Positively charged electrophotographic photoreceptor, process cartridge, and image forming apparatus

Abstract

The invention discloses a positively charged electrophotographic photoreceptor, a process cartridge, and an image forming apparatus, the positively charged electrophotographic photoreceptor having a single-layer photosensitive layer including a hole transport material, an electron transport material, a charge generating material, and a binder resin, the binder resin contains a resin A having an elastic deformation rate of 53.0% or more and a resin B having an elastic deformation rate difference of 12% or more and 17% or less with respect to the resin A.

Description

Technical Field

[0001] The present invention relates to a positively charged electrophotographic photoreceptor, a processing cartridge, and an image forming apparatus. Background Art

[0002] In International Publication No. 2018 / 154740, there is disclosed an electrophotographic photoreceptor which is a positively charged electrophotographic photoreceptor, and includes a conductive support and a single-layer photoreceptive layer. The single-layer photoreceptive layer contains a charge generating material, a hole transporting material, an electron transporting material, and a binder resin, and is provided on the conductive support. The charge generating material contains at least oxytitanium phthalocyanine, and the contact angle of the outermost surface with water is in the range of 81° or more and 87° or less.

[0003] In Japanese Patent Laid-Open No. 2010-237555, there is disclosed a single-layer electrophotographic photoreceptor for an image forming apparatus having a roller cleaning system. The single-layer electrophotographic photoreceptor is characterized in that a photoreceptive layer containing at least a charge generating material, a hole transporting agent, an electron transporting agent, and a binder resin is provided on a substrate not having an oxide film formed by anodic oxidation, and the binder resin is a polycarbonate resin having a viscosity average molecular weight in the range of 10,000 to 40,000, the film thickness of the photoreceptive layer is in the range of 20 to 45 μm, and the absolute value of the positive and negative withstand voltages of the single-layer electrophotographic photoreceptor measured according to JIS C2110 is 6 kV or more. Summary of the Invention

[0004] An object of the present invention is to provide a positively charged electrophotographic photoreceptor which is excellent in the suppression of color spot generation caused by corrosion and wear resistance as compared with the case where the binder resin in the single-layer photoreceptive layer contains a resin A having an elastic deformation rate of 53.0% or more and a resin B having an elastic deformation rate difference from the resin A of less than 12% or more than 17%.

[0005] According to a first aspect of the present invention, there is provided a positively charged electrophotographic photoreceptor having a single-layer photoreceptive layer containing a hole transporting material, an electron transporting material, a charge generating material, and a binder resin, the binder resin containing a resin A having an elastic deformation rate of 53.0% or more and a resin B having an elastic deformation rate difference from the resin A of 12% or more and 17% or less.

[0006] According to a second aspect of the present invention, in the positively charged electrophotographic photoreceptor according to the first aspect, the mass ratio MA / MB of the content MA of the resin A to the content MB of the resin B is 0.25 or more and 4 or less.

[0007] According to the third aspect of the present invention, in the positively charged electrophotographic photoreceptor according to the second aspect, the value of the mass ratio MA / MB of the content MA of the resin A to the content MB of the resin B is 0.4 or more and 2.5 or less.

[0008] According to the fourth aspect of the present invention, in the positively charged electrophotographic photoreceptor according to any one of the first to third aspects, the difference in elastic deformation rate between the resin B and the resin A is 13% or more and 16% or less.

[0009] According to the fifth aspect of the present invention, in the positively charged electrophotographic photoreceptor according to any one of the first to fourth aspects, the elastic deformation rate of the resin B is 12% or more and 17% or less smaller than the elastic deformation rate of the resin A.

[0010] According to the sixth aspect of the present invention, in the positively charged electrophotographic photoreceptor according to any one of the first to fifth aspects, the resin A is a polyarylate resin.

[0011] According to the seventh aspect of the present invention, in the positively charged electrophotographic photoreceptor according to any one of the first to sixth aspects, the resin B is a polycarbonate resin.

[0012] According to the eighth aspect of the present invention, in the positively charged electrophotographic photoreceptor according to any one of the first to seventh aspects, the resin A has a biphenyl structure.

[0013] According to the ninth aspect of the present invention, in the positively charged electrophotographic photoreceptor according to any one of the first to eighth aspects, the resin B has a biphenyl structure.

[0014] According to the tenth aspect of the present invention, there is provided a processing cartridge including the positively charged electrophotographic photoreceptor according to any one of the first to ninth aspects, which is detachable from an image forming apparatus.

[0015] According to the eleventh aspect of the present invention, there is provided an image forming apparatus including: the positively charged electrophotographic photoreceptor according to any one of the first to ninth aspects; a charging device that charges the surface of the electrophotographic photoreceptor; an electrostatic latent image forming device that forms an electrostatic latent image on the surface of the charged electrophotographic photoreceptor; a developing device that develops the electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing toner to form a toner image; and a transfer device that transfers the toner image onto the surface of a recording medium, wherein the charging device is a positively charged charging device.

[0016] (Effect)

[0017] According to the first aspect, there is provided a positively charged electrophotographic photoreceptor which is excellent in suppressing the generation of color spots caused by corrosion and in abrasion resistance as compared with the case where the binder resin in the single-layer photosensitive layer contains resin A having an elastic deformation rate of 53.0% or more and resin B having an elastic deformation rate difference from resin A of less than 12% or more than 17%.

[0018] According to the second aspect, there is provided a positively charged electrophotographic photoreceptor which is more excellent in suppressing the generation of color spots caused by corrosion as compared with the case where the value of the mass ratio MA / MB of the content MA of resin A to the content MB of resin B is less than 0.25 or more than 4.

[0019] According to the third aspect, there is provided a positively charged electrophotographic photoreceptor which is more excellent in suppressing the generation of color spots caused by corrosion as compared with the case where the value of the mass ratio MA / MB of the content MA of resin A to the content MB of resin B is less than 0.25 or more than 4.

[0020] According to the fourth aspect, there is provided a positively charged electrophotographic photoreceptor which is more excellent in suppressing the generation of color spots caused by corrosion as compared with the case where the elastic deformation rate difference between resin B and resin A is less than 13% or more than 16%.

[0021] According to the fifth aspect, there is provided a positively charged electrophotographic photoreceptor which is more excellent in suppressing the generation of color spots caused by corrosion as compared with the case where the elastic deformation rate of resin B is 12% or more and 17% or less greater than the elastic deformation rate of resin A.

[0022] According to the sixth aspect, there is provided a positively charged electrophotographic photoreceptor which is more excellent in suppressing the generation of color spots caused by corrosion and in abrasion resistance as compared with the case where resin A is a polyester resin that is not a polyarylate resin.

[0023] According to the seventh aspect, there is provided a positively charged electrophotographic photoreceptor which is excellent in abrasion resistance and more excellent in suppressing the generation of color spots caused by corrosion as compared with the case where resin B is a polyester resin.

[0024] According to the eighth aspect, there is provided a positively charged electrophotographic photoreceptor which is excellent in abrasion resistance and more excellent in suppressing the generation of color spots caused by corrosion as compared with the case where resin A does not have a biphenyl structure.

[0025] According to the ninth aspect, there is provided a positively charged electrophotographic photoreceptor which is excellent in abrasion resistance and more excellent in suppressing the generation of color spots caused by corrosion as compared with the case where resin B does not have a biphenyl structure.

[0026] According to the tenth or eleventh aspect, there is provided a processing cartridge or an image forming apparatus which is excellent in suppressing color spot generation caused by corrosion and wear resistance in a positively charged electrophotographic photoreceptor as compared with a case where a binder resin in a single-layer photosensitive layer of a positively charged electrophotographic photoreceptor contains a resin A having an elastic deformation rate of 53.0% or more and a resin B having an elastic deformation rate difference from the resin A of less than 12% or more than 17%. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 FIG. is a partial cross-sectional view showing an example of the layer structure of the electrophotographic photoreceptor according to the present embodiment;

[0028] Figure 2 FIG. is a schematic structural diagram showing an example of the image forming apparatus according to the present embodiment;

[0029] Figure 3 FIG. is a schematic structural diagram showing another example of the image forming apparatus according to the present embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] Hereinafter, embodiments as an example of the present invention will be described in detail.

[0031] In the present specification, a numerical range indicated by “~” means a range including the numerical values described before and after “~” as the minimum value and the maximum value, respectively.

[0032] In the numerical ranges described in sections in the present specification, the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value of another numerical range described in sections. Further, in the numerical ranges described in the present specification, the upper limit value or the lower limit value of the numerical range may be replaced with the values shown in the examples.

[0033] In the present specification, the term “step” includes not only independent steps, but also includes cases where it is not clearly distinguishable from other steps as long as the purpose of the step is achieved.

[0034] In the present specification, when describing an embodiment with reference to the drawings, the structure of the embodiment is not limited to the structure shown in the drawings. Further, the sizes of the components in each drawing are schematic, and the relative size relationships between the components are not limited thereto.

[0035] In the present specification, each component may include a plurality of substances corresponding to each component. In the present embodiment, when referring to the amount of each component in the composition, in the case where there are a plurality of substances corresponding to each component in the composition, unless otherwise specified, it means the total amount of the plurality of substances present in the composition.

[0036] In this specification, various particles corresponding to each component may be included. When there are various particles corresponding to each component in the composition, unless otherwise specified, the particle diameter of each component means a value for the mixture of the various particles present in the composition.

[0037] In this specification, unless otherwise specified, alkyl and alkylene include any of linear, branched, and cyclic.

[0038] In this specification, a hydrogen atom in a group such as an organic group, an aromatic ring, a linking group, an alkyl group, an alkylene group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, etc. may be substituted with a halogen atom.

[0039] In this specification, when representing a compound by a structural formula, sometimes a structural formula in which symbols (C and H) representing carbon atoms and hydrogen atoms on a hydrocarbon group and / or a hydrocarbon chain are omitted is used.

[0040] In this specification, the "structural unit" of a copolymer or a resin has the same meaning as a monomer unit.

[0041] In this specification, ppm is an abbreviation for parts per million (one millionth) and is based on mass.

[0042] <Positive-charge type electrophotographic photoreceptor>

[0043] The positive-charge type electrophotographic photoreceptor according to this embodiment has a single-layer type photosensitive layer containing a hole transport material, an electron transport material, a charge generation material, and a binder resin, and the binder resin contains a resin A having an elastic deformation rate of 53.0% or more and a resin B having an elastic deformation rate difference of 12% or more and 17% or less from the resin A.

[0044] The positive-charge type electrophotographic photoreceptor according to this embodiment preferably includes a conductive substrate and a single-layer type photosensitive layer disposed on the conductive substrate.

[0045] The positive-charge type electrophotographic photoreceptor according to this embodiment may further include other layers (for example, an undercoat layer, an intermediate layer).

[0046] Figure 1 It is a partial cross-sectional view schematically showing an example of the layer structure of the positive-charge type electrophotographic photoreceptor according to this embodiment. Figure 1 The shown photoreceptor 10B has a single-layer type photosensitive layer. The photoreceptor 10B has a structure in which an undercoat layer 2 and a photosensitive layer 5 are sequentially laminated 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.

[0047] In the existing single-layer electrophotographic photoreceptor, the electrical characteristics are determined by the electron migration rate in principle. Therefore, a positively charged method that can shorten the electron transport distance is generally adopted.

[0048] However, in an image forming apparatus using a positively charged method, there are the following problems: when long-term actual machine operation is carried out under high temperature and high humidity, leakage current is generated at the electrical specific points of the photosensitive layer, and the photosensitive layer is corroded, which may develop into color spots.

[0049] In the positively charged electrophotographic photoreceptor according to the present embodiment, as the binder resin of the single-layer photosensitive layer, by containing resin A having an elastic deformation rate of 53.0% or more and resin B having an elastic deformation rate difference of 12% to 17% from the elastic deformation rate of resin A, resin A having an elastic deformation rate of 53.0% or more and high durability and resin B having an elastic deformation rate difference of 12% to 17% from the elastic deformation rate of resin A are contained in the binder resin. Therefore, due to the difference in durability between resin A and resin B, physical unevenness is formed on the surface of the single-layer photosensitive layer after actual machine operation.

[0050] It is inferred that: current flows in the concave portions formed on the surface of the single-layer photosensitive layer, thereby suppressing the corrosion of the single-layer photosensitive layer. The inhibitory effect on the generation of color spots caused by corrosion is excellent. In addition, by containing resin A having an elastic deformation rate of 53.0% or more and high durability, the abrasion resistance is also excellent.

[0051] In addition, in the following description, the positively charged electrophotographic photoreceptor may sometimes be simply referred to as "electrophotographic photoreceptor".

[0052] (Single-layer photosensitive layer)

[0053] The positively charged electrophotographic photoreceptor according to the present embodiment has a single-layer photosensitive layer containing a hole transport material, an electron transport material, a charge generation material, and a binder resin.

[0054] [Binder resin]

[0055] In the positively charged electrophotographic photoreceptor according to the present embodiment, the binder resin in the single-layer photosensitive layer contains resin A having an elastic deformation rate of 53.0% or more and resin B having an elastic deformation rate difference of 12% or more and 17% or less from the elastic deformation rate of resin A.

[0056] From the viewpoint of the inhibitory effect on the generation of color spots caused by corrosion (hereinafter, also simply referred to as "inhibitory effect on color spot generation"), it is preferable that resin A and resin B are incompatible.

[0057] In addition, in the single-layer photosensitive layer, from the viewpoint of the inhibitory effect on color spot generation, resin A and resin B preferably form an interpenetrating polymer network structure or a sea-island structure according to their mixing ratio, and more preferably form an interpenetrating polymer network structure.

[0058] -Elastic deformation rate of Resin A-

[0059] The elastic deformation rate of Resin A is 53.0% or more. From the viewpoints of abrasion resistance and suppression of color spot generation, it is preferably 53.0% or more and 75.0% or less, more preferably 54.0% or more and 70.0% or less, and particularly preferably 56.0% or more and 65.0% or less.

[0060] -Elastic deformation rate of Resin B-

[0061] From the viewpoints of abrasion resistance and suppression of color spot generation, the elastic deformation rate of Resin B is preferably 36.0% or more and less than 53.0%, more preferably 40.0% or more and 50.0% or less, and particularly preferably 42.0% or more and 48.0% or less.

[0062] -Difference in elastic deformation rate between Resin B and Resin A-

[0063] The difference in elastic deformation rate between Resin B and Resin A is 12% or more and 17% or less. From the viewpoint of suppression of color spot generation, it is preferably 12% or more and 16% or less, more preferably 12% or more and 15% or less, and particularly preferably 12.5% or more and 14.5% or less.

[0064] In addition, from the viewpoint of suppression of color spot generation, it is preferable that the elastic deformation rate of Resin B is 12% or more and 17% or less smaller than the elastic deformation rate of Resin A.

[0065] The method for measuring the elastic deformation rate of the resin in this embodiment is as described below.

[0066] The elastic deformation rate of the resin is obtained by the following operation.

[0067] The so-called elastic deformation rate is a value defined by dividing the total deformation amount when a load is applied to the photosensitive layer into an elastic deformation amount and a plastic deformation amount, i.e., elastic deformation rate = elastic deformation amount / total deformation amount. Specifically, it is calculated by measuring the indentation depth and the indentation depth - stress curve using a Nanoindenter SA2 manufactured by MTS Corporation, a DCM indenter, and a diamond regular triangular pyramid indenter. Specifically, as the measurement conditions, the indentation depth when the indentation depth is set to 500 nm in an environment of temperature 24°C and humidity 50% is set as Dmax (nm), and then the indentation depth in the state of complete unloading is set as D1 (nm), and the elastic deformation rate R is calculated using the following formula.

[0068] 〔Formula〕Elastic deformation rate = (Dmax - D1) / Dmax

[0069] -Value of the mass ratio of Resin A and Resin B (MA / MB)-

[0070] From the viewpoint of suppressing the generation of color spots, the value of the mass ratio MA / MB of the content MA of resin A to the content MB of resin B in the single-layer photosensitive layer is preferably 0.1 or more and 10 or less, more preferably 0.25 or more and 4 or less, still more preferably 0.4 or more and 2.5 or less, and particularly preferably 0.5 or more and 2.0 or less.

[0071] In addition, from the viewpoint of abrasion resistance, the value of the mass ratio MA / MB of the content MA of resin A to the content MB of resin B in the single-layer photosensitive layer is preferably 0.4 or more and 10 or less, more preferably 0.5 or more and 10 or less, and particularly preferably 0.75 or more and 9 or less.

[0072] Examples of the binder resin for the single-layer photosensitive layer include polycarbonate resin, polyester 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, polysilane, etc.

[0073] From the viewpoints of abrasion resistance and suppression of color spot generation, resin A is preferably a polyester resin or a polycarbonate resin, and more preferably a polyester resin.

[0074] In addition, from the viewpoints of abrasion resistance and suppression of color spot generation, resin A is particularly preferably a polyarylate resin among polyester resins.

[0075] Examples of the polyarylate resin include condensates of bisphenols and aromatic dicarboxylic acids, etc.

[0076] Furthermore, from the viewpoints of abrasion resistance and suppression of color spot generation, resin A preferably has a biphenyl structure.

[0077] The weight-average molecular weight (Mw) of resin A is preferably 30,000 or more and 300,000 or less, more preferably 40,000 or more and 250,000 or less, and still more preferably 50,000 or more and 200,000 or less.

[0078] The weight-average molecular weight of the resin is the weight-average molecular weight in terms of polystyrene measured by GPC (gel permeation chromatography). Tetrahydrofuran is used as the eluent for GPC.

[0079] From the viewpoints of abrasion resistance and suppression of color spot generation, resin B is preferably a polyester resin or a polycarbonate resin, and more preferably a polycarbonate resin.

[0080] In addition, from the viewpoints of abrasion resistance and suppression of color spot generation, resin B preferably has a biphenyl structure.

[0081] From the viewpoint of generating inhibition from color dots, the viscosity average molecular weight of resin B is preferably 50,000 or less, more preferably 45,000 or less, and still more preferably 40,000 or less. Further, from the viewpoint of abrasion resistance, the viscosity average molecular weight of resin B is preferably 20,000 or more.

[0082] The viscosity average molecular weight of the resin in this embodiment is measured using the following one-point measurement method.

[0083] First, expose the single-layer photosensitive layer of the photoreceptor to be the measurement object. Then, cut out a part of the single-layer photosensitive layer to prepare a measurement sample.

[0084] Next, extract the resin from the measurement sample. Dissolve 1 g of the extracted resin in 100 cm of dichloromethane, and measure its specific viscosity ηsp with an Ubbelohde viscometer in a measurement environment of 25 °C. Then, from the relational expression of ηsp / c = [η] + 0.45[η] 3 c (where c is the concentration (g / cm 2 )) to obtain the intrinsic viscosity [η] (cm 3 / g), and from the formula given by H. Schnell, [η] = 1.23×10 3 Mv -4 Mv 0.83 to obtain the viscosity average molecular weight Mv.

[0085] - Polyarylate resin -

[0086] As the polyarylate resin, the polyarylate resin shown below is preferably used.

[0087] The polyarylate resin preferably has at least the dicarboxylic acid unit (A) represented by formula (A) and the diol unit (B) represented by formula (B).

[0088] The polyarylate resin may contain other dicarboxylic acid units other than the dicarboxylic acid unit (A).

[0089] The polyarylate resin may contain other diol units other than the diol unit (B).

[0090] The dicarboxylic acid unit (A) is a structural unit represented by the following formula (A).

[0091] Formula (A)

[0092]

[0093] In formula (A), n 1 is 1, 2 or 3, and n 1 number of m 1is independently 0, 1, 2, 3, or 4, m 1 number of Ra 1 is independently an alkyl group having 1 or more and 10 or less carbon atoms (also referred to as "number of carbon atoms"), an aryl group having 6 or more and 12 or less carbon atoms, or an alkoxy group having 1 or more and 6 or less carbon atoms.

[0094] In formula (A), n 1 is 1, 2, or 3, preferably 2.

[0095] n 1 When n is 2, for m 1 and Ra 1 the two benzene rings present in formula (A) may be the same benzene ring or different benzene rings.

[0096] n 1 When n is 3, for m 1 and Ra 1 the three benzene rings present in formula (A) may be the same benzene ring or different benzene rings.

[0097] In formula (A), when n 1 is 2 or 3, the bonding positions of the benzene rings with respect to each other may be any of ortho, meta, and para, preferably meta or para.

[0098] In formula (A), m 1 is 0, 1, 2, 3, or 4, preferably 0, 1, or 2, more preferably 0 or 1, and further preferably 0.

[0099] m 1 When m is 2, the two Ra bonded to the same benzene ring 1 may be groups of the same type or groups of different types.

[0100] m 1 When m is 3, the three Ra bonded to the same benzene ring 1 may be groups of the same type or groups of different types.

[0101] m 1 When m is 4, the four Ra bonded to the same benzene ring 1 may be groups of the same type or groups of different types.

[0102] In formula (A), the alkyl group having 1 or more and 10 or less carbon atoms may be any of linear, branched, and cyclic. The number of carbon atoms of the alkyl group is preferably 1 or more and 6 or less, more preferably 1 or more and 4 or less, and further preferably 1 or 2.

[0103] In formula (A), the aryl group having 6 to 12 carbon atoms can be either a monocyclic or polycyclic group. The number of carbon atoms of the aryl group is preferably 6 to 10, more preferably 6 to 9.

[0104] In formula (A), the alkyl group in the alkoxy group having 1 to 6 carbon atoms can be linear, branched or cyclic. The number of carbon atoms of the alkyl group in the alkoxy group having 1 to 6 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and further preferably 1 or 2.

[0105] In formula (A), examples of the linear alkyl group 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.

[0106] Examples of the branched alkyl group having 3 to 10 carbon atoms include isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, neopentyl, tert-pentyl, isohexyl, sec-hexyl, tert-hexyl, isoheptyl, sec-heptyl, tert-heptyl, isooctyl, sec-octyl, tert-octyl, isononyl, sec-nonyl, tert-nonyl, isodecyl, sec-decyl, tert-decyl, etc.

[0107] Examples of the cyclic alkyl group having 3 to 10 carbon atoms include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, and polycyclic (e.g., bicyclic, tricyclic, spirocyclic) alkyl groups formed by linking these monocyclic alkyl groups.

[0108] In formula (A), examples of the aryl group having 6 to 12 carbon atoms include phenyl, biphenyl, 1-naphthyl, 2-naphthyl, etc.

[0109] In formula (A), examples of the linear alkoxy group having 1 to 6 carbon atoms include methoxy, ethoxy, n-propoxy, n-butoxy, n-pentyloxy, and n-hexyloxy.

[0110] In formula (A), examples of the branched alkoxy group having 3 to 6 carbon atoms include isopropoxy, isobutoxy, sec-butoxy, tert-butoxy, isopentyloxy, neopentyloxy, tert-pentyloxy, isohexyloxy, sec-hexyloxy, tert-hexyloxy, etc.

[0111] In formula (A), examples of the cyclic alkoxy group having 3 to 6 carbon atoms include cyclopropoxy, cyclobutoxy, cyclopentyloxy, cyclohexyloxy, etc.

[0112] In formula (A), when m 1 is 1, 2, 3 or 4, Ra 1Preferably a linear alkyl group having 1 or more and 6 or less carbon atoms or a branched alkyl group having 3 or more and 6 or less carbon atoms, more preferably a linear alkyl group having 1 or more and 4 or less carbon atoms or a branched alkyl group having 3 or 4 carbon atoms, and still more preferably a methyl group or an ethyl group.

[0113] Hereinafter, as specific examples of the dicarboxylic acid unit (A), the dicarboxylic acid units (A-1) to (A-13) are listed. The dicarboxylic acid unit (A) is not limited thereto.

[0114]

[0115] As the dicarboxylic acid unit (A), (A-1), (A-7), and (A-10) to (A-13) of the above specific examples are preferred, (A-10) to (A-12) are more preferred, and (A-12) is particularly preferred.

[0116] The dicarboxylic acid unit (A) contained in the polyarylate resin may be one kind or two or more kinds.

[0117] The diol unit (B) is a structural unit represented by the following formula (B).

[0118] Formula (B)

[0119]

[0120] In formula (B), Rb 1 and Rb 2 are each independently a hydrogen atom, an alkyl group having 1 or more and 20 or less carbon atoms, an aryl group having 6 or more and 12 or less carbon atoms, or an aralkyl group having 7 or more and 20 or less carbon atoms, and Rb 3 , Rb 4 , Rb 5 , Rb 6 , Rb 7 , Rb 8 , Rb 9 and Rb 10 are each independently a hydrogen atom, an alkyl group having 1 or more and 10 or less carbon atoms, an aryl group having 6 or more and 12 or less carbon atoms, an aralkyl group having 7 or more and 20 or less carbon atoms, or an alkoxy group having 1 or more and 6 or less carbon atoms, and Rb 1 and Rb 2 may be bonded to form a cyclic alkyl group.

[0121] In formula (B), the alkyl group having 1 or more and 20 or less carbon atoms to which Rb 1 and Rb 2 relate may be any of linear, branched, and cyclic. The number of carbon atoms of the alkyl group is preferably 1 or more and 15 or less, more preferably 1 or more and 12 or less, and still more preferably 1 or more and 10 or less.

[0122] In formula (B), Rb 1 and Rb 2 The aryl group having 6 or more and 12 or less carbon atoms involved may be either monocyclic or polycyclic. The number of carbon atoms of the aryl group is preferably 6 or more and 10 or less, more preferably 6 or more and 9 or less.

[0123] In formula (B), Rb 1 and Rb 2 The aryl group in the aralkyl group having 7 or more and 20 or less carbon atoms involved may be either monocyclic or polycyclic, and the alkyl group in the aralkyl group having 7 or more and 20 or less carbon atoms may be linear, branched or cyclic. The number of carbon atoms of the aryl group is preferably 6 or more and 10 or less, more preferably 6 or more and 9 or less. The number of carbon atoms of the alkyl group is preferably 1 or more and 6 or less, more preferably 1 or more and 5 or less, and further preferably 1 or more and 4 or less.

[0124] In formula (B), Rb 1 and Rb 2 The number of carbon atoms of the cyclic alkyl group that can be formed by bonding is preferably 5 or more and 15 or less, more preferably 6 or more and 12 or less.

[0125] In formula (B), Rb 3 , Rb 4 , Rb 5 , Rb 6 , Rb 7 , Rb 8 , Rb 9 and Rb 10 The alkyl group having 1 or more and 10 or less carbon atoms involved may be linear, branched or cyclic. The number of carbon atoms of the alkyl group is preferably 1 or more and 6 or less, more preferably 1 or more and 4 or less, and further preferably 1 or 2.

[0126] In formula (B), Rb 3 , Rb 4 , Rb 5 , Rb 6 , Rb 7 , Rb 8 , Rb 9 and Rb 10 The aryl group having 6 or more and 12 or less carbon atoms involved may be either monocyclic or polycyclic. The number of carbon atoms of the aryl group is preferably 6 or more and 10 or less, more preferably 6 or more and 9 or less.

[0127] In formula (B), Rb 3 , Rb 4 , Rb 5 , Rb 6 , Rb 7 , Rb 8 , Rb9 and Rb 10 The aryl group in the aralkyl group having 7 or more and 20 or less carbon atoms involved may be any of monocyclic and polycyclic groups, and the alkyl group in the aralkyl group having 7 or more and 20 or less carbon atoms may be any of linear, branched, and cyclic groups. The carbon number of the aryl group is preferably 6 or more and 10 or less, more preferably 6 or more and 9 or less. The carbon number of the alkyl group is preferably 1 or more and 6 or less, more preferably 1 or more and 5 or less, and further preferably 1 or more and 4 or less.

[0128] In formula (B), Rb 3 , Rb 4 , Rb 5 , Rb 6 , Rb 7 , Rb 8 , Rb 9 and Rb 10 The alkyl group in the alkoxy group having 1 or more and 6 or less carbon atoms involved may be any of linear, branched, and cyclic groups. The carbon number of the alkyl group in the alkoxy group having 1 or more and 6 or less carbon atoms is preferably 1 or more and 4 or less, more preferably 1 or more and 3 or less, and further preferably 1 or 2.

[0129] In formula (B), examples of the linear alkyl group having 1 or more and 20 or less carbon atoms include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, tridecyl, n-tetradecyl, n-pentadecyl, n-heptadecyl, n-octadecyl, n-nonadecyl, n-icosyl, etc.

[0130] Examples of the branched alkyl group having 3 or more and 20 or less carbon atoms include isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, neopentyl, tert-pentyl, isohexyl, sec-hexyl, tert-hexyl, isoheptyl, sec-heptyl, tert-heptyl, isooctyl, sec-octyl, tert-octyl, isononyl, sec-nonyl, tert-nonyl, isodecyl, sec-decyl, tert-decyl, isododecyl, sec-dodecyl, tert-dodecyl, tert-tetradecyl, tert-pentadecyl, etc.

[0131] Examples of the cyclic alkyl group having 3 or more and 20 or less carbon atoms include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, etc., and polycyclic (e.g., bicyclic, tricyclic, spirocyclic) alkyl groups formed by linking these monocyclic alkyl groups.

[0132] In formula (B), examples of the aryl group having 6 or more and 12 or less carbon atoms include phenyl, biphenyl, 1-naphthyl, 2-naphthyl, etc.

[0133] In formula (B), examples of the aralkyl group having 7 or more and 20 or less carbon atoms include benzyl, phenylethyl, phenylpropyl, 4-phenylbutyl, phenylpentyl, phenylhexyl, phenylheptyl, phenyloctyl, phenylnonyl, naphthylmethyl, naphthylethyl, anthrylmethyl, phenyl-cyclopentylmethyl, and the like.

[0134] In formula (B), examples of the straight-chain alkoxy group having 1 or more and 6 or less carbon atoms include methoxy, ethoxy, n-propoxy, n-butoxy, n-pentyloxy, and n-hexyloxy.

[0135] In formula (B), examples of the branched-chain alkoxy group having 3 or more and 6 or less carbon atoms include isopropoxy, isobutoxy, sec-butoxy, tert-butoxy, isopentyloxy, neopentyloxy, tert-pentyloxy, isohexyloxy, sec-hexyloxy, tert-hexyloxy, and the like.

[0136] In formula (B), examples of the cyclic alkoxy group having 3 or more and 6 or less carbon atoms include cyclopropoxy, cyclobutoxy, cyclopentyloxy, cyclohexyloxy, and the like.

[0137] In formula (B), Rb 1 and Rb 2 are each independently preferably a hydrogen atom, a straight-chain alkyl group having 1 or more and 12 or less carbon atoms, a branched-chain alkyl group having 1 or more and 12 or less carbon atoms, an aryl group having 6 or more and 10 or less carbon atoms, or an aralkyl group having 7 or more and 10 or less carbon atoms, or Rb 1 and Rb 2 bond to form a cyclic alkyl group having 5 or more and 12 or less carbon atoms.

[0138] In formula (B), Rb 1 and Rb 2 are each more independently preferably a hydrogen atom, a straight-chain alkyl group having 1 or more and 10 or less carbon atoms, or a branched-chain alkyl group having 1 or more and 10 or less carbon atoms, or Rb 1 and Rb 2 bond to form a cyclic alkyl group having 5 or more and 12 or less carbon atoms.

[0139] In formula (B), Rb 1 and Rb 2 are each further independently preferably a hydrogen atom, a straight-chain alkyl group having 1 or more and 10 or less carbon atoms, or a branched-chain alkyl group having 1 or more and 10 or less carbon atoms.

[0140] In formula (B), it is preferred that at least one of Rb 1 and Rb 2 is a straight-chain alkyl group having 4 or more and 10 or less carbon atoms, a branched-chain alkyl group having 4 or more and 10 or less carbon atoms, an aryl group having 6 or more and 10 or less carbon atoms, or an aralkyl group having 7 or more and 10 or less carbon atoms, or Rb 1 and Rb 2Bonded to form a cyclic alkyl group having 5 or more and 12 or less carbon atoms.

[0141] In formula (B), Rb is more preferably 1 and Rb 2 at least one of which is a straight-chain alkyl group having 4 or more and 10 or less carbon atoms or a branched-chain alkyl group having 4 or more and 10 or less carbon atoms.

[0142] In the case where at least one of Rb 1 and Rb 2 is the above group, the other of Rb 1 and Rb 2 is preferably a hydrogen atom or a straight-chain alkyl group having 1 or more and 3 or less carbon atoms.

[0143] The diol unit (B) is preferably a structural unit represented by the following formula (B').

[0144] Formula (B')

[0145]

[0146] Rb in formula (B') 1 , Rb 2 , Rb 4 and Rb 9 are respectively the same as Rb in formula (B) 1 , Rb 2 , Rb 4 and Rb 9 in meaning, and the preferred modes are also the same.

[0147] As the diol unit (B), in formula (B'),

[0148] the following form is preferred: Rb 1 is a hydrogen atom, a straight-chain alkyl group having 1 or more and 3 or less carbon atoms or a branched-chain alkyl group having 3 carbon atoms, Rb 2 is a straight-chain alkyl group having 4 or more and 10 or less carbon atoms, a branched-chain alkyl group having 4 or more and 10 or less carbon atoms, an aryl group having 6 or more and 10 or less carbon atoms or an aralkyl group having 7 or more and 10 or less carbon atoms, and Rb 4 and Rb 9 are each independently a hydrogen atom or a methyl group;

[0149] More preferably, it is in the following form: Rb 1 is a hydrogen atom or a methyl group, Rb 2 is a straight-chain alkyl group having 4 or more and 10 or less carbon atoms or a branched-chain alkyl group having 4 or more and 10 or less carbon atoms, and Rb 4 and Rb 9 are each independently a hydrogen atom or a methyl group.

[0150] Hereinafter, as specific examples of the diol unit (B), diol units (B-1) to (B-38) are listed. The diol unit (B) is not limited thereto.

[0151]

[0152]

[0153]

[0154]

[0155]

[0156] Among them, as the diol unit (B), (B-19) is preferred.

[0157] The diol unit (B) contained in the polyarylate resin may be one kind or two or more kinds.

[0158] The mass ratio of the dicarboxylic acid unit (A) in the polyarylate resin is preferably 15% by mass or more and 60% by mass or less.

[0159] When the mass ratio of the dicarboxylic acid unit (A) is 15% by mass or more, the abrasion resistance of the photosensitive layer is good. From this viewpoint, the mass ratio of the dicarboxylic acid unit (A) is more preferably 20% by mass or more, and further preferably 25% by mass or more.

[0160] When the mass ratio of the dicarboxylic acid unit (A) is 60% by mass or less, the peeling of the photosensitive layer is more suppressed. From this viewpoint, the mass ratio of the dicarboxylic acid unit (A) is more preferably 55% by mass or less, and further preferably 50% by mass or less.

[0161] The mass ratio of the diol unit (B) in the polyarylate resin is preferably 25% by mass or more and 60% by mass or less.

[0162] When the mass ratio of the diol unit (B) is 25% by mass or more, the peeling of the photosensitive layer is more suppressed. From this viewpoint, the mass ratio of the diol unit (B) is more preferably 30% by mass or more, and further preferably 35% by mass or more.

[0163] When the mass ratio of the diol unit (B) is 60% by mass or less, the solubility in the coating liquid for forming the photosensitive layer is maintained and the abrasion resistance is improved. From this viewpoint, the mass ratio of the diol unit (B) is more preferably 55% by mass or less, and further preferably 50% by mass or less.

[0164] The polyarylate resin may contain other dicarboxylic acid units other than the dicarboxylic acid unit (A).

[0165] As other dicarboxylic acid units, for example, a dicarboxylic acid unit (C) represented by the following formula (C) can be cited.

[0166] Formula (C)

[0167]

[0168] In formula (C), Rc 1 、Rc 2 、Rc 3 、Rc 4 、Rc 5 and Rc 6 are each independently a hydrogen atom, an alkyl group having 1 or more and 10 or less carbon atoms, an aryl group having 6 or more and 12 or less carbon atoms, or an alkoxy group having 1 or more and 6 or less carbon atoms.

[0169] In formula (C), the alkyl group having 1 or more and 10 or less carbon atoms can be any of linear, branched, and cyclic. The number of carbon atoms of the alkyl group is preferably 1 or more and 6 or less, more preferably 1 or more and 4 or less, and further preferably 1 or 2.

[0170] In formula (C), the aryl group having 6 or more and 12 or less carbon atoms can be any of monocyclic and polycyclic. The number of carbon atoms of the aryl group is preferably 6 or more and 10 or less, more preferably 6 or more and 9 or less.

[0171] In formula (C), the alkyl group in the alkoxy group having 1 or more and 6 or less carbon atoms can be any of linear, branched, and cyclic. The number of carbon atoms of the alkyl group in the alkoxy group having 1 or more and 6 or less carbon atoms is preferably 1 or more and 4 or less, more preferably 1 or more and 3 or less, and further preferably 1 or 2.

[0172] As specific examples of the alkyl group, aryl group, and alkoxy group in formula (C), the same groups as those exemplified for formula (A) can be cited.

[0173] In formula (C), Rc 1 、Rc 2 、Rc 3 、Rc 4 、Rc 5 and Rc 6 are each independently preferably a hydrogen atom, a linear alkyl group having 1 or more and 6 or less carbon atoms, or a branched alkyl group having 1 or more and 6 or less carbon atoms, more preferably a hydrogen atom, a linear alkyl group having 1 or more and 4 or less carbon atoms, or a branched alkyl group having 1 or more and 4 or less carbon atoms, further preferably a hydrogen atom, a linear alkyl group having 1 or more and 3 or less carbon atoms, or a branched alkyl group having 1 or more and 3 or less carbon atoms, and particularly preferably a hydrogen atom.

[0174] As the dicarboxylic acid unit (C), 2,6-naphthalenedicarboxylic acid unit (the following unit (C-1)) is particularly preferred.

[0175]

[0176] The dicarboxylic acid unit (C) contained in the polyarylate resin may be one kind or two or more kinds.

[0177] When the polyarylate resin has the dicarboxylic acid unit (C), the mass ratio of the dicarboxylic acid unit (C) in the polyarylate resin is preferably 1% by mass or more and 20% by mass or less.

[0178] As other dicarboxylic acid units, for example, a dicarboxylic acid unit (D) represented by the following formula (D) can be mentioned.

[0179] Formula (D)

[0180]

[0181] In formula (D), Rd 1 , Rd 2 , Rd 3 , Rd 4 , Rd 5 , Rd 6 , Rd 7 and Rd8 are each independently a hydrogen atom, an alkyl group having 1 or more and 10 or less carbon atoms, an aryl group having 6 or more and 12 or less carbon atoms, or an alkoxy group having 1 or more and 6 or less carbon atoms.

[0182] In formula (D), the alkyl group having 1 or more and 10 or less carbon atoms can be any of linear, branched, and cyclic. The number of carbon atoms of the alkyl group is preferably 1 or more and 6 or less, more preferably 1 or more and 4 or less, and further preferably 1 or 2.

[0183] In formula (D), the aryl group having 6 or more and 12 or less carbon atoms can be any of monocyclic and polycyclic. The number of carbon atoms of the aryl group is preferably 6 or more and 10 or less, more preferably 6 or more and 9 or less.

[0184] In formula (D), the alkyl group in the alkoxy group having 1 or more and 6 or less carbon atoms can be any of linear, branched, and cyclic. The number of carbon atoms of the alkyl group in the alkoxy group having 1 or more and 6 or less carbon atoms is preferably 1 or more and 4 or less, more preferably 1 or more and 3 or less, and further preferably 1 or 2.

[0185] As specific examples of the alkyl group, aryl group, and alkoxy group in formula (D), the same groups as those listed for formula (A) can be mentioned.

[0186] In formula (D), Rd 1 , Rd 2 , Rd 3 , Rd 4 , Rd5 、Rd 6 、Rd 7 and Rd 8 Each of them is independently preferably a hydrogen atom, a straight-chain alkyl group having 1 to 6 carbon atoms, or a branched-chain alkyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom, a straight-chain alkyl group having 1 to 4 carbon atoms, or a branched-chain alkyl group having 1 to 4 carbon atoms, further preferably a hydrogen atom, a straight-chain alkyl group having 1 to 3 carbon atoms, or a branched-chain alkyl group having 1 to 3 carbon atoms, and particularly preferably a hydrogen atom.

[0187] The dicarboxylic acid unit (D) is preferably a structural unit represented by the following formula (D').

[0188] Formula (D')

[0189]

[0190] Rd in formula (D') 1 、Rd 2 、Rd 3 and Rd 4 Respectively with Rd in formula (D) 1 、Rd 2 、Rd 3 and Rd 4 The meaning is the same and the preferred method is also the same.

[0191] As the dicarboxylic acid unit (D), a diphenyl ether-4,4'-dicarboxylic acid unit (unit (D-1) described below) is particularly preferred.

[0192]

[0193] The dicarboxylic acid units (D) contained in the polyarylate resin may be one type or two or more types.

[0194] When the polyarylate resin has a dicarboxylic acid unit (D), the mass ratio of the dicarboxylic acid unit (D) in the polyarylate resin is preferably 1 mass % or more and 20 mass % or less.

[0195] 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, and sebacic acid), alicyclic dicarboxylic acid units (e.g., cyclohexanedicarboxylic acid), and lower (e.g., C1 to C5) alkyl ester units thereof. The polyarylate resin may contain one or more of these dicarboxylic acid units.

[0196] The polyarylate resin may contain other diol units in addition to the diol unit (B).

[0197] As other diol units, for example, a diol unit (E) represented by the following formula (E) can be mentioned.

[0198] Formula (E)

[0199]

[0200] In formula (E), Re 1 、Re 2 、Re 3 、Re 4 、Re 5 、Re 6 、Re 7 and Re 8 are each independently a hydrogen atom, an alkyl group having 1 or more and 10 or less carbon atoms, an aryl group having 6 or more and 12 or less carbon atoms, an aralkyl group having 7 or more and 20 or less carbon atoms, or an alkoxy group having 1 or more and 6 or less carbon atoms.

[0201] In formula (E), the alkyl group having 1 or more and 10 or less carbon atoms can be any of linear, branched, and cyclic. The number of carbon atoms of the alkyl group is preferably 1 or more and 6 or less, more preferably 1 or more and 4 or less, and further preferably 1 or 2.

[0202] In formula (E), the aryl group having 6 or more and 12 or less carbon atoms can be any of monocyclic and polycyclic. The number of carbon atoms of the aryl group is preferably 6 or more and 10 or less, more preferably 6 or more and 9 or less.

[0203] In formula (E), the aryl group in the aralkyl group having 7 or more and 20 or less carbon atoms can be any of monocyclic and polycyclic, and the alkyl group in the aralkyl group having 7 or more and 20 or less carbon atoms can be any of linear, branched, and cyclic. The number of carbon atoms of the aryl group is preferably 6 or more and 10 or less, more preferably 6 or more and 9 or less. The number of carbon atoms of the alkyl group is preferably 1 or more and 6 or less, more preferably 1 or more and 5 or less, and further preferably 1 or more and 4 or less.

[0204] In formula (E), the alkyl group in the alkoxy group having 1 or more and 6 or less carbon atoms can be any of linear, branched, and cyclic. The number of carbon atoms of the alkyl group in the alkoxy group having 1 or more and 6 or less carbon atoms is preferably 1 or more and 4 or less, more preferably 1 or more and 3 or less, and further preferably 1 or 2.

[0205] As specific examples of each of the alkyl group, aryl group, aralkyl group, and alkoxy group in formula (E), the same groups as those listed for formula (B) can be mentioned.

[0206] In formula (E), Re 1 、Re 2 、Re 3 、Re 4 、Re 5, Re 6 , Re 7 and Re 8 are each independently preferably a hydrogen atom, a linear alkyl group having 1 to 6 carbon atoms or a branched alkyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom, a linear alkyl group having 1 to 4 carbon atoms or a branched alkyl group having 1 to 4 carbon atoms, still more preferably a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms or a branched alkyl group having 1 to 3 carbon atoms, and particularly preferably a hydrogen atom or a methyl group.

[0207] The diol unit (E) is preferably a structural unit represented by the following formula (E').

[0208] Formula (E')

[0209]

[0210] Re in formula (E') 1 , Re 2 , Re 3 and Re 4 have the same meanings as Re in formula (E) 1 , Re 2 , Re 3 and Re 4 respectively, and the preferred modes are also the same.

[0211] As the diol unit (E), any one of the following unit (E-1), unit (E-2) and unit (E-3) is particularly preferred.

[0212]

[0213] The diol unit (E) contained in the polyarylate resin may be one kind or two or more kinds.

[0214] When the polyarylate resin has the diol unit (E), the mass ratio of the diol unit (E) in the polyarylate resin is preferably 1% by mass or more and 20% by mass or less.

[0215] As other diol units, for example, a diol unit (F) represented by the following formula (F) can be cited.

[0216] Formula (F)

[0217]

[0218] In formula (F), Rf 1 , Rf 2 , Rf 3 , Rf 4 , Rf 5 , Rf 6 , Rf7 and Rf 8 are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

[0219] In formula (F), the alkyl group having 1 to 10 carbon atoms may be any of linear, branched, and cyclic. The number of carbon atoms of the alkyl group is preferably 1 to 6, more preferably 1 to 4, and still more preferably 1 or 2.

[0220] In formula (F), the aryl group having 6 to 12 carbon atoms may be any of monocyclic and polycyclic. The number of carbon atoms of the aryl group is preferably 6 to 10, more preferably 6 to 9.

[0221] In formula (F), the aryl group in the aralkyl group having 7 to 20 carbon atoms may be any of monocyclic and polycyclic, and the alkyl group in the aralkyl group having 7 to 20 carbon atoms may be any of linear, branched, and cyclic. The number of carbon atoms of the aryl group is preferably 6 to 10, more preferably 6 to 9. The number of carbon atoms of the alkyl group is preferably 1 to 6, more preferably 1 to 5, and still more preferably 1 to 4.

[0222] In formula (F), the alkyl group in the alkoxy group having 1 to 6 carbon atoms may be any of linear, branched, and cyclic. The number of carbon atoms of the alkyl group in the alkoxy group having 1 to 6 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and still more preferably 1 or 2.

[0223] As specific examples of the alkyl group, aryl group, aralkyl group, and alkoxy group in formula (F), the same groups as those listed for formula (B) can be cited.

[0224] In formula (F), Rf 1 , Rf 2 , Rf 3 , Rf 4 , Rf 5 , Rf 6 , Rf 7 and Rf 8 are each independently preferably a hydrogen atom, a linear alkyl group having 1 to 6 carbon atoms, or a branched alkyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom, a linear alkyl group having 1 to 4 carbon atoms, or a branched alkyl group having 1 to 4 carbon atoms, still more preferably a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, or a branched alkyl group having 1 to 3 carbon atoms, and particularly preferably a hydrogen atom or a methyl group.

[0225] The diol unit (F) is preferably a structural unit represented by the following formula (F').

[0226] Formula (F')

[0227]

[0228] Rf in formula (F') 1 、Rf 2 、Rf 3 and Rf 4 respectively have the same meaning as Rf in formula (F) 1 、Rf 2 、Rf 3 and Rf 4 and the preferred modes are also the same.

[0229] As the diol unit (F), a bis(4-hydroxyphenyl) ether unit (the following unit (F-1)) is particularly preferred.

[0230]

[0231] The diol unit (F) contained in the polyarylate resin may be one kind or two or more kinds.

[0232] When the polyarylate resin has a diol unit (F), the mass ratio of the diol unit (F) in the polyarylate resin is preferably 1% by mass or more and 20% by mass or less.

[0233] As other diol units, for example, aliphatic diol (e.g., ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butylene glycol, hexylene glycol, neopentyl glycol) units, alicyclic diol (e.g., cyclohexanediol, cyclohexanedimethanol, hydrogenated bisphenol A) units can be cited. These diol units contained in the polyarylate resin may be one kind or two or more kinds.

[0234] The polyester resin containing the polyarylate resin is obtained by subjecting a monomer giving a dicarboxylic acid unit, a monomer giving a diol unit, and other monomers added as required to polycondensation by a conventional method. As the polycondensation method of the monomer, an interfacial polycondensation method, a solution polycondensation method, a melt polycondensation method, etc. can be cited. The interfacial polycondensation method is a polymerization method for obtaining a polyester by mixing a dicarboxylic acid halide dissolved in an organic solvent immiscible with water and a diol dissolved in an aqueous alkali solution. As the literature related to the interfacial polycondensation method, W.M.EARECKSON, J.Poly.Sci., XL399, 1959, Japanese Patent Publication No. 40-1959 can be cited. Since the interfacial polycondensation method has a faster reaction than the solution polycondensation method, hydrolysis of the dicarboxylic acid halide can be suppressed, and as a result, a high molecular weight polyester resin can be obtained.

[0235] The terminals of the polyester resin containing a polyarylate resin can be sealed or modified by a capping agent or a molecular weight regulator used during manufacturing. As the capping agent or molecular weight regulator, for example, monohydric phenols, monohydric acid chlorides, monohydric alcohols, and monohydric carboxylic acids can be cited.

[0236] As monohydric phenols, for example, 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, amylphenol, hexylphenol, octylphenol, nonylphenol, 2,6-dimethylphenol derivatives, 2-methylphenol derivatives, o-phenylphenol, m-phenylphenol, p-phenylphenol, o-methoxyphenol, m-methoxyphenol, p-methoxyphenol, 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, 2-phenyl-2-(3-hydroxyphenyl)propane can be cited.

[0237] As monohydric acid chlorides, for example, benzoyl chloride, benzoic acid chloride, methanesulfonyl chloride, phenyl chloroformate, acetyl chloride, butyryl chloride, octanoyl chloride, benzenesulfonyl chloride, benzenesulfinyl chloride, sulfinyl chloride, phenylphosphonyl chloride and their substituted products and other monofunctional acyl halides can be cited.

[0238] As monohydric alcohols, for example, methanol, ethanol, n-propanol, isopropanol, n-butanol, 2-butanol, pentanol, hexanol, dodecanol, stearyl alcohol, benzyl alcohol, phenethyl alcohol can be cited.

[0239] As monohydric carboxylic acids, for example, acetic acid, propionic acid, octanoic acid, cyclohexanecarboxylic acid, benzoic acid, methylbenzoic acid, phenylacetic acid, p-tert-butylbenzoic acid, p-methoxyphenylacetic acid can be cited.

[0240] - Polycarbonate resin -

[0241] As the polycarbonate resin, known polycarbonate resins can be used. As a preferred polycarbonate resin, for example, a polycarbonate resin containing a structural unit having at least one of a biphenyl skeleton and a bisphenol skeleton (hereinafter, also referred to as "BP polycarbonate resin") can be cited.

[0242] As the BP polycarbonate resin, for example, in addition to homopolymers composed of structural units having a biphenyl skeleton and homopolymers composed of structural units having a bisphenol skeleton, copolymers composed of at least one of a structural unit having a biphenyl skeleton and a structural unit having a bisphenol skeleton can be cited. Among them, from the viewpoint of wear resistance, the BP polycarbonate resin is preferably a homopolymer composed of a structural unit having a biphenyl skeleton.

[0243] In addition, as the bisphenol skeleton, for example, a bisphenol A skeleton, a bisphenol B skeleton, a bisphenol BP skeleton, a bisphenol C skeleton, a bisphenol F skeleton, a bisphenol Z skeleton, etc. can be cited.

[0244] As the BP polycarbonate resin, specifically, for example, a homopolymer of a dihydroxybiphenyl compound, a homopolymer of a dihydroxybisphenol compound, and a copolymer thereof can be cited. These polymers are obtained, for example, by using the above compounds as raw materials and through methods such as polycondensation with a carbonate-forming compound such as carbonyl chloride or transesterification reaction with a diaryl carbonate.

[0245] The dihydroxybiphenyl compound is a biphenyl compound having a biphenyl skeleton and having one hydroxyl group on each of the two benzene rings of the biphenyl skeleton. As the dihydroxybiphenyl compound, for example, 4,4'-dihydroxybiphenyl, 4,4'-dihydroxy-3,3'-dimethylbiphenyl, 4,4'-dihydroxy-2,2'-dimethylbiphenyl, 4,4'-dihydroxy-3,3'-dicyclohexylbiphenyl, 3,3'-difluoro-4,4'-dihydroxybiphenyl, 4,4'-dihydroxy-3,3'-diphenylbiphenyl, etc. can be cited.

[0246] These dihydroxybiphenyl compounds can be used alone or in combination of multiple kinds.

[0247] The dihydroxybisphenol compound is a bisphenol compound having a bisphenol skeleton and one hydroxyl group on each of the two benzene rings of the bisphenol skeleton. Examples of the dihydroxybisphenol compound include bis(4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane, 1,2-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(3-methyl-4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)octane, 4,4-bis(4-hydroxyphenyl)heptane, 1,1-bis(4-hydroxyphenyl)-1,1-diphenylmethane, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, 1,1-bis(4-hydroxyphenyl)-1-phenylmethane, bis(4-hydroxyphenyl)ether, bis(4-hydroxyphenyl)sulfide, bis(4-hydroxyphenyl)sulfone, 1,1-bis(4-hydroxyphenyl)cyclopentane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 2,2-bis(3-methyl-4-hydroxyphenyl)propane, 2-(3-methyl-4-hydroxyphenyl)-2-(4-hydroxyphenyl)-1-phenylethane, bis(3-methyl-4-hydroxyphenyl)sulfide, bis(3-methyl-4-hydroxyphenyl)sulfone, bis(3-methyl-4-hydroxyphenyl)methane, 1,1-bis(3-methyl-4-hydroxyphenyl)cyclohexane, 2,2-bis(2-methyl-4-hydroxyphenyl)propane, 1,1-bis(2-butyl-4-hydroxy-5-methylphenyl)butane, 1,1-bis(2-tert-butyl-4-hydroxy-3-methylphenyl)ethane, 1,1-bis(2-tert-butyl-4-hydroxy-5-methylphenyl)propane, 1,1-bis(2-tert-butyl-4-hydroxy-5-methylphenyl)butane, 1,1-bis(2-tert-butyl-4-hydroxy-5-methylphenyl)isobutane, 1,1-bis(2-tert-butyl-4-hydroxy-5-methylphenyl)heptane, 1,1-bis(2-tert-butyl-4-hydroxy-5-methylphenyl)-1-phenylmethane, 1,1-bis(2-tert-amyl-4-hydroxy-5-methylphenyl)butane, bis(3-chloro-4-hydroxyphenyl)methane, bis(3,5-dibromo-4-hydroxyphenyl)methane, 2,2-bis(3-chloro-4-hydroxyphenyl)propane, 2,2-bis(3-fluoro-4-hydroxyphenyl)propane, 2,2-bis(3-bromo-4-hydroxyphenyl)propane, 2,2-bis(3,5-difluoro-4-hydroxyphenyl)propane, 2,2-bis(3,5-dichloro-4-hydroxyphenyl)propane, 2,2-bis(3,5-dibromo-4-hydroxyphenyl)propane, 2,2-bis(3-bromo-4-hydroxy-5-chlorophenyl)propane, 2,2-bis(3,5-dichloro-4-hydroxyphenyl)butane, 2,2-bis(3,5-dibromo-4-hydroxyphenyl)butane, 1-phenyl-1,1-bis(3-fluoro-4-hydroxyphenyl)ethane, bis(3-fluoro-4-hydroxyphenyl)ether, 1,1-bis(3-cyclohexyl-4-hydroxyphenyl)cyclohexane, and the like.

[0248] These bisphenol compounds can be used alone or in combination of multiple kinds.

[0249] Among these compounds, from the viewpoint of wear resistance, the BP polycarbonate resin is preferably a polycarbonate resin containing at least one of the structural units represented by the following formula (PCA) and the structural units represented by the following formula (PCB). That is, as the preferred BP polycarbonate resin, there can be mentioned a homopolymer composed of the structural units represented by the following formula (PCA), a homopolymer composed of the structural units represented by the following formula (PCB), and a copolymer thereof.

[0250] Among them, from the viewpoint of wear resistance, a polycarbonate resin containing the structural units represented by the following formula (PCA) is more preferred.

[0251]

[0252] In formula (PCA) and (PCB), R P1 , R P2 , R P3 , and R P4 each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 or more and 6 or less carbon atoms, a cycloalkyl group having 5 or more and 7 or less carbon atoms, or an aryl group having 6 or more and 12 or less carbon atoms. X P1 represents a phenylene group, a biphenylene group, a naphthylene group, an alkylene group, or a cycloalkylene group.

[0253] In formula (PCA) and (PCB), as the alkyl group represented by R P1 , R P2 , R P3 , and R P4 , there can be mentioned a linear or branched alkyl group having 1 or more and 6 or less (preferably 1 or more and 3 or less) carbon atoms.

[0254] Specifically, as the linear alkyl group, there can be mentioned methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, etc.

[0255] Specifically, as the branched alkyl group, there can be mentioned isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, neopentyl, tert-pentyl, isohexyl, sec-hexyl, tert-hexyl, etc.

[0256] Among them, as the alkyl group, lower alkyl groups such as methyl and ethyl are preferred.

[0257] In formula (PCA) and (PCB), as the cycloalkyl group represented by R P1 , R P2 , R P3 , and R P4 , for example, there can be mentioned cyclopentyl, cyclohexyl, cycloheptyl.

[0258] In formulas (PCA) and (PCB), as R P1 , R P2 , R P3 , and R P4 represent aryl groups, for example, phenyl, naphthyl, biphenyl, etc. can be cited.

[0259] In formula (PCB), as X P1 represents an alkylene group, linear or branched alkylene groups having 1 or more and 12 or less carbon atoms (preferably 1 or more and 6 or less carbon atoms, more preferably 1 or more and 3 or less carbon atoms) can be cited.

[0260] Specifically, as the linear alkylene group, methylene, ethylene, n-propylene, n-butylene, n-pentylene, n-hexylene, n-heptylene, n-octylene, n-nonylene, n-decylene, n-undecylene, n-dodecylene, etc. can be cited.

[0261] Specifically, as the branched alkylene group, isopropylidene, isobutylene, sec-butylene, tert-butylene, isopentylene, neopentylene, tert-pentylene, isohexylene, sec-hexylene, tert-hexylene, isoheptylene, sec-heptylene, tert-heptylene, isooctylene, sec-octylene, tert-octylene, isononylene, sec-nonylene, tert-nonylene, isodecylene, sec-decylene, tert-decylene, isoundecylene, sec-undecylene, tert-undecylene, neoundecylene, isododecylene, sec-dodecylene, tert-dodecylene, neododecylene, etc. can be cited.

[0262] Among them, as the alkylene group, lower alkyl groups such as methylene, ethylene, and butylene are preferred.

[0263] In formula (PCB), as X P1 represents a cycloalkylene group, cycloalkylene groups having 3 or more and 12 or less carbon atoms (preferably 3 or more and 10 or less carbon atoms, more preferably 5 or more and 8 or less carbon atoms) can be cited.

[0264] Specifically, as the cycloalkylene group, cyclopropylidene, cyclopentylene, cyclohexylene, cyclooctylene, cyclododecylene, etc. can be cited.

[0265] Among them, as the cycloalkylene group, cyclohexylene is preferred.

[0266] In addition, in formulas (PCA) and (PCB), R P1 , R P2 , R P3 , R P4 , and X P1Each of the above substituents represented also includes a group further having a substituent. Examples of such a substituent include a halogen atom (e.g., a fluorine atom, a chlorine atom), an alkyl group (e.g., an alkyl group having 1 or more and 6 or less carbon atoms), a cycloalkyl group (e.g., a cycloalkyl group having 5 or more and 7 or less carbon atoms), an alkoxy group (e.g., an alkoxy group having 1 or more and 4 or less carbon atoms), an aryl group (e.g., a phenyl group, a naphthyl group, a biphenyl group, etc.).

[0267] In formula (PCA), R P1 , and R P2 each preferably independently represents a hydrogen atom or an alkyl group having 1 or more and 6 or less carbon atoms, and R P1 , and R P2 more preferably represents a hydrogen atom.

[0268] In formula (PCB), R P3 , and R P4 each preferably independently represents a hydrogen atom or an alkyl group having 1 or more and 6 or less carbon atoms, and X P1 represents an alkylene group or a cycloalkylene group.

[0269] Specific examples of the BP polycarbonate resin include, for example, the following polycarbonate resins, but are not limited thereto. In addition, in the exemplified compounds, pm and pn represent copolymerization ratios.

[0270] (PCA-1)

[0271]

[0272] (PCB-1)

[0273]

[0274] (PCB-2)

[0275]

[0276] (PCB-3)

[0277]

[0278] (PC-1)

[0279]

[0280] (PC-2)

[0281]

[0282] (PC-3)

[0283]

[0284] Here, in the polycarbonate resin, from the viewpoint of abrasion resistance, the content ratio (copolymerization ratio) of the structural unit represented by the formula (PCA) is preferably in the range of 5 mol% or more and 95 mol% or less, more preferably in the range of 5 mol% or more and 50 mol% or less, and still more preferably in the range of 15 mol% or more and 30 mol% or less, relative to the total structural units constituting the polycarbonate resin.

[0285] Specifically, in the above-exemplified compounds of the polycarbonate resin, pm and pn represent the copolymerization ratio (molar ratio), and preferably, the range of pm:pn = 95:5 to 5:95 can be cited, more preferably, the range of 50:50 to 5:95 can be cited, and still more preferably, the range of 15:85 to 30:70 can be cited.

[0286] The single-layer photosensitive layer contains Resin A and Resin B as binder resins. The total content of Resin A and Resin B preferably accounts for 50% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, particularly preferably 95% by mass or more, and most preferably 100% of the total content of the binder resins contained in the single-layer photosensitive layer.

[0287] 〔Hole transport material〕

[0288] The single-layer photosensitive layer contains a hole transport material.

[0289] Examples of the hole transport material include hole transport compounds such as triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted ethylene compounds, stilbene compounds, anthracene compounds, and hydrazone compounds. These hole transport materials can be used alone or in combination of two or more, but are not limited thereto.

[0290] Examples of the polymer hole transport material include known compounds having charge transport properties such as poly-N-vinylcarbazole and polysilane. For example, a polyester-based polymer charge transport material is preferably used. The polymer hole transport material can be used alone or in combination with the binder resin.

[0291] Examples of the hole transport material or the polymeric hole transport material include polycyclic aromatic compounds, aromatic nitro compounds, aromatic amine compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, enamine compounds, benzidine compounds, triarylamine compounds (especially triphenylamine compounds), diamine compounds, oxadiazole compounds, carbazole compounds, organopolysilane compounds, pyrazoline compounds, indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, triazole compounds, cyano compounds, benzofuran compounds, aniline compounds, butadiene compounds, and resins having groups derived from these substances. Specifically, examples include the compounds described in paragraphs 0078 to 0080 of Japanese Patent Application Laid-Open No. 2021-117377, paragraphs 0046 to 0048 of Japanese Patent Application Laid-Open No. 2019-035900, paragraphs 0052 to 0053 of Japanese Patent Application Laid-Open No. 2019-012141, paragraphs 0122 to 0134 of Japanese Patent Application Laid-Open No. 2021-071565, paragraphs 0101 to 0110 of Japanese Patent Application Laid-Open No. 2021-015223, paragraph 0116 of Japanese Patent Application Laid-Open No. 2013-097300, paragraphs 0309 to 0316 of International Publication No. 2019 / 070003, paragraphs 0103 to 0107 of Japanese Patent Application Laid-Open No. 2018-159087, and paragraphs 0102 to 0113 of Japanese Patent Application Laid-Open No. 2021-148818, respectively.

[0292] From the viewpoint of charge mobility, it is preferable that the hole transport material contains at least one selected from the group consisting of the compound (G1) represented by the following formula (G1), the compound (G2) represented by the formula (G2), the compound (G3) represented by the formula (G3), and the compound (G4) represented by the formula (G4).

[0293] Formula (G1)

[0294]

[0295] In formula (G1), Ar T1 , Ar T2 and Ar T3 are each independently an aryl group, -C6H4-C(R T4 )=C(R T5 )(R T6 ) or -C6H4-CH=CH-CH=C(R T7 )(R T8 ). R T4 , R T5 , R T6 , R T7 and R T8 are each independently a hydrogen atom, an alkyl group or an aryl group. When RT5 and R T6 When the aryl groups are aryl, the aryl groups may be linked to each other by a divalent group of -C(R 51 )(R 52 )- and / or -C(R 61 )=C(R 62 )-. R 51 , R 52 , R 61 and R 62 are each independently a hydrogen atom or an alkyl group having 1 or more and 3 or less carbon atoms.

[0296] The group in formula (G1) may be substituted by a halogen atom, an alkyl group having 1 or more and 5 or less carbon atoms, an alkoxy group having 1 or more and 5 or less carbon atoms, or a substituted amino group substituted by an alkyl group having 1 or more and 3 or less carbon atoms.

[0297] As the compound (G1), from the viewpoint of charge mobility, a compound having at least one aryl group or -C6H4-CH=CH-CH=C(R T7 )(R T8 ) is preferred, and a compound (G'1) represented by the following formula (G'1) is more preferred.

[0298]

[0299] In formula (G'1), R T111 , R T112 , R T121 , R T122 , R T131 and R T132 are each independently a hydrogen atom, a halogen atom, an alkyl group (preferably an alkyl group having 1 or more and 3 or less carbon atoms), an alkoxy group (preferably an alkoxy group having 1 or more and 3 or less carbon atoms), a phenyl group, or a phenoxy group. Tj1, Tj2, Tj3, Tk1, Tk2, and Tk3 are each independently 0, 1, or 2.

[0300] Formula (G2)

[0301]

[0302] In formula (G2), R T201 , R T202 , R T211 and R T212 are each independently a halogen atom, an alkyl group having 1 or more and 5 or less carbon atoms, an alkoxy group having 1 or more and 5 or less carbon atoms, an amino group substituted by an alkyl group having 1 or 2 carbon atoms, an aryl group, -C(R T21 )=C(R T22 )(R T23 ) or -CH=CH-CH=C(R T24 )(RT25 ). R T21 , R T22 , R T23 , R T24 and R T25 are each independently a hydrogen atom, an alkyl group or an aryl group. R T221 and R T222 are each independently 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. Tm1, Tm2, Tn1 and Tn2 are each independently 0, 1 or 2.

[0303] The group in formula (G2) may be substituted with a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms or a substituted amino group substituted with an alkyl group having 1 to 3 carbon atoms.

[0304] As the compound (G2), from the viewpoint of charge mobility, a compound having at least one alkyl group, aryl group or -CH=CH-CH=C(R T24 )(R T25 ) is preferred, and a compound having two alkyl groups, aryl groups or -CH=CH-CH=C(R T24 )(R T25 ) is more preferred.

[0305] Formula (G3)

[0306]

[0307] In formula (G3), R T301 , R T302 , R T311 and R T312 are each independently 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 or 2 carbon atoms, an aryl group, -C(R T31 )=C(R T32 )(R T33 ) or -CH=CH-CH=C(R T34 )(R T35 ). R T31 , R T32 , R T33 , R T34 and R T35 are each independently a hydrogen atom, an alkyl group or an aryl group. R T321 , R T322 and R T331 are each independently 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. To1, To2, Tp1, Tp2, Tq1, Tq2 and Tr1 are each independently 0, 1 or 2.

[0308] The group in formula (G3) may be substituted with a halogen atom, an alkyl group having 1 or more and 5 or less carbon atoms, an alkoxy group having 1 or more and 5 or less carbon atoms, or a substituted amino group substituted with an alkyl group having 1 or more and 3 or less carbon atoms.

[0309] Formula (G4)

[0310]

[0311] In formula (G4), R T401 , R T402 , R T411 and R T412 are each independently a halogen atom, an alkyl group having 1 or more and 5 or less carbon atoms, an alkoxy group having 1 or more and 5 or less carbon atoms, an amino group substituted with an alkyl group having 1 or 2 carbon atoms, an aryl group, -C(R T41 )=C(R T42 )(R T43 ) or -CH=CH-CH=C(R T44 )(R T45 ). R T41 , R T42 , R T43 , R T44 and R T45 are each independently a hydrogen atom, an alkyl group or an aryl group. R T421 , R T422 and R T431 are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 or more and 5 or less carbon atoms, or an alkoxy group having 1 or more and 5 or less carbon atoms. Ts1, Ts2, Tt1, Tt2, Tu1, Tu2 and Tv1 are each independently 0, 1 or 2.

[0312] The group in formula (G4) may be substituted with a halogen atom, an alkyl group having 1 or more and 5 or less carbon atoms, an alkoxy group having 1 or more and 5 or less carbon atoms, or a substituted amino group substituted with an alkyl group having 1 or more and 3 or less carbon atoms.

[0313] The content of the hole transport material contained in the single-layer photosensitive layer is preferably 5% by mass or more and 50% by mass or less relative to the total mass of the single-layer photosensitive layer.

[0314] 〔Electron transport material〕

[0315] The single-layer photosensitive layer contains an electron transport material.

[0316] Examples of the electron transport material include quinone compounds such as p-benzoquinone, chloroquinone, tetrabromobenzoquinone, and anthraquinone; tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone; xanthone compounds; benzophenone compounds; cyano vinyl compounds; ethylene compounds; and the like. The electron transport material may be used alone or in combination of two or more kinds.

[0317] As the electron transport material, from the viewpoints of sensitivity and suppression of color spot generation, a compound represented by the following formula is preferably used, and a compound represented by the following formula (3) is more preferably used.

[0318]

[0319] R t1 ~R t4 Each independently represents a hydrogen atom, an alkyl group, an alkoxy group, a cycloalkyl group, an aryl group, or an aralkyl group.

[0320] R t1 ~R t4 Each is independently preferably a hydrogen atom, an alkyl group having 1 or more and 12 or less carbon atoms, an alkoxy group having 1 or more and 12 or less carbon atoms, a cycloalkyl group, an aryl group, or an aralkyl group.

[0321] In addition, R t1 is preferably a group different from at least any one of R t2 to R t4 .

[0322] From the viewpoints of sensitivity and suppression of color spot generation, R t1 and R t3 are each independently preferably an alkyl group having 3 or more and 12 or less carbon atoms, an alkoxy group having 3 or more and 12 or less carbon atoms, a cycloalkyl group, an aryl group, or an aralkyl group, more preferably a branched alkyl group having 3 or more and 12 or less carbon atoms, a branched alkoxy group having 3 or more and 12 or less carbon atoms, a cycloalkyl group, an aryl group, or an aralkyl group, and further preferably a branched alkyl group having 3 or more and 8 or less carbon atoms or a branched alkoxy group having 3 or more and 8 or less carbon atoms, and particularly preferably a tert-butyl group.

[0323] In addition, from the viewpoints of sensitivity and suppression of color spot generation, R t1 and R t3 are preferably the same group.

[0324] From the viewpoints of sensitivity and suppression of color spot generation, R t2 and R t4are each independently preferably a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or an alkoxy group having 1 to 8 carbon atoms, more preferably a hydrogen atom, a linear alkyl group having 1 to 4 carbon atoms or a linear alkoxy group having 1 to 4 carbon atoms, still more preferably a linear alkyl group having 1 to 3 carbon atoms or a linear alkoxy group having 1 to 3 carbon atoms, and particularly preferably a methyl group.

[0325] In addition, from the viewpoints of sensitivity and suppression of color spot generation, R t2 and R t4 are preferably the same group.

[0326] Furthermore, from the viewpoints of sensitivity and suppression of color spot generation, R t1 and R t2 are preferably different groups. In addition, R t3 and R t4 are preferably different groups.

[0327] From the viewpoints of sensitivity and suppression of color spot generation, the compound represented by the formula (3) is preferably the compound represented by the following formula (3-1).

[0328]

[0329] In the formula (3-1), R t5 to R t8 each independently represent a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, a cycloalkyl group, an aryl group or an aralkyl group. In addition, R t5 is a group different from at least any one of R t6 to R t8 .

[0330] The preferred mode of R t5 to R t8 in the formula (3-1) is that the alkyl group and the alkoxy group in R t5 to R t8 have 1 to 12 carbon atoms, and R t5 is a group different from at least any one of R t6 to R t8 . Except for this, it is the same as the preferred mode of R t1 to R t4 in the formula (3) respectively.

[0331] Hereinafter, exemplary compounds of the electron transport material represented by the formula (3) are listed, but are not limited thereto.

[0332] In addition, from the viewpoints of sensitivity and suppression of color spot generation, the electron transport material is preferably one containing the following exemplified compounds 1 to 6, more preferably one containing the following exemplified compound 1, and particularly preferably the following exemplified compound 1.

[0333]

[0334] In addition, abbreviated symbols and the like in the above-exemplified compounds have the following meanings.

[0335] · t-C4H9: tert-butyl

[0336] · CH3O: methoxy

[0337] · t-C4H9O: tert-butoxy

[0338] · c-C6H 11 : cyclohexyl

[0339] · C6H5: phenyl

[0340] · C6H5CH2: benzyl

[0341] When using the compound represented by formula (3), it can be used in combination with other electron transport materials other than the compound represented by formula (3). When using the compound represented by formula (3) in combination with other electron transport materials, it is preferably 90% by mass or more of the compound represented by formula (3) relative to the total amount of the electron transport material.

[0342] In addition, as the electron transport material, from the viewpoint of increasing the sensitivity of the photosensitive layer, a fluorenone compound is preferred, and among the fluorenone compounds, the compound represented by formula (F2) is preferred.

[0343]

[0344] In formula (F2), R f11 , R f12 , R f13 , R f14 , R f15 , R f16 and R f17 each independently represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an aryl group or an aralkyl group, and R f18 represents an alkyl group, an aryl group, an aralkyl group or -L f19 -O-R f20 (wherein, L f19 represents an alkylene group, and R f20 represents an alkyl group.).

[0345] In formula (F2), as R f11 to R f17Examples of the halogen atom represented include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc., preferably a fluorine atom or a chlorine atom, and more preferably a chlorine atom.

[0346] In formula (F2), as R f11 ~R f17 Examples of the alkyl group represented include linear or branched alkyl groups having 1 or more and 20 or less carbon atoms (preferably 1 or more and 6 or less, more preferably 1 or more and 4 or less, and still more preferably 1 or more and 3 or less). Examples of the linear alkyl group include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, n-octadecyl, n-nonadecyl, n-icosyl, etc. Examples of the branched alkyl group include isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, neopentyl, tert-pentyl, isohexyl, sec-hexyl, tert-hexyl, isoheptyl, sec-heptyl, tert-heptyl, isooctyl, sec-octyl, tert-octyl, isononyl, sec-nonyl, tert-nonyl, isodecyl, sec-decyl, tert-decyl, isoundecyl, sec-undecyl, tert-undecyl, neoundecyl, isododecyl, sec-dodecyl, tert-dodecyl, neododecyl, isotridecyl, sec-tridecyl, tert-tridecyl, neotridecyl, isotetradecyl, sec-tetradecyl, tert-tetradecyl, neotetradecyl, 1-isobutyl-4-ethyl octyl, isopentadecyl, sec-pentadecyl, tert-pentadecyl, neopentadecyl, isohexadecyl, sec-hexadecyl, tert-hexadecyl, neohexadecyl, 1-methylpentadecyl, isoheptadecyl, sec-heptadecyl, tert-heptadecyl, neoheptadecyl, isooctadecyl, sec-octadecyl, tert-octadecyl, neooctadecyl, isononadecyl, sec-nonadecyl, tert-nonadecyl, neononadecyl, 1-methyloctyl, isoeicosyl, sec-eicosyl, tert-eicosyl, neoeicosyl, etc. Among them, as the alkyl group, methyl and ethyl are preferred.

[0347] In formula (F2), as R f11 ~R f17The alkoxy group represented may be a linear or branched alkoxy group having 1 to 20 carbon atoms (preferably 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, and still more preferably 1 to 3 carbon atoms). Examples of the linear alkoxy group include methoxy, ethoxy, n-propoxy, n-butoxy, n-pentyloxy, n-hexyloxy, n-heptyloxy, n-octyloxy, n-nonyloxy, n-decyloxy, n-undecyloxy, n-dodecyloxy, n-tridecyloxy, n-tetradecyloxy, n-pentadecyloxy, n-hexadecyloxy, n-heptadecyloxy, n-octadecyloxy, n-nonadecyloxy, n-icosyloxy, etc. Examples of the branched alkoxy group include isopropoxy, isobutoxy, sec-butoxy, tert-butoxy, isopentyloxy, neopentyloxy, tert-pentyloxy, isohexyloxy, sec-hexyloxy, tert-hexyloxy, isoheptyloxy, sec-heptyloxy, tert-heptyloxy, isooctyloxy, sec-octyloxy, tert-octyloxy, isononyloxy, sec-nonyloxy, tert-nonyloxy, isodecyloxy, sec-decyloxy, tert-decyloxy, isoundecyloxy, sec-undecyloxy, tert-undecyloxy, neoundecyloxy, isododecyloxy, sec-dodecyloxy, tert-dodecyloxy, neododecyloxy, isotridecyloxy, sec-tridecyloxy, tert-tridecyloxy, neoltridecyloxy, isotetradecyloxy, sec-tetradecyloxy, tert-tetradecyloxy, neoltetradecyloxy, 1-isobutyl-4-ethyloctyloxy, isopentadecyloxy, sec-pentadecyloxy, tert-pentadecyloxy, neolpentadecyloxy, isohexadecyloxy, sec-hexadecyloxy, tert-hexadecyloxy, neohexadecyloxy, 1-methylpentadecyloxy, isoheptadecyloxy, sec-heptadecyloxy, tert-heptadecyloxy, neoheptadecyloxy, isooctadecyloxy, sec-octadecyloxy, tert-octadecyloxy, neoctadecyloxy, isononadecyloxy, sec-nonadecyloxy, tert-nonadecyloxy, neononadecyloxy, 1-methyloctyloxy, isoeicosyloxy, sec-eicosyloxy, tert-eicosyloxy, neoeicosyloxy, etc. Among them, as the alkoxy group, methoxy is preferred.

[0348] In formula (F2), as R f11 ~R f17 The aryl group represented may be an aryl group having 6 to 30 carbon atoms (preferably 6 to 20 carbon atoms, more preferably 6 to 16 carbon atoms). Specifically, examples include phenyl, biphenyl, naphthyl, phenanthryl, etc., and phenyl and naphthyl are preferred. These aryl groups may have 1 to 5 (preferably 1 or 2) substituents. Examples of the substituents include linear or branched alkyl groups having 1 to 4 carbon atoms (such as methyl, ethyl, etc.); linear or branched alkoxy groups having 1 to 4 carbon atoms (such as methoxy, ethoxy, etc.); and halogen atoms (such as fluorine atom, chlorine atom, etc.).

[0349] In formula (F2), as R f11 ~R f17The aralkyl group represented may include a group in which a phenyl group, a biphenyl group, a naphthyl group, etc. are bonded to a linear or branched alkylene group having 1 to 6 carbon atoms (methylene, ethylene, n-propylene, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentylene, hexylene, etc.), and benzyl and phenethyl are preferred. The benzene ring of these aralkyl groups may have 1 to 5 (preferably 1 or 2) substituents. Examples of the substituents include linear or branched alkyl groups having 1 to 4 carbon atoms (methyl, ethyl, etc.); linear or branched alkoxy groups having 1 to 4 carbon atoms (methoxy, ethoxy, etc.); and halogen atoms (fluorine atom, chlorine atom, etc.).

[0350] In formula (F2), as R f18 The alkyl group represented may include the same group as the alkyl group represented by R f11 ~R f17 The alkyl group represented by, as R f18 The alkyl group represented is preferably an alkyl group having 1 to 12 carbon atoms, more preferably an alkyl group having 4 to 10 carbon atoms, and further preferably a branched alkyl group having 5 to 10 carbon atoms.

[0351] In formula (F2), as R f18 The aryl group represented may include the same group as the aryl group represented by R f11 ~R f17 The aryl group represented by, as R f18 The aryl group. From the viewpoint of solubility in an organic solvent, an alkyl-substituted aryl group substituted with an alkyl group is preferred. As R f18 The aryl group represented is preferably a phenyl group, a methylphenyl group, a dimethylphenyl group, or an ethylphenyl group.

[0352] In formula (F2), as R f18 The aralkyl group represented may include the same group as the aralkyl group represented by R 11 ~R 17 The aralkyl group represented by, as R f18 The aralkyl group. From the viewpoint of solubility in an organic solvent, an alkyl-substituted aralkyl group substituted with an alkyl group is preferred. As R f18 The aralkyl group represented is preferably benzyl, methylbenzyl, dimethylbenzyl, or phenethyl.

[0353] In formula (F2), in -L f18 represented by -O-R f19 (wherein, L 20 represents an alkylene group and R f19 represents an alkyl group.), as L f20 represented by, R f19, examples of the linear or branched alkylene group having 1 to 6 carbon atoms (methylene, ethylene, n-propylene, isopropylidene, n-butylene, isobutylene, sec-butylene, tert-butylene, pentylene, hexylene, etc.) can be cited as R f20 , groups the same as the alkyl group represented by R f11 ~R f17 can be cited.

[0354] As the compound represented by the formula (F2), from the viewpoint of increasing the sensitivity of the photosensitive layer, it is preferably a compound in which R f11 ~R f17 are each independently a hydrogen atom, a halogen atom or an alkyl group, and R f18 is an alkyl group having 4 to 10 carbon atoms.

[0355] Hereinafter, exemplary compounds of the compound represented by the formula (F2) are shown. The compound represented by the formula (F2) is not limited thereto.

[0356]

[0357] The electron transport material can be used alone or in combination of two or more.

[0358] The content of the electron transport material is preferably 5 parts by mass or more and 20 parts by mass or less, more preferably 10 parts by mass or more and 25 parts by mass or less, and further preferably 15 parts by mass or more and 20 parts by mass or less with respect to the total mass of the photosensitive layer.

[0359] [Charge generating material]

[0360] The single-layer photosensitive layer contains a charge generating material.

[0361] Examples of the charge generating material include azo pigments such as bisazo and trisazo; polycyclic aromatic pigments such as dibromoanthanthrone; perylene pigments; pyrrolopyrrole pigments; phthalocyanine pigments; zinc oxide; trigonal selenium, etc.

[0362] Among these compounds, in order to cope with laser exposure in the near-infrared region, as the charge generating material, a metal phthalocyanine pigment or a metal-free phthalocyanine pigment is preferably used. Specifically, for example, hydroxygallium phthalocyanine, chlorogallium phthalocyanine, dichlorotin phthalocyanine, and titanyl phthalocyanine are more preferable.

[0363] On the other hand, in order to cope with laser exposure in the near-ultraviolet region, as the charge generating material, polycyclic aromatic pigments such as dibromoanthanthrone, thioindigo pigments, squaraine compounds, zinc oxide, trigonal selenium, bisazo pigments, etc. are preferable.

[0364] In the case of using an incoherent light source such as an LED having a luminous center wavelength of more than 450 nm and less than 780 nm, an organic EL image array, etc., the above charge generation material can also be used.

[0365] When an n-type semiconductor such as a polycyclic aromatic pigment, a perylene pigment, or an azo pigment is used as the charge generation material, dark current is not easily generated, and even when formed into a thin film, image defects called black dots can be suppressed. The n-type determination is performed using the commonly used time-of-flight method and is determined based on the polarity of the flowing photocurrent. A material in which electrons are more easily transported than holes as carriers is defined as n-type.

[0366] In the single-layer photosensitive layer, the content of the charge generation material is preferably 0.1% by mass or more and 10% by mass or less, more preferably 0.8% by mass or more and 5% by mass or less, based on the total mass of the single-layer photosensitive layer.

[0367] The single-layer photosensitive layer may contain other known additives. Examples of the additives include antioxidants, leveling agents, defoaming agents, fillers, viscosity regulators, etc.

[0368] The formation of the single-layer photosensitive layer is not particularly limited, and a known formation method can be used. For example, a coating film of a coating liquid for forming a single-layer photosensitive layer prepared by adding the above components to a solvent is formed, the coating film is dried, and heated as needed.

[0369] Examples of the solvent for preparing the coating liquid for forming the single-layer photosensitive layer include aromatic hydrocarbons such as benzene, toluene, xylene, and chlorobenzene; ketones such as acetone and 2-butanone; halogenated aliphatic hydrocarbons such as dichloromethane, chloroform, and dichloroethane; and ordinary organic solvents such as cyclic or linear ethers such as tetrahydrofuran and diethyl ether. These solvents can be used alone or in combination of two or more.

[0370] Examples of the coating method when coating the coating liquid for forming the single-layer photosensitive layer include conventional methods such as a blade coating method, a wire bar coating method, a spray coating method, a dipping coating method, a bead coating method, an air knife coating method, and a curtain coating method.

[0371] The average thickness of the single-layer photosensitive layer is preferably 20 μm or more and 50 μm or less, more preferably 25 μm or more and 45 μm or less, and further preferably 30 μm or more and 40 μm or less.

[0372] (Conductive substrate)

[0373] The positively charged electrophotographic photoreceptor according to this embodiment preferably includes a conductive substrate and a single-layer photosensitive layer disposed on the conductive substrate.

[0374] As the conductive substrate, for example, metal plates, metal drums, and metal tapes containing metals (such as aluminum, copper, zinc, chromium, nickel, molybdenum, vanadium, indium, gold, platinum, etc.) or alloys (such as stainless steel) can be cited. Additionally, as the conductive substrate, for example, papers, resin films, tapes, etc. coated, vapor-deposited, or laminated with conductive compounds (such as conductive polymers, indium oxide, etc.), metals (such as aluminum, palladium, gold, etc.), or alloys can also be cited. Here, "conductivity" means that the volume resistivity is lower than 1×10 13 Ω·cm.

[0375] When the electrophotographic photoreceptor is used in a laser printer, for the purpose of suppressing interference fringes generated when irradiating a laser beam, the surface of the conductive substrate is preferably roughened to 0.04 μm or more and 0.5 μm or less in terms of the center line average roughness Ra. When a non-interfering light is used as the light source, roughening to prevent interference fringes is not particularly required, but since the generation of defects caused by the unevenness of the surface of the conductive substrate is suppressed, it is more suitable for long life.

[0376] As a roughening method, for example, wet honing in which an abrasive is suspended in water and blown onto the conductive substrate, centerless grinding in which the conductive substrate is pressed against a rotating grinding wheel and continuously ground, anodizing treatment, etc. can be cited.

[0377] As a roughening method, the following method can also be cited: Instead of roughening the surface of the conductive substrate, a conductive or semiconductive powder is dispersed in a resin, a layer is formed on the surface of the conductive substrate, and roughening is performed using the particles dispersed in the layer.

[0378] The roughening treatment by anodizing is a treatment in which a metal (such as aluminum) conductive substrate is used as the anode and anodized in an electrolyte solution to form an oxide film on the surface of the conductive substrate. As the electrolyte solution, for example, sulfuric acid solution, oxalic acid solution, etc. can be cited. However, the porous anodic oxide film formed by anodizing has chemical activity in its original state, is easily contaminated, and the resistance fluctuation caused by the environment is also large. Therefore, it is preferable to perform a sealing treatment on the porous anodic oxide film, that is, the micropores of the oxide film are blocked by volume expansion caused by a hydration reaction in pressurized steam or boiling water (metal salts such as nickel can also be added) and transformed into a more stable hydrated oxide.

[0379] The film thickness of the anodic oxide film is preferably 0.3 μm or more and 15 μm or less, for example. When the film thickness is within the above range, there is a tendency for the barrier property against injection to be exerted, and there is also a tendency for the increase in the residual potential caused by repeated use to be suppressed.

[0380] The conductive substrate can be treated with an acidic treatment solution or boehmite treatment.

[0381] The treatment with the acidic treatment liquid is carried out, for example, as follows. First, an acidic treatment liquid containing phosphoric acid, chromic acid, and hydrofluoric acid is prepared. The mixing ratio of phosphoric acid, chromic acid, and hydrofluoric acid in the acidic treatment liquid is, for example, in the range of 10% by mass or more and 11% by mass or less for phosphoric acid, 3% by mass or more and 5% by mass or less for chromic acid, 0.5% by mass or more and 2% by mass or less for hydrofluoric acid, and the concentration of these acids as a whole is preferably in the range of 13.5% by mass or more and 18% by mass or less. The treatment temperature is preferably, for example, 42°C or more and 48°C or less. The film thickness of the coating film is preferably 0.3 μm or more and 15 μm or less.

[0382] The boehmite treatment is carried out, for example, by immersing in pure water at 90°C or more and 100°C or less for 5 minutes to 60 minutes or contacting with heated steam at 90°C or more and 120°C or less for 5 minutes to 60 minutes. The film thickness of the coating film is preferably 0.1 μm or more and 5 μm or less. It can be anodized again with an electrolyte solution having low solubility of the coating film, such as adipic acid, boric acid, borate, phosphate, phthalate, maleate, benzoate, tartrate, citrate, etc.

[0383] (Undercoat layer)

[0384] The positively charged type electrophotographic photoreceptor according to the present embodiment may have an undercoat layer between the conductive substrate and the single-layer type photosensitive layer.

[0385] The undercoat layer is, for example, a layer containing inorganic particles and a binder resin.

[0386] As the inorganic particles, for example, inorganic particles having a powder resistance (volume resistivity) of 1 × 10 2 Ω·cm or more and 1 × 10 11 Ω·cm or less can be cited.

[0387] Among them, as the inorganic particles having the above resistance value, metal oxide particles such as tin oxide particles, titanium oxide particles, zinc oxide particles, and zirconium oxide particles are preferable, and zinc oxide particles are particularly preferable.

[0388] The specific surface area of the inorganic particles obtained by the BET method is, for example, preferably 10 m 2 / g or more.

[0389] The volume average particle diameter of the inorganic particles is, for example, preferably 50 nm or more and 2000 nm or less (more preferably 60 nm or more and 1,000 nm or less).

[0390] The content of the inorganic particles is, for example, preferably 10% by mass or more and 80% by mass or less, more preferably 40% by mass or more and 80% by mass or less, relative to the binder resin.

[0391] The inorganic particles can be surface-treated. Two or more kinds of particles with different surface treatments or particles with different particle sizes can be mixed and used as the inorganic particles.

[0392] Examples of the surface treatment agent include silane coupling agents, titanate coupling agents, aluminum coupling agents, surfactants, etc. In particular, a silane coupling agent is preferably used, and a silane coupling agent having an amino group is more preferably used.

[0393] Examples of the silane coupling agent having an amino group include 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, etc., but are not limited thereto.

[0394] Two or more kinds of silane coupling agents can be mixed and used. For example, a silane coupling agent having an amino group and other silane coupling agents can be used in combination. Examples of the other silane coupling agent include vinyltrimethoxysilane, 3-methacryloxypropyl-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, 3-chloropropyltrimethoxysilane, etc., but are not limited thereto.

[0395] The surface treatment method using the surface treatment agent may be any known method, and can be any method, and can be either a dry method or a wet method.

[0396] The treatment amount of the surface treatment agent is preferably 0.5% by mass or more and 10% by mass or less with respect to the inorganic particles, for example.

[0397] Here, from the viewpoints of improving the long-term stability of electrical properties and carrier blocking properties, it is preferable that the undercoat contains both inorganic particles and an electron-accepting compound (acceptor compound).

[0398] Examples of the electron-accepting compound include quinone compounds such as tetrachlorobenzoquinone and tetrabromobenzoquinone; tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone and 2,4,5,7-tetranitro-9-fluorenone; oxadiazole compounds such as 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole, 2,5-bis(4-naphthyl)-1,3,4-oxadiazole, and 2,5-bis(4-diethylaminophenyl)-1,3,4-oxadiazole; xanthone compounds; thiophene compounds; biphenylenequinone compounds such as 3,3',5,5'-tetra-tert-butylbiphenylenequinone; and electron-transporting materials such as benzophenone compounds.

[0399] In particular, as the electron-accepting compound, a compound having an anthraquinone structure is preferably used. Examples of the compound having an anthraquinone structure include hydroxyanthraquinone compounds, aminoanthraquinone compounds, amino-hydroxyanthraquinone compounds, etc. Specifically, for example, anthraquinone, alizarin, quinizarin, anthrarufin, purpurin, etc. are preferred.

[0400] The electron-accepting compound may be dispersed and contained in the undercoat together with the inorganic particles, or may be contained in the undercoat in a state of being attached to the surface of the inorganic particles.

[0401] Examples of the method for attaching the electron-accepting compound to the surface of the inorganic particles include a dry method or a wet method.

[0402] The dry method is, for example, a method in which while stirring the inorganic particles with a mixer having a large shearing force or the like, the electron-accepting compound is directly dropped or the electron-accepting compound dissolved in an organic solvent is dropped, and it is sprayed together with dry air or nitrogen to attach the electron-accepting compound to the surface of the inorganic particles. When dropping or spraying the electron-accepting compound, it is preferably carried out at a temperature below the boiling point of the solvent. After dropping or spraying the electron-accepting compound, sintering may be carried out at 100°C or higher. The sintering temperature and time are not particularly limited as long as they can obtain electrophotographic characteristics.

[0403] The wet method is, for example, a method in which the inorganic particles are dispersed in a solvent using a stirrer, ultrasonic waves, a sand mill, a grinder, a ball mill, etc., the electron-accepting compound is added at the same time, and after stirring or dispersing, the solvent is removed to attach the electron-accepting compound to the surface of the inorganic particles. The solvent removal method is, for example, filtration or distillation for distillation removal. After removing the solvent, sintering may be carried out at 100°C or higher. The sintering temperature and time are not particularly limited as long as they can obtain electrophotographic characteristics. In the wet method, the moisture contained in the inorganic particles may be removed before adding the electron-accepting compound. As an example, a method of removing while stirring and heating in a solvent or a method of removing by azeotropy with the solvent may be mentioned.

[0404] The attachment of the electron-accepting compound can be carried out before or after the surface treatment of the inorganic particles using a surface treatment agent, or the attachment of the electron-accepting compound and the surface treatment using the surface treatment agent can be carried out simultaneously.

[0405] The content of the electron-accepting compound is preferably 0.01% by mass or more and 20% by mass or less, more preferably 0.01% by mass or more and 10% by mass or less, relative to the inorganic particles.

[0406] Examples of the binder resin for the undercoat include known polymer compounds such as acetal resins (e.g., polyvinyl butyral, etc.), polyvinyl alcohol resins, polyvinyl acetal resins, casein resins, polyamide resins, cellulose resins, gelatin, polyurethane resins, polyester resins, unsaturated polyester resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinyl acetate resins, vinyl chloride-vinyl acetate-maleic anhydride resins, silicone resins, silicone-alkyd resins, urea resins, phenolic resins, phenol-formaldehyde resins, melamine resins, polyurethane resins, alkyd resins, epoxy resins, etc.; zirconium chelate compounds; titanium chelate compounds; aluminum chelate compounds; titanium alkoxide compounds; organotitanium compounds; silane coupling agents, etc.

[0407] Examples of the binder resin for the undercoat also include charge-transporting resins having charge-transporting groups, conductive resins (e.g., polyaniline, etc.).

[0408] Among them, as the binder resin for the undercoat, a resin insoluble in the coating solvent of the upper layer is preferred. In particular, a resin obtained by the reaction of at least one resin selected from the group consisting of thermosetting resins such as urea resins, phenolic resins, phenol-formaldehyde resins, melamine resins, polyurethane resins, unsaturated polyester resins, alkyd resins, and epoxy resins; polyamide resins, polyester resins, polyether resins, methacrylic resins, acrylic resins, polyvinyl alcohol resins, and polyvinyl acetal resins with a curing agent is preferred.

[0409] When two or more of these binder resins are used in combination, the mixing ratio is set as needed.

[0410] In order to improve the electrical properties, environmental stability, and image quality, various additives can be included in the undercoat.

[0411] Examples of the additives include known materials such as electron-transporting pigments such as polycyclic condensation type and azo type, zirconium chelate compounds, titanium chelate compounds, aluminum chelate compounds, titanium alkoxide compounds, organotitanium compounds, silane coupling agents, etc. The silane coupling agent is used for the surface treatment of inorganic particles as described above, but can also be added to the undercoat as an additive.

[0412] Examples of silane coupling agents used as additives include vinyltrimethoxysilane, 3-methacryloxypropyl-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, 3-chloropropyltrimethoxysilane, etc.

[0413] Examples of zirconium chelate compounds include zirconium butoxide, zirconium ethyl acetoacetate, zirconium triethanolamine, zirconium acetylacetate butoxide, zirconium ethyl acetoacetate butoxide, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octoate, zirconium naphthenate, zirconium laurate, zirconium stearate, zirconium isostearate, zirconium methacrylate butoxide, zirconium stearate butoxide, zirconium isostearate butoxide, etc.

[0414] Examples of titanium chelate compounds include tetraisopropyl titanate, tetra-n-butyl titanate, butyl titanate dimer, tetra(2-ethylhexyl) titanate, titanium acetylacetonate, poly(titanium acetylacetonate), titanium octylene glycolate, ammonium lactate titanate, titanium lactate, titanium ethyl lactate, titanium triethanolamine, titanium polyhydroxystearate, etc.

[0415] Examples of aluminum chelate compounds include aluminum isopropoxide, mono-butoxy diisopropanol aluminum, aluminum butoxide, aluminum ethyl acetoacetate diisopropanol, tris(ethyl acetoacetate) aluminum, etc.

[0416] These additives can be used alone, or as a mixture or condensate of multiple compounds.

[0417] The Vickers hardness of the undercoat is preferably 35 or more.

[0418] To suppress moiré images, the surface roughness (ten-point mean roughness) of the undercoat is preferably adjusted to 1 / (4n) (n is the refractive index of the upper layer) to 1 / 2 of the laser wavelength λ used for exposure.

[0419] To adjust the surface roughness, resin particles etc. can be added to the undercoat. Examples of resin particles include silicone resin particles, crosslinked polymethyl methacrylate resin particles, etc. In addition, to adjust the surface roughness, the surface of the undercoat can be ground. Examples of grinding methods include polishing, sandblasting, wet honing, grinding treatment, etc.

[0420] The formation of the undercoat layer is not particularly limited, and known formation methods can be used. For example, a coating film of a coating liquid for forming an undercoat layer formed by adding the above components to a solvent is formed, the coating film is dried, and heating is performed as needed.

[0421] As the solvent for preparing the coating liquid for forming the undercoat layer, known organic solvents can be cited, such as alcohol solvents, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, ketone solvents, keto-alcohol solvents, ether solvents, ester solvents, etc.

[0422] Specifically, as these solvents, for example, ordinary organic solvents such as methanol, ethanol, n-propanol, isopropanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, dichloromethane, chloroform, chlorobenzene, toluene, etc. can be cited.

[0423] As the method for dispersing inorganic particles when preparing the coating liquid for forming the undercoat layer, for example, known methods such as a roll mill, a ball mill, a vibration ball mill, a grinder, a sand mill, a colloid mill, a paint stirrer, etc. can be cited.

[0424] As the method for coating the coating liquid for forming the undercoat layer on the conductive substrate, for example, conventional methods such as a blade coating method, a wire bar coating method, a spray coating method, an immersion coating method, a bead coating method, an air knife coating method, a curtain coating method, etc. can be cited.

[0425] The thickness of the undercoat layer is, for example, set in a range of preferably 15 μm or more, more preferably 20 μm or more and 50 μm or less.

[0426] (Intermediate layer)

[0427] The positively charged type electrophotographic photoreceptor according to the present embodiment may further have an intermediate layer between the undercoat layer and the single-layer type photosensitive layer.

[0428] The intermediate layer is, for example, a layer containing a resin. As the resin for the intermediate layer, for example, acetal resins (such as polyvinyl butyral, etc.), polyvinyl alcohol resins, polyvinyl acetal resins, casein resins, polyamide resins, cellulose resins, gelatin, polyurethane resins, polyester resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinyl acetate resins, vinyl chloride-vinyl acetate-maleic anhydride resins, silicone resins, silicone-alkyd resins, phenol-formaldehyde resins, melamine resins, etc. can be cited.

[0429] The intermediate layer may also be a layer containing an organometallic compound. As the organometallic compound for the intermediate layer, organometallic compounds containing metal atoms such as zirconium, titanium, aluminum, manganese, silicon, etc. can be cited.

[0430] These compounds for the intermediate layer can be used alone, or can also be used as a mixture or condensate of multiple compounds.

[0431] Among them, the intermediate layer is preferably a layer containing an organometallic compound containing a zirconium atom or a silicon atom.

[0432] 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 a coating liquid for forming an intermediate layer obtained by adding the above components to a solvent, drying the coating film, and heating it as needed.

[0433] As the coating method for forming the intermediate layer, conventional methods such as dip coating method, push coating method, wire bar coating method, spray coating method, doctor blade coating method, air knife coating method, curtain coating method, etc. can be used.

[0434] The thickness of the intermediate layer is, for example, set in the range preferably of 0.1 μm or more and 3 μm or less. The intermediate layer can also be used as a primer coat.

[0435] (Protective layer)

[0436] The protective layer is provided on the single-layer photosensitive layer as needed. The protective layer is provided for purposes such as preventing chemical changes of the photosensitive layer during charging or further improving the mechanical strength of the single-layer photosensitive layer.

[0437] Therefore, it is appropriate for the protective layer to be a layer composed of a cured film (crosslinked film). As these layers, for example, the layers shown in the following 1) or 2) can be cited.

[0438] 1) A layer composed of a cured film of a composition containing a reactive group hole transport material having a reactive group and a hole transport skeleton in the same molecule (that is, a layer containing a polymer or crosslinked body of the reactive group hole transport material)

[0439] 2) A layer composed of a cured film of a composition containing a non-reactive hole transport material and a reactive group non-hole transport material having no hole transport skeleton and having a reactive group (that is, a layer containing a polymer or crosslinked body of the non-reactive hole transport material and the reactive group non-hole transport material)

[0440] As the reactive group of the reactive group hole transport material, chain polymerizable groups, epoxy groups, -OH, -OR [wherein, R represents an alkyl group], -NH2, -SH, -COOH, -SiR Q1 3-Qn (OR Q2 ) Qn [wherein, R Q1 represents a hydrogen atom, an alkyl group or a substituted or unsubstituted aryl group, R Q2Represents a hydrogen atom, an alkyl group, or a trialkylsilyl group. Qn represents an integer from 1 to 3, etc., which are well-known reactive groups.

[0441] As the chain polymerizable group, as long as it is a functional group capable of radical polymerization, there is no particular limitation. For example, it is a functional group having a group containing at least a carbon double bond. Specifically, groups containing at least one selected from vinyl, vinyl ether group, vinyl sulfide group, styryl, vinylphenyl, acryloyl, methacryloyl, and their derivatives can be cited. Among them, due to its excellent reactivity, as the chain polymerizable group, a group containing at least one selected from vinyl, styryl, vinylphenyl, acryloyl, methacryloyl, and their derivatives is preferably used.

[0442] As the hole-transporting skeleton of the hole-transporting material containing reactive groups, as long as it is a well-known structure in the electrophotographic photoreceptor, there is no particular limitation. For example, a skeleton derived from a nitrogen-containing hole-transporting compound such as a triarylamine compound, a benzidine compound, or a hydrazone compound, and a structure conjugated with a nitrogen atom can be cited. Among them, a triarylamine skeleton is preferably used.

[0443] The hole-transporting material containing reactive groups, the non-reactive hole-transporting material, and the non-hole-transporting material containing reactive groups having these reactive groups and hole-transporting skeletons can be selected from well-known materials.

[0444] Other well-known additives can be contained in the protective layer.

[0445] The formation of the protective layer is not particularly limited, and a well-known formation method can be used. For example, it can be carried out by forming a coating film of a coating liquid for forming a protective layer prepared by adding the above components to a solvent, drying the coating film, and performing a curing treatment such as heating as needed.

[0446] As the solvent for preparing the coating liquid for forming a protective layer, aromatic solvents such as toluene and xylene; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester solvents such as ethyl acetate and butyl acetate; ether solvents such as tetrahydrofuran and dioxane; cellosolve solvents such as ethylene glycol monomethyl ether; alcohol solvents such as isopropyl alcohol and butanol, etc. can be cited. These solvents can be used alone or in combination of two or more.

[0447] The coating liquid for forming a protective layer can be a solvent-free coating liquid.

[0448] As a method of coating the coating liquid for forming a protective layer on a photosensitive layer (for example, a charge transport layer), conventional methods such as dip coating method, push coating method, wire bar coating method, spray coating method, doctor blade coating method, air knife coating method, and curtain coating method can be cited.

[0449] The thickness of the protective layer is set, for example, within a range of preferably 1 μm or more and 20 μm or less, more preferably 2 μm or more and 10 μm or less.

[0450] <Image forming apparatus, processing cartridge>

[0451] The image forming apparatus according to the present embodiment includes: an electrophotographic photoreceptor; a charging device that charges the surface of the electrophotographic photoreceptor, an electrostatic latent image forming device that forms an electrostatic latent image on the surface of the charged electrophotographic photoreceptor; a developing device that develops the electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing toner to form a toner image; and a transfer device that transfers the toner image onto the surface of a recording medium, wherein the charging device is a positively charged charging device. Further, as the electrophotographic photoreceptor, the positively charged electrophotographic photoreceptor according to the present embodiment is applied.

[0452] The image forming apparatus according to the present embodiment is applicable to the following known image forming apparatuses: an apparatus having a fixing device that fixes the toner image transferred onto the surface of a recording medium; a direct transfer type apparatus that directly transfers the toner image formed on the surface of the electrophotographic photoreceptor onto a recording medium; an intermediate transfer type apparatus that transfers the toner image formed on the surface of the electrophotographic photoreceptor once onto the surface of an intermediate transfer member and then transfers the toner image transferred onto the surface of the intermediate transfer member a second time onto the surface of a recording medium; an apparatus having a cleaning device that cleans the surface of the electrophotographic photoreceptor before charging after transferring the toner image; an apparatus having a destaticizing device that irradiates the surface of the electrophotographic photoreceptor with destaticizing light to eliminate static electricity before charging after transferring the toner image; an apparatus having an electrophotographic photoreceptor heating member for raising the temperature of the electrophotographic photoreceptor and lowering the relative humidity, and the like.

[0453] In the case of an intermediate transfer type apparatus, the transfer device is, for example, applicable to a structure having the following devices: an intermediate transfer member onto which the toner image is transferred, a primary transfer device that transfers the toner image formed on the surface of the electrophotographic photoreceptor once onto the surface of the intermediate transfer member, and a secondary transfer device that transfers the toner image transferred onto the surface of the intermediate transfer member a second time onto the surface of a recording medium.

[0454] The image forming apparatus according to the present embodiment may be either a dry developing type image forming apparatus or a wet developing type (developing method using a liquid developer) image forming apparatus.

[0455] In the image forming apparatus according to the present embodiment, for example, the portion including the electrophotographic photoreceptor may be a cartridge structure (processing cartridge) that can be attached to and detached from the image forming apparatus. As the processing cartridge, for example, a processing cartridge including the electrophotographic photoreceptor according to the present embodiment is preferably used. In addition to the electrophotographic photoreceptor, the processing cartridge may include at least one selected from the group consisting of a charging device, an electrostatic latent image forming device, a developing device, and a transfer device.

[0456] Hereinafter, an example of the image forming apparatus according to the present embodiment will be described, but the present invention is not limited thereto. The main parts shown in the drawings will be described, and the description of the other parts will be omitted.

[0457] Figure 2 It is a schematic structural diagram showing an example of the image forming apparatus according to the present embodiment.

[0458] As shown in Figure 2 the image forming apparatus 100 according to the present embodiment includes a processing cartridge 300 having an electrophotographic photoreceptor 7, an exposure device 9 (an example of an electrostatic latent image forming device), a transfer device 40 (a primary transfer device), and an intermediate transfer member 50. In the image forming apparatus 100, the exposure device 9 is disposed at a position where the electrophotographic photoreceptor 7 can be exposed through an opening of the processing cartridge 300, the transfer device 40 is disposed at a position facing the electrophotographic photoreceptor 7 with the intermediate transfer member 50 interposed therebetween, and a part of the intermediate transfer member 50 is disposed in contact with the electrophotographic photoreceptor 7. Although not shown, it further includes a secondary transfer device that transfers the toner image transferred onto the intermediate transfer member 50 onto a recording medium (e.g., paper). The intermediate transfer member 50, the transfer device 40 (primary transfer device), and the secondary transfer device (not shown) are examples of the transfer device.

[0459] Figure 2 In the processing cartridge 300 in

[0460] Figure 2 the 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) are integrally supported in a housing. The cleaning device 13 has a cleaning blade (an example of a cleaning member) 131 disposed in contact with the surface of the electrophotographic photoreceptor 7. The cleaning member may not be in the form of the cleaning blade 131, but may be a conductive or insulating fibrous member, which may be used alone or in combination with the cleaning blade 131.

[0461] Hereinafter, each structure of the image forming apparatus according to the present embodiment will be described.

[0462] - Charging device -

[0463] The charging device 8 is a charging device of the positive charging type.

[0464] As the charging device 8, any charging device that can be positively charged may be used. For example, a contact type charger using a conductive or semiconductive charging roller, charging brush, charging film, charging rubber blade, charging hose, etc. may be used. In addition, a non-contact type roller charger, a grid electrode charger using corona discharge, a corona tube charger, or other publicly known chargers may also be used.

[0465] - Exposure device -

[0466] As the exposure device 9, for example, an optical system device that exposes light such as a semiconductor laser beam, LED light, or liquid crystal shutter light in a predetermined image form on the surface of the electrophotographic photoreceptor 7 may be cited. The wavelength of the light source is set within the spectral sensitivity region of the electrophotographic photoreceptor. As the wavelength of the semiconductor laser, the mainstream is near-infrared light having an oscillation wavelength near 780 nm. However, it is not limited to this wavelength, and lasers having an oscillation wavelength in the range of 600 nm band or blue lasers, or lasers having an oscillation wavelength in the range of 400 nm or more and 450 nm or less may also be used. In addition, for forming a color image, a surface-emitting type laser light source capable of outputting multiple light beams is also effective.

[0467] - Developing device -

[0468] As the developing device 11, for example, a general developing device that develops by contacting or non-contacting with a developer may be cited. As the developing device 11, as long as it has the above functions, there is no particular limitation, and it is selected according to the purpose. For example, a publicly known developer having a function of attaching a single-component developer or a two-component developer to the electrophotographic photoreceptor 7 using a brush, a roller, etc. may be cited. Among them, a developer using a developing roller that holds the developer on its surface is preferably used.

[0469] The developer for the developing device 11 may be a single-component developer of a single toner, or a two-component developer containing a toner and a carrier. In addition, the developer may be magnetic or non-magnetic. These developers are applicable to publicly known developers.

[0470] - Cleaning device -

[0471] As the cleaning device 13, a cleaning blade type device having a cleaning blade 131 may be used. In addition to the cleaning blade method, a brush cleaning method or a developing and cleaning parallel method may also be adopted.

[0472] - Transfer device -

[0473] As the transfer device 40, for example, a contact type transfer charger using a belt, roller, film, rubber blade, etc., a grid electrode type transfer charger using corona discharge, or a corona tube transfer charger, which are well-known transfer chargers in themselves, can be cited.

[0474] - Intermediate transfer member -

[0475] As the intermediate transfer member 50, a belt-shaped intermediate transfer member (intermediate transfer belt) containing polyimide, polyamideimide, polycarbonate, polyarylate, polyester, rubber, etc. with semi-conductivity imparted can be used. In addition, as the form of the intermediate transfer member, in addition to the belt shape, a cylindrical intermediate transfer member can also be used.

[0476] Figure 3 It is a schematic structural diagram showing another example of the image forming apparatus according to the present embodiment.

[0477] Figure 3 The image forming apparatus 120 shown is a tandem type multi-color image forming apparatus equipped with four process cartridges 300. In the image forming apparatus 120, four process cartridges 300 are arranged side by side on the intermediate transfer member 50, forming a structure in which one electrophotographic photoreceptor is used for one color. The image forming apparatus 120 has the same structure as the image forming apparatus 100 except for the tandem type.

[0478] [Examples]

[0479] Hereinafter, the disclosed embodiments will be described in detail based on examples, but the disclosed embodiments are not limited to these examples in any way.

[0480] In the following description, unless otherwise specified, "parts" and "%" are based on mass.

[0481] In the following description, unless otherwise specified, synthesis, processing, manufacturing, etc. are carried out at room temperature (25°C ± 3°C).

[0482] The elastic deformation rate of the resin is measured by the following method.

[0483] The elastic deformation rate of the resin is obtained by the following formula.

[0484] Elastic deformation rate = (Dmax - D1) / Dmax

[0485] Here, the elastic deformation rate is a value defined by elastic deformation rate = elastic deformation amount / total deformation amount, which divides the total deformation amount when a load is applied to the photosensitive layer into elastic deformation amount and plastic deformation amount.

[0486] The elastic deformation rate is tested and measured as follows: In an environment of 24°C and 50% RH, using a Nanoindenter SA2 manufactured by MTS, for the surface of each resin exposed in the photosensitive layer, a diamond regular triangular pyramid indenter is used to press in to a depth of 0.5 μm at a pressing speed of 0.025 μm / s. Through this measurement, the deformation depth is the amount of deformation that has not recovered due to the load, and the deformation amount (depth) of the resin at the end of the measurement is obtained. The maximum pressing depth sets the diamond regular triangular pyramid indenter to a pressing depth of 0.5 μm.

[0487] <Production of polyarylate resin PA1>

[0488] Add 12.7220 g of 2,2'-dimethyl-4,4'-(1,3-dimethylbutylene) diphenol, 0.1233 g of 4-tert-butylphenol, 0.0632 g of sodium dithionite, and 240 mL of water into a reaction vessel equipped with a stirring device to form a suspension. In this suspension, add 4.8392 g of sodium hydroxide, 0.1981 g of benzyltributylammonium chloride, and 160 mL of water under stirring at a temperature of 20°C, and stir for 30 minutes under a nitrogen atmosphere. Add 220 mL of o-dichlorobenzene to this aqueous solution, stir for 30 minutes under a nitrogen atmosphere, and then add 12.0000 g of 4,4'-biphenyl dicarbonyl chloride in a powder state. After the addition is completed, stir at a temperature of 20°C under a nitrogen atmosphere for 4 hours for reaction. Dilute the polymerized solution with 300 mL of o-dichlorobenzene and remove the water layer. After washing with a dilute acetic acid solution and ion-exchanged water, pour it into methanol to precipitate the polymer. Filter and separate the precipitated polymer and dry it at 50°C.

[0489] As the post-treatment of the obtained polymer, the following operations are carried out to obtain the final product.

[0490] Dissolve the polymer again in 900 mL of tetrahydrofuran, pour it into methanol to precipitate the polymer. Filter and separate the precipitated polymer, wash it with methanol, and dry it at 50°C. Repeat this operation 3 times to obtain 17.5 g of a white polymer, namely polyarylate resin PA1.

[0491]

[0492] <Polyester resin PA2>

[0493] As polyester resin PA2, prepare a polyester resin PA2 in which the aforementioned dicarboxylic acid unit (A-12) is 50 mol% and the aforementioned diol unit (B-24) is 50 mol%.

[0494] <Polycarbonate resins PB1 to PB3>

[0495] Prepare polycarbonate resins PB1 to PB3 shown below, respectively.

[0496]

[0497] In addition, the numerical values in the lower right of the parentheses of PA1 and PB1 to PB3 represent molar ratios.

[0498] <Polyester resin PB4>

[0499] As the polyester resin PB4, prepare a polyester resin PB4 in which the aforementioned dicarboxylic acid unit (A-12) is 50 mol%, the aforementioned diol unit (B-2) is 37.5 mol%, and the aforementioned diol unit (B-4) is 12.5 mol%.

[0500] (Examples 1 to 15 and Comparative Examples 1 to 4)

[0501] A total of 52.75 parts and 1.25 parts of resin A and resin B described in Table 1 by the mass ratio described in Table 1, V-type hydroxygallium phthalocyanine (having diffraction peaks at positions of at least 7.3°, 16.0°, 24.9°, and 28.0° in the Bragg angle (2θ ± 0.2°) of the X-ray diffraction spectrum using CuKα characteristic X-rays) as a charge generation material, 7.8 parts of an electron transport material, i.e., the aforementioned exemplified compound 2-2, 38.2 parts of a hole transport material, i.e., the following compound CTM-1 contained in formula (G2) (the mass ratio of the electron transport material (formula 2-2) to the hole transport material CTM-1 is 17:83), 175 parts of tetrahydrofuran, and 75 parts of toluene as solvents are mixed, and dispersed using a glass bead with a diameter of 1 mm in a sand mill for 4 hours to obtain a coating liquid for forming a single-layer photosensitive layer. The coating liquid for forming a photosensitive layer is coated on an aluminum substrate with an outer diameter of 30 mm, a length of 244.5 mm, and a thickness of 1 mm by dip coating, and dried and cured at a temperature of 110 °C for 40 minutes to form a single-layer photosensitive layer with an average thickness of 37 μm, thereby obtaining a positively charged electrophotographic photoreceptor.

[0502]

[0503] <Evaluation>

[0504] [Inhibitory effect on the generation of color spots due to corrosion]

[0505] For the evaluation of color spots due to corrosion, a modified machine of Brother HL5340D equipped with a photoreceptor is used. Under a high-temperature and high-humidity environment of 28 °C and 85% RH, 50% of 2,000 photographic copper plates are printed at a charging voltage of +800 V, the device is left overnight, and the next morning, the number of color spots generated on the paper when a white paper is fed into the device is calculated and evaluated according to the following criteria.

[0506] A: No color spots are generated.

[0507] B: The number of color spots is from 1 to 9.

[0508] C: The number of color spots is more than 10.

[0509] [Abrasion resistance]

[0510] As an evaluation of abrasion resistance, before and after outputting 10,000 sheets of a photographic copperplate image with an image density of 30% on A4 paper using the above-mentioned modified machine, the thickness of the photoreceptor layer was measured using an eddy current film thickness measuring device (manufactured by Fischer Instrumentation), and the film reduction rate was obtained by dividing the film thickness reduction amount by the number of test cycles.

[0511] The evaluation criteria are as follows.

[0512] A: 5 nm / kcy or less

[0513] B: More than 5 nm / kcy and 10 nm / kcy or less

[0514] C: More than 10 nm / kcy and 20 nm / kcy or less

[0515] D: More than 20 nm / kcy

[0516] [Table 1]

[0517]

[0518] As shown in Table 1, compared with the positively charged electrophotographic photoreceptors in Comparative Examples 1 to 4, the positively charged electrophotographic photoreceptors in Examples 1 to 15 are excellent in both the suppression of color spot generation due to corrosion and abrasion resistance.

[0519] [Supplementary note]

[0520] (((1))) A positively charged electrophotographic photoreceptor having a single-layer photoreceptor layer containing a hole transport material, an electron transport material, a charge generation material, and a binder resin, wherein the binder resin contains a resin A having an elastic deformation rate of 53.0% or more and a resin B having an elastic deformation rate difference of 12% or more and 17% or less from the resin A.

[0521] (((2))) The positively charged electrophotographic photoreceptor according to (((1))), wherein the mass ratio MA / MB of the content MA of the resin A to the content MB of the resin B is 0.25 or more and 4 or less.

[0522] (((3)))The positively charged electrophotographic photoreceptor according to ((2)), wherein the value of the mass ratio MA / MB of the content MA of the resin A to the content MB of the resin B is 0.4 or more and 2.5 or less.

[0523] (((4)))The positively charged electrophotographic photoreceptor according to any one of ((1)) to ((3)), wherein the difference in the elastic deformation rate between the resin B and the resin A is 13% or more and 16% or less.

[0524] (((5)))The positively charged electrophotographic photoreceptor according to any one of ((1)) to ((4)), wherein the elastic deformation rate of the resin B is 12% or more and 17% less than the elastic deformation rate of the resin A.

[0525] (((6)))The positively charged electrophotographic photoreceptor according to any one of ((1)) to ((5)), wherein the resin A is a polyarylate resin.

[0526] (((7)))The positively charged electrophotographic photoreceptor according to any one of ((1)) to ((6)), wherein the resin B is a polycarbonate resin.

[0527] (((8)))The positively charged electrophotographic photoreceptor according to any one of ((1)) to ((7)), wherein the resin A has a biphenyl structure.

[0528] (((9)))The positively charged electrophotographic photoreceptor according to any one of ((1)) to ((8)), wherein the resin B has a biphenyl structure.

[0529] (((10)))A processing cartridge including the positively charged electrophotographic photoreceptor according to any one of ((1)) to ((9)), and being detachable from an image forming apparatus.

[0530] (((11)))An image forming apparatus including: the positively charged electrophotographic photoreceptor according to any one of ((1)) to ((9)); a charging device configured to charge a surface of the electrophotographic photoreceptor; an electrostatic latent image forming device configured to form an electrostatic latent image on the charged surface of the electrophotographic photoreceptor; a developing device configured to develop the electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing toner to form a toner image; and a transfer device configured to transfer the toner image onto a surface of a recording medium, wherein the charging device is a positively charged charging device.

[0531] According to ((1)), there is provided a positively charged electrophotographic photoreceptor which is excellent in the suppression of color spot generation caused by corrosion and in abrasion resistance as compared with the case where the binder resin in the single-layer photosensitive layer contains resin A having an elastic deformation rate of 53.0% or more and resin B having an elastic deformation rate difference from resin A of less than 12% or more than 17%.

[0532] According to ((2)), there is provided a positively charged electrophotographic photoreceptor which is more excellent in the suppression of color spot generation caused by corrosion as compared with the case where the value of the mass ratio MA / MB of the content MA of resin A to the content MB of resin B is less than 0.25 or more than 4.

[0533] According to ((3)), there is provided a positively charged electrophotographic photoreceptor which is more excellent in the suppression of color spot generation caused by corrosion as compared with the case where the value of the mass ratio MA / MB of the content MA of resin A to the content MB of resin B is less than 0.25 or more than 4.

[0534] According to ((4)), there is provided a positively charged electrophotographic photoreceptor which is more excellent in the suppression of color spot generation caused by corrosion as compared with the case where the elastic deformation rate difference between resin B and resin A is less than 13% or more than 16%.

[0535] According to ((5)), there is provided a positively charged electrophotographic photoreceptor which is more excellent in the suppression of color spot generation caused by corrosion as compared with the case where the elastic deformation rate of resin B is 12% or more and 17% or less greater than the elastic deformation rate of resin A.

[0536] According to ((6)), there is provided a positively charged electrophotographic photoreceptor which is more excellent in the suppression of color spot generation caused by corrosion and in abrasion resistance as compared with the case where resin A is a polyester resin that is not a polyarylate resin.

[0537] According to ((7)), there is provided a positively charged electrophotographic photoreceptor which is excellent in abrasion resistance and more excellent in the suppression of color spot generation caused by corrosion as compared with the case where resin B is a polyester resin.

[0538] According to ((8)), there is provided a positively charged electrophotographic photoreceptor which is excellent in abrasion resistance and more excellent in the suppression of color spot generation caused by corrosion as compared with the case where resin A does not have a biphenyl structure.

[0539] According to ((9)), there is provided a positively charged electrophotographic photoreceptor which is excellent in abrasion resistance and more excellent in the suppression of color spot generation caused by corrosion as compared with the case where resin B does not have a biphenyl structure.

[0540] According to ((10)) or ((11)), there is provided a process cartridge or an image forming apparatus which is excellent in suppressing the generation of color spots caused by corrosion and in wear resistance in a positively charged electrophotographic photoreceptor as compared with the case where a binder resin in a single-layer photosensitive layer of a positively charged electrophotographic photoreceptor contains resin A having an elastic deformation rate of 53.0% or more and resin B having an elastic deformation rate difference from resin A of less than 12% or more than 17%.

Claims

1. A positively charged electrophotographic photoreceptor having a single-layer photosensitive layer containing a hole transport material, an electron transport material, a charge generation material, and a binder resin. The binder resin contains resin A having an elastic deformation rate of 53.0% or more and resin B having an elastic deformation rate difference from resin A of 12% or more and 17% or less.

2. The positively charged electrophotographic photoreceptor according to claim 1, wherein the value of the mass ratio MA / MB of the content MA of resin A to the content MB of resin B is 0.25 or more and 4 or less.

3. The positively charged electrophotographic photoreceptor according to claim 2, wherein the value of the mass ratio MA / MB of the content MA of resin A to the content MB of resin B is 0.4 or more and 2.5 or less.

4. The positively charged electrophotographic photoreceptor according to any one of claims 1 to 3, wherein the elastic deformation rate difference between resin B and resin A is 13% or more and 16% or less.

5. The positively charged electrophotographic photoreceptor according to any one of claims 1 to 4, wherein the elastic deformation rate of resin B is 12% or more and 17% or less smaller than the elastic deformation rate of resin A.

6. The positively charged electrophotographic photoreceptor according to any one of claims 1 to 5, wherein resin A is a polyarylate resin.

7. The positively charged electrophotographic photoreceptor according to any one of claims 1 to 6, wherein resin B is a polycarbonate resin.

8. The positively charged electrophotographic photoreceptor according to any one of claims 1 to 7, wherein resin A has a biphenyl structure.

9. The positively charged electrophotographic photoreceptor according to any one of claims 1 to 8, wherein resin B has a biphenyl structure.

10. A process cartridge including the positively charged electrophotographic photoreceptor according to any one of claims 1 to 9, which is detachable from an image forming apparatus.

11. An image forming apparatus including: the positively charged electrophotographic photoreceptor according to any one of claims 1 to 9; a charging device that charges the surface of the electrophotographic photoreceptor; an electrostatic latent image forming device that forms an electrostatic latent image on the surface of the charged electrophotographic photoreceptor; a developing device that develops the electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing toner to form a toner image; and a transfer device that transfers the toner image onto the surface of a recording medium, wherein the charging device is a positively charged charging device.

Images