Electrophotographic photoreceptor, process cartridge, and image forming device

Abstract

The present invention provides an electrophotographic photoreceptor, a process cartridge, and an image forming apparatus with suppressed residual potential. The electrophotographic photoreceptor comprises a conductive substrate and a photosensitive layer disposed on the conductive substrate. The outermost layer contains a fluorine-based graft polymer and fluorine-containing resin particles. The fluorine-based graft polymer comprises at least a first structural unit having no acidic group with a pKa value of 3 or less and containing a fluorine atom, a second structural unit derived from a macromonomer, and a third structural unit having an acidic group with a pKa value of 3 or less.

Description

Technical Field

[0001] The present invention relates to an electronic photographic photoreceptor, a processing box and an image forming device. Background Art

[0002] In recent years, in order to extend the life of electrophotographic photoreceptors, a technique of reducing the surface energy of the surface layer by incorporating fluorine-based resin particles into the surface layer has been studied.

[0003] Patent Document 1 discloses an electrophotographic photoreceptor having a photosensitive layer on a conductive support, wherein the surface layer of the electrophotographic photoreceptor contains fluorine-based resin powder and a fluorine-based graft polymer.

[0004] Patent document 2 discloses an electronic photographic photoreceptor having at least a photosensitive layer on a conductive support, and a surface layer containing a fluorine-based graft polymer and fluorine-containing resin particles in such a manner that the content of the fluorine-based graft polymer is greater than or equal to 0.5% by mass and less than or equal to 5.0% by mass relative to the fluorine-containing resin particles, wherein the fluorine-based graft polymer contains specific structural units, has a fluorine content of greater than or equal to 10% by mass and less than or equal to 40% by mass, a weight-average molecular weight Mw of greater than or equal to 50,000 and less than or equal to 200,000, a ratio of the weight-average molecular weight Mw to the number-average molecular weight Mn [Mw / Mn] of greater than or equal to 1 and less than 8, and has a perfluoroalkyl group having a carbon number of greater than or equal to 1 and less than 6.

[0005] Patent document 3 discloses an electrophotographic photoreceptor having a support and a photosensitive layer arranged on the support, and the surface layer of the electrophotographic photoreceptor contains a fluorine-based grafted polymer and fluorine-containing resin particles, wherein the fluorine-based grafted polymer contains a specific repeating structural unit having a perfluoroalkyl group with 4 to 6 carbon atoms.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 63-221355

[0009] Patent Document 2: Japanese Patent No. 5544850

[0010] Patent Document 3: Japanese Patent No. 4436456 Summary of the Invention

[0011] Problems to be solved by the invention

[0012] Conventionally, fluorine-containing resin particles have been blended into the surface layer of electrophotographic photoreceptors to improve cleanability. Furthermore, dispersants such as fluorine-based graft polymers have been used to improve the dispersibility of the fluorine-containing resin particles.

[0013] However, depending on the combination of fluorine-containing resin particles and fluorine-based graft polymers used, the absolute value of the potential on the surface of the electrophotographic photoreceptor is unlikely to decrease due to exposure. As a result, potential may remain on the surface of the electrophotographic photoreceptor, forming a residual potential.

[0014] Therefore, an object of the present invention is to provide an electrophotographic photoreceptor having a suppressed residual potential compared to a case where the electrophotographic photoreceptor comprises a conductive substrate and a photosensitive layer provided on the conductive substrate, wherein the outermost layer comprises fluorine-containing resin particles and a fluorine-based graft polymer having no acidic group with a pKa of 3 or less.

[0015] Technical means to solve the problem

[0016] The above-mentioned problems can be solved by the following means.

[0017] <1>

[0018] An electrophotographic photoreceptor comprises a conductive substrate and a photosensitive layer disposed on the conductive substrate, and

[0019] The outermost layer contains fluorine-based graft polymer and fluorine-containing resin particles.

[0020] The fluorine-based graft polymer includes at least a first structural unit having no acidic group with a pKa of 3 or less and having a fluorine atom, a second structural unit derived from a macromonomer, and a third structural unit having an acidic group with a pKa of 3 or less.

[0021] <2>

[0022] The electrophotographic photoreceptor according to <1>, wherein the acidic group with a pKa of 3 or less includes an acidic group (Ac), and the acidic group (Ac) is at least one selected from the group consisting of a sulfonic acid group, a phosphoric acid group, a phosphonic acid group, and a fluorinated alkylcarboxylic acid group.

[0023] <3>

[0024] An electrophotographic photoreceptor comprises a conductive substrate and a photosensitive layer disposed on the conductive substrate, and

[0025] The outermost layer contains fluorine-based graft polymer and fluorine-containing resin particles.

[0026] The fluorine-based graft polymer comprises at least a first structural unit having no acidic group (Ac) and having a fluorine atom, a second structural unit derived from a macromonomer, and a third structural unit having an acidic group (Ac), wherein the acidic group (Ac) is at least one selected from the group consisting of a sulfonic acid group, a phosphoric acid group, a phosphonic acid group, and a fluorinated alkyl carboxylic acid group.

[0027] <4>

[0028] The electrophotographic photoreceptor according to <1> or <2>, wherein the number of moles of the acidic groups having a pKa of 3 or less per 1 g of the fluorine-containing resin particles is 0.2 μmol / g to 5 μmol / g.

[0029] <5>

[0030] The electrophotographic photoreceptor according to <2> or <3>, wherein the number of moles of the acidic group (Ac) per 1 g of the fluorine-containing resin particles is 0.2 μmol / g or more and 5 μmol / g or less.

[0031] <6>

[0032] The electrophotographic photoreceptor according to any one of <1> to <5>, wherein the macromonomer includes at least one selected from the group consisting of poly(meth)acrylate having a radical polymerizable group at one terminal and polystyrene having a radical polymerizable group at one terminal.

[0033] <7>

[0034] The electrophotographic photoreceptor according to any one of <1> to <6>, wherein the first structural unit is a structural unit represented by the following general formula (1), the second structural unit is a structural unit represented by the following general formula (2), and the third structural unit is a structural unit represented by the following general formula (3).

[0035] [Chemistry 1]

[0036]

[0037] In the general formula (1), R 1 represents a hydrogen atom or an alkyl group, and Rf represents an organic group having a fluorine atom.

[0038] In the general formula (2), n represents an integer greater than or equal to 2, q represents an integer greater than or equal to 1, and R 2 and R 3 Each independently represents a hydrogen atom or an alkyl group, Y represents a substituted or unsubstituted alkylene group, -O-, -NH-, -S-, -C(=O)-, a divalent linking group obtained by any combination thereof, or a single bond, and Z represents a group represented by the following general formula (2A) or (2B).

[0039] In the general formula (3), L represents a substituted or unsubstituted alkylene group, -O-, -C(=O)-, or -NR 10 -, -C6H4-, a divalent linking group or a single bond obtained by any combination thereof, Q represents a sulfonic acid group, a phosphonic acid group, a phosphoric acid group or a fluorinated alkyl carboxylic acid group, R 6represents a hydrogen atom, a halogen atom or an alkyl group. 10 represents a hydrogen atom or a substituted or unsubstituted alkyl group.

[0040] [Chemistry 2]

[0041]

[0042] In the general formula (2A), R 4 represents a substituted or unsubstituted alkyl group or a mono- or polyalkyleneoxy chain, and * represents a bonding position to a carbon atom.

[0043] In the general formula (2B), Ra to Re each independently represent a hydrogen atom, an alkyl group having 4 or less carbon atoms, or an alkoxy group having 4 or less carbon atoms, and * represents a bonding position to a carbon atom.

[0044] <8>

[0045] The electrophotographic photoreceptor according to any one of <1> to <7>, wherein the content of the fluorine-based graft polymer is 0.5 parts by mass or more and 10 parts by mass or less based on 100 parts by mass of the fluorine-containing resin particles.

[0046] <9>

[0047] The electrophotographic photoreceptor according to any one of <1> to <8>, wherein the fluorine-containing resin particles contain polytetrafluoroethylene.

[0048] <10>

[0049] The electrophotographic photoreceptor according to any one of <1> to <9>, wherein the number of carboxyl groups in the fluorine-containing resin particles is 10 6 The number of items in the table is 0 or more and 30 or less.

[0050] <11>

[0051] The electrophotographic photoreceptor according to <10>, wherein the number of carboxyl groups in the fluorine-containing resin particles is 10 6 The number of items in the table is 0 or more and 20 or less.

[0052] <12>

[0053] The electrophotographic photoreceptor according to any one of <1> to <11>, wherein the amount of perfluorooctanoic acid relative to the mass of the fluorine-containing resin particles is 0 ppb or more and 25 ppb or less.

[0054] <13>

[0055] The electrophotographic photoreceptor according to <12>, wherein the amount of perfluorooctanoic acid relative to the mass of the fluorine-containing resin particles is 0 ppb to 20 ppb.

[0056] <14>

[0057] The electrophotographic photoreceptor according to any one of <1> to <13>, wherein the outermost surface layer contains a hole transport material.

[0058] <15>

[0059] A process cartridge comprising the electrophotographic photoreceptor according to any one of <1> to <14>, and

[0060] The process cartridge is detachably mounted in the image forming apparatus.

[0061] <16>

[0062] An image forming device, comprising:

[0063] The electrophotographic photoreceptor according to any one of <1> to <14>;

[0064] a charging mechanism for charging the surface of the electrophotographic photoreceptor;

[0065] an electrostatic latent image forming mechanism for forming an electrostatic latent image on the charged surface of the electrophotographic photoreceptor;

[0066] a developing mechanism for developing the electrostatic latent image formed on the surface of the electrophotographic photoreceptor using a developer containing toner to form a toner image; and

[0067] The transfer mechanism transfers the toner image to the surface of the recording medium.

[0068] Effects of the Invention

[0069] According to the invention <1> or <2>, there is provided an electrophotographic photoreceptor having a suppressed residual potential compared to a case where the electrophotographic photoreceptor comprises a conductive substrate and a photosensitive layer provided on the conductive substrate, wherein the outermost layer comprises fluorine-containing resin particles and a fluorine-based graft polymer having no acidic group with a pKa of 3 or less.

[0070] According to the invention <3>, there is provided an electrophotographic photoreceptor having a suppressed residual potential compared to a case where the electrophotographic photoreceptor comprises a conductive substrate and a photosensitive layer provided on the conductive substrate, wherein the outermost layer contains a fluorine-based graft polymer having no acidic group (Ac).

[0071] According to the invention <4>, there is provided an electrophotographic photoreceptor having a suppressed residual potential compared to a case where the number of moles of the acidic groups having a pKa of 3 or less per 1 g of the fluorine-containing resin particles is less than 0.2 μmol / g.

[0072] According to the invention of <5>, there is provided an electrophotographic photoreceptor having a suppressed residual potential compared to a case where the number of moles of the acidic group (Ac) per 1 g of fluorine-containing resin particles is less than 0.2 μmol / g.

[0073] According to the invention of <6>, <7>, <9> or <14>, an electronic photographic photosensitive body is provided, in which the residual potential is suppressed compared to a case where the photosensitive body has a conductive substrate and a photosensitive layer arranged on the conductive substrate, and the outermost layer contains fluorine-containing resin particles and a fluorine-based graft polymer that does not have an acidic group with a pKa of less than 3 and the acidic group (Ac).

[0074] According to the invention of <8>, there is provided an electrophotographic photoreceptor having a suppressed residual potential compared to a case where the content of the fluorine-based graft polymer is less than 0.5 parts by mass based on 100 parts by mass of the fluorine-containing resin particles.

[0075] According to the invention of <10>, there is provided an electrophotographic photoreceptor, wherein even if the number of carboxyl groups in the fluorine-containing resin particles is 10 per carbon number, 6 The number of the fluorine-containing resin particles is 0 or more and 30 or less, and the residual potential is suppressed compared to the case where the outermost layer contains fluorine-containing resin particles and a fluorine-based graft polymer having no acidic group with a pKa of 3 or less and no acidic group (Ac).

[0076] According to the invention of <11>, there is provided an electrophotographic photoreceptor, wherein even if the number of carboxyl groups in the fluorine-containing resin particles is 10 6 The number of the fluorine-containing resin particles is 0 or more and 20 or less, and the residual potential is suppressed compared to the case where the outermost layer contains fluorine-containing resin particles and a fluorine-based graft polymer having no acidic group with a pKa of 3 or less and no acidic group (Ac).

[0077] According to the invention of <12>, an electrophotographic photoreceptor is provided, in which, even when the amount of perfluorooctanoic acid relative to the mass of the fluorine-containing resin particles is 0 ppb or more and 25 ppb or less, the residual potential is suppressed compared to a case where the outermost layer contains fluorine-containing resin particles and a fluorine-based graft polymer that does not have an acidic group with a pKa of 3 or less and the acidic group (Ac).

[0078] According to the invention of <13>, an electrophotographic photoreceptor is provided, in which, even when the amount of perfluorooctanoic acid relative to the mass of the fluorine-containing resin particles is 0 ppb or more and 20 ppb or less, the residual potential is suppressed compared to a case where the outermost layer contains fluorine-containing resin particles and a fluorine-based graft polymer that does not have an acidic group with a pKa of 3 or less and the acidic group (Ac).

[0079] According to the invention of <15> or <16>, there is provided a processing box or image forming apparatus comprising an electrophotographic photoreceptor, wherein the residual potential of the electrophotographic photoreceptor is suppressed compared to the case where the electrophotographic photoreceptor has a conductive substrate and a photosensitive layer provided on the conductive substrate, and the outermost layer contains fluorine-containing resin particles and a fluorine-based graft polymer having no acidic group with a pKa of 3 or less and the acidic group (Ac). BRIEF DESCRIPTION OF THE DRAWINGS

[0080] Figure 1 This is a schematic cross-sectional view showing an example of the layer structure of the electrophotographic photoreceptor according to this embodiment.

[0081] Figure 2 This is a diagram schematically illustrating the configuration of an example of the image forming apparatus according to the present embodiment.

[0082] Figure 3 This is a schematic structural diagram showing another example of the image forming apparatus according to the present embodiment.

[0083] Explanation of symbols

[0084] 1: Base coat

[0085] 2: Charge generation layer

[0086] 3: Charge transfer layer

[0087] 4: Conductive substrate

[0088] 7A, 7: Electrophotographic photoreceptor

[0089] 8: Live device

[0090] 9: Exposure device

[0091] 11: Development device

[0092] 13: Cleaning device

[0093] 14: Lubricant

[0094] 40: Transfer device

[0095] 50: Intermediate transfer body

[0096] 100: Image forming device

[0097] 120: Image forming device

[0098] 131: Cleaning scraper

[0099] 132: Fibrous member (roller)

[0100] 133: Fibrous member (flat brush shape)

[0101] 300: Processing box DETAILED DESCRIPTION

[0102] Hereinafter, an embodiment as an example of the present invention will be described in detail.

[0103] [Electrophotographic photoreceptor]

[0104] The electronic photographic photoreceptor of the first embodiment has a conductive substrate and a photosensitive layer arranged on the conductive substrate, and the outermost layer contains a fluorine-based grafted polymer and fluorine-containing resin particles, and the fluorine-based grafted polymer at least includes a first structural unit that does not have an acidic group with a pKa of less than 3 and has a fluorine atom, a second structural unit derived from a macromolecular monomer, and a third structural unit that has an acidic group with a pKa of less than 3.

[0105] Hereinafter, the electrophotographic photoreceptor is also simply referred to as a "photoreceptor."

[0106] The photoreceptor of the second embodiment comprises a conductive substrate and a photosensitive layer disposed on the conductive substrate, wherein the outermost layer contains a fluorine-based graft polymer and fluorine-containing resin particles. The fluorine-based graft polymer comprises at least a first structural unit having no acidic group (Ac) and having a fluorine atom, a second structural unit derived from a macromolecular monomer, and a third structural unit having an acidic group (Ac). The acidic group (Ac) is at least one selected from the group consisting of a sulfonic acid group, a phosphoric acid group, a phosphonic acid group, and a fluorinated alkyl carboxylic acid group.

[0107] Hereinafter, a photoreceptor that conforms to at least one of the photoreceptor of the first embodiment and the photoreceptor of the second embodiment will be referred to as the "photoreceptor of this embodiment." Furthermore, the photoreceptor of this embodiment may conform to both the photoreceptor of the first embodiment and the photoreceptor of the second embodiment.

[0108] In addition, an acidic group that meets at least one of the above-mentioned “acidic group with a pKa of 3 or less” and the above-mentioned “acidic group (Ac)” is also referred to as a “specific acidic group”.

[0109] In addition, the first structural unit having no specific acidic group and having a fluorine atom is also referred to as a "first structural unit" or "(a) first structural unit", the second structural unit derived from the macromolecular monomer is also referred to as a "second structural unit" or "(b) second structural unit", and the third structural unit having a specific acidic group is also referred to as a "third structural unit" or "(c) third structural unit".

[0110] In addition, a fluorine-containing graft polymer comprising at least (a) a first structural unit, (b) a second structural unit, and (c) a third structural unit is also referred to as a "specific fluorine-containing graft polymer" or "(A) specific fluorine-containing graft polymer", and fluorine-containing resin particles are also referred to as "(B) fluorine-containing resin particles".

[0111] The photoreceptor of this embodiment can suppress the residual potential due to the above-mentioned configuration. The reason for this is presumably as follows.

[0112] Conventionally, fluorine-containing resin particles have been blended into the surface layer of electrophotographic photoreceptors to improve cleanability, and dispersants such as fluorine-based graft polymers have been used to improve the dispersibility of the fluorine-containing resin particles.

[0113] However, depending on the combination of fluorine-containing resin particles and fluorine-based graft polymers used, the absolute value of the potential on the surface of the electrophotographic photoreceptor is unlikely to decrease due to exposure. As a result, potential may remain on the surface of the electrophotographic photoreceptor, forming a residual potential.

[0114] In contrast, the photoreceptor of this embodiment comprises (A) a specific fluorine-based graft polymer and (B) fluorine-containing resin particles in its outermost layer. Therefore, the specific fluorine-based graft polymer (A) exhibits ionicity due to the specific acidic group in its third structural unit (C), reducing the overall resistance of the outermost layer and thus facilitating a decrease in the absolute value of the potential upon exposure. As a result, it is speculated that the photoreceptor of this embodiment can suppress residual potential.

[0115] Based on the above reasons, it is presumed that in this embodiment, a photoreceptor with suppressed residual potential can be obtained.

[0116] Furthermore, since the specific fluorine-based graft polymer (A) comprises the first structural unit (a) having no specific acidic group and having a fluorine atom, and the second structural unit (b) derived from a macromonomer, the dispersibility of the fluorine-containing resin particles (B) in the outermost layer is also improved. Specifically, the dispersion stability of the fluorine-containing resin particles (B) in the outermost layer-forming coating liquid used to form the outermost layer is improved, and the dispersibility of the fluorine-containing resin particles (B) in the coating film obtained by applying the outermost layer-forming coating liquid is improved, thereby obtaining an outermost layer having well-dispersed fluorine-containing resin particles (B).

[0117] Therefore, in the present embodiment, it is possible to obtain a photoreceptor in which the dispersibility of the fluorine-containing resin particles (B) is obtained and the residual potential is suppressed.

[0118] In particular, the specific fluorine-containing graft polymer (A) further comprises a third structural unit (c) in addition to the first structural unit (a) and the second structural unit (b), thereby further improving the dispersibility of the fluorine-containing resin particles (B). The reason for this is not certain, but it is presumed that the third structural unit (c) has a specific acidic group, which improves the dispersion stability of the fluorine-containing resin particles (B) in the coating liquid and the coating film during the formation of the outermost layer.

[0119] Furthermore, in the photoreceptor of this embodiment, as described above, the absolute value of the potential on the photoreceptor surface is easily reduced by exposure. Therefore, it is easy to maintain a potential difference between exposed and unexposed areas (i.e., potential contrast), and it is easy to obtain high-quality images. Furthermore, since the absolute value of the potential on the photoreceptor surface is easily reduced by exposure, the accumulation of residual potential during long-term image formation is suppressed, not only during the initial stage of image formation.

[0120] Furthermore, in this embodiment, the specific fluorine-based graft polymer (A) contains specific acidic groups. Therefore, in the coating film, the specific fluorine-based graft polymer (A) is adsorbed and fixed to the surface of the fluorine-containing resin particles (B), thereby minimizing the migration of the specific acidic groups within the film. Consequently, the resulting outermost layer exhibits highly uniform electrical resistance, suppressing temporal fluctuations in the electrical properties of the photoreceptor due to surface wear during use.

[0121] Hereinafter, the photoreceptor according to this embodiment will be described in detail.

[0122] In the photoreceptor of this embodiment, the outermost layer contains (A) a specific fluorine-based graft polymer and (B) fluorine-containing resin particles.

[0123] The outermost layer includes the charge transport layer, protective layer, and single-layer photosensitive layer. Depending on the type of layer, the outermost layer may also contain other components besides the fluorinated graft polymer and fluorinated resin particles. These other components are described together with the structure of each layer of the photoreceptor.

[0124] Furthermore, the outermost layer may contain a fluorine-based graft polymer other than the specific fluorine-based graft polymer (A) as needed. The content of the specific fluorine-based graft polymer (A) relative to the total fluorine-based graft polymer contained in the outermost layer is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more.

[0125] <(A) Specific fluorine-based graft polymer>

[0126] First, the (A) specific fluorine-based graft polymer will be described.

[0127] The specific fluorine-based graft polymer (A) is used, for example, to disperse the fluorine-containing resin particles (B) described later.

[0128] The specific fluorine-based graft polymer (A) contains at least the (a) first structural unit, the (b) second structural unit, and the (c) third structural unit. The specific fluorine-based graft polymer (A) may further contain other structural units as needed. The total content of the (a) first structural unit, the (b) second structural unit, and the (c) third structural unit in all the structural units contained in the specific fluorine-based graft polymer (A) is preferably 70% by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass or more.

[0129] The (a) first structural unit, (b) second structural unit, and (c) third structural unit can be obtained, for example, by known polymerization methods (chain polymerization, condensation polymerization, and addition polymerization). From the perspectives of raw material acquisition, polymerization method, and the range of options for controlling the composition ratio, structural units obtained by chain polymerization of compounds having unsaturated double bonds are preferred.

[0130] Hereinafter, (a) the first structural unit, (b) the second structural unit, and (c) the third structural unit will be described respectively.

[0131] -(a) First Structural Unit-

[0132] (a) The first structural unit is not limited in type as long as it does not have a specific acidic group and contains a fluorine atom in the structural unit. The fluorine atom may be substituted on any carbon, preferably on a carbon other than the carbon participating in the polymerization reaction. Furthermore, the fluorine atom is preferably an atom that forms the main chain of the specific fluorine-based graft polymer, and may be present as a perfluoroalkyl group having 6 or fewer carbon atoms via a linking group.

[0133] As the (a) first structural unit, for example, a structural unit represented by the following general formula (1) is preferable.

[0134] [Chemistry 3]

[0135]

[0136] In the general formula (1), R 1 represents a hydrogen atom or an alkyl group, and Rf represents an organic group having a fluorine atom.

[0137] R 1 It is preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom, a methyl group, an ethyl group or a propyl group, further preferably a hydrogen atom or a methyl group, and particularly preferably a methyl group.

[0138] The organic group having a fluorine atom represented by Rf represents a structure having carbon atoms and fluorine atoms as essential and further comprising hydrogen atoms, oxygen atoms, etc. As the oxygen atom contained in the organic group having a fluorine atom, for example, an oxygen atom contained in the form of a hydroxyl group, an oxygen atom contained in the form of an ether bond, etc. can be cited. A preferred embodiment of the organic group having a fluorine atom is a structure having carbon atoms and fluorine atoms as essential and further comprising hydrogen atoms, oxygen atoms in the form of an ether bond (i.e., "-O-").

[0139] Specific examples of the organic group having a fluorine atom include a fluorinated alkyl group, a fluorinated alkyl group having a hydroxyl group, a fluorinated alkyloxyfluorinated alkylene group, and a poly(fluorinated alkyleneoxy) group.

[0140] The total carbon number of the organic group having fluorine atoms is, for example, 15 or less, and preferably 12 or less. The number of fluorine atoms contained in the organic group having fluorine atoms is preferably 5 or more and 20 or less, and more preferably 7 or more and 18 or less.

[0141] The chemical formula weight of the first structural unit (a) is preferably 150 or more and 600 or less, more preferably 200 or more and 550 or less, and even more preferably 250 or more and 500 or less.

[0142] -(b) Second structural unit-

[0143] (b) The second structural unit is a structural unit derived from a macromonomer.

[0144] Here, the term "macromonomer" refers to a high molecular weight (e.g., molecular weight 300 or greater) polymerizable monomer having a polymerizable group. For example, a macromonomer has a polymer chain represented by a repeating structure. Examples of macromonomers include linear polymer compounds having a polymerizable functional group at one end of the molecular chain.

[0145] The graft (comb-type) polymer is formed by copolymerizing a macromonomer serving as a precursor of the (b) second structural unit with a monomer serving as a precursor of the (a) first structural unit and a monomer serving as a precursor of the (c) third structural unit.

[0146] The type of the second structural unit (b) is not limited as long as it has a polymer chain represented by a repeating structure as a graft chain derived from the main chain of the specific fluorine-based graft polymer. Examples of the graft chain include poly(meth)acrylate, polystyrene, polyalkylene oxide, and polysiloxane.

[0147] As the (b) second structural unit, for example, a structural unit represented by the following general formula (2) is preferable.

[0148] [Chemistry 4]

[0149]

[0150] In the general formula (2), n represents an integer greater than or equal to 2, q represents an integer greater than or equal to 1, and R 2 and R 3 Each independently represents a hydrogen atom or an alkyl group, Y represents a substituted or unsubstituted alkylene group, -O-, -NH-, -S-, -C(=O)-, a divalent linking group obtained by any combination thereof, or a single bond, and Z represents a group represented by the general formula (2A) or (2B) described below.

[0151] n in the general formula (2) may be an integer of 2 or greater, preferably an integer of 2 or greater and 500 or less, more preferably an integer of 2 or greater and 200 or less, and still more preferably an integer of 10 or greater and 100 or less.

[0152] In the general formula (2), q may be an integer greater than or equal to 1, and is preferably greater than or equal to 1 and less than or equal to 10, and more preferably greater than or equal to 1 and less than or equal to 5.

[0153] R in general formula (2) 2 and R 3 Each independently is preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom, a methyl group, an ethyl group or a propyl group, and still more preferably a hydrogen atom or a methyl group.

[0154] Y in the general formula (2) is preferably a substituted or unsubstituted alkylene group, -O-, -S-, -OC(=O)-, -C(=O)-O-, -NH-C(=O)-, -C(=O)-NH-, or a divalent linking group obtained by combining any of them. It is more preferably an unsubstituted alkylene group, a hydroxy-substituted alkylene group, a cyano-substituted alkylene group, an alkyl-substituted alkylene group, -S-, -OC(=O)-, -C(=O)-O-, -NH-C(=O)-, -C(=O)-NH-, or a divalent linking group obtained by combining any of them. It is even more preferably an unsubstituted alkylene group, a hydroxy-substituted alkylene group, -S-, -OC(=O)-, -C(=O)-O-, or a divalent linking group obtained by combining any of them.

[0155] The carbon number of the substituted or unsubstituted alkylene group may be, for example, 1 or more and 10 or less, preferably 1 or more and 5 or less, and more preferably 1 or more and 3 or less.

[0156] Examples of the substituent in the substituted alkylene group include an alkyl group having 4 or less carbon atoms, a halogen atom, a hydroxyl group, a lower alkoxy group having 4 or less carbon atoms, an ester group, and a cyano group.

[0157] [Chemistry 5]

[0158]

[0159] In the general formula (2A), R 4 represents a substituted or unsubstituted alkyl group or a mono- or polyalkyleneoxy chain, and * represents a bonding position to a carbon atom.

[0160] In the general formula (2B), Ra to Re each independently represent a hydrogen atom, an alkyl group having 4 or less carbon atoms, or an alkoxy group having 4 or less carbon atoms, and * represents a bonding position to a carbon atom.

[0161] As R in the general formula (2A) 4 Examples of the substituent of the substituted alkyl group include a halogen atom, a hydroxyl group, an alkoxy group having 4 or less carbon atoms, and an ester group.

[0162] As R in the general formula (2A) 4 Examples of the alkyleneoxy chain include an ethyleneoxy chain and a propyleneoxy chain. The number of repetitions of the alkyleneoxy chain may be, for example, 6 or less, preferably 4 or less. Examples of the terminal group of the alkyleneoxy chain include a hydroxyl group and an alkoxy group having 4 or less carbon atoms.

[0163] R in the general formula (2A) 4 An alkyl group having 8 or less carbon atoms or an alkyleneoxy chain having 4 or less repeating numbers is preferred, and an alkyl group having 4 or less carbon atoms or an ethyleneoxy chain or a propyleneoxy chain having 2 or less repeating numbers is more preferred.

[0164] In the general formula (2B), Ra to Re are each independently preferably a hydrogen atom, a methyl group, an ethyl group, an n-propyl group or a methoxy group, and more preferably a hydrogen atom, a methyl group or a methoxy group.

[0165] Z in the general formula (2) is preferably a group represented by the general formula (2A).

[0166] (b) The second structural unit may be a structural unit other than the structural unit represented by the general formula (2).

[0167] For example, when the second structural unit (b) is a chain polymerization type repeating unit, the second structural unit (b) may be, for example, a structural unit represented by the following general formula (2X). In such a case, the chemical formula weight of the second structural unit (b) is, for example, 1000 or more and 30000 or less, preferably 2000 or more and 20000 or less, and more preferably 3000 or more and 10000 or less.

[0168] In addition, examples of the (b) second structural unit include structural units represented by the following general formula (2Y) (ie, vinyl ether-type structural units).

[0169] For example, when the second structural unit (b) is a condensation-type repeating unit, the second structural unit (b) may be a structural unit in which a structure represented by the following general formula (2C) is substituted on the side chain of a diol, a dicarboxylic acid, or a dicarboxylic acid derivative.

[0170] [Chemistry 6]

[0171]

[0172] In the general formula (2X) and the general formula (2Y), R 8 and R in the general formula (2) 2 For the same meaning.

[0173] In the general formula (2X), R 9 It represents a group having a polyalkyleneoxy chain or a polysiloxane chain.

[0174] In the general formula (2Y), A represents a structure represented by the following general formula (2C).

[0175] [Chemistry 7]

[0176]

[0177] In the general formula (2C), q, Y, and R 3 , n and Z are respectively the same as q, Y, R in the general formula (2) 3 , n and Z have the same meaning, and * indicates the bonding position to the oxygen atom.

[0178] Next, a method for synthesizing a macromonomer serving as a precursor of the (b) second structural unit will be described.

[0179] Regarding the macromonomer that serves as a precursor of the second structural unit (b), for example, chain polymerization, condensation polymerization, or the like is initiated based on a compound having functional groups such as a carboxyl group or a hydroxyl group to synthesize a polymer having a functional group such as a carboxyl group or a hydroxyl group at one end, and a polymerizable group is introduced based on the functional group to obtain a macromonomer having a polymerizable group at one end.

[0180] For example, when the second structural unit (b) is a structural unit represented by the general formula (2), polymerization of a (meth)acrylic compound or a styrene compound is initiated using a radical polymerization initiator or chain transfer agent having a functional group such as a carboxyl group or a hydroxyl group to synthesize a (meth)acrylic polymer or a styrene polymer having a functional group such as a carboxyl group or a hydroxyl group at one end. Based on the functional group, a radical polymerizable group (e.g., a (meth)acrylic acid group) is introduced to obtain a macromonomer corresponding to a precursor of the structural unit represented by the general formula (2). Detailed methods for synthesizing the macromonomer include the methods described in Japanese Patent Application Laid-Open No. 58-164656 and Japanese Patent Application Laid-Open No. 60-133007.

[0181] The chemical formula weight of the second structural unit (b) is preferably 1,000 or more and 30,000 or less, more preferably 2,000 or more and 20,000 or less, and still more preferably 3,000 or more and 10,000 or less.

[0182] -(c) Third structural unit-

[0183] The type of the (c) third structural unit is not limited as long as it is a structural unit having a specific acidic group.

[0184] The pKa values ​​of specific acidic groups can be determined from literature values ​​of model compounds having these specific acidic groups, measurements using known methods such as titration, and the like. Examples of specific acidic groups include sulfonic acid groups (methanesulfonic acid: -2.6), phosphonic acid groups (first dissociation: 1.5), phosphoric acid groups (first dissociation: 2.12), and fluorinated alkyl carboxylic acid groups (e.g., trifluoroacetic acid: -0.25, difluoroacetic acid: 1.24, monofluoroacetic acid: 2.66). In addition, reference values ​​for specific examples of compounds, dissociation stages, and pKa values ​​are shown in parentheses.

[0185] As the (c) third structural unit, for example, a structural unit represented by the following general formula (3) is preferable.

[0186] [Chemistry 8]

[0187]

[0188] In the general formula (3), L represents a substituted or unsubstituted alkylene group, -O-, -C(=O)-, or -NR 10 -, -C6H4-, a divalent linking group or a single bond obtained by any combination thereof, Q represents a sulfonic acid group, a phosphonic acid group, a phosphoric acid group or a fluorinated alkyl carboxylic acid group, R 6 represents a hydrogen atom, a halogen atom or an alkyl group. 10 represents a hydrogen atom or a substituted or unsubstituted alkyl group.

[0189] In the general formula (3), L is preferably a substituted or unsubstituted alkylene group, -O-, -C(=O)O-, -C(=O)NR 10 -, -C6H4-, a divalent linking group or a single bond formed by any combination thereof, more preferably a substituted or unsubstituted alkylene group, -C(=O)O-, -C(=O)NR 10 -, -C6H4-, and any combination thereof. In particular, from the viewpoint of polymerizability, the -C(=O)O-, -C(=O)NR 10 - and -C6H4- are preferably directly linked to the carbon atom C in formula (3).

[0190] The substituents of the substituted alkylene group represented by L in the general formula (3) are the same as the substituents of the substituted alkylene group represented by Y in the general formula (2). However, the substituted alkylene group represented by L in the general formula (3) preferably does not have a fluorine atom.

[0191] In addition, the R 10 The substituent of the substituted alkyl represented by 4 The substituents of the substituted alkyl groups represented are the same.

[0192] In addition, when L in the general formula (3) contains -C6H4-, it may be any of the ortho, meta, and para positions, and among them, the meta or para position is preferred.

[0193] Specific examples of L in the general formula (3) include, in addition to a single bond, linking groups represented by the following general formulae (L-1) to (L-3).

[0194] [Chemistry 9]

[0195]

[0196] In the general formulas (L-1) to (L-3), L L1 and L L2 represents -O- or -NH-, R L1 and R L2 each independently represents a hydrogen atom or a methyl group, m represents an integer of 1 to 5, k represents 0 or 1, and p represents an integer of 2 to 10. 1 * represents the bonding position directly bonded to the carbon atom of the general formula (3), * 2 It represents the bonding position directly bonding to Q in the general formula (3).

[0197] In general formulas (L-1) to (L-3), L L1 and L L2 It is preferably -O-, m is preferably an integer of 2 to 3, and p is preferably an integer of 4 to 6. In addition, when Q in the general formula (3) is a sulfonic acid group, a phosphonic acid group, or a phosphoric acid group, k in the general formula (L-1) is preferably 0, and when Q in the general formula (3) is a fluorinated alkylcarboxylic acid group, k in the general formula (L-1) is preferably 1.

[0198] The sulfonic acid group represented by Q in the general formula (3) is represented by -SO3H, and the phosphonic acid group is represented by -P(=O)(OH) r (OR 11 ) 2-r Indicated by -OP(=O)(OH) s (OR 12 ) 2-sIndicates that the fluorinated alkyl carboxylic acid group is represented by -(CF z H (2-z) ) y -CO2H. Here, r and s each independently represent 1 or 2, z represents 1 or 2, and y represents an integer of 1 to 5 (preferably an integer of 1 to 3). 11 and R 12 Independently with the R 10 For the same meaning.

[0199] Q in the general formula (3) is not limited as long as it satisfies the above conditions. From the viewpoint of material availability and molecular design, a sulfonic acid group, a phosphoric acid group, or a fluorinated alkyl carboxylic acid group is suitable.

[0200] R in the general formula (3) 6 It is preferably a hydrogen atom, fluorine, or an alkyl group having 1 to 6 carbon atoms.

[0201] In addition, when the fluorinated alkyl carboxylic acid group represented by Q in the general formula (3) is directly bonded to the alkylene group of the group represented by L in the general formula (3), the carbon farthest from the carboxyl group among the carbons bonded to the fluorine atom is set as the group represented by Q, and the alkylene group having no fluorine atom and containing only carbon atoms is included in the group represented by L.

[0202] Examples of the structural unit other than the structural unit represented by the general formula (3) in the third structural unit (c) include structural units in which both a fluorine atom and a carboxyl group are directly bonded to a carbon atom constituting the main chain. The carboxyl group becomes a specific acidic group with a pKa of 3 or less by directly bonding both the fluorine atom and the carboxyl group to a carbon atom.

[0203] The chemical formula weight of the (c) third structural unit is preferably 80 or more and 600 or less, more preferably 90 or more and 550 or less, and still more preferably 100 or more and 500 or less.

[0204] -Specific Examples of Each Structural Unit-

[0205] Specific examples of the structural unit represented by the general formula (1) are listed in Tables 1 and 2 below, but the present invention is not limited to these.

[0206] [Chemistry 10]

[0207] [Table 1]

[0208] <![CDATA[R 1 ]]> Rf Formula (1-1) -H <![CDATA[-CH2CF3]]> Formula (1-2) <![CDATA[-CH3]]> <![CDATA[-CH2CF3]]> Formula (1-3) -H <![CDATA[-CH2C2F5]]> Formula (1-4) <![CDATA[-CH3]]> <![CDATA[-CH2C2F5]]> Formula (1-5) <![CDATA[-CH3]]> <![CDATA[-CH2(CF2)2CF3]]> Formula (1-6) -H <![CDATA[-CH(CF3)2]]> Formula (1-7) <![CDATA[-CH3]]> <![CDATA[-CH(CF3)2]]> Formula (1-8) -H <![CDATA[-CH2CH2(CF2)3CF3]]> Formula (1-9) <![CDATA[-CH3]]> <![CDATA[-CH2CH2(CF2)3CF3]]> Formula (1-10) -H <![CDATA[-CH2(CF2)3CF2H]]> Formula (1-11) <![CDATA[-CH3]]> <![CDATA[-CH2(CF2)3CF2H]]> Formula (1-12) -H <![CDATA[-CH2CH(OH)CH2(CF2)3CF3]]> Formula (1-13) <![CDATA[-CH3]]> <![CDATA[-CH2CH(OH)CH2(CF2)3CF3]]> Formula (1-14) -H <![CDATA[-CH2CH(OH)CH2(CF2)2CF(CF3)2]]> Formula (1-15) <![CDATA[-CH3]]> <![CDATA[-CH2CH(OH)CH2(CF2)2CF(CF3)2]]>

[0209] [Chemistry 11]

[0210] [Table 2]

[0211] <![CDATA[R 1 ]]> Rf Formula (1-16) -H <![CDATA[-CH2CH2(CF2)5CF3]]> Formula (1-17) <![CDATA[-CH3]]> <![CDATA[-CH2CH2(CF2)5CF3]]> Formula (1-18) -H <![CDATA[-CH2(CF2)5CF2H]]> Formula (1-19) <![CDATA[-CH3]]> <![CDATA[-CH2(CF2)5CF2H]]> Formula (1-20) -H <![CDATA[-CH2CH(OH)CH2(CF2)5CF3]]> Formula (1-21) <![CDATA[-CH3]]> <![CDATA[-CH2CH(OH)CH2(CF2)5CF3]]> Formula (1-22) -H <![CDATA[-CH2(CF2)6CF3]]> Formula (1-23) -H <![CDATA[-CH2CH2(CF2)7CF3]]> Formula (1-24) <![CDATA[-CH3]]> <![CDATA[-CH2CH2(CF2)7CF3]]> Formula (1-25) -H <![CDATA[-CH2CF(CF3)-O-(CF2)2CF3]]> Formula (1-26) -H <![CDATA[-CH2CF(CF3)-O-CF2CF(CF3)-O-(CF2)2CF3]]>

[0212] Specific examples of the structural unit represented by the general formula (2) are listed below, but the present invention is not limited to these.

[0213] In the following tables, the linking group represented by Y means that the left end is bonded to a carbon atom on the side closer to the main chain, and the right end is bonded to a carbon atom on the side farther from the main chain.

[0214] [Chemistry 12]

[0215] [Table 3]

[0216] <![CDATA[R 2 ]]> q Y <![CDATA[R 3 ]]> Z n Formula (2-1) -H 2 <![CDATA[-O-C(=O)-CH2-S-]]> <![CDATA[-CH3]]> <![CDATA[-CO2-CH3]]> 50 Formula (2-2) -H 2 <![CDATA[-NH-C(=O)-O-(CH2)2-S-]]> <![CDATA[-CH3]]> <![CDATA[-CO2-CH3]]> 50 Formula (2-3) <![CDATA[-CH3]]> 2 <![CDATA[-NH-C(=O)-O-(CH2)2-S-]]> <![CDATA[-CH3]]> <![CDATA[-CO2-CH3]]> 50 Formula (2-4) <![CDATA[-CH3]]> 2 <![CDATA[-O-(CH2)2-NH-C(=O)-O-(CH2)2-S-]]> <![CDATA[-CH3]]> <![CDATA[-CO2-CH3]]> 40 Formula (2-5) <![CDATA[-CH3]]> 1 <![CDATA[-C(=O)-O-(CH2)2-S-]]> <![CDATA[-CH3]]> <![CDATA[-CO2-CH3]]> 60 Formula (2-6) -H 2 <![CDATA[-C(=O)-O-(CH2)2-S-]]> <![CDATA[-CH3]]> <![CDATA[-CO2-CH3]]> 70 Formula (2-7) <![CDATA[-CH3]]> 1 <![CDATA[-CH(OH)-CH2-O-C(=O)-(CH2)2-C(CH3)(CN)-]]> <![CDATA[-CH3]]> <![CDATA[-CO2-CH3]]> 60 Formula (2-8) -H 2 <![CDATA[-C(=O)-O-(CH2)2-NH-C(=O)-C(CH3)2-]]> <![CDATA[-CH3]]> <![CDATA[-CO2-CH3]]> 60 Formula (2-9) -H 2 <![CDATA[-O-C(=O)-CH2-S-]]> <![CDATA[-CH3]]> <![CDATA[-CO2-CH3]]> 40 Formula (2-10) <![CDATA[-CH3]]> 2 <![CDATA[-O-C(=O)-CH2-S-]]> <![CDATA[-CH3]]> <![CDATA[-CO2-CH3]]> 50 Formula (2-11) -H 2 <![CDATA[-C(=O)-O-(CH2)2-S-]]> <![CDATA[-CH3]]> <![CDATA[-CO2-CH3]]> 70 Formula (2-12) -H 1 <![CDATA[-CH(OH)-CH2-O-C(=O)-CH2-S-]]> <![CDATA[-CH3]]> <![CDATA[-CO2-CH3]]> 60 Formula (2-13) <![CDATA[-CH3]]> 1 <![CDATA[-CH(OH)-CH2-O-C(=O)-CH2-S-]]> <![CDATA[-CH3]]> <![CDATA[-CO2-CH3]]> 30 Formula (2-14) <![CDATA[-CH3]]> 1 <![CDATA[-CH(OH)-CH2-O-C(=O)-CH2-S-]]> <![CDATA[-CH3]]> <![CDATA[-CO2-CH3]]> 60 Formula (2-15) <![CDATA[-CH3]]> 1 <![CDATA[-CH(OH)-CH2-O-C(=O)-CH2-S-]]> <![CDATA[-CH3]]> <![CDATA[-CO2-C2H5]]> 70

[0217] [Chemistry 13]

[0218] [Table 4]

[0219] <![CDATA[R 2 ]]> q Y <![CDATA[R 3 ]]> Z n Formula (2-16) <![CDATA[-CH3]]> 1 <![CDATA[-CH(OH)-CH2-O-C(=O)-CH2-S-]]> -H <![CDATA[-CO2-nC4H9]]> 60 Formula (2-17) <![CDATA[-CH3]]> 1 <![CDATA[-CH(OH)-CH2-O-C(=O)-(CH2)2-S-]]> <![CDATA[-CH3]]> <![CDATA[-CO2-CH3]]> 50 Formula (2-18) <![CDATA[-CH3]]> 1 <![CDATA[-CH(OH)-CH2-O-C(=O)-(CH2)2-S-]]> -H <![CDATA[-CO2-CH3]]> 60 Formula (2-19) <![CDATA[-CH3]]> 1 <![CDATA[-CH(OH)-CH2-O-C(=O)-(CH2)2-S-]]> <![CDATA[-CH3]]> <![CDATA[-CO2-CH3]]> 60 Formula (2-20) <![CDATA[-CH3]]> 1 <![CDATA[-CH(OH)-CH2-O-C(=O)-(CH2)2-S-]]> <![CDATA[-CH3]]> <![CDATA[-CO2-CH3]]> 80 Formula (2-21) <![CDATA[-CH3]]> 1 <![CDATA[-CH(OH)-CH2-O-C(=O)-(CH2)2-S-]]> -H <![CDATA[-CO2-nC4H9]]> 60 Formula (2-22) <![CDATA[-CH3]]> 1 <![CDATA[-CH(OH)-CH2-O-C(=O)-CH2-S-]]> -H <![CDATA[-C6H5]]> 60 Formula (2-23) <![CDATA[-CH3]]> 1 <![CDATA[-CH(OH)-CH2-O-C(=O)-(CH2)2-S-]]> -H <![CDATA[-C6H5]]> 60 Formula (2-24) <![CDATA[-CH3]]> 1 <![CDATA[-CH(OH)-CH2-O-C(=O)-(CH2)2-S-]]> <![CDATA[-CH3]]> <![CDATA[-CO2-CH2CH2-OCH3]]> 50 Formula (2-25) -H 4 <![CDATA[-O-C(=O)-(CH2)2-S-]]> <![CDATA[-CH3]]> <![CDATA[-CO2-CH3]]> 70

[0220] Specific examples of the structural unit represented by the general formula (3) are listed below, but the present invention is not limited to these.

[0221] In the following tables, the linking group represented by L means that the left end is bonded to a carbon atom constituting the main chain, and the right end is bonded to the group represented by Q in the general formula (3).

[0222] [Chemistry 14]

[0223] [Table 5]

[0224]

[0225] [Chemistry 15]

[0226] [Table 6]

[0227] <![CDATA[R 6 ]]> L Q Acidic group type Formula (3-16) <![CDATA[-CH3]]> <![CDATA[-C(=O)-O-(CH2)2-O-C(=O)-]]> <![CDATA[-(CF2)3-CO2H]]> Fluorinated alkyl carboxylic acid Formula (3-17) -H <![CDATA[-C(=O)-O-CH2CH(CH3)-O-C(=O)-]]> <![CDATA[-(CF2)2-CO2H]]> Fluorinated alkyl carboxylic acid Formula (3-18) <![CDATA[-CH3]]> <![CDATA[-C(=O)-O-CH2CH(CH3)-O-C(=O)-]]> <![CDATA[-(CF2)2-CO2H]]> Fluorinated alkyl carboxylic acid Formula (3-19) -H <![CDATA[-C(=O)-O-CH2CH(CH3)-O-C(=O)-]]> <![CDATA[-(CF2)3-CO2H]]> Fluorinated alkyl carboxylic acid Formula (3-20) <![CDATA[-CH3]]> <![CDATA[-C(=O)-O-CH2CH(CH3)-O-C(=O)-]]> <![CDATA[-(CF2)3-CO2H]]> Fluorinated alkyl carboxylic acid

[0228] Next, specific examples other than the formulae (1-1) to (1-26) listed as specific examples of the structural unit represented by the general formula (1) in the (a) first structural unit are listed below.

[0229] [Chemistry 16]

[0230]

[0231] Next, specific examples other than the formulae (2-1) to (2-25) listed as specific examples of the structural unit represented by the general formula (2) in the (b) second structural unit will be listed.

[0232] [Chemistry 17]

[0233]

[0234] Next, specific examples other than the formulae (3-1) to (3-20) listed as specific examples of the structural unit represented by the general formula (3) in the (c) third structural unit are listed below.

[0235] [Chemistry 18]

[0236]

[0237] [Chemistry 19]

[0238]

[0239] -Other structural units-

[0240] As described above, the specific fluorine-based graft polymer (A) may further include other structural units in addition to the (a) first structural unit, the (b) second structural unit, and the (c) third structural unit. When the (a) first structural unit, the (b) second structural unit, and the (c) third structural unit are respectively the structural unit represented by the general formula (1), the structural unit represented by the general formula (2), and the structural unit represented by the general formula (3), the other structural unit may be, for example, a structural unit represented by the following general formula (4).

[0241] [Chemistry 20]

[0242]

[0243] In the general formula (4), R 5 represents a hydrogen atom or an alkyl group, R 7 represents a substituted or unsubstituted alkyl group.

[0244] R 5 It is preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

[0245] As R in the general formula (4) 7 Examples of the substituent of the substituted alkyl group include a hydroxyl group, an alkoxy group, an aryl group, and an ester group.

[0246] R 7 Preferred are alkyl groups having 30 or less carbon atoms, alkyl groups substituted with a hydroxyl group, and alkyl groups substituted with an alkoxy group having 10 or less carbon atoms, an aryl group, or an ester group. More preferred are alkyl groups having 20 or less carbon atoms, and alkyl groups substituted with an alkoxy group having 4 or less carbon atoms, an aryl group, or an ester group.

[0247] -Synthesis and Identification of Specific Fluorine-Based Graft Polymers-

[0248] Next, an example of a method for synthesizing the (A) specific fluorine-based graft polymer will be described.

[0249] When the specific fluorine-based graft polymer (A) comprises a structural unit represented by the general formula (1), a structural unit represented by the general formula (2), and a structural unit represented by the general formula (3), each of these can be synthesized, for example, by chain polymerization of a compound having an unsaturated double bond derived from each structural unit (specifically, a compound in which the carbon-carbon bond in the main chain of each structural unit becomes an unsaturated double bond, i.e., a monomer serving as a precursor of each structural unit). Examples of chain polymerization include free radical polymerization and anionic polymerization, which can be achieved by heating in the presence of a free radical polymerization initiator or anionic polymerization initiator, respectively, as needed.

[0250] When the specific fluorine-based graft polymer (A) contains structural units other than those represented by general formulae (1) to (3), for example, when it contains structural units represented by (a-1) to (a-3), (b-1) to (b-3), and (c-1) to (c-6), a high molecular weight can be achieved by cationic polymerization of vinyl ether or polyesterification by polycondensation of a diol with a dicarboxylic acid or a dicarboxylic acid derivative. In the case of cationic polymerization, this can be achieved by heating in the presence of a cationic polymerization initiator, if necessary; in the case of polycondensation, this can be achieved by heating in the presence of a catalyst or a condensation agent, if necessary.

[0251] Alternatively, if necessary, a method may be adopted in which the specific acidic group in the third structural unit (c) is protected or neutralized before polymerization, and after the molecular weight is increased, the specific acidic group is deprotected or restored to acidic state to generate the specific acidic group.

[0252] The structure and content of the constituent units of the fluorine-based graft polymer can be analyzed by, for example, infrared absorption spectroscopy (IR (Infrared) spectroscopy) or nuclear magnetic resonance spectroscopy (NMR (Nuclear Magnetic Resonance) spectroscopy).

[0253] When measuring the IR spectrum, NMR spectrum, etc. of the fluorine-based graft polymer from the outermost surface layer containing the fluorine-based graft polymer, the fluorine-based graft polymer can be collected as a measurement sample as follows.

[0254] Specifically, the outermost layer is dissolved in a soluble solvent such as tetrahydrofuran, and the fluororesin particles are filtered through a 0.1 μm mesh filter. The filtered fluororesin particles are then heated at 100°C or lower in a mixed solvent of two or more of the following: aromatic hydrocarbons such as toluene and xylene; halogen solvents such as fluorocarbons, perfluorocarbons, hydrochlorofluorocarbons, dichloromethane, and chloroform; ester solvents such as ethyl acetate and butyl acetate; and ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclopentanone. The filtered particles are then filtered and dried to remove and collect the fluorinated graft polymer adsorbed on the surface of the fluororesin particles.

[0255] -Content of each structural unit-

[0256] The number of each of the (a) first constitutional unit, (b) second constitutional unit, and (c) third constitutional unit contained in the specific fluorine-based graft polymer (A) is an integer of 1 or greater, preferably an integer of 5 or greater and 300 or less, and more preferably an integer of 10 or greater and 200 or less.

[0257] In addition, when the (A) specific fluorine-based graft polymer contains the structural unit represented by the general formula (1), the structural unit represented by the general formula (2) and the structural unit represented by the general formula (3), the number of each structural unit is an integer greater than 1, preferably an integer greater than 5 and less than 300, and more preferably an integer greater than 10 and less than 200.

[0258] When the total molar amount of the (a) first constitutional unit, (b) second constitutional unit, and (c) third constitutional unit contained in the (A) specific fluorine-based graft polymer is set to 100 mol%, the molar ratio of the (a) first constitutional unit is preferably 20 mol% to 95 mol%, more preferably 40 mol% to 90 mol%. The molar ratio of the (c) third constitutional unit is preferably 1 mol% to 30 mol%, more preferably 2 mol% to 20 mol%.

[0259] In addition, when the specific fluorine-based graft polymer (A) contains the structural unit represented by the general formula (1), the structural unit represented by the general formula (2), and the structural unit represented by the general formula (3), the content of the structural unit represented by the general formula (1) is preferably 20 mol% or more and 95 mol% or less, and more preferably 40 mol% or more and 90 mol% or less, relative to the total molar number of the structural unit represented by the general formula (1), the structural unit represented by the general formula (2), and the structural unit represented by the general formula (3). In addition, the content of the structural unit represented by the general formula (3) is preferably 1 mol% or more and 30 mol% or less, and more preferably 2 mol% or more and 20 mol% or less, relative to the total molar number of the structural unit represented by the general formula (1), the structural unit represented by the general formula (2), and the structural unit represented by the general formula (3).

[0260] When the (A) specific fluorine-based graft polymer contains other structural units in addition to the (a) first structural unit, the (b) second structural unit and the (c) third structural unit, the molar ratio of the other structural units is preferably 30 mol% or less, more preferably 15 mol% or less, when the total molar ratio of the (a) first structural unit, the (b) second structural unit, the (c) third structural unit and the other structural units is set to 100 mol%.

[0261] In addition, when the (A) specific fluorine-based graft polymer contains the structural unit represented by the general formula (1), the structural unit represented by the general formula (2), the structural unit represented by the general formula (3) and the structural unit represented by the general formula (4) as another structural unit, the content of the structural unit represented by the general formula (4) is preferably 30 mol% or less, and more preferably 15 mol% or less, relative to the total molar number of the structural unit represented by the general formula (1), the structural unit represented by the general formula (2), the structural unit represented by the general formula (3) and the structural unit represented by the general formula (4).

[0262] - Characteristics and specific examples of specific fluorine-based graft polymers -

[0263] The acid value of the (A) specific fluorine-based graft polymer is preferably 0.1 mgKOH / g or more and 50 mgKOH / g or less, more preferably 0.2 mgKOH / g or more and 30 mgKOH / g or less, and most preferably 0.3 mgKOH / g or more and 20 mgKOH / g or less. By setting the acid value of the (A) specific fluorine-based graft polymer to the range described above, it is easier to obtain an effect of reducing the absolute value of the potential of the photoreceptor after exposure compared to a case where the acid value is below the range described above. In addition, by setting the acid value of the (A) specific fluorine-based graft polymer to the range described above, it is less likely to cause the resistance of the surface layer of the photoreceptor to become too low and difficult to charge, compared to a case where the acid value is above the range described above, and dark decay of the potential after charging can be suppressed.

[0264] (A) The weight average molecular weight Mw and number average molecular weight Mn of the specific fluorine-based graft polymer are polystyrene-equivalent values ​​measured by gel permeation chromatography.

[0265] The weight average molecular weight Mw of the specific fluorine-based graft polymer (A) is preferably 40,000 to 400,000, more preferably 50,000 to 300,000. The molecular weight dispersion represented by Mw / Mn is preferably 1 to 8, more preferably 1 to 6.

[0266] The content of the specific fluorinated graft polymer (A) in the outermost layer is preferably 0.5 to 10 parts by mass, more preferably 1 to 7 parts by mass, per 100 parts by mass of the fluorinated resin particles (B).

[0267] The number of moles of the specific acidic groups contained in the specific fluorine-based graft polymer (A) is preferably 0.2 μmol / g to 5 μmol / g, more preferably 0.3 μmol / g to 4 μmol / g, per 1 g of the fluorine-containing resin particles (B).

[0268] Furthermore, the specific fluorine-based graft polymer (A) may be used alone or in combination of two or more. When two or more specific fluorine-based graft polymers (A) are used in combination, the content and the number of moles of the specific acidic groups refer to the total of the two or more specific fluorine-based graft polymers (A).

[0269] Specific examples of the (A) specific fluorine-based graft polymer are shown in Tables 7 and 8 below, but the present invention is not limited to these.

[0270] [Chemistry 21]

[0271] [Table 7]

[0272]

[0273] [Chemistry 22]

[0274] [Table 8]

[0275]

[0276] <(B) Fluorine-containing resin particles>

[0277] Examples of the fluorine-containing resin particles (B) include particles of fluoroolefin homopolymers and particles of copolymers of one or more fluoroolefins and a non-fluorine-containing monomer (ie, a monomer having no fluorine atoms).

[0278] Examples of fluoroolefins include perfluoroolefins such as tetrafluoroethylene (TFE), perfluorovinyl ether, hexafluoropropylene (HFP), chlorotrifluoroethylene (CTFE), and dichlorodifluoroethylene; and non-perfluoroolefins such as vinylidene fluoride (VdF), trifluoroethylene, and vinyl fluoride. Among these, VdF, TFE, CTFE, and HFP are preferred.

[0279] On the other hand, examples of non-fluorine-containing monomers include hydrocarbon olefins such as ethylene, propylene, and butene; alkyl vinyl ethers such as cyclohexyl vinyl ether (CHVE), ethyl vinyl ether (EVE), butyl vinyl ether, and methyl vinyl ether; alkenyl vinyl ethers such as polyoxyethylene allyl ether (POEAE) and ethyl allyl ether; organosilicon compounds having a reactive α,β-unsaturated group such as vinyltrimethoxysilane (VSi), vinyltriethoxysilane, and vinyltri(methoxyethoxy)silane; acrylic esters such as methyl acrylate and ethyl acrylate; methacrylic esters such as methyl methacrylate and ethyl methacrylate; and vinyl esters such as vinyl acetate, vinyl benzoate, and "Beova" (a trade name for vinyl esters manufactured by Shell). Among these, alkyl vinyl ethers, allyl vinyl ethers, vinyl esters, and organosilicon compounds having a reactive α,β-unsaturated group are preferred.

[0280] Among these, the fluorine-containing resin particles (B) are preferably particles having a high fluorination rate, more preferably particles of polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymer (PFA), ethylene-tetrafluoroethylene copolymer (ETFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE), etc., further preferably particles of PTFE, PVDF, FEP, and PFA, and particularly preferably particles of PTFE and PVDF.

[0281] Examples of the (B) fluorine-containing resin particles include particles obtained by irradiation with radiation (also referred to herein as "radiation-irradiated fluorine-containing resin particles") and particles obtained by polymerization (also referred to herein as "polymerized fluorine-containing resin particles").

[0282] The radiation-irradiated fluororesin particles (fluororesin particles obtained by irradiation) refer to fluororesin particles granulated simultaneously with radiation polymerization, or fluororesin particles whose molecular weight is reduced and finely divided due to decomposition of the polymerized fluororesin by radiation irradiation.

[0283] Irradiated fluororesin particles generate a large amount of carboxylic acid due to exposure to radiation in the air, and therefore also contain a large number of carboxyl groups. Furthermore, it is speculated that the generation of these carboxylic acids is caused by the decomposition of the fluororesin backbone by irradiation with atmospheric radiation, and the resulting free radicals reacting with atmospheric oxygen.

[0284] On the other hand, polymerizable fluorine-containing resin particles (fluorine-containing resin particles obtained by a polymerization method) refer to fluorine-containing resin particles that are granulated while being polymerized by a suspension polymerization method, an emulsion polymerization method, or the like, and that have not been irradiated with radiation.

[0285] Since the polymerizable fluorine-containing resin particles are produced by polymerization in the presence of a basic compound, they contain the basic compound as a residue.

[0286] The production of fluororesin particles by suspension polymerization involves, for example, suspending monomers for forming the fluororesin together with additives such as a polymerization initiator and a catalyst in a dispersion medium, and then polymerizing the monomers to form polymer particles.

[0287] In addition, the production of fluororesin particles using emulsion polymerization is a method in which, for example, additives such as a polymerization initiator and a catalyst are emulsified together with monomers for forming a fluororesin in a dispersion medium using a surfactant (i.e., an emulsifier), and the monomers are polymerized while the polymer is particle-formed.

[0288] When the fluorine-containing resin particles contain a large number of carboxyl groups, they exhibit ion conductivity and thus have a property of being difficult to be charged.

[0289] Therefore, if fluorine-containing resin particles containing a large number of carboxyl groups are contained in the outermost layer of an electrophotographic photoreceptor, the chargeability of the photoreceptor decreases under high temperature and high humidity environments, and toner may adhere to non-image areas (hereinafter also referred to as "fog").

[0290] In addition, if the fluorine-containing resin particles contain a large number of carboxyl groups, the dispersibility tends to decrease. This is presumably because the affinity between the structural units having fluorine atoms in the specific fluorine-based graft polymer and the fluorine-containing resin particles decreases.

[0291] Therefore, when fluorine-containing resin particles containing a large number of carboxyl groups are contained in the outermost layer of an electrophotographic photoreceptor, the cleaning properties tend to be locally reduced.

[0292] Therefore, the number of carboxyl groups in the fluorine-containing resin particles (B) is preferably 6 The number of carbon atoms is 0 or more and 30 or less.

[0293] From the viewpoint of suppressing a decrease in local cleaning properties and suppressing fogging, the number of carboxyl groups in the fluorine-containing resin particles (B) is more preferably 6 The number of carbon atoms is 0 or more and 20 or less.

[0294] Here, examples of the carboxyl groups of the (B) fluorine-containing resin particles include carboxyl groups derived from terminal carboxylic acids contained in the fluorine-containing resin particles.

[0295] Methods for reducing the number of carboxyl groups in the fluorine-containing resin particles (B) include: 1) not irradiating the particles with radiation during production; 2) irradiating the particles with radiation in the absence of oxygen or with a reduced oxygen concentration (e.g., in an inert gas such as nitrogen).

[0296] (B) The number of carboxyl groups in the fluorine-containing resin particles is measured as described in Japanese Patent Application Laid-Open No. 4-20507 and the like, and is described below.

[0297] The fluorine-containing resin particles (B) were preformed using a press to produce a film with a thickness of 0.1 mm. The infrared absorption spectrum of the produced film was measured. The infrared absorption spectrum of the fluorine-containing resin particles with completely fluorinated carboxylic acid terminals produced by contacting the fluorine-containing resin particles with fluorine gas was also measured. The difference between the two spectra was used to calculate the following formula for every 10 6 The number of terminal carboxyl groups in the carbon number.

[0298] Formula: Number of terminal carboxyl groups (per 10 6 carbon number) = (l×K) / t

[0299] l: absorbance

[0300] K: Correction coefficient

[0301] t: film thickness (mm)

[0302] In addition, the absorption wave number of carboxyl group is set to 3560 cm -1 , the correction factor is set to 440.

[0303] In the fluororesin particles (B), from the viewpoint of suppressing a local decrease in cleanability, the amount of perfluorooctanoic acid (hereinafter also referred to as "PFOA") relative to the fluororesin particles (B) is preferably from 0 ppb to 25 ppb, more preferably from 0 ppb to 20 ppb, and even more preferably from 0 ppb to 15 ppb. Note that "ppb" is a mass basis.

[0304] Here, PFOA is sometimes used or generated as a by-product during the production process of fluororesin particles (particularly fluororesin particles such as polytetrafluoroethylene particles, modified polytetrafluoroethylene particles, and perfluoroalkyl ether / tetrafluoroethylene copolymer particles). Therefore, PFOA is often contained in the fluororesin particles.

[0305] It is believed that if PFOA is present, then in the state of the surface layer forming coating liquid, the fluorine-containing resin particles are highly dispersible due to the fluorine-based grafted polymer as a fluorine-containing dispersant. On the other hand, if the state of the coating liquid changes (specifically, if the concentration of the components in the coating film changes during the drying process after the coating liquid is applied), the adhesion state of the fluorine-based grafted polymer to the fluorine-containing resin particles changes. Specifically, it is believed that a portion of the fluorine-based grafted polymer is detached from the fluorine-containing resin particles due to PFOA. Therefore, the dispersibility of the fluorine-containing resin particles is reduced, resulting in the aggregation of the fluorine-containing resin particles, thereby having a tendency to reduce local cleanliness.

[0306] Methods for reducing the amount of PFOA include thoroughly washing the fluororesin particles with pure water, alkaline water, alcohols (methanol, ethanol, isopropyl alcohol, etc.), ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.), esters (ethyl acetate, etc.), or other common organic solvents (toluene, tetrahydrofuran, etc.). While washing can be performed at room temperature, heating effectively reduces PFOA.

[0307] The amount of PFOA is a value measured by the following method.

[0308] - Sample Pretreatment -

[0309] When the amount of PFOA is measured from the outermost layer containing fluorine-containing resin particles, the outermost layer is immersed in a solvent (e.g., tetrahydrofuran), and the components other than the fluorine-containing resin particles and the substances insoluble in the solvent are dissolved in the solvent (e.g., tetrahydrofuran). The solution containing PFOA obtained at this time is collected. After the insoluble matter obtained by filtering and separating again is dissolved in the solvent, it is added dropwise to pure water and the precipitate is filtered and separated. The operation of collecting the solution containing PFOA obtained at this time is repeated 5 times, and the aqueous solution collected in all operations is used as the aqueous solution to complete the pretreatment.

[0310] When the amount of PFOA was measured from the fluorine-containing resin particles themselves, the fluorine-containing resin particles were subjected to the same treatment as in the case of the layered product to obtain a pre-treated aqueous solution.

[0311] -Determination-

[0312] The pretreated aqueous solution obtained by the above-mentioned means was used to prepare and measure a sample solution according to the method described in "Analysis of Perfluorooctanesulfonic Acid (PFOS) and Perfluorooctane Acid (PFOA) in Environmental Water, Sediments, and Organisms - Iwate Prefecture Environmental Health Research Center".

[0313] (B) average secondary particle size of fluororesin particles is not particularly limited, preferably more than 0.2 μm and less than 4.5 μm, more preferably more than 0.2 μm and less than 4 μm. Average secondary particle size is more than 0.2 μm and there is a tendency containing a large amount of PFOA in the fluororesin particles (especially fluororesin particles such as PTFE particles) below 4.5 μm. Therefore, average secondary particle size is more than 0.2 μm and there is especially the tendency that dispersibility becomes low in the fluororesin particles below 4.5 μm. But, by the amount of PFOA being controlled to described scope, even if average secondary particle size is more than 0.2 μm and there is the fluororesin particles below 4.5 μm, dispersibility also improves.

[0314] The average primary particle size of the fluorine-containing resin particles (B) can be freely selected without particular limitation as long as the desired photoreceptor properties can be obtained, but is preferably 0.05 μm to 1 μm, more preferably 0.1 μm to 0.5 μm.

[0315] When the average primary particle size is 0.05 μm or more, aggregation during dispersion can be further suppressed. On the other hand, when the average primary particle size is 1 μm or less, image quality defects can be further suppressed.

[0316] (B) The average primary particle size and average secondary particle size of the fluorine-containing resin particles are values ​​measured by the following method.

[0317] The maximum diameter of the fluororesin particles (primary particles or secondary particles formed by aggregation of primary particles) is measured using a scanning electron microscope (SEM) at a magnification of, for example, 5000 times or more, and the average value of the maximum diameters of 50 particles is defined as the average particle size of the fluororesin particles (average primary particle size or average secondary particle size, respectively). Furthermore, a JSM-6700F manufactured by JEOL Ltd. is used as an SEM to observe secondary electron images at an accelerating voltage of 5 kV.

[0318] The weight average molecular weight of the fluorine-containing resin particles (B) can be freely selected without particular limitation as long as it is within a range that allows desired photoreceptor properties to be obtained.

[0319] From the viewpoint of dispersion stability, the specific surface area (Brunauer-Emmett-Tellern (BET) specific surface area) of the fluorine-containing resin particles (B) is preferably 5 m2 / g or above and 15m 2 / g or less, more preferably 7m 2 / g or above and 13m 2 / g or less.

[0320] The specific surface area is a value measured by a nitrogen replacement method using a BET-type specific surface area meter (FlowSorb II2300 manufactured by Shimadzu Corporation).

[0321] From the viewpoint of dispersion stability, the apparent density of the fluorine-containing resin particles (B) is preferably 0.2 g / ml or more and 0.5 g / ml or less, and more preferably 0.3 g / ml or more and 0.45 g / ml or less.

[0322] In addition, the apparent density is a value measured in accordance with Japanese Industrial Standards (JIS) K6891 (1995).

[0323] The melting temperature of the fluorine-containing resin particles (B) is preferably 300°C or higher and 340°C or lower, more preferably 325°C or higher and 335°C or lower.

[0324] The melting temperature is a melting point measured in accordance with JIS K6891 (1995).

[0325] The content of the fluorine-containing resin particles (B) is preferably 1% by mass to 30% by mass, more preferably 3% by mass to 20% by mass, and still more preferably 5% by mass to 15% by mass, based on the total solid content of the outermost layer.

[0326] The fluorine-containing resin particles (B) may be used alone or in combination of two or more. When two or more fluorine-containing resin particles (B) are used in combination, the above content refers to the total of the two or more fluorine-containing resin particles (B).

[0327] Hole transport materials

[0328] The outermost layer preferably contains at least (A) the specific fluorine-based graft polymer and (B) the fluorine-containing resin particles, and further contains a hole transport material. When the outermost layer contains a hole transport material, the effect of suppressing the residual potential is further enhanced.

[0329] Specifically, first, the fluorine atoms present in the (A) specific fluorine-based graft polymer are adsorbed on the surface of the (B) fluorine-containing resin particles, and the specific acidic groups present in the (A) specific fluorine-based graft polymer interact with the hole transport material through the (A) specific fluorine-based graft polymer. The compatibility of the (B) fluorine-containing resin particles and the hole transport material is improved. As a result, the dispersion stability of the (B) fluorine-containing resin particles in the coating liquid for forming the outermost layer and in the coating film of the coating liquid for forming the outermost layer is improved. In addition, the ionicity is exhibited by the acid-base interaction, the resistance of the outermost layer is reduced, and the potential of the photoreceptor after exposure is easily reduced. Furthermore, the specific acidic group is fixed in the (A) specific fluorine-based graft polymer adsorbed on the (B) fluorine-containing resin particles, and is not easy to move in the outermost layer. Therefore, the uniformity of the film resistance of the outermost layer is high, which can suppress the time-varying changes in electrical properties caused by the outermost layer being worn due to use.

[0330] As mentioned above, the outermost layer includes a charge transport layer, a protective layer, a single-layer photosensitive layer, etc. Furthermore, when the outermost layer contains a hole transport material, the preferred type and content of the hole transport material vary depending on the type of the outermost layer, and therefore will be described together with the configuration of each layer.

[0331] Hereinafter, the electrophotographic photoreceptor according to this embodiment will be described with reference to the drawings.

[0332] Figure 1 The electrophotographic photoreceptor 7A shown has a structure in which, for example, an undercoat layer 1, a charge generating layer 2, and a charge transporting layer 3 are sequentially stacked on a conductive substrate 4. In the electrophotographic photoreceptor 7A, the charge generating layer 2 and the charge transporting layer 3 constitute a photosensitive layer 5.

[0333] Alternatively, the electrophotographic photoreceptor 7A may have a layer structure in which the undercoat layer 1 is not provided.

[0334] Alternatively, the electrophotographic photoreceptor 7A may include a single-layer photosensitive layer integrating the functions of the charge generating layer 2 and the charge transporting layer 3. In the case of a photoreceptor including a single-layer photosensitive layer, the single-layer photosensitive layer constitutes the outermost layer.

[0335] Alternatively, the electrophotographic photoreceptor 7A may include a surface protective layer on the charge transport layer 3 or a single-layer photosensitive layer. In the case of a photoreceptor including a surface protective layer, the surface protective layer constitutes the outermost layer.

[0336] Hereinafter, each layer of the electrophotographic photoreceptor of this embodiment will be described in detail, with reference numerals omitted for explanation.

[0337] (Conductive substrate)

[0338] Examples of the conductive substrate include metal plates, metal drums, and metal belts made of metals (aluminum, copper, zinc, chromium, nickel, molybdenum, vanadium, indium, gold, platinum, etc.) or alloys (stainless steel, etc.). Examples of the conductive substrate include paper, resin films, and belts coated, vapor-deposited, or laminated with conductive compounds (e.g., conductive polymers, indium oxide, etc.), metals (e.g., aluminum, palladium, gold, etc.), or alloys. Here, "conductive" means a material having a volume resistivity of less than 10 13 Ω·cm.

[0339] When using electrophotographic photoreceptors in laser printers, it is preferable to roughen the surface of the conductive substrate to a centerline average roughness Ra of 0.04 μm to 0.5 μm to suppress interference fringes generated during laser irradiation. When using incoherent light as the light source, surface roughening is not particularly necessary to prevent interference fringes. However, it can suppress defects caused by surface irregularities on the conductive substrate, thereby extending its lifespan.

[0340] Examples of surface roughening methods include wet honing in which an abrasive is suspended in water and sprayed onto a conductive substrate, centerless grinding in which a conductive substrate is pressed against a rotating grindstone and continuously ground, and anodizing.

[0341] As a method for roughening the surface, there is also a method in which, instead of roughening the surface of the conductive substrate, conductive or semiconductive powder is dispersed in a resin to form a layer on the surface of the conductive substrate, and the surface is roughened using particles dispersed in the layer.

[0342] The surface roughening treatment performed by anodic oxidation is to form an oxide film on the surface of the conductive substrate by using a conductive substrate of a metal system (such as aluminum) as an anode and performing anodic oxidation in an electrolyte solution. As the electrolyte solution, for example, sulfuric acid solution, oxalic acid solution, etc. can be listed. However, the porous anodized film formed by anodic oxidation is chemically active under the state of maintaining the original state, and is easily contaminated, and the resistance change caused by the environment is also large. Therefore, it is preferred that the porous anodized film is sealed: in pressurized steam or boiling water (metal salts such as nickel can also be added), the volume expansion caused by the hydration reaction is utilized to block the micropores of the oxide film, thereby becoming a more stable hydrated oxide.

[0343] The thickness of the anodic oxide film is preferably 0.3 μm to 15 μm, for example. If the thickness is within the above range, the film tends to exhibit barrier properties against injection and tends to suppress an increase in residual potential due to repeated use.

[0344] The conductive substrate may be treated with an acidic treatment solution or subjected to a boehmite treatment.

[0345] The treatment using an acidic treatment solution is carried out, for example, in the following manner. First, an acidic treatment solution containing phosphoric acid, chromic acid, and hydrofluoric acid is prepared. Regarding the mixing ratio of phosphoric acid, chromic acid, and hydrofluoric acid in the acidic treatment solution, for example, phosphoric acid is in the range of 10% by mass to 11% by mass, chromic acid is in the range of 3% by mass to 5% by mass, and hydrofluoric acid is in the range of 0.5% by mass to 2% by mass. The overall concentration of these acids is preferably in the range of 13.5% by mass to 18% by mass. The treatment temperature is preferably, for example, 42°C to 48°C. The film thickness of the film is preferably 0.3 μm to 15 μm.

[0346] The boehmite treatment can be performed, for example, by immersing the conductive substrate in pure water at a temperature of 90°C to 100°C for 5 to 60 minutes, or by contacting the conductive substrate with heated steam at a temperature of 90°C to 120°C for 5 to 60 minutes. The film thickness is preferably 0.1 μm to 5 μm. The conductive substrate can also be anodized using an electrolyte solution with low film solubility, such as adipic acid, boric acid, a borate, a phosphate, a phthalate, a maleate, a benzoate, a tartrate, or a citrate.

[0347] (Base coating)

[0348] The primer layer is, for example, a layer containing inorganic particles and a binder resin.

[0349] Examples of inorganic particles include powder resistance (volume resistivity) of 10 2 Ω·cm or more and 10 11 Inorganic particles with a particle size of Ω·cm or less.

[0350] Among these, suitable inorganic particles having the above-mentioned resistance value include metal oxide particles such as tin oxide particles, titanium oxide particles, zinc oxide particles, and zirconium oxide particles, and zinc oxide particles are particularly preferred.

[0351] The specific surface area of ​​the inorganic particles obtained by the BET method is preferably 10 m 2 / g or above.

[0352] The volume average particle size of the inorganic particles is preferably, for example, 50 nm to 2000 nm (preferably 60 nm to 1000 nm).

[0353] The content of the inorganic particles relative to the binder resin is, for example, preferably 10% by mass or more and 80% by mass or less, and more preferably 40% by mass or more and 80% by mass or less.

[0354] The inorganic particles may be surface-treated. Two or more inorganic particles having different surface treatments or different particle sizes may be mixed and used.

[0355] Examples of the surface treatment agent include silane coupling agents, titanate coupling agents, aluminum coupling agents, surfactants, etc. Silane coupling agents are particularly preferred, and silane coupling agents having an amino group are more preferred.

[0356] Examples of the silane coupling agent having an amino group include, but are not limited to, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, and N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane.

[0357] Silane coupling agents can also be mixed with two or more for use. For example, a silane coupling agent with an amino group can also be used in combination with other silane coupling agents. As the other silane coupling agents, for example, vinyl trimethoxysilane, 3-methacryloxypropyl-tris (2-methoxyethoxy) silane, 2- (3,4-epoxycyclohexyl) ethyl trimethoxysilane, 3-glycidoxypropyl trimethoxysilane, vinyl triacetoxysilane, 3-mercaptopropyl trimethoxysilane, 3-aminopropyl triethoxysilane, N-2- (aminoethyl) -3-aminopropyl trimethoxysilane, N-2- (aminoethyl) -3-aminopropyl methyl dimethoxysilane, N, N-bis (2-hydroxyethyl) -3-aminopropyl triethoxysilane, 3-chloropropyl trimethoxysilane, but are not limited to these.

[0358] The surface treatment method using the surface treatment agent may be any method as long as it is a known method, and may be either a dry method or a wet method.

[0359] The treatment amount of the surface treatment agent is preferably, for example, 0.5% by mass or more and 10% by mass or less relative to the inorganic particles.

[0360] Here, from the viewpoint of improving the long-term stability of electrical characteristics and carrier-blocking properties, it is preferred that the undercoat layer contain inorganic particles and an electron-accepting compound (acceptor compound).

[0361] As electron-accepting compounds, for example, there can be listed: quinone compounds such as chloranil and bromoquinone; 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; diphenoquinone compounds such as 3,3',5,5'-tetra-tert-butyldiphenoquinone; and other electron-transporting substances.

[0362] In particular, the electron-accepting compound is preferably a compound having an anthraquinone structure. Examples of the compound having an anthraquinone structure include hydroxyanthraquinone compounds, aminoanthraquinone compounds, and aminohydroxyanthraquinone compounds. Specifically, examples include anthraquinone, alizarin, quinizarin, anthrarufin, and purpurin.

[0363] The electron-accepting compound may be dispersed together with the inorganic particles and contained in the undercoat layer, or may be contained in the undercoat layer in a state of being attached to the surfaces of the inorganic particles.

[0364] Examples of a method for attaching the electron-accepting compound to the surface of the inorganic particles include a dry method and a wet method.

[0365] The dry method is, for example, a method in which the inorganic particles are stirred using a stirrer having a large shear force, while an electron-accepting compound is directly added dropwise or an electron-accepting compound dissolved in an organic solvent is added dropwise, and the dropwise addition is sprayed together with dry air or nitrogen, thereby attaching the electron-accepting compound to the surface of the inorganic particles. When the electron-accepting compound is added dropwise or sprayed, it is preferably done at a temperature below the boiling point of the solvent. After the electron-accepting compound is added dropwise or sprayed, baking at 100°C or above is also possible. There are no particular restrictions on baking as long as the temperature and time are such that electrophotographic properties can be obtained.

[0366] The wet method is, for example, a method in which inorganic particles are dispersed in a solvent using stirring, ultrasonic waves, a sand mill, an attritor, a ball mill, or the like, and an electron-accepting compound is added. After stirring or dispersing, the solvent is removed, thereby attaching the electron-accepting compound to the surface of the inorganic particles. Regarding the solvent removal method, the solvent can be removed by distillation, for example, by filtration or distillation. After removing the solvent, baking can also be further performed at a temperature of 100°C or above. Regarding baking, there is no particular limitation as long as the temperature and time are such that electronic photographic properties can be obtained. In the wet method, the water contained in the inorganic particles can also be removed before adding the electron-accepting compound. Examples thereof include a method of removing water while stirring and heating the inorganic particles in a solvent, and a method of removing water by azeotropically co-existing the inorganic particles with the solvent.

[0367] The electron-accepting compound may be attached before or after the inorganic particles are surface-treated with a surface treatment agent, or the electron-accepting compound may be attached and the surface treatment with a surface treatment agent may be performed simultaneously.

[0368] The content of the electron-accepting compound relative to the inorganic particles is, for example, preferably 0.01% by mass or more and 20% by mass or less, and preferably 0.01% by mass or more and 10% by mass or less.

[0369] Examples of the binder resin used for the primer layer include known polymer compounds such as acetal resins (e.g., polyvinyl butyral), 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, phenol resins, phenol-formaldehyde resins, melamine resins, urethane resins, alkyd resins, and epoxy resins; and known materials such as zirconium chelate compounds, titanium chelate compounds, aluminum chelate compounds, titanium alkoxide compounds, organic titanium compounds, and silane coupling agents.

[0370] Examples of the binder resin used for the primer layer include charge-transporting resins having a charge-transporting group and conductive resins (eg, polyaniline).

[0371] Among these, the binder resin for the primer layer is preferably a resin that is insoluble in the coating solvent of the upper layer, and is particularly preferably a thermosetting resin such as urea resin, phenol resin, phenol-formaldehyde resin, melamine resin, urethane resin, unsaturated polyester resin, alkyd resin, epoxy resin, or a resin obtained by reacting at least one resin selected from the group consisting of polyamide resin, polyester resin, polyether resin, methacrylic resin, acrylic resin, polyvinyl alcohol resin, and polyvinyl acetal resin with a hardener.

[0372] When two or more of these binder resins are used in combination, the mixing ratio thereof is set as needed.

[0373] In order to improve electrical characteristics, improve environmental stability, and improve image quality, various additives may be included in the undercoat layer.

[0374] Examples of additives include known materials such as polycyclic condensed and azo-based electron-transporting pigments, zirconium chelate compounds, titanium chelate compounds, aluminum chelate compounds, titanium alkoxide compounds, organic titanium compounds, and silane coupling agents. As mentioned above, silane coupling agents are used for surface treatment of inorganic particles, but they can also be added to the primer layer as an additive.

[0375] Examples of the silane coupling agent as an additive 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, and 3-chloropropyltrimethoxysilane.

[0376] Examples of the zirconium chelate compound include zirconium butoxide, zirconium ethyl acetoacetate, zirconium triethanolamine, zirconium acetylacetonate butoxide, zirconium ethyl acetoacetate butoxide, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octylate, zirconium naphthenate, zirconium laurate, zirconium stearate, zirconium isostearate, zirconium methacrylate butoxide, zirconium stearate butoxide, and zirconium isostearate butoxide.

[0377] Examples of the titanium chelate compound include tetraisopropyl titanate, tetra-n-butyl titanate, butyl titanate dimer, tetra(2-ethylhexyl) titanate, titanium acetylacetonate, titanium polyacetylacetonate, titanium octyl glycolate, titanium ammonium lactate, titanium lactate, titanium ethyl lactate, triethanolamine titanium, and titanium polyhydroxystearate.

[0378] Examples of the aluminum chelate compound include aluminum isopropoxide, monobutoxyaluminum diisopropoxide, aluminum butoxide, diethyl acetoacetate aluminum diisopropoxide, and tris(ethyl acetoacetate)aluminum.

[0379] These additives may be used alone or as a mixture or polycondensate of a plurality of compounds.

[0380] The Vickers hardness of the primer layer is preferably 35 or higher.

[0381] In order to suppress moire images, the surface roughness (ten-point average roughness) of the undercoat layer is preferably adjusted to 1 / (4n) (n is the refractive index of the upper layer) to 1 / 2 of the wavelength λ of the exposure laser used.

[0382] To adjust the surface roughness, resin particles may be added to the primer layer. Examples of the resin particles include silicone resin particles and cross-linked polymethyl methacrylate resin particles. Furthermore, to adjust the surface roughness, the primer layer may be ground. Examples of the grinding method include buffing, sandblasting, wet honing, and grinding.

[0383] The undercoat layer can be formed by any known method without particular limitation. For example, a coating film of an undercoat layer-forming coating solution prepared by adding the above components to a solvent is formed, and the coating film is dried and optionally heated.

[0384] Examples of the solvent used for preparing the coating liquid for forming the undercoat layer include known organic solvents such as alcohol solvents, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, ketone solvents, ketone alcohol solvents, ether solvents, and ester solvents.

[0385] Specific examples of these solvents include common 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, and toluene.

[0386] Examples of a method for dispersing the inorganic particles when preparing the coating liquid for forming an undercoat layer include known methods such as a roll mill, a ball mill, a vibration ball mill, an attritor, a sand mill, a colloid mill, and a paint shaker.

[0387] Examples of a method for applying the undercoat layer-forming coating liquid to the conductive substrate include common methods such as blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating.

[0388] The film thickness of the primer layer is set, for example, preferably within the range of 15 μm or more, more preferably 20 μm or more and 50 μm or less.

[0389] (Middle layer)

[0390] Although not shown in the figure, an intermediate layer may be further provided between the undercoat layer and the photosensitive layer.

[0391] The intermediate layer is, for example, a layer containing a resin. Examples of the resin used for the intermediate layer include polymer compounds such as acetal resins (e.g., polyvinyl butyral), 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, and melamine resins.

[0392] The intermediate layer may also be a layer containing an organic metal compound. Examples of the organic metal compound used in the intermediate layer include organic metal compounds containing metal atoms such as zirconium, titanium, aluminum, manganese, and silicon.

[0393] These compounds for the intermediate layer may be used alone or as a mixture or polycondensate of a plurality of compounds.

[0394] Among these, the intermediate layer is preferably a layer containing an organometallic compound containing a zirconium atom or a silicon atom.

[0395] The intermediate layer can be formed by any known method without particular limitation. For example, a coating film of an intermediate layer-forming coating solution prepared by adding the aforementioned components to a solvent is formed, and the coating film is dried and optionally heated.

[0396] As a coating method for forming the intermediate layer, a common method such as dip coating, push-up coating, wire bar coating, spray coating, blade coating, knife coating, curtain coating, etc. can be used.

[0397] The film thickness of the intermediate layer is preferably set within a range of, for example, 0.1 μm or more and 3 μm or less.

[0398] (Charge Generation Layer)

[0399] The charge generating layer is, for example, a layer comprising a charge generating material and a binder resin. Alternatively, the charge generating layer may be a vapor-deposited layer of the charge generating material. Vapor-deposited layers of charge generating material are suitable for use with incoherent light sources such as light-emitting diodes (LEDs) and organic electroluminescence (EL) image arrays.

[0400] Examples of the charge generating material include azo pigments such as disazo and trisazo; condensed-ring aromatic pigments such as dibromoanthraquinone; perylene pigments; pyrrolopyrrole pigments; phthalocyanine pigments; zinc oxide; and trigonal selenium.

[0401] Among these, metal phthalocyanine pigments or metal-free phthalocyanine pigments are preferably used as charge-generating materials to cope with near-infrared laser exposure. Specifically, more preferred are: hydroxygallium phthalocyanine disclosed in Japanese Patent Application Laid-Open Nos. 5-263007 and 5-279591; chlorogallium phthalocyanine disclosed in Japanese Patent Application Laid-Open No. 5-98181; dichlorotin phthalocyanine disclosed in Japanese Patent Application Laid-Open Nos. 5-140472 and 5-140473; and oxytitanium phthalocyanine disclosed in Japanese Patent Application Laid-Open No. 4-189873.

[0402] On the other hand, in order to cope with laser exposure in the near-ultraviolet region, preferred charge-generating materials include: fused-ring aromatic pigments such as dibromoanthraquinone; thioindigo pigments; porphyrazine compounds; zinc oxide; trigonal selenium; and disazo pigments disclosed in Japanese Patent Application Publication No. 2004-78147 and Japanese Patent Application Publication No. 2005-181992.

[0403] These charge-generating materials can also be used when using incoherent light sources such as LEDs and organic EL image arrays that emit light with a central wavelength between 450 nm and 780 nm. However, from a resolution perspective, when using a photosensitive layer in a thin film of 20 μm or less, the electric field intensity in the photosensitive layer becomes high, making it prone to charge injection from the substrate, leading to a decrease in charge and image defects known as so-called black spots. This problem becomes more pronounced when using charge-generating materials such as trigonal selenium and phthalocyanine pigments, which are prone to generating dark current in p-type semiconductors.

[0404] In contrast, when using n-type semiconductors such as fused aromatic pigments, perylene pigments, and azo pigments as charge-generating materials, dark current generation is less likely to occur, and image defects known as black spots can be suppressed even when formed into thin films. Examples of n-type charge-generating materials include, but are not limited to, compounds (CG-1) to (CG-27) described in paragraphs

[0288] to

[0291] of Japanese Patent Application Laid-Open No. 2012-155282.

[0405] Furthermore, the n-type can be determined by the polarity of the flowing photocurrent using the commonly used Time of Flight method, and the one in which electrons flow more easily as carriers than holes is considered n-type.

[0406] The binder resin used in the charge generating layer can be selected from a wide range of insulating resins. Alternatively, the binder resin can be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, polyvinylpyrene, and polysilane.

[0407] Examples of the binder resin include polyvinyl butyral resin, polyarylate resin (a polycondensate of bisphenols and aromatic dicarboxylic acids), polycarbonate resin, polyester resin, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyamide resin, acrylic resin, polyacrylamide resin, polyvinyl pyridine resin, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol resin, and polyvinyl pyrrolidone resin. Here, the term "insulating property" refers to a volume resistivity of 10 13 Ω·cm or more.

[0408] These binder resins may be used alone or in combination of two or more.

[0409] Furthermore, the mixing ratio of the charge generating material to the binder resin is preferably within a range of 10:1 to 1:10 in terms of mass ratio.

[0410] Furthermore, the charge generating layer may also contain well-known additives.

[0411] The charge generating layer can be formed using any known method, without particular limitation. For example, a coating film of a charge generating layer-forming coating solution prepared by adding the aforementioned components to a solvent can be formed, followed by drying and, if necessary, heating the coating film. Alternatively, the charge generating layer can be formed by vapor deposition of the charge generating material. Formation of the charge generating layer by vapor deposition is particularly suitable when using condensed-ring aromatic pigments or perylene pigments as the charge generating material.

[0412] Examples of solvents used for preparing the charge generating layer-forming coating solution include methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, dichloromethane, chloroform, chlorobenzene, and toluene. These solvents may be used alone or in combination of two or more.

[0413] Methods for dispersing particles (e.g., charge generating material) in the charge generating layer-forming coating liquid include, for example, a media disperser such as a ball mill, a vibrating ball mill, an attritor, a sand mill, or a horizontal sand mill; or a media-free disperser such as a stirrer, an ultrasonic disperser, a roll mill, or a high-pressure homogenizer. Examples of high-pressure homogenizers include a collision method in which the dispersion is dispersed by liquid-liquid collision or liquid-wall collision under high pressure, and a penetration method in which the dispersion is dispersed by passing through fine flow paths under high pressure.

[0414] Furthermore, when performing the dispersion, it is effective to adjust the average particle size of the charge generating material in the charge generating layer-forming coating liquid to 0.5 μm or less, preferably 0.3 μm or less, and more preferably 0.15 μm or less.

[0415] Examples of methods for applying the charge generating layer-forming coating liquid onto the undercoat layer (or intermediate layer) include common methods such as blade coating, wire bar coating, spray coating, dip coating, droplet coating, air knife coating, and curtain coating.

[0416] The film thickness of the charge generating layer is set, for example, preferably within the range of 0.1 μm to 5.0 μm, more preferably within the range of 0.2 μm to 2.0 μm.

[0417] (Charge Transport Layer)

[0418] The charge transport layer is, for example, a layer comprising a charge transport material and a binder resin. The charge transport layer may also be a layer comprising a polymer charge transport material.

[0419] Examples of charge transport materials include electron-transporting compounds such as p-benzoquinone, chloranil, bromoquinone, and anthraquinone; tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone; xanthone compounds; benzophenone compounds; cyanovinyl compounds; and vinyl compounds. Other examples of charge transport materials include hole-transporting compounds such as triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted vinyl compounds, stilbene compounds, anthracene compounds, and hydrazone compounds. These charge transport materials may be used alone or in combination of two or more, but are not limited to these.

[0420] As the charge transport material, from the viewpoint of charge mobility, a triarylamine derivative represented by the following structural formula (a-1) and a benzidine derivative represented by the following structural formula (a-2) are preferred.

[0421] [Chemistry 23]

[0422]

[0423] In the structural formula (a-1), Ar T1 、Ar T2 and Ar T3 Each independently represents a substituted or unsubstituted aryl group, -C6H4-C(R T4 )=C(R T5 )(R T6 ), or -C6H4-CH=CH-CH=C(R T7 )(R T8 ). R T4 、R T5 、R T6 、R T7 and R T8 Each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group.

[0424] Examples of substituents for the above groups include halogen atoms, alkyl groups having 1 to 5 carbon atoms, and alkoxy groups having 1 to 5 carbon atoms. Examples of substituents for the above groups include substituted amino groups substituted with alkyl groups having 1 to 3 carbon atoms.

[0425] [Chemistry 24]

[0426]

[0427] In the structural formula (a-2), R T91 and R T92 Each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. T101 、R T102 、R T111 and R T112 Each independently represents a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an amino group substituted with an alkyl group having 1 to 2 carbon atoms, a substituted or unsubstituted aryl group, -C(R T12 )=C(R T13 )(R T14 ), or -CH=CH-CH=C(R T15 )(R T16 ), R T12 、RT13 、R T14 、R T15 and R T16 Each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. Tm1, Tm2, ​​Tn1, and Tn2 each independently represent an integer of 0 or more and 2 or less.

[0428] Examples of substituents for the above groups include halogen atoms, alkyl groups having 1 to 5 carbon atoms, and alkoxy groups having 1 to 5 carbon atoms. Examples of substituents for the above groups include substituted amino groups substituted with alkyl groups having 1 to 3 carbon atoms.

[0429] Here, among the triarylamine derivatives represented by the structural formula (a-1) and the benzidine derivatives represented by the structural formula (a-2), the one having "-C6H4-CH=CH-CH=C(R T7 )(R T8 )" and triarylamine derivatives having "-CH=CH-CH=C(R T15 )(R T16 )" benzidine derivatives.

[0430] As the polymeric charge transport material, known charge transport materials such as poly-N-vinylcarbazole and polysilane can be used. Polyester-based polymeric charge transport materials disclosed in Japanese Patent Application Laid-Open No. 8-176293 and Japanese Patent Application Laid-Open No. 8-208820 are particularly preferred. The polymeric charge transport material may be used alone or in combination with a binder resin.

[0431] The binder resin for the charge transport layer can be listed as follows: polycarbonate resin, polyester resin, polyarylate resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer, vinylidene chloride-acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin, poly-N-vinyl carbazole, polysilane, etc. Among these, as the binder resin, it is suitable to be polycarbonate resin or polyarylate resin. These binder resins are used alone or in combination of two or more.

[0432] Furthermore, the mixing ratio of the charge transport material to the binder resin is preferably 10:1 to 1:5 in terms of mass ratio.

[0433] Furthermore, well-known additives may also be contained in the charge transport layer.

[0434] The charge transport layer can be formed by any known method without particular limitation. For example, a coating film of a charge transport layer-forming coating solution prepared by adding the aforementioned components to a solvent is formed, and the coating film is dried and optionally heated.

[0435] Examples of solvents used to prepare the charge transport layer coating solution 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 common 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.

[0436] Examples of the coating method for coating the charge transport layer-forming coating liquid on the charge generating layer include common methods such as blade coating, wire bar coating, spray coating, dip coating, droplet coating, air knife coating, and curtain coating.

[0437] The film thickness of the charge transport layer is set, for example, preferably within the range of 5 μm to 50 μm, more preferably within the range of 10 μm to 30 μm.

[0438] (Protective layer)

[0439] A protective layer is provided on the photosensitive layer as needed. The protective layer is provided, for example, to prevent chemical changes in the photosensitive layer during charging or to further improve the mechanical strength of the photosensitive layer.

[0440] Therefore, a layer including a cured film (crosslinked film) can be applied as the protective layer. Examples of these layers include the layers shown in the following 1) or 2).

[0441] 1) A layer comprising a cured film of a composition containing a reactive group-containing charge transport material having a reactive group and a charge transport skeleton in the same molecule (i.e., a layer comprising a polymer or crosslinked product of the reactive group-containing charge transport material)

[0442] 2) A layer comprising a cured film of a composition comprising a non-reactive charge transport material and a reactive group-containing non-charge transport material having no charge transport skeleton but a reactive group (i.e., a layer comprising a non-reactive charge transport material and a polymer or crosslinked product of the reactive group-containing non-charge transport material)

[0443] Examples of the reactive group of the charge transport material containing a reactive group include a chain polymerizable group, an epoxy group, -OH, -OR [wherein R represents an alkyl group], -NH2, -SH, -COOH, -SiR Q1 3-Qn (OR Q2 ) Qn [Among them, RQ1 represents a hydrogen atom, an alkyl group, or a substituted or unsubstituted aryl group, R Q2 represents a hydrogen atom, an alkyl group, a trialkylsilyl group; Qn represents an integer of 1 to 3] or the like.

[0444] The chain-polymerizable group is not particularly limited as long as it is a functional group capable of free radical polymerization. For example, it is a functional group having at least a group containing a carbon double bond. Specifically, it includes a group containing at least one selected from a vinyl group, a vinyl ether group, a vinyl sulfide group, a vinylphenyl group, an acryloyl group, a methacryloyl group, and derivatives thereof. Among these, a group containing at least one selected from a vinyl group, a vinylphenyl group, an acryloyl group, a methacryloyl group, and derivatives thereof is preferred as a chain-polymerizable group due to its excellent reactivity.

[0445] The charge transport skeleton of the reactive group-containing charge transport material is not particularly limited as long as it is a known structure in electrophotographic photoreceptors. Examples thereof include skeletons derived from nitrogen-containing hole transport compounds such as triarylamine compounds, benzidine compounds, and hydrazone compounds, and having a structure conjugated with a nitrogen atom. Among these, a triarylamine skeleton is preferred.

[0446] These reactive group-containing charge transport materials, non-reactive charge transport materials, and reactive group-containing non-charge transport materials having a reactive group and a charge-transporting skeleton can be selected from well-known materials.

[0447] Furthermore, the protective layer may also contain well-known additives.

[0448] The protective layer can be formed by any known method without particular limitation. For example, a coating film of a protective layer-forming coating solution prepared by adding the aforementioned components to a solvent is formed, the coating film is dried, and optionally hardened by heating or the like.

[0449] Examples of solvents used to prepare the protective layer-forming coating liquid include 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; and alcohol solvents such as isopropyl alcohol and butanol. These solvents may be used alone or in combination of two or more.

[0450] Furthermore, the protective layer-forming coating liquid may be a solvent-free coating liquid.

[0451] Examples of methods for applying the protective layer-forming coating liquid onto the photosensitive layer (eg, charge transport layer) include common methods such as dip coating, push-up coating, wire bar coating, spray coating, blade coating, knife coating, and curtain coating.

[0452] The film thickness of the protective layer is set, for example, preferably within the range of 1 μm to 20 μm, more preferably within the range of 2 μm to 10 μm.

[0453] (Single-layer photosensitive layer)

[0454] The single-layer photosensitive layer (charge generation / charge transport layer) is, for example, a layer containing a charge generation material and a charge transport material, and optionally a binder resin and other well-known additives. These materials are the same as those described for the charge generation layer and charge transport layer.

[0455] Furthermore, in a single-layer photosensitive layer, the content of the charge generating material is preferably from 0.1% to 10% by mass, and preferably from 0.8% to 5% by mass, relative to the total solids. Furthermore, in a single-layer photosensitive layer, the content of the charge transporting material is preferably from 5% to 50% by mass, relative to the total solids.

[0456] The method for forming the single-layer photosensitive layer is the same as the method for forming the charge generating layer or the charge transporting layer.

[0457] The film thickness of the single-layer photosensitive layer is preferably, for example, 5 μm or more and 50 μm or less, and preferably 10 μm or more and 40 μm or less.

[0458] <Image forming apparatus (and process cartridge)>

[0459] The image forming apparatus of this embodiment includes: an electrophotographic photoreceptor; a charging mechanism for charging the surface of the electrophotographic photoreceptor; an electrostatic latent image forming mechanism for forming an electrostatic latent image on the charged surface of the electrophotographic photoreceptor; a developing mechanism for developing the electrostatic latent image formed on the surface of the electrophotographic photoreceptor using a developer containing toner to form a toner image; and a transfer mechanism for transferring the toner image to the surface of a recording medium. The electrophotographic photoreceptor described in this embodiment can be used as the electrophotographic photoreceptor.

[0460] The image forming device of this embodiment can be applied to the following well-known image forming devices: a device including a fixing mechanism, which fixes the toner image transferred to the surface of the recording medium; a device using a direct transfer method to directly transfer the toner image formed on the surface of the electronic photographic photoreceptor to the recording medium; a device using an intermediate transfer method to transfer the toner image formed on the surface of the electronic photographic photoreceptor once to the surface of the intermediate transfer body, and to transfer the toner image transferred to the surface of the intermediate transfer body to the surface of the recording medium for a second time; a device including a cleaning mechanism, which cleans the surface of the electronic photographic photoreceptor before charging after the transfer of the toner image; a device including a de-staticizing mechanism, which irradiates the surface of the electronic photographic photoreceptor with de-staticizing light after the transfer of the toner image and before charging; a device including an electronic photographic photoreceptor heating component, which is used to increase the temperature of the electronic photographic photoreceptor and reduce the relative temperature.

[0461] In the case of an intermediate transfer device, the transfer mechanism can, for example, be applied to the following structure, which includes: an intermediate transfer body, the surface of which is provided with a toner image for transfer; a primary transfer mechanism, which transfers the toner image formed on the surface of the electronic photographic photosensitive body to the surface of the intermediate transfer body for the first time; and a secondary transfer mechanism, which transfers the toner image transferred to the surface of the intermediate transfer body to the surface of the recording medium for the second time.

[0462] The image forming apparatus of the present embodiment may be either a dry development system image forming apparatus or a wet development system (development system using a liquid developer) image forming apparatus.

[0463] Furthermore, in the image forming apparatus of this embodiment, for example, the portion including the electrophotographic photoreceptor may be a cartridge structure (process cartridge) that is detachably mounted to the image forming apparatus. As the process cartridge, for example, a process cartridge including the electrophotographic photoreceptor of this embodiment can be suitably used. Furthermore, in addition to the electrophotographic photoreceptor, the process cartridge may also include, for example, at least one selected from the group consisting of a charging mechanism, an electrostatic latent image forming mechanism, a developing mechanism, and a transfer mechanism.

[0464] An example of the image forming apparatus according to the present embodiment is shown below, but the present invention is not limited thereto. The main parts shown in the drawings will be described below, and descriptions of the other parts will be omitted.

[0465] Figure 2 This is a diagram schematically illustrating the configuration of an example of the image forming apparatus according to the present embodiment.

[0466] like Figure 2As shown, the image forming apparatus 100 of this embodiment includes a process cartridge 300 having an electrophotographic photoreceptor 7, an exposure device 9 (an example of an electrostatic latent image forming mechanism), a transfer device 40 (a primary transfer device), and an intermediate transfer body 50. Furthermore, in the image forming apparatus 100, the exposure device 9 is arranged at a position where it can expose the electrophotographic photoreceptor 7 from the opening of the process cartridge 300, and the transfer device 40 is arranged at a position opposite to the electrophotographic photoreceptor 7 via the intermediate transfer body 50, with the intermediate transfer body 50 being arranged so that a portion thereof contacts the electrophotographic photoreceptor 7. Although not shown, a secondary transfer device is also provided for transferring the toner image transferred to the intermediate transfer body 50 to a recording medium (e.g., paper). Furthermore, the intermediate transfer body 50, the transfer device 40 (a primary transfer device), and the secondary transfer device (not shown) correspond to an example of a transfer mechanism.

[0467] Figure 2 The process cartridge 300 in the embodiment integrally supports the electrophotographic photoreceptor 7, the charging device 8 (an example of a charging mechanism), the developing device 11 (an example of a developing mechanism), and the cleaning device 13 (an example of a cleaning mechanism) within a housing. The cleaning device 13 includes a cleaning blade (an example of a cleaning member) 131, which is arranged to contact the surface of the electrophotographic photoreceptor 7. The cleaning member may be a conductive or insulating fibrous member other than the cleaning blade 131, and the fibrous member may be used alone or in combination with the cleaning blade 131.

[0468] also, Figure 2 In the example shown, the image forming apparatus includes a fibrous member 132 (roller-shaped) for supplying lubricant 14 to the surface of the electrophotographic photoreceptor 7 and a fibrous member 133 (flat brush-shaped) for assisting cleaning, and these can be arranged as needed.

[0469] Hereinafter, each structure of the image forming apparatus according to this embodiment will be described.

[0470] -Electrified device-

[0471] As the charging device 8, for example, a contact type charging device using a conductive or semi-conductive charging roller, a charging brush, a charging film, a charging rubber blade, a charging tube, etc. can be used. In addition, a non-contact roller charging device, a scorotron type charging device using corona discharge, a scorotron type charging device or a corotron type charging device, etc., which are known per se, can also be used.

[0472] -Exposure device-

[0473] As the exposure device 9, for example, there can be cited an optical system device that exposes the surface of the electrophotographic photoreceptor 7 to light such as semiconductor laser light, light emitting diode (LED) light, and liquid crystal shutter light as specified. The wavelength of the light source is set to be within the spectral sensitivity range of the electrophotographic photoreceptor. As the wavelength of the semiconductor laser, the mainstream is near-infrared with an oscillation wavelength around 780nm. However, it is not limited to the above wavelength, and a laser with an oscillation wavelength of about 600nm or a laser with an oscillation wavelength of more than 400nm and less than 450nm as a blue laser can also be used. In addition, in order to form a color image, a surface-emitting laser light source that can output multiple beams is also effective.

[0474] -Developing device-

[0475] Examples of the developing device 11 include conventional developing devices that perform development with or without contacting the developer. The developing device 11 is not particularly limited as long as it has the aforementioned functions, and may be selected based on the intended purpose. Examples include known developers that adhere a single-component developer or a two-component developer to the electrophotographic photoreceptor 7 using a brush, roller, or the like. Of these, a developing roller that holds the developer on its surface is preferred.

[0476] The developer used in the developing device 11 may be a single-component developer containing only toner or a two-component developer containing toner and a carrier. Furthermore, the developer may be magnetic or non-magnetic. These developers may be well-known ones.

[0477] -Cleaning device-

[0478] The cleaning device 13 may be a cleaning blade type device including a cleaning blade 131 .

[0479] In addition to the cleaning blade method, a brush cleaning method and a simultaneous development and cleaning method may also be employed.

[0480] -Transfer device-

[0481] Examples of the transfer device 40 include known transfer chargers such as contact transfer chargers using a belt, roller, film, or rubber blade, and transfer chargers with or without grid electrodes using corona discharge.

[0482] -Intermediate transfer body-

[0483] As the intermediate transfer member 50, a belt-shaped one (intermediate transfer belt) made of polyimide, polyamideimide, polycarbonate, polyarylate, polyester, rubber, etc. imparted with semiconductivity can be used. In addition, as an example of the intermediate transfer member, a roller-shaped one can also be used.

[0484] Figure 3 This is a schematic structural diagram showing another example of the image forming apparatus according to the present embodiment.

[0485] Figure 3 The illustrated image forming apparatus 120 is a tandem-type multicolor image forming apparatus equipped with four process cartridges 300. Image forming apparatus 120 is configured such that the four process cartridges 300 are arranged in parallel on an intermediate transfer member 50 and utilize a single electrophotographic photoreceptor for each color. Aside from being a tandem-type apparatus, image forming apparatus 120 has the same configuration as image forming apparatus 100.

[0486] Example

[0487] Hereinafter, examples of the present invention will be described, but the present invention is not limited to the following examples. In addition, "parts" or "%" are based on mass unless otherwise specified.

[0488] <(A) Specific fluorine-based graft polymer>

[0489] (Synthesis Example 1) Synthesis of Macromonomer (2-19) [Synthesis of Precursor of Structural Unit Represented by Formula (2-19)]

[0490] In a glass flask equipped with a stirrer, a reflux cooler, a thermometer, and a nitrogen inlet, a mixed solution of 105.5 parts by mass of butyl acetate, 100 parts by mass of methyl methacrylate, 1.75 parts by mass of 3-mercaptopropionic acid, and 1 part by mass of 2,2'-azobis(isobutyronitrile) was continuously added dropwise over 4 hours at a temperature of 80°C to 85°C under nitrogen flow to carry out polymerization. The mixture was then heated at the same temperature for 2 hours and then at 95°C for 1 hour to complete the polymerization.

[0491] Then, 3 parts by mass of glycidyl methacrylate, 0.6 parts by mass of tetra-n-butylammonium bromide and 0.03 parts by mass of hydroquinone monomethyl ether were added, and the reaction was carried out at a reaction temperature of 95°C for 8 hours. After the reaction solution was returned to room temperature (25°C), it was added to 700 parts by mass of stirred hexane to precipitate the solid. 200 parts by mass of methanol were added to the filtered solid, and after stirring and washing, it was filtered and vacuum-dried to obtain 97 parts by mass of macromonomer (2-19). The weight average molecular weight of the polystyrene conversion obtained by GPC measurement was 11000, and the number average molecular weight was 6000. In addition, the macromonomer (2-19) is a precursor of the structural unit represented by formula (2-19) listed as a specific example of the structural unit represented by general formula (2).

[0492] Macromonomers serving as precursors of the structural units represented by Formulae (2-1) to (2-18) and (2-20) to (2-25) were synthesized in the same manner as the macromonomer serving as a precursor of the structural unit represented by Formula (2-19).

[0493] (Synthesis Example 2) Synthesis of Specific Fluorine-Based Graft Polymer (A-19)

[0494] In a glass flask equipped with a stirrer, reflux cooler, thermometer, and nitrogen inlet, a mixed solution of 100 parts by mass of methyl isobutyl ketone, 25.4 parts by mass of monomer (1-16) [a precursor of the structural unit represented by formula (1-16)], 73.0 parts by mass of macromonomer (2-19), 1.6 parts by mass of monomer (3-3) [a precursor of the structural unit represented by formula (3-3)], and 0.67 parts by mass of 2,2'-azobis(isobutyronitrile) was continuously added dropwise at 85°C over 4 hours under nitrogen flow to carry out polymerization. The mixture was then heated at the same temperature for 2 hours and then at 95°C for 1 hour to terminate the polymerization. The reaction solution was returned to room temperature (25°C) and then added to 700 parts by mass of stirred hexane to precipitate a solid. 200 parts by mass of methanol was added to the filtered solid, stirred and washed, then filtered and vacuum-dried to obtain 95 parts by mass of a specific fluorinated graft polymer (A-19). The polystyrene-equivalent weight average molecular weight determined by GPC was 150,000, and the number average molecular weight was 45,000. The acid value was 4.55 mgKOH / g.

[0495] Specific fluorine-based graft polymers (A-1) to (A-18) and specific fluorine-based graft polymers (A-20) to (A-22) were synthesized in the same manner as the specific fluorine-based graft polymer (A-19).

[0496] <(B) Fluorine-containing resin particles>

[0497] Fluorine-containing resin particles (B-1) were produced as follows.

[0498] An autoclave was charged with 3 liters of deionized water and 3.0 g of ammonium perfluorooctanoate, followed by 120 g of paraffin wax (manufactured by Nippon Oil Corporation) as an emulsion stabilizer. The system was purged with nitrogen three times and with tetrafluoroethylene (TFE) twice to remove oxygen. The internal pressure was then brought to 1.0 MPa with TFE, and the internal temperature was maintained at 70°C while stirring at 250 rpm. Next, a 20 ml aqueous solution containing 150 cc of ethane at normal pressure as a chain transfer agent and 300 mg of ammonium persulfate as a polymerization initiator was added to the system to initiate the reaction. During the reaction, TFE was continuously supplied, maintaining the system temperature at 70°C and the internal pressure of the autoclave at 1.0 ± 0.05 MPa. When the TFE consumed in the reaction reached 1000 g after the addition of the initiator, the TFE supply and stirring were stopped, terminating the reaction. The particles were then separated by centrifugation, and 400 parts by mass of methanol was added. The mixture was then washed with a stirrer at 250 rpm for 10 minutes while irradiating with ultrasound, and the supernatant was filtered. This operation was repeated three times, and the filtrate was dried at 60°C under reduced pressure for 17 hours.

[0499] Through the above steps, fluorine-containing resin particles (B-1) are produced.

[0500] The obtained fluorine-containing resin particles (B-1) had an average primary particle size of 0.21 μm, an average secondary particle size of 5.0 μm, and a BET specific surface area of ​​10 m 2 / g, apparent density 0.40g / ml, and melting temperature 328°C PTFE particles.

[0501] In the obtained fluorine-containing resin particles (B-1), each carbon number 10 6 The number of carboxyl groups in the fluorinated resin was 7, and the amount of perfluorooctanoic acid based on the total amount of the fluorinated resin particles was 5 ppb on a mass basis.

[0502] As fluorine-containing resin particles (B-2) to (B-6), the following fluorine-containing resin particles were prepared, respectively.

[0503] B-2: Fluon PTFE L172JE (Asahi Glass), PTFE particles, average primary particle size 0.3 μm, melting temperature 330°C

[0504] B-3: Fluon PTFE L173JE (Asahi Glass), PTFE particles, average primary particle size 0.3 μm, melting temperature 330°C

[0505] B-4: TLP 10F-1 (Chemours-Mitsui Fluoroproducts), PTFE particles, average primary particle size 0.2 μm

[0506] B-5: KTL-500F (Kitamura), PTFE particles, average primary particle size 0.6μm

[0507] B-6: Dyneon TF9201Z (3M), PTFE particles, average primary particle size 0.2 μm

[0508] Fluorine-containing resin particles (B-7) were produced as follows.

[0509] 100 parts by mass of commercially available homopolytetrafluoroethylene fine powder (standard specific gravity 2.175 as measured in accordance with ASTM D4895 (2004)) and 2.4 parts by mass of ethanol as an additive were placed in a barrier nylon bag. The bag was then irradiated with 150 kGy of cobalt-60 gamma rays in air at room temperature to obtain a low-molecular-weight polytetrafluoroethylene powder. The resulting powder was pulverized to obtain fluorine-containing resin particles (B-7).

[0510] The obtained fluorine-containing resin particles (B-7) were PTFE particles having an average secondary particle size of 3.5 μm and a melting temperature of 328°C.

[0511] In the obtained fluorine-containing resin particles (B-7), each carbon number 10 6 The number of carboxyl groups in the fluorine-containing resin particles was 75, and the amount of perfluorooctanoic acid based on the total amount of the fluorine-containing resin particles was 200 ppb on a mass basis.

[0512] Example 1

[0513] Zinc oxide (average primary particle size 70 nm, manufactured by Tayca, specific surface area 15 m 2 100 parts by mass of zinc oxide (ZnO) (100 parts by mass of 0.5% tantalum / g) and 500 parts by mass of methanol were stirred and mixed, and 1.25 parts by mass of KBM603 (manufactured by Shin-Etsu Chemical Co., Ltd.) as a silane coupling agent was added, followed by stirring for 2 hours. The methanol was then distilled off by reduced pressure distillation, and the mixture was baked at 120° C. for 3 hours to obtain silane coupling agent surface-treated zinc oxide particles.

[0514] 60 parts by mass of the silane coupling agent surface-treated zinc oxide particles obtained by the surface treatment, 0.6 parts by mass of alizarin, 13.5 parts by mass of a blocked isocyanate (Sumidur 3173, manufactured by Bayer Urethane, Sumitomo) as a hardener, 15 parts by mass of a butyral resin (S-LEC BM-1, manufactured by Sekisui Chemical) and 85 parts by mass of methyl ethyl ketone were mixed to obtain a mixed solution. 38 parts by mass of the mixed solution was mixed with 25 parts by mass of methyl ethyl ketone, and the mixture was dispersed for 4 hours using 1 mm glass beads and a sand mill to obtain a dispersion. 0.005 parts by mass of dioctyltin dilaurate and 4.0 parts by mass of silicone resin particles (Tospearl 145, manufactured by Momentive Performance Materials) as a catalyst were added to the obtained dispersion to obtain a coating solution for an undercoat layer. The coating liquid was applied to an aluminum substrate having a diameter of 30 mm by dip coating, and dried and hardened at 180° C. for 40 minutes to obtain a primer layer having a thickness of 25 μm.

[0515] Next, a mixture containing 15 parts by mass of chlorogallium phthalocyanine crystals (a charge-generating material having strong diffraction peaks at Bragg angles (2θ±0.2°) with CuKα characteristic X-rays at at least 7.4°, 16.6°, 25.5°, and 28.3°, 10 parts by mass of a vinyl chloride-vinyl acetate copolymer resin (VMCH, manufactured by NUC Co., Ltd.), and 300 parts by mass of n-butanol was dispersed using a sand mill for 4 hours using 1 mm diameter glass beads to prepare a charge-generating layer coating solution. This charge-generating layer coating solution was then dip-coated onto the undercoat layer and dried to provide a charge-generating layer having a thickness of 0.2 μm.

[0516] Next, 1.00 parts by mass of the fluorinated resin particles (B-1) as tetrafluoroethylene resin particles were added to a solution obtained by dissolving 0.04 parts by mass of the specific fluorinated graft polymer (A-3) in 2.40 parts by mass of toluene. The mixture was stirred and mixed for 48 hours while maintaining the liquid temperature at 20°C to obtain a tetrafluoroethylene resin particle suspension (liquid A).

[0517] Next, 5.32 parts by mass of N,N'-bis(3-methylphenyl)-N,N'-diphenylbenzidine as a hole transport material, 7.05 parts by mass of bisphenol Z polycarbonate resin (viscosity average molecular weight: 40,000), and 0.13 parts by mass of 2,6-di-tert-butyl-4-methylphenol as an antioxidant were mixed and dissolved in 24 parts by mass of tetrahydrofuran and 11 parts by mass of toluene to obtain liquid B.

[0518] The above solution A was added to the above solution B, stirred and mixed, and then the pressure was increased to 500 kgf / cm2 by using a high-pressure homogenizer equipped with a through-type chamber with a fine flow path (manufactured by Yoshida Machinery Co., Ltd.) for 4 times. 2 To the resulting solution, silicone oil (trade name: KP340, manufactured by Shin-Etsu Chemical Co., Ltd.) was added to give a concentration of 5 ppm (mass basis), and the mixture was stirred thoroughly to obtain a coating solution for forming a charge transport layer.

[0519] The charge transport layer-forming coating liquid was applied onto the charge generating layer by dip coating and dried at 135° C. for 40 minutes to form a charge transport layer having a thickness of 30 μm, thereby obtaining an electrophotographic photoreceptor.

[0520] <Evaluation of Charge Transport Layer-Forming Coating Liquid>

[0521] (Evaluation of dispersibility in liquid)

[0522] The resulting charge transport layer coating solution was stored in a thermostatic chamber at 45°C for one month, then diluted 10-fold with tetrahydrofuran. The particle size distribution was measured using a Horiba LA920 laser diffraction scattering particle size analyzer. Specifically, dispersibility was evaluated based on the proportion of particles with a diameter of 0.3 μm or less in the particle size distribution measurement results, according to the following evaluation criteria. The results are shown in Table 9.

[0523] -Evaluation Criteria-

[0524] A... The proportion of particles with a diameter of 0.3 μm or less is 90% by number or more, and the dispersibility is extremely excellent.

[0525] B... The ratio of particles with a particle size of 0.3 μm or less is 75% by number or more and less than 90% by number, and the dispersibility is excellent.

[0526] The proportion of particles C having a size of 0.3 μm or less was 60% by number or more and less than 75% by number, and the dispersibility was within a practically acceptable range.

[0527] The proportion of particles with a D size of 0.3 μm or less was less than 60% by number, and the dispersibility was outside the practically acceptable range.

[0528] <Evaluation of Charge Transport Layer>

[0529] (Particle dispersion in film)

[0530] The photoreceptor formed on a cylindrical substrate by dip coating was visually evaluated for particle dispersion uniformity on the surface of the charge transport layer.

[0531] -Evaluation Criteria-

[0532] A: No stripes are visible at all locations

[0533] B: Slight streak defects are visible within 5 mm of the end of the cylinder (photoreceptor) in the axial direction.

[0534] C: Streak-like defects are seen within 10 mm of the end of the cylinder (photoreceptor) in the axial direction.

[0535] D: Streak-like defects are observed in the center and ends of the cylinder (photoreceptor) in the axial direction.

[0536] <Image Formation Evaluation Using Photoreceptor>

[0537] The obtained electrophotographic photoreceptor was assembled into a drum cartridge and mounted on an image forming apparatus Apeos Port C4300 manufactured by Fuji Xerox equipped with a potential sensor. 10,000 sheets of 10% halftone images were output on A4 paper at 28°C / 85% humidity.

[0538] (Evaluation of residual potential (1 sheet))

[0539] The residual potential on the surface of the electrophotographic photoreceptor after the first sheet was output was measured and evaluated according to the following criteria. The results are shown in Table 9.

[0540] -Evaluation Criteria-

[0541] A: The absolute value of the residual potential is less than 50V

[0542] B: The absolute value of the residual potential is 50V or more and less than 70V

[0543] C: The absolute value of the residual potential is 70V or more and less than 90V

[0544] D: The absolute value of the residual potential is 90V or more

[0545] (Evaluation of residual potential difference)

[0546] The residual potential on the surface of the electrophotographic photoreceptor after the first sheet was output and the residual potential on the surface of the electrophotographic photoreceptor after 10,000 sheets were output. The difference in absolute value (absolute value of the residual potential after 10,000 sheets - absolute value of the residual potential after 1 sheet) was calculated and defined as the increase in the absolute value of the residual potential. Evaluation was performed according to the following criteria. The results are shown in Table 9.

[0547] -Evaluation Criteria-

[0548] A: The absolute value of the residual potential rises less than 5V

[0549] B: The absolute value of the residual potential rises by 5 V or more and less than 10 V

[0550] C: The absolute value of the residual potential rises by 10 V or more and less than 20 V

[0551] D: The absolute value of the residual potential rises by 20 V or more

[0552] (Image quality evaluation)

[0553] The first and ten thousandth output images were observed and evaluated for image defects. The results are shown in Table 9.

[0554] -Evaluation Criteria-

[0555] A: No image defects

[0556] B: Slight image defects can be seen when observed with a magnifying glass, but they are within the practical tolerance range.

[0557] C: Image defects are visually observed

[0558] D: Image defects are seen and extend in the form of streaks

[0559] Example 2 to Example 24

[0560] Except that the type of specific fluorine-based graft polymer used, the type of fluorine-containing resin particles used, and the amount of the specific fluorine-based graft polymer added relative to 1.00 parts by mass of the fluorine-containing resin particles (the "mass ratio relative to particles" in the table) were set as shown in Tables 9 and 10, the electrophotographic photoreceptors of Examples 2 to 24 were obtained in the same manner as in Example 1.

[0561] In addition, for Examples 2 to 24, evaluation of the charge transport layer-forming coating liquid, evaluation of the charge transport layer, and evaluation of image formation using the photoreceptor were performed in the same manner as in Example 1. The results are shown in Tables 9 and 10.

[0562] Comparative Examples 1 and 2

[0563] Electrophotographic photoreceptors of Comparative Examples 1 and 2 were obtained in the same manner as in Example 6 except that the fluorine-based graft polymers shown in Table 10 were used instead of the specific fluorine-based graft polymer (A-19).

[0564] In addition, for Comparative Examples 1 and 2, evaluation of the charge transport layer-forming coating liquid, evaluation of the charge transport layer, and evaluation of image formation using the photoreceptor were performed in the same manner as in Example 6. The results are shown in Table 10.

[0565] The fluorine-based graft polymer (CA-1) and the fluorine-based graft polymer (CA-2) shown in Table 10 are the fluorine-based graft polymer (CA-1) and the fluorine-based graft polymer (CA-2) shown in Table 11 below, respectively.

[0566] [Table 9]

[0567]

[0568] [Table 10]

[0569]

[0570] [Table 11]

[0571]

[0572] In Tables 9 and 10, the "acid group molar ratio relative to particles" refers to the number of moles of specific acid groups per 1 g of fluororesin particles.

[0573] In addition, in Table 11, "Formula (CA)" represents a structural unit represented by the following structural formula (CA).

[0574] [Chemistry 25]

[0575]

[0576] The results show that the residual potential difference (ie, the increase in the absolute value of the residual potential) is smaller in the present embodiment than in the comparative example, and the residual potential can be suppressed.

Claims

1. An electrophotographic photoreceptor comprising a conductive substrate and a photosensitive layer provided on the conductive substrate, The outermost layer contains fluorine-based graft polymer and fluorine-containing resin particles. The fluorine-based graft polymer includes at least a first structural unit having no acidic group with a pKa of 3 or less and having a fluorine atom, a second structural unit derived from a macromonomer, and a third structural unit having an acidic group with a pKa of 3 or less. 2 . The electrophotographic photoreceptor according to claim 1 , wherein the acidic group with a pKa of 3 or less comprises an acidic group Ac, and the acidic group Ac is at least one selected from the group consisting of a sulfonic acid group, a phosphoric acid group, a phosphonic acid group, and a fluorinated alkyl carboxylic acid group.

3. An electrophotographic photoreceptor comprising a conductive substrate and a photosensitive layer provided on the conductive substrate, and The outermost layer contains fluorine-based graft polymer and fluorine-containing resin particles. The fluorine-based graft polymer comprises at least a first structural unit having no acidic group Ac and having a fluorine atom, a second structural unit derived from a macromonomer, and a third structural unit having an acidic group Ac, wherein the acidic group Ac is at least one selected from the group consisting of a sulfonic acid group, a phosphoric acid group, a phosphonic acid group, and a fluorinated alkyl carboxylic acid group. The electrophotographic photoreceptor according to claim 1 or 2, wherein the number of moles of the acidic groups having a pKa of 3 or less per 1 g of the fluorine-containing resin particles is 0.2 μmol / g or more and 5 μmol / g or less. 5 . The electrophotographic photoreceptor according to claim 2 , wherein the number of moles of the acidic groups Ac per 1 g of the fluorine-containing resin particles is 0.2 μmol / g or more and 5 μmol / g or less. 6 . The electrophotographic photoreceptor according to claim 1 , wherein the macromonomer comprises at least one selected from the group consisting of poly(meth)acrylate having a radical polymerizable group at one terminal and polystyrene having a radical polymerizable group at one terminal.

7. The electrophotographic photoreceptor according to any one of claims 1 to 3, wherein the first structural unit is a structural unit represented by the following general formula (1), the second structural unit is a structural unit represented by the following general formula (2), and the third structural unit is a structural unit represented by the following general formula (3); In the general formula (1), R 1 represents a hydrogen atom or an alkyl group, Rf represents an organic group having a fluorine atom; in the general formula (2), n represents an integer greater than 2, q represents an integer greater than 1, and R 2 and R 3 Each independently represents a hydrogen atom or an alkyl group; Y represents a substituted or unsubstituted alkylene group, -O-, -NH-, -S-, -C(=O)-, a divalent linking group obtained by any combination thereof, or a single bond; Z represents a group represented by the following general formula (2A) or the following general formula (2B); in the general formula (3), L represents a substituted or unsubstituted alkylene group, -O-, -C(=O)-, -NR 10 -, -C6H4-, a divalent linking group or a single bond obtained by any combination thereof, Q represents a sulfonic acid group, a phosphonic acid group, a phosphoric acid group or a fluorinated alkyl carboxylic acid group, R 6 represents a hydrogen atom, a halogen atom or an alkyl group; R 10 represents a hydrogen atom or a substituted or unsubstituted alkyl group In the general formula (2A), R 4 represents a substituted or unsubstituted alkyl group or a mono- or polyalkyleneoxy chain, and * represents the bonding position to the carbon atom; in the general formula (2B), Ra to Re each independently represent a hydrogen atom, an alkyl group having 4 or less carbon atoms, or an alkoxy group having 4 or less carbon atoms, and * represents the bonding position to the carbon atom. 8 . The electrophotographic photoreceptor according to claim 1 , wherein the content of the fluorine-based graft polymer is 0.5 parts by mass or more and 10 parts by mass or less relative to 100 parts by mass of the fluorine-containing resin particles. 9 . The electrophotographic photoreceptor according to claim 1 , wherein the fluorine-containing resin particles contain polytetrafluoroethylene.

10. The electrophotographic photoreceptor according to claim 1, wherein the number of carboxyl groups in the fluorine-containing resin particles is 10 6 The number of items in the table is 0 or more and 30 or less.

11. The electrophotographic photoreceptor according to claim 10, wherein the number of carboxyl groups in the fluorine-containing resin particles is 10 6 The number of items in the table is 0 or more and 20 or less. 12 . The electrophotographic photoreceptor according to claim 1 , wherein the amount of perfluorooctanoic acid relative to the mass of the fluorine-containing resin particles is 0 ppb or more and 25 ppb or less. 13 . The electrophotographic photoreceptor according to claim 12 , wherein the amount of perfluorooctanoic acid relative to the mass of the fluorine-containing resin particles is 0 ppb or more and 20 ppb or less. 14 . The electrophotographic photoreceptor according to claim 1 , wherein the outermost surface layer contains a hole transport material.

15. A process cartridge comprising the electrophotographic photoreceptor according to any one of claims 1 to 14, and The process cartridge is detachably mounted in the image forming apparatus.

16. An image forming apparatus comprising: The electrophotographic photoreceptor according to any one of claims 1 to 14; a charging mechanism for charging the surface of the electrophotographic photoreceptor; an electrostatic latent image forming mechanism for forming an electrostatic latent image on the charged surface of the electrophotographic photoreceptor; a developing mechanism for developing the electrostatic latent image formed on the surface of the electrophotographic photoreceptor using a developer containing toner to form a toner image; as well as The transfer mechanism transfers the toner image to the surface of the recording medium.

Images