts by mass

[0318] <Evaluation of the abrasion resistance of the photoreceptor> The obtained electrophotographic photoreceptor, charging roll, and cleaning roll were mounted on the image forming apparatus "ApeosPort-V C7776 manufactured by Fujifilm Business Innovation Co., Ltd." Using the aforementioned image forming apparatus, 100,000 images with an average image density (area coverage) of 10% were formed on A3-sized paper under conditions of 28°C and 85% relative humidity. Then, another 100,000 images were formed under conditions of 10°C and 15% relative humidity. The average thickness of the outermost layer before image formation (TBEFORE, μm) and the average thickness of the outermost layer after image formation (TAFTER, μm) were determined, and the difference ΔT (=TBEFORE-TAFTER) was defined as the amount of wear. A Permascope manufactured by Fischerscope was used as the film thickness measuring instrument. The contact pressure of the cleaning blade against the surface of the electrophotographic photoreceptor in the image forming apparatus was 2.6 gf / mm, and the contact angle was 11 degrees. The amount of wear was evaluated according to the following criteria. S to C represents the acceptable range. The results are shown in Table 1. -Evaluation Criteria- S: Wear amount less than 15 μm A: Wear amount is between 15 μm and less than 20 μm B: Wear amount between 20 μm and less than 25 μm C: Wear amount is 25 μm or more but less than 30 μm D: Wear amount is 30 μm or more

[0319] <Evaluation of the stain resistance of electrostatically charged materials> The evaluation test involved printing 100,000 strip-shaped image quality patterns, 320 mm in length and 30 mm in width, at 100% image density on A3 recording paper under conditions of 28°C and 85% RH. Then, another 100,000 strips were formed under conditions of 10°C and 15% relative humidity. The cleanability of adhering substances was evaluated by observing the surface condition of the charged roll 14 at the image quality pattern printing location. The charged roll was observed directly using a confocal laser microscope (OLS1100, manufactured by Olympus Corporation), and the contamination resistance of the charged component was evaluated based on the following criteria. -Evaluation Criteria- S: The surface of the charged roll has deposits of 1 μm. 2 It is seen in less than 10% of cases. A: The surface of the charged roll has deposits of 1 μm. 2 It is observed in a range greater than 10% but less than or equal to 20%. B: The surface of the charged roll has deposits of 1 μm. 2It is seen in a range greater than 20% but less than or equal to 30%. C: The surface of the charged roll has deposits of 1 μm. 2 The probability of success is greater than 30% but less than or equal to 50%. D: The surface of the charged roll has deposits of 1 μm. 2 It can be seen in a range greater than 50% of cases.

[0320] (Examples 2 to 29, and Comparative Examples 1 to 6) As shown in Table 1, an electrophotographic photoreceptor, a charging roll, and a cleaning roll were manufactured in the same manner as in Example 1, except that the composition of the charge transport layer, the shape of the cleaning member, and the surface roughness Rz of the charging member were changed. Furthermore, the evaluation was carried out in the same manner as in Example 1. The evaluation results are summarized in Table 1.

[0321] [Table 1]

[0322] Note that the resin mass ratio PAR:PC in Table 1 is the ratio of polyarylate resin to polycarbonate resin. Furthermore, the polycarbonate resin used in Example 29 is polycarbonate resin PC-3 with the following structure.

[0323] [ka]

[0324] The CTM used in Examples 27 to 28 consisted of CTM-1 and CTM-2 in a mass ratio of 30:70.

[0325] [ka]

[0326] (Examples 30 to 34, and Comparative Examples 7 to 8) Furthermore, for Examples 30 to 34 and Comparative Examples 7 to 8 described in Table 2, cleaning rolls were manufactured in the same manner as in Example 1, except that the shape of the cleaning member was changed. The modified components were then mounted on a drum cartridge in the image forming apparatus "Konica Minolta, Inc. bizhub C287," and the abrasion resistance of the photoreceptor and the contamination resistance of the charged component were evaluated in the same manner as in Example 1. The evaluation results are summarized in Table 2.

[0327] [Table 2]

[0328] As shown in Tables 1 and 2, the image forming apparatuses of Examples 1 to 34 were superior to the image forming apparatuses of Comparative Examples 1 to 8 in terms of suppression of photoreceptor wear and contamination of charged members.

[0329] (((1))) An image forming apparatus comprising an electrophotographic photoreceptor, a charging member for charging the surface of the electrophotographic photoreceptor, and a cleaning member positioned in contact with the charging member, wherein the electrophotographic photoreceptor comprises a conductive substrate and a photosensitive layer disposed on the conductive substrate, and the outermost layer of the electrophotographic photoreceptor comprises a charge transport material and a polyarylate resin having dicarboxylic acid units represented by the following formula (A) and diol units represented by formula (B), and the cleaning member comprises a core metal and a foamed elastic layer helically provided on the outer peripheral surface of the core metal, and the ratio T / W of the thickness T of the foamed elastic layer to the width W of the foamed elastic layer is 0.6 or more and 1.2 or less.

[0330] [ka]

[0331] In equation (A), Ar A1 and Ar A2 Each of these is an aromatic ring which may independently have substituents, L A is a single bond or a divalent linking group, n A1 It is 0, 1, or 2. In equation (B), Ar B1 and Ar B2 Each of these is an aromatic ring which may independently have substituents, L B is a single bond, oxygen atom, sulfur atom or -C(Rb 1 )(Rb 2 )- and n B1 Rb is 0, 1, or 2. 1 and Rb 2 Each of these is independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms, and Rb 1 and Rb 2 These may be bonded together to form a cyclic alkyl group.

[0332] (((2))) The image forming apparatus according to (((1))), wherein the coverage area ratio A of the foamed elastic layer provided on the cleaning member is 20 area% or more and 60 area% or less. (((3))) The image forming apparatus according to (((1))) or (((2))), wherein the surface roughness Rz of the charging member is 5 μm or more and 10 μm or less. (((4))) The image forming apparatus according to any one of (((1))) to (((3))) wherein the outermost surface layer of the electrophotographic photoreceptor further comprises a polycarbonate resin. (((5))) The image forming apparatus according to (((4))), wherein the mass ratio of the polyarylate resin to the polycarbonate resin in the outermost surface layer of the electrophotographic photoreceptor is 3:7 to 7:3. (((6))) The image forming apparatus according to any one of (((1))) to (((5))), wherein the dicarboxylic acid unit represented by formula (A) includes at least one selected from the group consisting of a dicarboxylic acid unit represented by formula (A1) (A1), a dicarboxylic acid unit represented by formula (A2) (A2), a dicarboxylic acid unit represented by formula (A3) (A3), a dicarboxylic acid unit represented by formula (A4) (A4), and a dicarboxylic acid unit represented by formula (A5) (A5).

[0333] [ka]

[0334] In equation (A1), n 101 n is an integer between 0 and 4, and 101 Individual Ra 101 Each of these is independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. In equation (A2), n 201 and n 202 Each of these is an independent integer between 0 and 4, and n 201 Individual Ra 201 and n 202 Individual Ra 202 Each of these is independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. In equation (A3), n 301 and n 302 Each of these is an independent integer between 0 and 4, and n 301 Individual Ra 301 and n 302 Individual Ra 302 Each of these is independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. In equation (A4), n 401 n is an integer between 0 and 6, and 401 Individual Ra 401 Each of these is independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. In equation (A5), n 501 , n 502 and n 503 Each of these is an independent integer between 0 and 4, and n 501 Individual Ra 501 , n 502 Individual Ra 502 and n 503 Individual Ra 503 Each of these is independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

[0335] (((7))) The image forming apparatus according to any one of (((1))) to (((6))) wherein the diol unit represented by formula (B) includes at least one selected from the group consisting of the diol unit represented by formula (B1) (B1), the diol unit represented by formula (B2) (B2), the diol unit represented by formula (B3) (B3), the diol unit represented by formula (B4) (B4), the diol unit represented by formula (B5) (B5), the diol unit represented by formula (B6) (B6), the diol unit represented by formula (B7) (B7), and the diol unit represented by formula (B8) (B8).

[0336] [ka]

[0337] [ka]

[0338] In equation (B1), Rb 101 Rb is a branched alkyl group having 4 to 20 carbon atoms. 201 Rb is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. 401 , Rb 501 , Rb 801 and Rb 901 Each of these is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. In equation (B2), Rb 102 Rb is a linear alkyl group having 4 to 20 carbon atoms. 202 Rb is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. 402 , Rb 502 , Rb 802 and Rb 902 Each of these is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. In equation (B3), Rb 113 and Rb 213Each of these is independently a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom, d is an integer between 7 and 15, and Rb 403 , Rb 503 , Rb 803 and Rb 903 Each of these is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. In equation (B4), Rb 104 and Rb 204 Each is independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and Rb 404 , Rb 504 , Rb 804 and Rb 904 Each of these is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. In equation (B5), Ar 105 Rb is an aryl group having 6 to 12 carbon atoms or an aralkyl group having 7 to 20 carbon atoms. 205 Rb is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. 405 , Rb 505 , Rb 805 and Rb 905 Each of these is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. In equation (B6), Rb 116 and Rb 216 Each of these is independently a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom, e is an integer between 4 and 6, and Rb 406 , Rb 506 , Rb 806 and Rb 906 Each of these is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. In equation (B7), Rb 407 , Rb 507 , Rb 807 and Rb 907Each of these is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. In equation (B8), Rb 408 , Rb 508 , Rb 808 and Rb 908 Each of these is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. (((8))) The image forming apparatus according to (((4))), wherein the polyarylate resin and the polycarbonate resin each have a constituent unit containing biphenyl represented by the following formula (BP).

[0339] [ka]

[0340] In equation (BP), j is an integer between 0 and 4, and j R 1 Each is independently either a methyl group or an ethyl group, k is an integer between 0 and 4, and there are k R 2 These are independently either a methyl group or an ethyl group.

[0341] According to the invention of (((1))), an image forming apparatus is provided that is superior in terms of suppressing wear of the photoreceptor and suppressing contamination of the charged member compared to a case in which the outermost surface layer of the electrophotographic photoreceptor does not contain a charge transport material and a polyarylate resin having dicarboxylic acid units represented by the following formula (A) and diol units represented by formula (B), or a case in which the cleaning member has a core metal and a foamed elastic layer helically provided on the outer peripheral surface of the core metal, and the ratio T / W of the thickness T of the foamed elastic layer to the width W of the foamed elastic layer is less than 0.6 or greater than 1.2. According to the invention of (((2))), an image forming apparatus is provided that is superior in its ability to suppress contamination of the charged member compared to the case in which the coverage area ratio A of the foamed elastic layer provided on the cleaning member is less than 20 area% or more than 60 area%. According to the invention of (((3))), an image forming apparatus is provided that is superior in its ability to suppress contamination of the charged member compared to the case where the surface roughness Rz of the charged member is less than 5 μm or greater than 10 μm. According to the invention of (((4))), an image forming apparatus is provided that is superior in terms of suppressing wear of the photoreceptor and suppressing contamination of the charged member compared to the case in which the outermost surface layer of the electrophotographic photoreceptor contains only polyarylate resin. According to the invention of (((5))), an image forming apparatus is provided that is superior in terms of suppressing wear of the photoreceptor and suppressing contamination of the charged member compared to cases where the mass ratio of the polyarylate resin to the polycarbonate resin in the outermost surface layer of the electrophotographic photoreceptor is less than 3:7 or greater than 7:3. According to the invention of (((6))), an image forming apparatus is provided that is superior in terms of suppressing wear of the photoreceptor and suppressing contamination of the charged member compared to the case in which the dicarboxylic acid unit represented by formula (A) does not include at least one selected from the group consisting of the dicarboxylic acid unit represented by formula (A1) (A1), the dicarboxylic acid unit represented by formula (A2) (A2), the dicarboxylic acid unit represented by formula (A3) (A3), the dicarboxylic acid unit represented by formula (A4) (A4), and the dicarboxylic acid unit represented by formula (A5) (A5). According to the invention of (((7))), compared to the case in which the diol unit represented by formula (B) does not include at least one selected from the group consisting of the diol unit represented by formula (B1) (B1), the diol unit represented by formula (B2) (B2), the diol unit represented by formula (B3) (B3), the diol unit represented by formula (B4) (B4), the diol unit represented by formula (B5) (B5), the diol unit represented by formula (B6) (B6), the diol unit represented by formula (B7) (B7), and the diol unit represented by formula (B8) (B8), an image forming apparatus is provided that is superior in terms of suppressing wear of the photoreceptor and suppressing contamination of the charged member. According to the invention of (((8))), an image forming apparatus is provided that is superior in suppressing wear of the photoreceptor compared to the case in which the polyarylate resin and the polycarbonate resin each do not have a constituent unit containing biphenyl represented by the following formula (BP). [Explanation of Symbols]

[0342] 102 Core metal, 104 Foamed elastic layer, 106 Adhesive layer (double-sided tape), 108 Elastic member, 110 Notch, T1, T2 Thickness of foamed elastic layer 104, W3, W4 Width of foamed elastic layer 104

[0343] 1A Charging device, 10 Charging roll (charging component), 12 Cleaning roll (cleaning component), 18 Core metal, 20 Foamed elastic layer, 24 Photoreceptor (image holder)

[0344] 1 Conductive substrate, 2 Undercoat layer, 3 Charge generation layer, 4 Charge transport layer, 5 Photosensitive layer, 10A photoreceptor, 10B photoreceptor

[0345] 7 Electrophotographic photoreceptor, 8 Charging device, 9 Exposure device, 11 Developing device, 13 Cleaning device, 14 Lubricant, 40 Transfer device, 50 Intermediate transfer body, 100 Image forming device, 120 Image forming device, 131 Cleaning blade, 132 Fibrous material (roll type), 133 Fibrous material (flat brush type), 300 Process cartridge

Claims

1. Electrophotographic photoreceptor, and, The charging device comprises a charging member for charging the surface of the electrophotographic photoreceptor and a cleaning member positioned in contact with the charging member, The electrophotographic photoreceptor comprises a conductive substrate and a photosensitive layer disposed on the conductive substrate, and the outermost layer of the electrophotographic photoreceptor comprises a charge transport material and a polyarylate resin having dicarboxylic acid units represented by the following formula (A) and diol units represented by the following formula (B). The cleaning member comprises a core metal and a foamed elastic layer spirally provided on the outer surface of the core metal. The ratio T / W of the thickness T of the foamed elastic layer to the width W of the foamed elastic layer is 0.6 or more and 1.2 or less. Image forming apparatus. 【Chemistry 1】 In equation (A), Ar Ａ１ and Ar Ａ２ Each of these is an aromatic ring which may independently have substituents, L Ａ is a single bond or a divalent linking group, n Ａ１ It is 0, 1, or 2. In formula (B), Ar Ｂ１ and Ar Ｂ２ are each independently an aromatic ring which may have a substituent, L Ｂ is a single bond, an oxygen atom, a sulfur atom or -C(Rb １ )(Rb ２ )-, n Ｂ１ is 0, 1 or 2. Rb １ and Rb ２ are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 12 carbon atoms or an aralkyl group having 7 to 20 carbon atoms, and Rb １ and Rb ２ may combine with each other to form a cyclic alkyl group.

2. The image forming apparatus according to claim 1, wherein the coverage area ratio A of the foamed elastic layer provided on the cleaning member is 20 area% or more and 60 area% or less.

3. The image forming apparatus according to claim 1, wherein the surface roughness Rz of the charging member is 5 μm or more and 10 μm or less.

4. The image forming apparatus according to claim 1, wherein the outermost surface layer of the electrophotographic photoreceptor further comprises a polycarbonate resin.

5. The image forming apparatus according to claim 4, wherein the mass ratio of the polyarylate resin to the polycarbonate resin in the outermost surface layer of the electrophotographic photoreceptor is 3:7 to 7:

3.

6. The image forming apparatus according to claim 1, wherein the dicarboxylic acid unit represented by formula (A) includes at least one selected from the group consisting of a dicarboxylic acid unit represented by the following formula (A1) (A1), a dicarboxylic acid unit represented by formula (A2) (A2), a dicarboxylic acid unit represented by formula (A3) (A3), a dicarboxylic acid unit represented by formula (A4) (A4), and a dicarboxylic acid unit represented by formula (A5) (A5). 【Chemistry 2】 In equation (A1), n １０１ n is an integer between 0 and 4, and １０１ Individual Ra １０１ Each of these is independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. In equation (A2), n ２０１ and n ２０２ Each of these is an independent integer between 0 and 4, and n ２０１ Individual Ra ２０１ and n ２０２ Individual Ra ２０２ Each of these is independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. In equation (A3), n ３０１ and n ３０２ Each of these is an independent integer between 0 and 4, and n ３０１ Individual Ra ３０１ and n ３０２ Individual Ra ３０２ Each of these is independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. In equation (A4), n ４０１ n is an integer between 0 and 6, and ４０１ Individual Ra ４０１ Each of these is independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. In equation (A5), n ５０１ , n ５０２ and n ５０３ Each of these is an independent integer between 0 and 4, and n ５０１ Individual Ra ５０１ , n ５０２ Individual Ra ５０２ and n ５０３ Individual Ra ５０３ Each of these is independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

7. The image forming apparatus according to claim 1, wherein the diol unit represented by formula (B) includes at least one selected from the group consisting of the diol unit represented by formula (B1) (B1), the diol unit represented by formula (B2) (B2), the diol unit represented by formula (B3) (B3), the diol unit represented by formula (B4) (B4), the diol unit represented by formula (B5) (B5), the diol unit represented by formula (B6) (B6), the diol unit represented by formula (B7) (B7), and the diol unit represented by formula (B8) (B8). 【Transformation 3】 【Chemistry 4】 In equation (B1), Rb １０１ Rb is a branched alkyl group having 4 to 20 carbon atoms. ２０１ Rb is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. ４０１ , Rb ５０１ , Rb ８０１ and Rb ９０１ Each of these is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. In equation (B2), Rb １０２ Rb is a linear alkyl group having 4 to 20 carbon atoms. ２０２ Rb is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. ４０２ , Rb ５０２ , Rb ８０２ and Rb ９０２ Each of these is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. In equation (B3), Rb １１３ and Rb ２１３ Each of these is independently a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom, d is an integer between 7 and 15, and Rb ４０３ , Rb ５０３ , Rb ８０３ and Rb ９０３ Each of these is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. In equation (B4), Rb １０４ and Rb ２０４ Each is independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and Rb ４０４ , Rb ５０４ , Rb ８０４ and Rb ９０４ Each of these is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. In formula (B5), Ar １０５ Rb is an aryl group having 6 to 12 carbon atoms or an aralkyl group having 7 to 20 carbon atoms. ２０５ Rb is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. ４０５ , Rb ５０５ , Rb ８０５ and Rb ９０５ Each of these is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. In equation (B6), Rb １１６ and Rb ２１６ Each of these is independently a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom, e is an integer between 4 and 6, and Rb ４０６ , Rb ５０６ , Rb ８０６ and Rb ９０６ Each of these is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. In equation (B7), Rb ４０７ , Rb ５０７ , Rb ８０７ and Rb ９０７ Each of these is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. In equation (B8), Rb ４０８ , Rb ５０８ , Rb ８０８ and Rb ９０８ Each of these is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

8. The image forming apparatus according to claim 1, wherein the polyarylate resin and the polycarbonate resin each have a constituent unit containing biphenyl represented by the following formula (BP). 【Transformation 5】 In equation (BP), j is an integer between 0 and 4, and j R １ Each is independently either a methyl group or an ethyl group, k is an integer between 0 and 4, and there are k R ２ These are independently either a methyl group or an ethyl group.

Images