Electrophotographic photoreceptor, process cartridge, and image forming apparatus

Abstract

This electrophotographic photoreceptor comprises an electrically conductive substrate (2), a photosensitive layer (3), and a protective layer (5). The photosensitive layer (3) contains a charge generating agent and a hole transport agent. The protective layer (5) is an outermost surface layer of the electrophotographic photoreceptor and contains a resin having a halogen group. The mass proportion of halogen atoms contained in the protective layer (5) is 2-20 mass% or less on the basis of the mass of the protective layer (5). The Martens hardness of the protective layer (5) is 280 N / mm2 or more and 450 N / mm2 or less.

Description

[Technical Field]

[0001] The present invention relates to an electrophotographic photoreceptor, a process cartridge, and an image forming apparatus. [Background technology]

[0002] When images are repeatedly formed using an image forming apparatus equipped with an electrophotographic photoreceptor, the electrophotographic photoreceptor may gradually wear down. To suppress wear and extend the lifespan of the electrophotographic photoreceptor, a hard protective layer may be provided on the surface of the electrophotographic photoreceptor. For example, the electrophotographic photoreceptor described in Patent Document 1 consists of a substrate and a plurality of layers formed on the substrate. The protective layer, which is the outermost layer of the plurality of layers, is composed of a crosslinking material. This crosslinking material is formed using a coating solution containing at least one type of curable charge-transporting material. The elastic deformation rate of the protective layer, which is the outermost layer, is 45% to 55%, and the universal hardness is 185 N / mm². 2 More than 210N / mm 2 The following applies: [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2010-224304 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] However, the electrophotographic photoreceptor described in Patent Document 1 has a universal hardness of 185 N / mm² in its protective layer. 2 More than 210N / mm 2 The abrasion resistance is low and insufficient. Furthermore, our investigations have revealed that when an image is formed using an electrophotographic photoreceptor equipped with a protective layer, image blurring is likely to occur in the formed image.

[0005] The present invention has been made in view of the above problems, and its objective is to provide an electrophotographic photoreceptor, a process cartridge, and an image forming apparatus that have excellent wear resistance and can suppress the occurrence of image flow in the formed image. [Means for solving the problem]

[0006] The electrophotographic photoreceptor of the present invention comprises a conductive substrate, a photosensitive layer, and a protective layer. The photosensitive layer contains a charge generating agent and a hole transport agent. The protective layer is the outermost layer of the electrophotographic photoreceptor and contains a resin having halogen groups. The mass ratio of halogen atoms contained in the protective layer to the mass of the protective layer is 2% by mass or more and 20% by mass or less. The Martens hardness of the protective layer is 280 N / mm². 2 More than 450N / mm 2 The following applies:

[0007] The process cartridge of the present invention comprises at least one selected from the group consisting of a charging device, an exposure device, a developing device, a transfer device, a cleaning member, a rubbing roller, and a static elimination device, and the electrophotographic photoreceptor.

[0008] The image forming apparatus of the present invention comprises an image carrier, a charging device for charging the surface of the image carrier, an exposure device for exposing the charged surface of the image carrier to form an electrostatic latent image on the surface of the image carrier, a developing device for supplying toner to the surface of the image carrier to develop the electrostatic latent image as a toner image, and a transfer device for transferring the toner image from the image carrier to a transfer target. The image carrier is the electrophotographic photoreceptor described above. [Effects of the Invention]

[0009] The electrophotographic photoreceptor, process cartridge, and image forming apparatus of the present invention exhibit excellent wear resistance and can suppress the occurrence of image flow in the formed image. [Brief explanation of the drawing]

[0010] [Figure 1]This is a partial cross-sectional view of a single-layer electrophotographic photoreceptor, which is an example of an electrophotographic photoreceptor according to the first embodiment of the present invention. [Figure 2] This is a partial cross-sectional view of a single-layer electrophotographic photoreceptor, which is an example of an electrophotographic photoreceptor according to the first embodiment of the present invention. [Figure 3] This is a partial cross-sectional view of a stacked electrophotographic photoreceptor, which is an example of an electrophotographic photoreceptor according to the first embodiment of the present invention. [Figure 4] This is a partial cross-sectional view of a stacked electrophotographic photoreceptor, which is an example of an electrophotographic photoreceptor according to the first embodiment of the present invention. [Figure 5] This is a partial cross-sectional view of a stacked electrophotographic photoreceptor, which is an example of an electrophotographic photoreceptor according to the first embodiment of the present invention. [Figure 6] This figure shows an example of an image forming apparatus according to a second embodiment of the present invention. [Figure 7] Figure 6 shows an example of the configuration of a developing apparatus. [Modes for carrying out the invention]

[0011] The embodiments of the present invention will be described in detail below. However, the present invention is not limited to the following embodiments and can be implemented with appropriate modifications within the scope of the object of the present invention.

[0012] First, let's explain the terminology used in this specification. Unless otherwise specified, viscosity-average molecular weight is the value measured according to JIS (Japanese Industrial Standards) K7252-1:2016. Acrylics and methacrylics are sometimes collectively referred to as "(meth)acrylics". Unless otherwise specified, hydroxyl value is the value measured according to JIS (Japanese Industrial Standards) K0070-1992. Unless otherwise specified, number-average primary particle diameter is the number-average value of the equivalent circle diameter (Heywood diameter: the diameter of a circle having the same area as the projected area of ​​the primary particle) of primary particles measured using a scanning electron microscope. For example, the number-average primary particle diameter is the number-average value of the equivalent circle diameter of 100 primary particles. Unless otherwise specified, glass transition temperature (Tg) is the value measured according to JIS (Japanese Industrial Standards) K7121-2012 using a differential scanning calorimeter (SEIKO INSTRUCTIONS DSC-6220). In an endothermic curve measured by a differential scanning calorimeter (vertical axis: heat flow (DSC signal), horizontal axis: temperature), the temperature at the inflection point due to the glass transition (specifically, the temperature at the intersection of the baseline extrapolation line and the falling line extrapolation line) corresponds to Tg (glass transition point). Unless otherwise specified, the BET specific surface area is the value measured by the BET method using nitrogen adsorption, in accordance with "JIS (Japanese Industrial Standards) Z8830:2001 Method for measuring the specific surface area of ​​powders (solids) by gas adsorption". The term "system" may be added after a compound name to comprehensively refer to the compound and its derivatives. Also, when "system" is added after a compound name to represent a polymer name, it means that the repeating units of the polymer originate from the compound or its derivative. Furthermore, "general formula" and "chemical formula" are collectively referred to as "formula". In the explanation of a formula, "each independently" means that they may represent the same group or different groups. "At least one of a, b, and c" and "at least one of a, b, and c" mean "at least one selected from the group consisting of a, b, and c." "At least one type of a, b, and c" means "at least one type selected from the group consisting of a, b, and c." Note that a, b, and c are examples and may be replaced with other terms as appropriate. Unless otherwise specified, each component described herein may be used alone or in combination of two or more types.The terms used in this specification have now been explained.

[0013] [First Embodiment: Electrophotographic Photoreceptor] A first embodiment of the present invention relates to an electrophotographic photoreceptor (hereinafter sometimes referred to as a photoreceptor). The photoreceptor of the first embodiment comprises a conductive substrate, a photosensitive layer, and a protective layer. The photosensitive layer contains a charge generating agent and a hole transporting agent. The protective layer is the outermost surface layer of the photoreceptor. The protective layer contains a resin having halogen groups. The mass ratio of halogen atoms contained in the protective layer to the mass of the protective layer is 2% by mass or more and 20% by mass or less. The Martens hardness of the protective layer is 280 N / mm². 2 More than 450N / mm 2 The following applies:

[0014] Hereinafter, "resin containing halogen groups" may be referred to as "halogen-containing resin." "The mass ratio of halogen atoms contained in the protective layer to the mass of the protective layer" may be referred to as "specified halogen ratio."

[0015] The photoreceptor of the first embodiment, by having the above configuration, exhibits excellent wear resistance and can suppress the occurrence of image flow in the formed image. The reason for this is presumed to be as follows.

[0016] The predetermined halogen content of the protective layer of the photoreceptor in the first embodiment is 2% by mass or more and 20% by mass or less. If the predetermined halogen content of the protective layer is 2% by mass or more, the water repellency of the protective layer, which is the outermost layer, is sufficiently increased. As a result, discharge products are less likely to adhere to the surface of the photoreceptor, and problems such as the inability to transport charge to areas on the surface of the photoreceptor where discharge products have adhered are less likely to occur. As a result, the occurrence of image blurring in the formed image can be suppressed. On the other hand, if the predetermined halogen content of the protective layer is 20% by mass or less, the polymerization reaction (for example, a radical polymerization reaction such as a photocuring reaction) for forming the halogen-containing resin contained in the protective layer in the protective layer formation process described later is less likely to be inhibited by halogen atoms. As a result, the polymerization reaction proceeds favorably, and a halogen-containing resin with high hardness is formed. As a result, the abrasion resistance of the photoreceptor is improved.

[0017] Furthermore, the Martens hardness of the protective layer included in the photoreceptor of the first embodiment is 280 N / mm 2 or more and 450 N / mm 2 or less. If the Martens hardness of the protective layer is 280 N / mm 2 or more, since the hardness of the protective layer is sufficiently high, the abrasion resistance of the photoreceptor is improved. On the other hand, if the Martens hardness of the protective layer is 450 N / mm 2 or less, since the hardness is not excessively high, the discharge products adhering to the surface of the photoreceptor can be suitably removed by the cleaning member and the rubbing roller. As a result, a problem such as the charge not being transported to the region of the surface of the photoreceptor where the discharge products adhere is less likely to occur. As a result, it is possible to suppress the occurrence of image flow in the formed image.

[0018] As described above, the reason why the photoreceptor of the first embodiment is excellent in abrasion resistance and can suppress the occurrence of image flow in the formed image has been explained. Hereinafter, the photoreceptor will be further described.

[0019] The photoreceptor is, for example, a single-layer type electrophotographic photoreceptor (hereinafter, may be referred to as a single-layer type photoreceptor), or a laminated type electrophotographic photoreceptor (hereinafter, may be referred to as a laminated type photoreceptor).

[0020] Hereinafter, referring to FIGS. 1 to 2, the structure of a single-layer type photoreceptor 1 which is an example of the photoreceptor will be described. FIGS. 1 to 2 each show a partial cross-sectional view of the single-layer type photoreceptor 1. As shown in FIG. 1, the single-layer type photoreceptor 1 includes, for example, a conductive substrate 2, a photosensitive layer 3, and a protective layer 5. The photosensitive layer 3 is a single layer. Hereinafter, the "single-layer photosensitive layer" may be referred to as a "single-layer type photosensitive layer". In the example shown in FIG. 1, a single-layer type photosensitive layer 3a is provided on the conductive substrate 2, and a protective layer 5 is provided on the single-layer type photosensitive layer 3a. The single-layer type photosensitive layer 3a is directly provided on the conductive substrate 2. The protective layer 5 is the outermost surface layer of the single-layer type photoreceptor 1.

[0021] As shown in Figure 2, the single-layer photoreceptor 1 may further include an intermediate layer 4 (undercoat layer) in addition to the conductive substrate 2, the single-layer photoreceptor layer 3a, and the protective layer 5. In the example shown in Figure 2, the intermediate layer 4 is provided on the conductive substrate 2, the single-layer photoreceptor layer 3a is provided on the intermediate layer 4, and the protective layer 5 is provided on the single-layer photoreceptor layer 3a. The single-layer photoreceptor layer 3a is provided on the conductive substrate 2 via the intermediate layer 4.

[0022] The thickness of the single-layer photosensitive layer 3a is not particularly limited, but is preferably 5 μm or more and 100 μm or less, and more preferably 10 μm or more and 50 μm or less.

[0023] The thickness of the protective layer 5 is not particularly limited, but is preferably 1 μm or more, more preferably 1 μm to 30 μm, even more preferably 1 μm to 10 μm, and particularly preferably 1 μm to 4 μm. In the examples shown in Figures 1 and 2, the protective layer 5 is a single layer. However, the protective layer 5 may be multiple layers. If the protective layer 5 is multiple layers, at least the outermost layer of the multiple layers contains a halogen-containing resin. The structure of a single-layer photoreceptor 1, which is an example of a photoreceptor, has been described above with reference to Figures 1 and 2.

[0024] The structure of a multilayer photoreceptor 10, an example of a photoreceptor, will be described below with reference to Figures 3 to 5. Figures 3 to 5 each show a partial cross-sectional view of the multilayer photoreceptor 10. As shown in Figure 3, the multilayer photoreceptor 10 comprises, for example, a conductive substrate 2, a photosensitive layer 3, and a protective layer 5. The photosensitive layer 3 includes a charge generation layer 3b and a charge transport layer 3c. In the example shown in Figure 3, the charge generation layer 3b is provided on the conductive substrate 2, the charge transport layer 3c is provided on the charge generation layer 3b, and the protective layer 5 is provided on the charge transport layer 3c. However, as shown in Figure 4, in the multilayer photoreceptor 10, the charge transport layer 3c may be provided on the conductive substrate 2, the charge generation layer 3b may be provided on the charge transport layer 3c, and the protective layer 5 may be provided on the charge generation layer 3b. In the examples shown in Figures 3 and 4, the photosensitive layer 3 is provided directly on the conductive substrate 2. The protective layer 5 is the outermost layer of the stacked photoreceptor 10.

[0025] As shown in Figure 5, the stacked photoreceptor 10 may further include an intermediate layer 4 (undercoat layer) in addition to the conductive substrate 2, the photosensitive layer 3, and the protective layer 5. In the example shown in Figure 5, the intermediate layer 4 is provided on the conductive substrate 2, the charge generation layer 3b is provided on the intermediate layer 4, the charge transport layer 3c is provided on the charge generation layer 3b, and the protective layer 5 is provided on the charge transport layer 3c. The photosensitive layer 3 (for example, the charge generation layer 3b) is provided on the conductive substrate 2 via the intermediate layer 4.

[0026] The thickness of the charge generation layer 3b is not particularly limited, but is preferably 0.01 μm or more and 5 μm or less, and more preferably 0.1 μm or more and 3 μm or less. In the examples shown in Figures 3 to 5, the charge generation layer 3b is a single layer. However, the charge generation layer 3b may consist of multiple layers.

[0027] The thickness of the charge transport layer 3c is not particularly limited, but is preferably 2 μm to 100 μm, and more preferably 5 μm to 50 μm. In the examples shown in Figures 3 to 5, the charge transport layer 3c is a single layer. However, the charge transport layer 3c may consist of multiple layers.

[0028] The protective layer 5 of the stacked photoreceptor 10 is the same as the protective layer 5 of the single-layer photoreceptor 1, so its explanation is omitted. The structure of the stacked photoreceptor 10, which is an example of a photoreceptor, has been explained above with reference to Figures 3 to 5.

[0029] <Protective layer> As already mentioned, the predetermined halogen ratio of the protective layer is 2% by mass or more and 20% by mass or less. To suppress the occurrence of image flow in the formed image, the predetermined halogen ratio of the protective layer is preferably 5% by mass or more. To improve the abrasion resistance of the photoreceptor, the predetermined halogen ratio of the protective layer is preferably 18% by mass or less, and more preferably 15% by mass or less. If the only component containing halogen groups among the components contained in the protective layer is the halogen-containing resin, the predetermined halogen ratio corresponds to the mass ratio of halogen groups (i.e., halogen atoms) contained in the halogen-containing resin to the mass of the protective layer.

[0030] The predetermined halogen ratio of the protective layer can be changed, for example, by adjusting one or both of the type and amount of halogen-containing resin contained in the protective layer. The predetermined halogen ratio of the protective layer can be calculated, for example, by performing elemental analysis using an energy-dispersive X-ray analyzer and measuring the composition ratio of the elements contained in the protective layer. The predetermined halogen ratio is calculated from the measured composition ratio of the elements and the atomic weight of each element based on the formula "(determined halogen ratio) = (mass of halogen atoms contained in the protective layer) / (mass of the protective layer)". If the chemical formula of the compound contained in the protective layer is known, the molecular weight of that compound, the number of halogen groups (i.e., halogen atoms) that the compound has, and the atomic weight of the halogen atoms may be used instead of the above measured values.

[0031] In the first embodiment, the Martens hardness of the protective layer is the Martens hardness of the protective layer at an indentation depth of 0.4 μm. As already mentioned, the Martens hardness of the protective layer is 280 N / mm². 2 More than 450N / mm 2 The following applies: To improve the abrasion resistance of the photoreceptor, the Martens hardness of the protective layer is 290 N / mm². 2 Preferably, it is 300 N / mm 2 It is more preferable that the value be greater than or equal to 320 N / mm 2 It is even more preferable that the value be greater than or equal to 350 N / mm 2 It is even more preferable that the value be greater than or equal to 370 N / mm 2 The above is particularly preferable. In order to suppress the occurrence of image flow in the formed image, the Martens hardness of the protective layer should be 385 N / mm². 2 The following is preferable: The Martens hardness of the protective layer is measured by nanoindentation in accordance with ISO 14577.

[0032] The protective layer contains a halogen-containing resin. Preferably, the protective layer further contains metal oxide particles. The protective layer may further contain, if necessary, one or both of a polymerization initiator and / or an additive.

[0033] (Halogen-containing resin) The halogen-containing resin content in the protective layer is preferably 50% by mass or more and 99% by mass or less, and more preferably 70% by mass or more and 90% by mass or less, relative to the mass of the protective layer.

[0034] Halogen-containing resins have halogen groups (i.e., halogen atoms). Examples of halogen groups include fluoro groups, chloro groups, bromo groups, and iodine groups. Note that halogen-containing resins do not necessarily have nitrogen atoms.

[0035] Halogen-containing resins are, for example, photocurable resins having halogen groups. Examples of photocurable resins having halogen groups include (meth)acrylic resins having halogen groups and epoxy resins having halogen groups. Since stopping ultraviolet irradiation also stops the photocuring reaction, and the progress of the photocuring reaction is easy to control, (meth)acrylic resins having halogen groups are preferred as photocurable resins having halogen groups.

[0036] The halogen-containing resin contains at least repeating units having halogen groups. It is preferable that the halogen-containing resin further contains repeating units without halogen groups, in addition to repeating units having halogen groups, because this makes it easier to adjust the predetermined halogen ratio of the protective layer to a predetermined range. For the same reason, it is more preferable that the halogen-containing resin contains a first repeating unit, a second repeating unit, and a third repeating unit. The first repeating unit does not have halogen groups. The second repeating unit has halogen groups but does not have siloxane bond-containing groups. The third repeating unit has halogen groups and siloxane bond-containing groups.

[0037] The first repeating units, second repeating units, and third repeating units contained in the halogen-containing resin may each consist of one type or two or more types (for example, two types). The total content of the first repeating units, second repeating units, and third repeating units in the halogen-containing resin is preferably 80% by mass or more, more preferably 90% by mass or more, and particularly preferably 100% by mass.

[0038] The first repeating unit is described below. The first repeating unit does not have a halogen group. The first repeating unit is a repeating unit derived from the first compound. Examples of the first compound include acrylic acid esters and acrylic polymers having polymerizable functional groups. Hereinafter, the first compound when it is an acrylic acid ester will be referred to as the first compound (M), and the repeating unit derived from the first compound (M) will be referred to as the first repeating unit (M). Also, the first compound when it is an acrylic polymer having polymerizable functional groups will be referred to as the first compound (P), and the repeating unit derived from the first compound (P) will be referred to as the first repeating unit (P).

[0039] To improve wear resistance and suppress image flow in the formed image, the mass ratio of the first repeating unit to the mass of the halogen-containing resin is preferably 10.0% by mass or more and 90.0% by mass or less, and more preferably 10.0% by mass or more and 79.0% by mass or less. If the halogen-containing resin contains both the first repeating unit (M) and (P), the mass ratio of the first repeating unit is the total mass ratio of the first repeating units (M) and (P).

[0040] The first repeating unit (M) is described below. In order to improve wear resistance and suppress the occurrence of image flow in the formed image, the mass ratio of the first repeating unit (M) to the mass of the halogen-containing resin is preferably 10.0% by mass or more and 90.0% by mass or less, and more preferably 30.0% by mass or more and 79.0% by mass or less. Note that the halogen-containing resin does not necessarily have to contain the first repeating unit (M) as the first repeating unit.

[0041] To increase the hardness of the halogen-containing resin and improve the abrasion resistance of the photoreceptor, the first compound (M) preferably has two or more polymerizable functional groups, and more preferably has three to six polymerizable functional groups. Examples of polymerizable functional groups include vinyl groups and epoxy groups.

[0042] Examples of the first compound (M) include trimethylolpropane triacrylate, glycerin triacrylate, tris-(2-acryloxyethyl) isocyanurate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol pentaacrylate, and dipentaerythritol hexaacrylate. These first compounds (M) may be ethoxylated.

[0043] The above-mentioned pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, and dipentaerythritol hexaacrylate are compounds represented by the following formulas (EA-1), (EA-2), (EA-3), and (EA-4), respectively.

[0044] [ka]

[0045] The first repeating unit (M) is preferably derived from at least one compound selected from the group consisting of compounds represented by formulas (EA-1), (EA-2), (EA-3), and (EA-4), and more preferably from one or two compounds. The first repeating unit (M) is even more preferably comprised of a repeating unit derived from a compound represented by formula (EA-3) and a repeating unit derived from a compound represented by formula (EA-4).

[0046] The first repeating unit (M) is formed by polymerizing the polymerizable functional group of the first compound (M). For example, by a photocuring reaction (more specifically, an addition polymerization reaction of vinyl groups), repeating units represented by formulas (EA-1a), (EA-2a), (EA-3a), and (EA-4a), which are the first repeating units (M), are formed from the first compound (M) represented by formulas (EA-1), (EA-2), (EA-3), and (EA-4), respectively.

[0047] [ka]

[0048] Y in equation (EA-1a) 1 ~Y 3 At least one of them represents a group represented by formula (Yb), and Y 1 ~Y 3 The remaining part represents the base expressed by equation (Ya). Y in equation (EA-2a) 4 ~Y 7 At least one of them represents a group represented by formula (Yb), and Y 4 ~Y 7 The remaining part represents the group expressed by equation (Ya). Y in equation (EA-3a) 8 ~Y 12 At least one of them represents a group represented by formula (Yb), and Y 8 ~Y 12 The remaining part represents the group represented by equation (Ya). Y in equation (EA-4a) 13 ~Y 18At least one of them represents a group represented by formula (Yb), and Y 13 ~Y 18 The remaining part represents the base expressed by formula (Ya).

[0049] [ka]

[0050] * in equations (Ya) and (Yb) 1 * is a bond that attaches to the carbon atom of the carbonyl group in formulas (EA-1a) to (EA-4a). 2 This is a coupling that connects to other repeating units.

[0051] The first compound (M) is preferably a mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate. The content of pentaerythritol triacrylate in the mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate is preferably 40% by mass or more and 60% by mass or less. The first compound (M) is also preferably a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate.

[0052] The hydroxyl value of the first compound (M) is preferably 1 mg KOH / g or more and 50 mg KOH / g or less, and more preferably 5 mg KOH / g or more and 15 mg KOH / g or less.

[0053] The first repeating unit (P) is described below. To improve wear resistance and suppress the occurrence of image flow in the formed image, the mass ratio of the first repeating unit (P) to the mass of the halogen-containing resin is preferably 10.0% by mass or more and 90.0% by mass or less, and more preferably 15.0% by mass or more and 79.0% by mass or less. Note that the halogen-containing resin does not have to contain the first repeating unit (P) as the first repeating unit. An example of the first compound (P) for forming the first repeating unit (P) is a UV-curable acrylic polymer having polymerizable functional groups (preferably vinyl groups). Since the first compound (P) has unreacted polymerizable functional groups, even if the first compound (P) is a polymer, the first compound (P) can polymerize with the compound for forming the halogen-containing resin. The polymerizable functional group equivalent (e.g., vinyl group equivalent) of the first repeating unit (P) is preferably 100 g / mol or more and 500 g / mol or less, and more preferably 200 g / mol or more and 250 g / mol or less.

[0054] The second repeating unit is described below. The second repeating unit has a halogen group and does not have a siloxane bond-containing group. The second repeating unit is a repeating unit derived from the second compound. In order to improve wear resistance and suppress the occurrence of image flow in the formed image, the mass ratio of the second repeating unit to the mass of the halogen-containing resin is preferably 3.0% by mass or more and 42.0% by mass or less.

[0055] Examples of the second repeating unit include repeating units derived from (meth)acrylic acid esters that have a halogen group and do not have a siloxane bond-containing group. A preferred example of the second repeating unit is a repeating unit derived from a compound represented by formula (EB-1).

[0056] [ka]

[0057] In formula (EB-1), R 1represents the group represented by formula (b1), and R 2 represents a hydrogen atom or a methyl group.

[0058] [ka]

[0059] In equation (b1), m represents 0 or 1, n represents an integer between 1 and 3, and R 3 represents a hydrogen atom or a fluorine atom, and * represents a bonding bond.

[0060] The second repeating unit is formed by polymerizing the polymerizable functional group of the second compound. For example, the second repeating unit, represented by formula (EB-1), is formed by a photocuring reaction (more specifically, an addition polymerization reaction of vinyl groups) of the compound represented by formula (EB-1a).

[0061] [ka]

[0062] * in equation (EB-1a) 3 R represents a bond, and more specifically, a bond that connects to another repeating unit. 1 and R 2 R in equation (EB-1) 1 and R 2 It is synonymous with [the above].

[0063] As an example of the second compound, the compound represented by formula (EB-1) is preferably a compound represented by formula (C-3), (C-4), or (C-6).

[0064] [ka]

[0065] In order to suitably allow the second compound to penetrate the voids of the first compound (M) and form a halogen-containing resin in which the first repeating units (M) and the second repeating units are densely arranged, it is preferable that the first repeating units (M) are larger than the second repeating units. For the same reason, it is preferable that the molecular weight of the first compound (M) is higher than the molecular weight of the second compound.

[0066] If the mass of the first repeating unit (M) is M1 and the mass of the second repeating unit is M2, then in order to promote the photocuring reaction and increase the hardness of the protective layer, the ratio of the mass of the second repeating unit (M2) to the mass of the first repeating unit (M) (M1), M2 / M1, is preferably 0.1 or more and 0.9 or less, more preferably 0.5 or more and 0.8 or less, and even more preferably 0.6 or more and 0.7 or less.

[0067] The third repeating unit is described below. The third repeating unit has a halogen group and a siloxane bond-containing group. The third repeating unit is a repeating unit derived from the third compound. In order to improve wear resistance and suppress the occurrence of image flow in the formed image, the mass ratio of the third repeating unit to the mass of the halogen-containing resin is preferably 1.0% by mass or more and 45.0% by mass or less. The siloxane bond of the group containing the siloxane bond is of the formula "-O-SiR A R B - is represented as R in the formula A and R B Each of these independently represents either a hydrogen atom or a methyl group. The third compound for forming the third repeating unit has polymerizable reactive groups. Because the third compound has unreacted polymerizable functional groups, even if the third compound is a polymer, the third compound can polymerize with the compound for forming the halogen-containing resin. The polymerizable functional group equivalent (e.g., vinyl group equivalent) of the third compound is preferably 100 g / mol or more and 500 g / mol or less, and more preferably 260 g / mol or more and 450 g / mol or less. Examples of the third repeating unit include repeating units derived from fluorosilicone-modified acrylic polymers having vinyl groups.

[0068] (metal oxide particles) Examples of metal oxide particles include alumina particles, zinc oxide particles, titanium oxide particles, and tin oxide particles. The metal oxide particles do not need to be doped. However, it is preferable that the metal oxide particles be doped in order to improve the conductivity of the protective layer. Examples of doped metal oxide particles include phosphorus-doped tin oxide particles and antimond-doped tin oxide particles. Alumina particles and tin oxide particles are preferred as metal oxide particles.

[0069] The BET specific surface area of ​​metal oxide particles is 30 m². 2 / g or more 200m 2 It is preferable that it be less than or equal to / g, and 55m 2 / g or more 130m 2 It is more preferable that the amount is less than or equal to / g. The number-average primary particle diameter of the metal oxide particles is preferably 5 nm to 50 nm, and more preferably 20 nm to 35 nm.

[0070] The content of metal oxide particles in the protective layer is preferably 1% by mass or more and 20% by mass or less, and more preferably 5% by mass or more and 15% by mass or less, relative to the mass of the protective layer.

[0071] (Polymerization initiator) The polymerization initiator is, for example, a photopolymerization initiator. Examples of photopolymerization initiators include acylphosphine oxide compounds, acetophenone compounds, ketal compounds, benzoin ether compounds, anthraquinone compounds, and thioxanthone compounds. Due to their high UV absorption efficiency, acylphosphine oxide compounds are preferred as photopolymerization initiators. Examples of acylphosphine oxide compounds include 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, and lithiumphenyl(2,4,6-trimethylbenzoyl)phosphonate. The content of the polymerization initiator in the protective layer is preferably 1% by mass or more and 20% by mass or less, and more preferably 5% by mass or more and 10% by mass or less, relative to the mass of the protective layer.

[0072] (Additives) Examples of additives contained in the protective layer include leveling agents and silica. If the leveling agent has polymerizable reactive groups, the halogen-containing resin may have repeating units derived from the leveling agent as repeating units. Preferably, the protective layer does not contain charge generating agents and charge transport materials (e.g., hole transporters and electron transporters).

[0073] <Photosensitive layer> The photosensitive layer contains a charge generating agent, a hole transporter, and a binder resin. When the photoreceptor is a single-layer photoreceptor, the single-layer photosensitive layer contains a charge generating agent, a hole transporter, and a binder resin. Preferably, the single-layer photosensitive layer further contains an electron transporter. The single-layer photosensitive layer may further contain additives as needed.

[0074] If the photoreceptor is a multilayer photoreceptor, the charge generation layer included in the photosensitive layer contains a charge generating agent. The charge transport layer included in the photosensitive layer contains a hole transport agent and a binder resin. The charge generation layer may further contain a base resin as needed. The charge generation layer and the charge transport layer may each further contain additives as needed. The charge generation layer and the charge transport layer may each contain a radical acceptor compound. However, the charge generation layer and the charge transport layer do not each contain a radical acceptor compound.

[0075] (Charge-generating agent) Examples of charge generating agents include phthalocyanine pigments, perylene pigments, bisazo pigments, trisazo pigments, dithioketopyrrolopyrrole pigments, metal-free naphthalocyanine pigments, metallic naphthalocyanine pigments, squaline pigments, indigo pigments, azulenium pigments, cyanine pigments, powders of inorganic photoconductive materials (e.g., selenium, selenium-tellurium, selenium-arsenide, cadmium sulfide, and amorphous silicon), pyryllium pigments, ancencelon pigments, triphenylmethane pigments, surene pigments, toluidine pigments, pyrazoline pigments, and quinacridone pigments.

[0076] Phthalocyanine pigments have a phthalocyanine structure. Examples of phthalocyanine pigments include metallic phthalocyanines and metal-free phthalocyanines. Examples of metallic phthalocyanines include titanyl phthalocyanine, hydroxygallium phthalocyanine, and chlorogallium phthalocyanine. Titanyl phthalocyanine is preferred as the metallic phthalocyanine. Titanyl phthalocyanine is represented by formula (CG-1). Metal-free phthalocyanines are represented by formula (CG-2).

[0077] [ka]

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

[0079] For example, in digital optical image forming apparatuses (e.g., laser beam printers or facsimile machines using light sources such as semiconductor lasers), it is preferable to use a photoreceptor that is sensitive to wavelengths of 700 nm or more. As a charge generating agent, phthalocyanine-based pigments are preferred because they have a high quantum yield in the wavelength range of 700 nm or more, with titanyl phthalocyanine or metal-free phthalocyanine being more preferred, and Y-type titanyl phthalocyanine or X-type metal-free phthalocyanine being particularly preferred.

[0080] Y-type titanyl phthalocyanine has a major peak at, for example, 27.2° of the Bragg angle (2θ±0.2°) in its CuKα-characterized X-ray diffraction spectrum. The major peak in a CuKα-characterized X-ray diffraction spectrum is the peak with the first or second highest intensity in the range where the Bragg angle (2θ±0.2°) is between 3° and 40°. Y-type titanyl phthalocyanine does not have a peak at 26.2° in its CuKα-characterized X-ray diffraction spectrum.

[0081] The CuKα characteristic X-ray diffraction spectrum can be measured, for example, by the following method. First, the sample (titanyl phthalocyanine) is placed in the sample holder of an X-ray diffractometer (for example, RIGAK Corporation's "RINT(registered trademark) 1100"), and the X-ray diffraction spectrum is measured under the following conditions: X-ray tube Cu, tube voltage 40kV, tube current 30mA, and CuKα characteristic X-ray wavelength 1.542Å. The measurement range (2θ) is, for example, 3° to 40° (start angle 3°, stop angle 40°), and the scanning speed is, for example, 10° / min. The main peak is determined from the obtained X-ray diffraction spectrum, and the Bragg angle of the main peak is read.

[0082] When the photoreceptor is a single-layer photoreceptor, the content of the charge generating agent in the single-layer photoreceptor layer is preferably 0.1 parts by mass or more and 50 parts by mass or less, and more preferably 0.5 parts by mass or more and 30 parts by mass or less, per 100 parts by mass of the binder resin. When the photoreceptor is a multilayer photoreceptor, the content of the charge generating agent in the photoreceptor layer (specifically the charge generating layer) is preferably 10 parts by mass or more and 300 parts by mass or less, and more preferably 100 parts by mass or more and 200 parts by mass or less, per 100 parts by mass of the base resin.

[0083] (Hole transport agent) Examples of hole transporters include triphenylamine derivatives, diamine derivatives (e.g., N,N,N',N'-tetraphenylbenzidine derivatives, N,N,N',N'-tetraphenylphenylenediamine derivatives, N,N,N',N'-tetraphenylnaphthylenediamine derivatives, N,N,N',N'-tetraphenylphenantolylenediamine derivatives, and di(aminophenylethenyl)benzene derivatives), oxadiazole compounds (e.g., 2,5-di(4-methylaminophenyl)-1,3,4-oxadiazo Examples include oxymethylcellulose, styryl compounds (e.g., 9-(4-diethylaminostyryl)anthracene), carbazole compounds (e.g., polyvinylcarbazole), organic polysilane compounds, pyrazoline compounds (e.g., 1-phenyl-3-(p-dimethylaminophenyl)pyrazoline), hydrazone compounds, indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, and triazole compounds.

[0084] To improve the sensitivity characteristics of the photoreceptor, the hole transporter preferably contains at least one compound represented by formulas (1), (2), and (3), and more preferably contains at least one compound represented by formulas (1) and (2). Hereinafter, the compounds represented by formulas (1), (2), and (3) may be referred to as hole transporters (1), (2), and (3), respectively.

[0085] [ka]

[0086] In formula (1), R 41 , R 42 , R 43 , R 44 , R 45 , and R 46 Each of these independently represents an alkyl group having 1 to 8 carbon atoms, or a phenyl group. 47 and R 48Each of these independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a phenyl group. Each of these independently represents an integer between 0 and 5, and each of these independently represents an integer between 0 and 4

[0087] In equation (1), when e1 represents an integer between 2 and 5, multiple R 41 These may represent the same base or different bases. When e2 represents an integer between 2 and 5, multiple R 42 These may represent the same base or different bases. When e3 represents an integer between 2 and 5, multiple R 43 These may represent the same base or different bases. When e4 represents an integer between 2 and 5, multiple R 44 These may represent the same base or different bases. When e5 represents an integer between 2 and 4, multiple R 45 These may represent the same base or different bases. When e6 represents an integer between 2 and 4, multiple R 46 These may represent the same group or different groups.

[0088] In formula (1), R 41 ~R 46 Each of these groups preferably independently represents an alkyl group having 1 to 8 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms, and even more preferably a methyl group or an ethyl group. 47 and R 48 e1, e2, e3, and e4 each preferably represent an integer between 0 and 2, with e1 and e2 representing 0 and e3 and e4 representing 2. e5 and e6 preferably represent 0.

[0089] In formula (2), R 50 , R 51 , and R 54 Each of these independently represents an alkyl group having 1 to 8 carbon atoms, or a phenyl group. 52 , and R 53Each independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a phenyl group which may be substituted with an alkyl group having 1 to 8 carbon atoms. f3, f4, and f5 each independently represent an integer of 0 or more and 5 or less.

[0090] In formula (2), when f3 represents an integer of 2 or more and 5 or less, a plurality of R 50 may represent the same group as each other or different groups. When f4 represents an integer of 2 or more and 5 or less, a plurality of R 51 may represent the same group as each other or different groups. When f5 represents an integer of 2 or more and 5 or less, a plurality of R 54 may represent the same group as each other or different groups.

[0091] In formula (2), R 50 , R 51 , and R 54 each independently preferably represents an alkyl group having 1 to 8 carbon atoms, more preferably represents an alkyl group having 1 to 3 carbon atoms, and even more preferably represents a methyl group. R 52 and R 53 each independently preferably represents a hydrogen atom, an unsubstituted phenyl group, or a phenyl group substituted with an alkyl group having 1 to 8 carbon atoms. When the phenyl group is substituted with an alkyl group having 1 to 8 carbon atoms, such an alkyl group having 1 to 8 carbon atoms is preferably an alkyl group having 1 to 3 carbon atoms, and more preferably a methyl group. f3, f4, and f5 each independently preferably represent 0 or 1.

[0092] In formula (3), R 11 , R 12 , R 13 , and R 14 each independently represents an alkyl group having 1 to 8 carbon atoms or a phenyl group. a1, a2, a3, and a4 each independently represent an integer of 0 or more and 5 or less.

[0093] In formula (3), when a1 represents an integer of 2 or more and 5 or less, a plurality of R 11may represent the same group as each other, or may represent different groups. When a2 represents an integer of 2 or more and 5 or less, a plurality of Rs 12 may represent the same group as each other, or may represent different groups. When a3 represents an integer of 2 or more and 5 or less, a plurality of Rs 13 may represent the same group as each other, or may represent different groups. When a4 represents an integer of 2 or more and 5 or less, a plurality of Rs 14 may represent the same group as each other, or may represent different groups.

[0094] In formula (3), R 11 , R 12 , R 13 , and R 14 each preferably independently represents an alkyl group having 1 to 3 carbon atoms, more preferably represents a methyl group or an ethyl group. a1, a2, a3, and a4 each preferably independently represents an integer of 1 or more and 3 or less, more preferably represents 1.

[0095] Suitable examples of the hole transport agent include compounds represented by formula (HT- \alpha), (HT-3), and (HT-4) (hereinafter, each may be described as hole transport agent (HT- \alpha), (HT-3), and (HT-4)). The photosensitive layer preferably contains hole transport agents (HT- \alpha) and (HT-3) as the hole transport agent.

[0096] [Chemical formula]

[0097] The content of hole transport agents (1) to (3) in all the hole transport agents in the photosensitive layer is preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably 100% by mass, based on the total mass of the hole transport agents in the photosensitive layer. <00​​When ultraviolet irradiation is performed in the protective layer formation process, it is preferable that the hole transporter has two or fewer (one or two) linear ethene-1,2-diyl groups, or does not have linear ethene-1,2-diyl groups, in order to suppress the decomposition of the hole transporter by ultraviolet irradiation. Hereinafter, "linear ethene-1,2-diyl group" may be referred to as "predetermined double bond". The predetermined double bond is a bond represented by the following formula (DB). In formula (DB), * represents a bond. The predetermined double bond is an unsubstituted ethene-1,2-diyl group. Since the predetermined double bond is linear, it is a double bond that constitutes a linear group. Since the predetermined double bond is linear, it is not a double bond that constitutes a ring such as a benzene ring.

[0099] [ka]

[0100] When the photoreceptor is a single-layer photoreceptor, the content of the hole transporter in the single-layer photoreceptor, which is the photosensitive layer, is preferably 10 parts by mass or more and 200 parts by mass or less, and more preferably 80 parts by mass or more and 130 parts by mass or less, per 100 parts by mass of the binder resin.

[0101] To improve the sensitivity characteristics of the photoreceptor, when the photoreceptor is a single-layer photoreceptor, the total content of hole transporters and electron transporters in the single-layer photoreceptor layer is preferably 40% by mass or more, and more preferably 40% by mass or more and 60% by mass or less, relative to the mass of the single-layer photoreceptor layer.

[0102] When the photoreceptor is a laminated photoreceptor, the content of the hole transport agent in the photosensitive layer (specifically the charge transport layer) is preferably 10 parts by mass or more and 200 parts by mass or less, and more preferably 50 parts by mass or more and 100 parts by mass or less, per 100 parts by mass of the binder resin.

[0103] To improve the sensitivity characteristics of the photoreceptor, when the photoreceptor is a multilayer photoreceptor, the content of the hole transporter in the charge transport layer is preferably 40% by mass or more, and more preferably 40% by mass or more and 60% by mass or less, relative to the mass of the charge transport layer.

[0104] (Electron transport agent) Examples of electron transport agents include quinone compounds, diimide compounds, hydrazone compounds, malononitrile compounds, thiopyran compounds, trinitrothioxanthone compounds, 3,4,5,7-tetranitro-9-fluorenone compounds, dinitroanthracene compounds, dinitroacridine compounds, tetracyanoethylene, 2,4,8-trinitrothioxanthone, dinitrobenzene, dinitroacridine, succinic anhydride, maleic anhydride, and dibromomaleic anhydride. Examples of quinone compounds include diphenoquinone compounds, azoquinone compounds, anthraquinone compounds, naphthoquinone compounds, nitroanthraquinone compounds, and dinitroanthraquinone compounds.

[0105] The electron transport agent preferably contains at least one of the compounds represented by formulas (11), (12), (13), (14), (15), and (16). Hereinafter, the compounds represented by formulas (11), (12), (13), (14), (15), and (16) may be referred to as electron transport agents (11), (12), (13), (14), (15), and (16), respectively.

[0106] [ka]

[0107] Q in equation (11) 1 and Q 2 Q in equation (12) 21 Q 22 Q 23 , and Q 24 Q in equation (13) 31 and Q 32 Q in equation (14) 41 Q42 , and Q 43 Q in equation (15) 71 Q 72 Q 73 Q 74 Q 75 , and Q 76 , and Q in equation (16) 61 and Q 62 Each independently represents a hydrogen atom, a halogen atom, a cyano group, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 14 carbon atoms which may be substituted with at least one substituent selected from the group consisting of an alkyl group having 1 to 6 carbon atoms and a halogen atom. In formula (15), Y 1 and Y 2 This represents an oxygen atom.

[0108] Q in equation (11) 1 and Q 2 Q in equation (12) 21 Q 22 Q 23 , and Q 24 Q in equation (13) 31 and Q 32 Q in equation (14) 41 Q 42 , and Q 43 Q in equation (15) 71 Q 72 Q 73 Q 74 Q 75 , and Q 76 , and Q in equation (16) 61 and Q 62 Preferably, each of these independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 14 carbon atoms which may be substituted with at least one substituent selected from the group consisting of an alkyl group having 1 to 6 carbon atoms and a halogen atom.

[0109] Q in equation (11) 1 and Q 2 Q in equation (12) 21 Q 22 Q 23, and Q 24 Q in equation (13) 31 and Q 32 Q in equation (14) 41 Q 42 , and Q 43 Q in equation (15) 71 Q 72 Q 73 Q 74 Q 75 , and Q 76 , and Q in equation (16) 61 and Q 62 The alkyl group having 1 to 6 carbon atoms represented by is preferably an alkyl group having 1 to 5 carbon atoms, and preferably a methyl group, ethyl group, propyl group, butyl group, or pentyl group, and particularly preferably a methyl group, tert-butyl group, or 1,1-dimethylpropyl group.

[0110] Q in equation (11) 1 and Q 2 Q in equation (12) 21 Q 22 Q 23 , and Q 24 Q in equation (13) 31 and Q 32 Q in equation (14) 41 Q 42 , and Q 43 Q in equation (15) 71 Q 72 Q 73 Q 74 Q 75 , and Q 76 , and Q in equation (16) 61 and Q 62The aryl group having 6 to 14 carbon atoms represented by is preferably an aryl group having 6 to 10 carbon atoms, and more preferably a phenyl group. The aryl group having 6 to 14 carbon atoms may be substituted with at least one substituent selected from the group consisting of alkyl groups having 1 to 6 carbon atoms and halogen atoms. The alkyl group having 1 to 6 carbon atoms is preferably an alkyl group having 1 to 3 carbon atoms, and more preferably a methyl group or an ethyl group. The halogen atom used as a substituent is preferably a fluorine atom, a chlorine atom, or a bromine atom, and particularly preferably a chlorine atom. When the aryl group having 6 to 14 carbon atoms is substituted with a substituent, the number of substituents is preferably one to five, and more preferably one or two. The aryl group having 6 to 14 carbon atoms substituted with at least one substituent selected from the group consisting of alkyl groups having 1 to 6 carbon atoms and halogen atoms is preferably a chlorophenyl group, a dichlorophenyl group, or an ethylmethylphenyl group, and more preferably a 4-chlorophenyl group, a 2,5-dichlorophenyl group, or a 2-ethyl-6-methylphenyl group.

[0111] More preferred examples of electron transport agents include compounds represented by formulas (ET-1) to (ET-7) (hereinafter, these may be referred to as electron transport agents (ET-1) to (ET-7), respectively).

[0112] [ka]

[0113] The content of electron transporters (11) to (16) in the total electron transporters in the photosensitive layer is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 100% by mass, based on the total mass of electron transporters in the photosensitive layer.

[0114] When the photoreceptor is a single-layer photoreceptor, the content of the electron transport agent in the single-layer photoreceptor layer is preferably 5 parts by mass or more and 150 parts by mass or less, and preferably 10 parts by mass or more and 50 parts by mass or less, per 100 parts by mass of the binder resin.

[0115] (Binder resin) Examples of binder resins include thermoplastic resins (more specifically, polyarylate resins, polycarbonate resins, styrene-based resins, styrene-butadiene copolymers, styrene-acrylonitrile copolymers, styrene-maleic acid copolymers, styrene-acrylic acid copolymers, acrylic copolymers, polyethylene resins, ethylene-vinyl acetate copolymers, chlorinated polyethylene resins, polyvinyl chloride resins, polypropylene resins, ionomers, vinyl chloride-vinyl acetate copolymers, polyester resins, alkyd resins, polyamide resins, polyurethane resins, polysulfone resins, diallyl phthalate resins, ketone resins, polyvinyl butyral resins, polyvinyl acetal resins, and polyether resins), thermosetting resins (more specifically, silicone resins, epoxy resins, phenolic resins, urea resins, melamine resins, and other crosslinkable thermosetting resins), and photocurable resins (more specifically, epoxy-acrylic acid resins and urethane-acrylic acid copolymers).

[0116] Among these resins, polycarbonate resin is preferred because it provides a single-layer photosensitive layer and charge transport layer with an excellent balance of processability, mechanical strength, optical properties, and abrasion resistance. Examples of polycarbonate resins include bisphenol Z type polycarbonate resin, bisphenol B type polycarbonate resin, bisphenol ZC type polycarbonate resin, bisphenol C type polycarbonate resin, and bisphenol A type polycarbonate resin. As the binder resin, bisphenol Z type polycarbonate resin or bisphenol B type polycarbonate resin is preferred. Bisphenol Z type polycarbonate resin is a resin having repeating units represented by the formula (BisZ). Bisphenol B type polycarbonate resin is a resin having repeating units represented by the formula (BisB).

[0117] [ka]

[0118] (Base resin) The base resin contained in the charge generation layer is the same as the binder resin contained in the charge transport layer. However, in order to suitably form the charge generation layer and the charge transport layer, it is preferable to select a resin as the base resin that is different from the resin used as the binder resin from the above examples of binder resins. The base resin is, for example, polyvinyl acetal resin.

[0119] (Additives) Additives contained in the photosensitive layer include, for example, UV absorbers, antioxidants, radical scavengers, singlet quenchers, softeners, surface modifiers, bulking agents, thickening agents, dispersion stabilizers, waxes, donors, surfactants, plasticizers, sensitizers, electron acceptor compounds, and leveling agents. Examples of leveling agents include silicone oil, and more specifically, dimethyl silicone oil.

[0120] <Middle class> The presence of an intermediate layer allows for a degree of insulation sufficient to suppress leakage while facilitating the flow of current generated when the photoreceptor is exposed, thereby suppressing an increase in resistance. The intermediate layer (undercoat) contains, for example, one or both of inorganic particles and organic particles, and a resin used in the intermediate layer (hereinafter sometimes referred to as "intermediate layer resin"). Hereinafter, the inorganic particles and organic particles contained in the intermediate layer will be collectively referred to as intermediate layer particles. The ratio of the mass of intermediate layer particles to the mass of intermediate layer resin is, for example, 1 to 4. The thickness of the intermediate layer is, for example, 0.1 μm to 5 μm.

[0121] Examples of inorganic particles for the intermediate layer include white pigments (more specifically, titanium dioxide, zinc oxide, zinc oxide, zinc sulfide, lead white, and lithopone, etc.) and extender pigments (more specifically, alumina, calcium carbonate, and barium sulfate, etc.). Examples of organic particles for the intermediate layer include fluororesin particles, benzoguanamine resin particles, and styrene resin particles. The number-mean primary particle size of the intermediate layer particles is preferably 100 nm or less, and more preferably 1 nm to 50 nm. Inorganic particles are preferred for the intermediate layer particles, and titanium dioxide is more preferred. Titanium dioxide may be surface-treated. Surface treatment of titanium dioxide may be performed once or multiple times (for example, twice). Examples of surface treatment agents used for surface treatment of titanium dioxide include alumina, silica, and organosilicon compounds (for example, polysiloxane, more specifically, methylhydrogenpolysiloxane).

[0122] Examples of intermediate layer resins are the same as examples of binder resins contained in the photosensitive layer. However, in order to suitably form the photosensitive layer, it is preferable to select an intermediate layer resin from the above examples of binder resins that is different from the resin used as the binder resin. The intermediate layer resin is, for example, a polyamide resin.

[0123] <Conductive substrate> The conductive substrate is not particularly limited, and only needs to be composed of a material whose surface is conductive. An example of a conductive substrate is a conductive substrate composed of a conductive material. Another example of a conductive substrate is a conductive substrate coated with a conductive material. Examples of conductive materials include aluminum, iron, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, and indium. Two or more conductive materials may be combined to form an alloy (more specifically, an aluminum alloy, stainless steel, or brass, etc.). Aluminum and aluminum alloys are preferred as conductive materials because they allow for good charge transfer from the photosensitive layer to the conductive substrate. The shape of the conductive substrate is appropriately selected according to the structure of the image forming apparatus. Examples of conductive substrate shapes include sheet-like and drum-like shapes. The thickness of the conductive substrate is appropriately selected according to the shape of the conductive substrate.

[0124] <Method for manufacturing photoreceptors> Next, a method for manufacturing a photoreceptor according to the first embodiment will be described. The method for manufacturing a photoreceptor includes, for example, a photosensitive layer formation step and a protective layer formation step.

[0125] (Photosensitive layer formation process for single-layer photoreceptors) The photosensitive layer formation process for a single-layer photoreceptor is described below. The photosensitive layer formation process for a single-layer photoreceptor includes a single-layer photosensitive layer formation process. In the single-layer photosensitive layer formation process, a coating solution for forming a single-layer photosensitive layer (hereinafter sometimes referred to as a single-layer photosensitive layer coating solution) is prepared. The single-layer photosensitive layer coating solution contains, for example, a charge generating agent, a hole transporter, a binder resin, a solvent, an electron transporter if necessary, and additives if necessary. The single-layer photosensitive layer coating solution is prepared by mixing these. Next, the single-layer photosensitive layer coating solution is applied onto a conductive substrate. Then, at least a portion of the solvent contained in the applied photosensitive layer coating solution is removed to form a single-layer photosensitive layer.

[0126] (Photosensitive layer formation process for stacked photoreceptors) The photosensitive layer formation process for a stacked photoreceptor will be described below. The photosensitive layer formation process for a stacked photoreceptor includes a charge generation layer formation process and a charge transport layer formation process.

[0127] In the charge generation layer formation step, a coating solution for forming the charge generation layer (hereinafter sometimes referred to as the charge generation layer coating solution) is prepared. The charge generation layer coating solution contains, for example, a charge generating agent, a base resin, a solvent, and additives as needed. The charge generation layer coating solution is prepared by mixing these components. Next, the charge generation layer coating solution is applied onto a conductive substrate. Then, at least a portion of the solvent contained in the applied charge generation layer coating solution is removed to form the charge generation layer.

[0128] In the charge transport layer formation process, a coating solution for forming the charge transport layer (hereinafter sometimes referred to as the charge transport layer coating solution) is prepared. The charge transport layer coating solution contains a hole transport agent, a binder resin, a solvent, and additives as needed. The charge transport layer coating solution is prepared by mixing these components. Next, the charge transport layer coating solution is applied onto the charge generating layer. Then, at least a portion of the solvent contained in the applied charge transport layer coating solution is removed to form the charge transport layer.

[0129] (Protective layer formation process) In the protective layer formation process, a protective layer containing a halogen-containing resin is formed on the photosensitive layer. First, a coating solution for forming the protective layer (hereinafter sometimes referred to as the protective layer coating solution) is prepared. The protective layer coating solution contains compounds for forming the halogen-containing resin (e.g., compounds 1 to 3), a solvent, a polymerization initiator as needed, metal oxide particles as needed, and additives as needed. The protective layer coating solution is prepared by mixing these. Next, the protective layer coating solution is applied onto the photosensitive layer. Then, the compounds for forming the halogen-containing resin are polymerized to form the halogen-containing resin polymer.

[0130] When the halogen-containing resin is a photocurable resin having halogen groups, the protective layer coating solution on the photosensitive layer (more specifically, the compound for forming the halogen-containing resin contained in the protective layer coating solution) is irradiated with ultraviolet light to polymerize the compound for forming the halogen-containing resin. The ultraviolet light irradiated in the protective layer formation step is, for example, irradiated from a light-emitting diode light source. In order to allow the photocuring reaction to proceed smoothly, the wavelength of the ultraviolet light irradiated in the protective layer formation step is preferably 200 nm to 420 nm, more preferably 270 nm to 420 nm, and more preferably 365 nm. The light energy of the ultraviolet light irradiated in the protective layer formation step is preferably 10,000 mW·s to 100,000 mW·s, and more preferably 60,300 mW·s to 86,400 mW·s. If the light energy of the ultraviolet light is 10,000 mW·s or more, the photocuring reaction will proceed sufficiently and the protective layer can be sufficiently cured. If the power is 100,000 mW·s or less, the decomposition of the hole transporter contained in the photosensitive layer can be further suppressed, and the sensitivity characteristics of the photoreceptor can be improved.

[0131] The photosensitive layer formation process and the protective layer formation process have been described above. The method for manufacturing the photoreceptor will now be described further.

[0132] The solvents contained in the above-mentioned single-layer photosensitive layer coating solution, charge generation layer coating solution, charge transport layer coating solution, and protective layer coating solution (hereinafter, these may be collectively referred to as "coating solution") are not particularly limited, as long as they can dissolve or disperse each component contained in the coating solution. Examples of solvents include alcohols (more specifically methanol, ethanol, isopropanol, and butanol), aliphatic hydrocarbons (more specifically n-hexane, octane, and cyclohexane), aromatic hydrocarbons (more specifically benzene, toluene, and xylene), halogenated hydrocarbons (more specifically methylene chloride, chloroform, ethylene chloride, dichloromethane, dichloroethane, carbon tetrachloride, and chlorobenzene), ethers (more specifically dioxane, dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, propylene glycol monomethyl ether, and diethylene glycol dimethyl ether), ketones (more specifically acetone, methyl ethyl ketone, 2-butanone, and cyclohexanone), esters (more specifically ethyl acetate and methyl acetate), dimethylformaldehyde, dimethylformamide, and dimethyl sulfoxide.

[0133] The coating solution is prepared by mixing each component and dissolving or dispersing them in a solvent. For mixing, for example, a bead mill, ball mill, roll mill, paint shaker, or ultrasonic disperser can be used.

[0134] The method of applying the coating solution is not particularly limited, as long as it allows for uniform application of the coating solution. Examples of application methods include dip coating, spray coating, bead coating, blade coating, and roller coating.

[0135] Methods for removing at least a portion of the solvent contained in the above-mentioned single-layer photosensitive layer coating solution, charge generation layer coating solution, and charge transport layer coating solution include, for example, heating, reduced pressure, or a combination of heating and reduced pressure. More specifically, a method of heat treatment (hot air drying) using a high-temperature dryer or a reduced-pressure dryer is used. The heat treatment temperature is, for example, 40°C to 150°C. The heat treatment time is, for example, 3 minutes to 150 minutes.

[0136] The method for manufacturing a photoreceptor may further include an intermediate layer formation step of forming an intermediate layer on a conductive substrate, if necessary. The intermediate layer formation step may be carried out by appropriately selecting a known method.

[0137] [Second Embodiment: Image Forming Apparatus] Next, with reference to Figure 6, an image forming apparatus 100, which is an example of an image forming apparatus according to a second embodiment of the present invention, will be described. Figure 6 is a diagram showing an example of the configuration of the image forming apparatus 100. The image forming apparatus 100 is, for example, a tandem-type color printer.

[0138] As shown in Figure 6, the image forming apparatus 100 comprises a control unit 15, an operating unit 20, a paper feeding unit 30, a transport unit 40, a toner supply unit 50, an image forming unit 60, a transfer device 70, a fixing device 80, and a discharge unit 90.

[0139] The control unit 15 controls the operation of each part of the image forming apparatus 100. The control unit 15 includes a processor (not shown) and a storage unit (not shown). The processor includes, for example, a CPU (Central Processing Unit). The storage unit includes memory such as semiconductor memory, and may also include an HDD (Hard Disk Drive). The processor controls the operation of the image forming apparatus 100 by executing a control program. The storage unit stores the control program.

[0140] The operation unit 20 receives instructions from the user. Upon receiving instructions from the user, the operation unit 20 transmits a signal indicating the user's instructions to the control unit 15. As a result, the image forming operation by the image forming apparatus 100 is started.

[0141] The paper feeding unit 30 includes a paper feeding cassette 31 and a group of paper feeding rollers 32. The paper feeding cassette 31 can accommodate multiple recording media P (for example, paper). The group of paper feeding rollers 32 feeds the recording media P stored in the paper feeding cassette 31 one sheet at a time to the transport unit 40.

[0142] The transport unit 40 is equipped with rollers and guide members. The transport unit 40 extends from the paper feeding unit 30 to the discharge unit 90. The transport unit 40 transports the recording medium P from the paper feeding unit 30 to the discharge unit 90, passing through the image forming unit 60 and the fixing device 80.

[0143] The toner supply unit 50 supplies toner to the image forming unit 60. The toner supply unit 50 comprises a first mounting unit 51Y, a second mounting unit 51C, a third mounting unit 51M, and a fourth mounting unit 51K.

[0144] The first toner container 52Y is mounted in the first mounting section 51Y. Similarly, the second toner container 52C is mounted in the second mounting section 51C, the third toner container 52M is mounted in the third mounting section 51M, and the fourth toner container 52K is mounted in the fourth mounting section 51K.

[0145] The first toner container 52Y, the second toner container 52C, the third toner container 52M, and the fourth toner container 52K each contain toner. In the second embodiment, the first toner container 52Y contains yellow toner. The second toner container 52C contains cyan toner. The third toner container 52M contains magenta toner. The fourth toner container 52K contains black toner.

[0146] The image forming unit 60 comprises an exposure apparatus 61, a first image forming unit 62Y, a second image forming unit 62C, a third image forming unit 62M, and a fourth image forming unit 62K.

[0147] Each of the first image forming units 62Y to the fourth image forming unit 62K includes a charging device 63, a developing device 64, an image carrier 65, a cleaning device 66, and a static elimination device 67.

[0148] Note that the configurations of the first image forming unit 62Y to the fourth image forming unit 62K are the same except for the type of toner supplied from the toner supply unit 50. Therefore, in Figure 6, the reference numerals are omitted for the components of the second image forming unit 62C to the fourth image forming unit 62K.

[0149] The image carrier 65 is the photoreceptor of the first embodiment (more specifically, the single-layer photoreceptor 1 and the stacked photoreceptor 10). As described in the first embodiment, the photoreceptor of the first embodiment has excellent wear resistance and can suppress the occurrence of image flow in the formed image. Therefore, the image forming apparatus 100 of the second embodiment has excellent wear resistance and can suppress the occurrence of image flow in the formed image.

[0150] In the second embodiment, the image carrier 65 rotates in the direction indicated by arrow R1 in Figure 6 (clockwise in Figure 6). The charging device 63, developing device 64, cleaning device 66, and static elimination device 67 are arranged along the circumferential surface of the image carrier 65 in the order listed from the upstream side in the rotational direction of the image carrier 65.

[0151] The charging device 63 charges the surface (circumferential surface) of the image carrier 65. The charging device 63 uniformly charges the image carrier 65 to a predetermined polarity by discharge. The charging device 63 is, for example, a charging roller.

[0152] The exposure apparatus 61 exposes the surface of the charged image carrier 65. More specifically, the exposure apparatus 61 irradiates the surface of the charged image carrier 65 with laser light. As a result, an electrostatic latent image is formed on the surface of the image carrier 65.

[0153] The developing device 64 receives toner from the toner supply unit 50. The developing device 64 supplies the toner supplied from the toner supply unit 50 to the surface of the image carrier 65. As a result, the electrostatic latent image formed on the surface of the image carrier 65 is developed as a toner image.

[0154] In the second embodiment, the developing device 64 of the first image forming unit 62Y is connected to the first toner container 52Y. Therefore, yellow toner is supplied to the developing device 64 of the first image forming unit 62Y. As a result, a yellow toner image is formed on the surface of the image carrier 65 of the first image forming unit 62Y.

[0155] Similarly, the developing device 64 of the second image forming unit 62C, the developing device 64 of the third image forming unit 62M, and the developing device 64 of the fourth image forming unit 62K are connected to the second toner container 52C, the third toner container 52M, and the fourth toner container 52K, respectively. Therefore, the developing devices 64 of the second image forming unit 62C, the third image forming unit 62M, and the fourth image forming unit 62K are supplied with cyan toner, magenta toner, and black toner, respectively. As a result, cyan toner images, magenta toner images, and black toner images are formed on the surfaces of the image carrier 65 of the second image forming unit 62C, the third image carrier 65 of the third image forming unit 62M, and the fourth image carrier 65 of the fourth image forming unit 62K, respectively.

[0156] The cleaning device 66 includes a cleaning member 661 and a scraping roller 662. After transfer by the primary transfer roller 71, which will be described later, the cleaning member 661 is pressed against the surface of the image carrier 65 to collect toner adhering to the surface of the image carrier 65. The cleaning member 661 is, for example, a cleaning blade. The scraping roller 662 scrapes the surface of the image carrier 65 to polish the surface of the image carrier 65.

[0157] The static elimination device 67 irradiates the surface of the image carrier 65 with static elimination light to eliminate static electricity from the surface of the image carrier 65.

[0158] The transfer device 70 transfers the toner image from the image carrier 65 to the recording medium P, which is the object to be transferred. Specifically, the transfer device 70 transfers each toner image formed on the surface of each image carrier 65 of the first image forming unit 62Y to the fourth image forming unit 62K onto the recording medium P. In the second embodiment, the transfer device 70 transfers each toner image onto the recording medium P using a secondary transfer method (intermediate transfer method). The transfer device 70 has four primary transfer rollers 71, an intermediate transfer belt 72, a drive roller 73, a driven roller 74, and a secondary transfer roller 75.

[0159] The intermediate transfer belt 72 is an endless belt stretched over four primary transfer rollers 71, a drive roller 73, and a driven roller 74. The intermediate transfer belt 72 is driven in accordance with the rotation of the drive roller 73. The intermediate transfer belt 72 rotates counterclockwise in Figure 6. The driven roller 74 is rotationally driven in accordance with the drive of the intermediate transfer belt 72.

[0160] The first image forming unit 62Y to the fourth image forming unit 62K are arranged facing the lower surface of the intermediate transfer belt 72. In the second embodiment, the first image forming unit 62Y to the fourth image forming unit 62K are arranged in the order of the first image forming unit 62Y to the fourth image forming unit 62K from the upstream side to the downstream side in the driving direction D of the lower surface of the intermediate transfer belt 72.

[0161] Each primary transfer roller 71 is positioned opposite each image carrier 65 via an intermediate transfer belt 72 and is pressed toward each image carrier 65. As a result, the toner images formed on the surface of each image carrier 65 are sequentially transferred to the intermediate transfer belt 72 by each primary transfer roller 71. In the second embodiment, yellow toner images, cyan toner images, magenta toner images, and black toner images are transferred to the intermediate transfer belt 72 in this order. Hereinafter, the toner image formed by the superimposition of yellow toner images, cyan toner images, magenta toner images, and black toner images may be referred to as a "layered toner image".

[0162] The secondary transfer roller 75 is positioned opposite the drive roller 73 via the intermediate transfer belt 72. The secondary transfer roller 75 is pressed toward the drive roller 73. This forms a transfer nip between the secondary transfer roller 75 and the drive roller 73. As the recording medium P passes through the transfer nip, the secondary transfer roller 75 transfers the laminated toner image on the intermediate transfer belt 72 to the recording medium P. In the second embodiment, the yellow toner image, cyan toner image, magenta toner image, and black toner image are transferred to the recording medium P in this order, from top to bottom. The recording medium P on which the laminated toner image has been transferred is transported toward the fuser 80 by the transport unit 40.

[0163] The fixing device 80 includes a heating element 81 and a pressurizing element 82. The heating element 81 and the pressurizing element 82 are arranged facing each other to form a fixing nip. The recording medium P, transported from the image forming unit 60, is heated to a predetermined fixing temperature and pressurized as it passes through the fixing nip. As a result, the stacked toner image is fixed to the recording medium P. The recording medium P is transported from the fixing device 80 to the discharge unit 90 by the transport unit 40.

[0164] The discharge unit 90 includes a pair of discharge rollers 91 and a discharge tray 93. The pair of discharge rollers 91 transports the recording medium P to the discharge tray 93 via a discharge port 92. The discharge port 92 is formed on the upper part of the image forming apparatus 100.

[0165] Next, the configuration of the developing apparatus 64 will be described in detail with reference to Figure 7. Figure 7 is a diagram showing an example of the configuration of the developing apparatus 64. Specifically, Figure 7 shows the developing apparatus 64 of the first image forming unit 62Y. In Figure 7, the image carrier 65 is shown with a dashed line for ease of understanding. In the second embodiment, the developing apparatus 64 employs a two-component developing method using a two-component developer and a touchdown developing method.

[0166] As already explained with reference to Figure 6, the developing container 640 of the developing device 64 is connected to the first toner container 52Y. Therefore, yellow toner is supplied to the developing container 640 of the developing device 64 through the toner supply port 640h.

[0167] As shown in Figure 7, the developing apparatus 64 has a developing roller 641, a magnetic roller 642, a first stirring screw 643, a second stirring screw 644, and a blade 645 inside the developing container 640. Specifically, the developing roller 641 is positioned opposite the magnetic roller 642. The magnetic roller 642 is positioned opposite the second stirring screw 644. The blade 645 is positioned opposite the magnetic roller 642.

[0168] The developing container 640 is divided into a first stirring chamber 640a and a second stirring chamber 640b by a partition wall 640c. The partition wall 640c extends in the axial direction of the developing roller 641. The first stirring chamber 640a and the second stirring chamber 640b are in communication with each other at the outer ends of the longitudinal direction of the partition wall 640c.

[0169] The first stirring chamber 640a houses the first stirring screw 643. The first stirring chamber 640a contains a carrier, which is a magnetic material. The first stirring chamber 640a is supplied with toner, which is a non-magnetic material, through the toner supply port 640h. In the example shown in Figure 7, yellow toner is supplied to the first stirring chamber 640a.

[0170] The second stirring chamber 640b houses the second stirring screw 644. The second stirring chamber 640b contains a carrier which is a magnetic material.

[0171] The yellow toner is agitated with the carrier by the first agitation screw 643 and the second agitation screw 644. As a result, a two-component developer containing the carrier and the yellow toner is formed. This two-component developer is then placed in the developing container 640 (more specifically, the first agitation chamber 640a and the second agitation chamber 640b).

[0172] The first stirring screw 643 and the second stirring screw 644 agitate the two-component developer between the first stirring chamber 640a and the second stirring chamber 640b while circulating it. As a result, the toner becomes charged to a predetermined polarity due to friction with the carrier.

[0173] When the image carrier 65 is a single-layer photoreceptor 1, the surface of the image carrier 65 and the toner are charged with, for example, a positive polarity. When the image carrier 65 is a multilayer photoreceptor 10, the surface of the image carrier 65 and the toner are charged with, for example, a negative polarity.

[0174] The magnetic roller 642 consists of a non-magnetic rotating sleeve 642a and a magnet body 642b. The magnet body 642b is fixedly positioned inside the rotating sleeve 642a. The magnet body 642b contains multiple magnetic poles. The two-component developer is attracted to the magnetic roller 642 by the magnetic force of the magnet body 642b. As a result, magnetic brushes are formed on the surface of the magnetic roller 642.

[0175] The blade 645 is positioned upstream of the magnetic roller 642 in the direction of rotation of the magnetic roller 642, above the position where the magnetic roller 642 and the developing roller 641 face each other. In the second embodiment, the magnetic roller 642 rotates in the direction indicated by arrow R3 in Figure 7 (counterclockwise in Figure 7). By rotating, the magnetic roller 642 transports the magnetic brush to a position facing the blade 645. The blade 645 is positioned such that a gap is formed between it and the magnetic roller 642. The blade 645 is made of a magnetic material. Therefore, the thickness of the magnetic brush is regulated by the magnetic force of the blade 645.

[0176] After the thickness of the magnetic brush on the magnetic roller 642 is regulated, a predetermined voltage is applied to the magnetic roller 642 and the developing roller 641. When the predetermined voltage is applied and a predetermined potential difference is reached between the magnetic roller 642 and the developing roller 641, the yellow toner contained in the two-component developer is transferred to the developing roller 641. As a result, a thin layer of yellow toner is formed on the surface of the developing roller 641.

[0177] The developing roller 641 rotates in the direction indicated by arrow R2 in Figure 7 (counterclockwise in Figure 7). This transports the thin layer of toner formed on the surface of the developing roller 641 to a position facing the image carrier 65, where it adheres to the image carrier 65. In this way, the developing device 64 supplies toner, which has been charged by friction with the carrier, to the surface of the image carrier 65.

[0178] The developing device 64 of the first image forming unit 62Y has been described above with reference to Figure 7. The configuration of the developing device 64 of each of the first image forming unit 62Y to the fourth image forming unit 62K is the same except for the type of toner supplied from the toner supply unit 50. Therefore, the configuration of the developing device 64 of the second image forming unit 62C to the fourth image forming unit 62K will not be described.

[0179] The image forming apparatus 100, an example of an image forming apparatus of the second embodiment, has been described above with reference to Figures 6 and 7. However, the image forming apparatus of the second embodiment is not limited to the image forming apparatus 100. For example, the image forming apparatus may be a monochrome image forming apparatus. In this case, the image forming apparatus only needs to have one image forming unit. The image forming apparatus may employ a rotary system. The charging device may be a charging device other than a charging roller (for example, a scorotron charger, a charging brush, or a scorotron charger). The image forming apparatus may employ a one-component development method using a one-component developer. The image forming apparatus may employ a development method other than the touchdown development method (for example, a development method in which there is no development roller and the magnetic roller also serves as the development roller). The image forming apparatus may employ a direct transfer method. When the image forming apparatus employs a direct transfer method, the toner image is directly transferred from the image carrier to the recording medium while the image carrier is in contact with the recording medium. The image forming apparatus does not need to be equipped with a cleaning device. The image forming apparatus does not need to be equipped with a static elimination device. The image forming apparatus of the second embodiment has been described above.

[0180] [Third Embodiment: Process Cartridge] Next, with continued reference to Figure 6, a first process cartridge 101, a second process cartridge 102, a third process cartridge 103, and a fourth process cartridge 104, which are examples of process cartridges according to the third embodiment of the present invention, will be described. The first to fourth process cartridges 101 to 104 of the third embodiment correspond to the first to fourth image forming units 62Y to 62K, respectively. Each of the first to fourth process cartridges 101 to 104 comprises an image carrier 65. The image carrier 65 is a photoreceptor of the first embodiment (more specifically, a single-layer photoreceptor 1 and a stacked photoreceptor 10).

[0181] As described in the first embodiment, the photoreceptor of the first embodiment has excellent wear resistance and can suppress the occurrence of image flow in the formed image. Therefore, the process cartridge of the third embodiment, which is equipped with the photoreceptor of the first embodiment, has excellent wear resistance and can suppress the occurrence of image flow in the formed image.

[0182] The process cartridge of the third embodiment may further include, in addition to the image carrier 65, at least one (for example, one to seven) selected from the group consisting of a charging device 63, an exposure device 61, a developing device 64, a transfer device 70 (particularly a primary transfer roller 71), a cleaning member 661, a rubbing roller 662, and a static elimination device 67.

[0183] The first process cartridge 101, second process cartridge 102, third process cartridge 103, and fourth process cartridge 104 shown in Figure 6 each include an image carrier 65, a charging device 63, a developing device 64, a cleaning device 66 having a cleaning member 661 and a rubbing roller 662, and a static elimination device 67, similar to the first image forming unit 62Y, second image forming unit 62C, third image forming unit 62M, and fourth image forming unit 62K. However, the process cartridges of the third embodiment are not limited to the first process cartridge 101 to the fourth process cartridge 104. As described above, the process cartridge of the third embodiment may further include at least one of the exposure device 61 and the transfer device 70, or it may include only one of the cleaning member 661 and the rubbing roller 662 (for example, only the cleaning member 661). In any case, the process cartridge of the third embodiment only needs to include the photoreceptor of the first embodiment as the image carrier 65.

[0184] The process cartridge of the third embodiment is designed to be detachably attached to the image forming apparatus 100. Therefore, the process cartridge is easy to handle, and if the sensitivity characteristics of the image carrier 65 deteriorate, it can be easily and quickly replaced, including the image carrier 65. The process cartridge of the third embodiment has been described above with reference to Figure 6.

[0185] [Substituent] The substituents used in this specification are described below. Examples of halogen atoms (halogen groups) include fluorine atoms (fluoro groups), chlorine atoms (chloro groups), bromine atoms (bromo groups), and iodine atoms (iodine groups).

[0186] Alkyl groups having 1 to 8 carbon atoms, alkyl groups having 1 to 6 carbon atoms, alkyl groups having 1 to 5 carbon atoms, and alkyl groups having 1 to 3 carbon atoms are, unless otherwise specified, linear or branched and unsubstituted. Examples of alkyl groups having 1 to 8 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, 1-methylbutyl group, 2-methylbutyl group, 3-methylbutyl group, 1-ethylpropyl group, 2-ethylpropyl group, 1,1-dimethylpropyl group, 1,2-dimethylpropyl group, 2,2-dimethylpropyl group, n-hexyl group, 1-methylpentyl group, and 2-methylpentyl group. Examples include the 1,1-methylbutyl group, 3-methylpentyl group, 4-methylpentyl group, 1,1-dimethylbutyl group, 1,2-dimethylbutyl group, 1,3-dimethylbutyl group, 2,2-dimethylbutyl group, 2,3-dimethylbutyl group, 3,3-dimethylbutyl group, 1,1,2-trimethylpropyl group, 1,2,2-trimethylpropyl group, 1-ethylbutyl group, 2-ethylbutyl group, 3-ethylbutyl group, linear and branched heptyl groups, and linear and branched octyl groups. Examples of alkyl groups having 1 to 6 carbon atoms, alkyl groups having 1 to 5 carbon atoms, and alkyl groups having 1 to 3 carbon atoms are, respectively, groups having the corresponding number of carbon atoms from the groups described as examples of alkyl groups having 1 to 8 carbon atoms.

[0187] Unless otherwise specified, alkoxy groups having 1 to 6 carbon atoms are linear or branched and unsubstituted. Examples of alkoxy groups having 1 to 6 carbon atoms include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, tert-butoxy, n-pentoxy, 1-methylbutoxy, 2-methylbutoxy, 3-methylbutoxy, 1-ethylpropoxy, 2-ethylpropoxy, 1,1-dimethylpropoxy, 1,2-dimethylpropoxy, 2,2-dimethylpropoxy, n-hexyloxy, and 1-methylpropoxy. Examples include the methylpentyloxy group, 2-methylpentyloxy group, 3-methylpentyloxy group, 4-methylpentyloxy group, 1,1-dimethylbutoxy group, 1,2-dimethylbutoxy group, 1,3-dimethylbutoxy group, 2,2-dimethylbutoxy group, 2,3-dimethylbutoxy group, 3,3-dimethylbutoxy group, 1,1,2-trimethylpropoxy group, 1,2,2-trimethylpropoxy group, 1-ethylbutoxy group, 2-ethylbutoxy group, and 3-ethylbutoxy group.

[0188] Unless otherwise specified, aryl groups having 6 to 14 carbon atoms and aryl groups having 6 to 10 carbon atoms are unsubstituted. Examples of aryl groups having 6 to 14 carbon atoms include the phenyl group, naphthyl group, indacenyl group, biphenylenyl group, acenaphthyrenyl group, anthryl group, and phenanthryl group. Examples of aryl groups having 6 to 10 carbon atoms are those groups among the examples of aryl groups having 6 to 14 carbon atoms that have the corresponding number of carbon atoms.

[0189] Alkenyl groups having 2 to 6 carbon atoms are linear or branched and unsubstituted unless otherwise specified. Alkenyl groups having 2 to 6 carbon atoms have one to three double bonds. Examples of alkenyl groups having 2 to 6 carbon atoms include ethenyl, propenyl, butenyl, butadienyl, pentenyl, hexenyl, hexadienyl, and hexatrinyl groups. The substituents used in this specification have been described above. [Examples]

[0190] The present invention will be described in more detail below using examples, but the present invention is not limited in any way to the scope of these examples.

[0191] [Compounds for forming halogen-containing resins] The following compounds were used to form the halogen-containing resin. • Compound (A-DPH): "A-DPH" manufactured by Shin-Nakamura Chemical Industry Co., Ltd. (a mixture of compounds represented by formulas (EA-3) and (EA-4) as described in the first embodiment; the compound represented by formula (EA-3) has 5 polymerizable functional groups, the compound represented by formula (EA-4) has 6 polymerizable functional groups, and a hydroxyl value of 10 mg KOH / g) • Compound (V-8F): "Viscoat 8F" manufactured by Osaka Organic Chemical Industry Co., Ltd. (a compound represented by formula (C-3) as described in the first embodiment, with 1 polymerizable functional group) • Compound (8FS): "8FS-001" manufactured by Taisei Fine Chemical Co., Ltd. (UV-curable fluorosilicone-modified acrylic polymer with vinyl groups, double bond equivalent (vinyl group equivalent): 420 g / mol) • Compound (8KX): "8KX-078" manufactured by Taisei Fine Chemical Co., Ltd. (UV-curable acrylic polymer with vinyl groups, double bond equivalent (vinyl group equivalent): 240 g / mol)

[0192] Compound (A-DPH) does not have a halogen group and can form a first repeating unit (M). Compound (8KX) does not have a halogen group and can form a first repeating unit (P). Compound (V-8F) has a halogen group and does not have a siloxane bond-containing group and can form a second repeating unit. Compound (8FS) has a halogen group and a siloxane bond-containing group and can form a third repeating unit. Although compounds (8FS) and (8KX) are polymers, they have vinyl groups and are therefore capable of vinyl polymerization reactions.

[0193] [Manufacturing of stacked photoreceptors] The stacked photoreceptors (P-A1) to (P-A9) and (P-B1) to (P-B7) were manufactured using the following method. The composition of these stacked photoreceptors is shown in Table 1, described later. The mass ratio of repeating units derived from the corresponding compounds to the mass of the halogen-containing resin composed of the compounds shown in Table 1 is shown in Table 2, described later.

[0194] <Manufacturing of stacked photoreceptor (P-A1)> (Formation of the intermediate layer) Two parts by mass of titanium dioxide, one part by mass of polyamide resin, ten parts by mass of methanol, one part by mass of butanol, and one part by mass of toluene were mixed using a bead mill for 5 hours to obtain mixture a. As titanium dioxide, prototype "SMT-A" manufactured by Teika Co., Ltd. (number average primary particle size of 10 nm, titanium dioxide primary surface-treated with alumina and silica, and then secondary surface-treated with methylhydrogenpolysiloxane) was used. As polyamide resin, "Amiran® ​​CM8000" manufactured by Toray Industries, Inc. (a quaternary copolymer polyamide resin of polyamide 6, polyamide 12, polyamide 66, and polyamide 610) was used. The obtained mixture a was filtered using a 5 μm mesh filter to obtain an intermediate layer coating solution. Next, the intermediate layer coating solution was applied to the surface of a conductive substrate by dip coating. An aluminum drum-shaped support was used as the conductive substrate. Next, the applied intermediate layer coating solution was dried at 130°C for 30 minutes to form an intermediate layer (film thickness: 0.5 μm) on the conductive substrate.

[0195] (Formation of a charge generation layer) 1.5 parts by mass of Y-type titanyl phthalocyanine as a charge generating agent, 1.0 part by mass of polyvinyl acetal resin ("Esrec BX-5" manufactured by Sekisui Chemical Co., Ltd.) as a base resin, 40.0 parts by mass of propylene glycol monomethyl ether, and 40.0 parts by mass of tetrahydrofuran were mixed using a bead mill for 12 hours to obtain a mixed solution d. The obtained mixed solution d was filtered using a filter with a pore size of 3 μm to obtain a coating solution for the charge generation layer. Next, the coating solution for the charge generation layer was applied to the intermediate layer on the conductive substrate by the dip coating method. The applied coating solution for the charge generation layer was dried at 50 °C for 5 minutes to form a charge generation layer (film thickness: 0.3 μm) on the intermediate layer.

[0196] (Formation of Charge Transport Layer) 60.00 parts by mass of a hole transport agent (HT-2) and 30.00 parts by mass of a hole transport agent (HT-3), 100.00 parts by mass of bisphenol Z-type polycarbonate resin, 0.05 part by mass of a leveling agent, 340.00 parts by mass of tetrahydrofuran, and 60.00 parts by mass of toluene were mixed using a roll mill for 24 hours to obtain a coating solution for the charge transport layer. As the bisphenol Z-type polycarbonate resin, "Upizer PCZ-200" (viscosity average molecular weight 21,500, glass transition point 174 °C) manufactured by Mitsubishi Gas Chemical Company, Inc. was used. As the leveling agent, dimethyl silicone oil ("KF96-50CS" manufactured by Shin-Etsu Chemical Co., Ltd.) was used. Next, the coating solution for the charge transport layer was applied to the charge generation layer by the dip coating method. The applied coating solution for the charge transport layer was dried at 120 °C for 40 minutes to form a charge transport layer (film thickness: 25 μm) on the charge generation layer.

[0197] (Formation of Protective Layer) 10 parts by mass of indium-doped tin oxide, 6 parts by mass of alumina, 33 parts by mass of compound (V-8F), 1 part by mass of compound (8FS), 56 parts by mass of compound (8KX), 10 parts by mass of a polymerization initiator, and 110 parts by mass of methanol were mixed using a bead mill for 12 hours to obtain a mixed solution c. As the indium-doped tin oxide, "SP-2" (BET specific surface area 105 ± 25 m 2 / g) was used. As the alumina, “Nanotek Al2O3” manufactured by CIK Nanotech Co., Ltd. (BET specific surface area: 55 m 2 / g, number average primary particle diameter: 31 nm) was used. As the polymerization initiator, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (“OMNIRAD TPO” manufactured by IGM RESINS) was used. The obtained mixed solution c was filtered using a filter with a pore size of 5 μm to obtain a coating solution for the protective layer.

[0198] Next, the coating solution for the protective layer was applied onto the charge transport layer by the dip coating method. The applied coating solution for the protective layer was irradiated with ultraviolet light having a wavelength of 365 nm and 86400 mW·seconds. By the irradiation of the ultraviolet light, the compound for forming the halogen-containing resin in the coating solution for the protective layer was polymerized (photo-curing reaction), and the halogen-containing resin was formed. In this way, a protective layer (film thickness: 2.0 μm) was formed on the charge transport layer, and a laminated photoreceptor (P-A1) was obtained. The protective layer contained a halogen-containing resin cured by the photo-curing reaction, indium-doped tin oxide, alumina, and a polymerization initiator.

[0199] <Production of laminated photoreceptors (P-A2) to (P-A7) and (P-B1) to (P-B6)> The laminated photoreceptors (P-A2) to (P-A7) and (P-B1) to (P-B6) were produced in the same manner as the production of the laminated photoreceptor (P-A1), except that the compounds for forming the halogen-containing resin of the types and amounts shown in Table 1 were used.

[0200] <Production of laminated photoreceptor (P-A8)> The laminated photoreceptor (P-A8) was produced in the same manner as the production of the laminated photoreceptor (P-A1), except that the compounds for forming the halogen-containing resin of the types and amounts shown in Table 1 were used, and 60.00 parts by mass of the hole transport agent (HT-2) and 30.00 parts by mass of the hole transport agent (HT-3) were changed to 45.00 parts by mass of the hole transport agent (HT-2) and 25.00 parts by mass of the hole transport agent (HT-3).

[0201] <Production of laminated photoreceptor (P-A9)> A stacked photoreceptor (P-A9) was manufactured in the same manner as the stacked photoreceptor (P-A1), except that the compounds for forming the halogen-containing resin of the types and amounts shown in Table 1 were used, and the 60.00 parts by mass of hole transporter (HT-2) and 30.00 parts by mass of hole transporter (HT-3) were changed to 75.00 parts by mass of hole transporter (HT-2) and 35.00 parts by mass of hole transporter (HT-3).

[0202] <Manufacturing of stacked photoreceptor (P-B7)> The stacked photoreceptor (P-B7) was manufactured using the same method as the stacked photoreceptor (P-A1), except that the protective layer described above was not formed.

[0203] [Measurement of stacked photoreceptors] The predetermined halogen ratios and Martens hardness of the protective layers of the stacked photoreceptors (P-A1) to (P-A9) and (P-B1) to (P-B7) were measured by the following method. The measurement results are shown in Table 1.

[0204] <Specified halogen ratio> First, for the compounds containing halogen atoms among those contained in the protective layer, the percentage of the mass of halogen atoms relative to the mass of the halogen-containing compound (hereinafter sometimes referred to as the halogen atom percentage) was measured. Among the compounds contained in the protective layer of each multilayer photoreceptor, the compounds containing halogen atoms were compound (8FS) and compound (V-8F).

[0205] The halogen atom percentage of compound (8FS) was measured by the following method. Elemental analysis of compound (8FS) was performed using a scanning electron microscope (SEM, Hitachi High-Tech Corporation's "Regulus® 8200") equipped with an energy-dispersive X-ray spectrometer (EDX, Oxford Instruments' "EDX Aztec 4.1") under the following measurement conditions, and the composition ratio of each element contained in compound (8FS) was measured. From the composition ratio of each element and the atomic weight of each element, the percentage of the mass of halogen atoms (more specifically, fluorine atoms) in the mass of compound (8FS) was calculated. The halogen atom percentage of compound (8FS) was 8.6% by mass.

[0206] (Measurement conditions) Acceleration voltage: 5kV Spot size (setting for aperture adjustment): 60 X-ray fluorescence intensity measurement range: 0 cps to 500 cps Count: 50 Magnification: 100x

[0207] Since the chemical formula of compound (V-8F) is known, instead of using measurements obtained by SEM-EDX, the calculated value from the following formula was used as the halogen atom percentage of compound (V-8F). Specifically, the halogen atom percentage of compound (V-8F) was determined from the formula "Halogen atom percentage of compound (V-8F) = 100 × (atomic weight of halogen atom × number of halogen atoms) / (molecular weight of compound (V-8F))". The halogen atom percentage of compound (V-8F) was 53.1 mass% (= 100 × (19 × 8) / 286).

[0208] The predetermined halogen ratio of the protective layer was determined from the halogen atom percentages of compound (8FS) and compound (V-8F) according to the following formula: "(Determined halogen ratio) = (Mass of halogen atoms contained in the protective layer) / (Mass of protective layer) = {(Mass of compounds containing halogen atoms contained in the protective layer) × [(Halogen atom percentage) / 100]} / [Mass of protective layer] = {(Mass of compound (V-8F)) × [(Halogen atom content of compound (V-8F)) / 100] + (Mass of compound (8FS)) × [(Halogen atom content of compound (8FS)) / 100]} / [(Mass of phosphorus-doped tin oxide) + (Mass of alumina) + (Mass of compound (A-DPH)) + (Mass of compound (V-8F)) + (Mass of compound (8FS)) + (Mass of compound (8KX)) + (Mass of polymerization initiator)]" to determine the predetermined halogen ratio of the protective layer. For example, the predetermined halogen ratio in the protective layer of the stacked photoreceptor (P-A1) was 15.2% by mass (={33 × [53.1 / 100] + 1 × [8.6 / 100]} / [10 + 6 + 0 + 33 + 1 + 56 + 10]).

[0209] <Martens hardness> The Martens hardness of the protective layer was measured by nanoindentation in accordance with ISO 14577. Using a hardness tester (FISCHERSCOPE® HM2000XYp, manufactured by Fischer Instruments Co., Ltd.), the following measurement conditions were used to determine the Martens hardness of the protective layer (unit: N / mm²) at the point when the indenter depth reached 0.4 μm. 2 ) was measured.

[0210] (Measurement conditions) Measurement environment: Temperature 23°C and relative humidity 50%RH Indenter: Diamond-made square pyramidal indenter with 135-degree face angles. Indenter penetration direction: The indenter penetrates from the outer surface of the protective layer in the direction of the thickness of the protective layer. Indenter indentation depth: 0.4 μm Load application acceleration: 10mN / 20 seconds Load holding time: 5 seconds Unloading speed: 10mN / 20 seconds Maximum indentation load: 10mN

[0211] [Evaluation of the laminated photoreceptor] The initial sensitivity characteristics, abrasion resistance, and image flow of the laminated photoreceptors (P-A1) to (P-A9) and (P-B1) to (P-B7) were evaluated by the following methods.

[0212] [Initial sensitivity characteristics] Under an environment of a temperature of 23°C and a relative humidity of 50% RH, the sensitivity characteristics of the photoreceptor were evaluated using a drum sensitivity tester (manufactured by Gentec). Using the drum sensitivity tester, the surface of the photoreceptor was charged to -550 V. Next, monochromatic light (wavelength: 780 nm, exposure amount: 0.87 μJ / cm 2 ) was extracted from the light of a halogen lamp using a band-pass filter and irradiated onto the surface of the photoreceptor. The surface potential of the photoreceptor was measured at the time when 50 milliseconds had elapsed since the end of the irradiation of the monochromatic light. The measured surface potential was defined as the post-exposure potential VL (unit: -V) of the photoreceptor. The post-exposure potential VL is shown in Table 3. The criteria for determining the initial sensitivity characteristics of the photoreceptor are shown below.

[0213] [Criteria for initial sensitivity characteristics] Good: The absolute value of VL is 150 V or less. Poor: The absolute value of VL exceeds 150 V.

[0214] [Abrasion resistance] A color printer (OKI Data Corporation's "C711dn") was used as an evaluation machine for the abrasion resistance of a stacked photoreceptor. Cyan toner was filled into the evaluation machine's toner cartridge. First, the film thickness T1 of the photosensitive layer of the photoreceptor was measured. Next, the photoreceptor was mounted in the evaluation machine. Then, under normal temperature and humidity conditions of 23°C and 50% RH, image I (a pattern image with a print density of 1%) was printed on 10,000 sheets of paper using the evaluation machine. Next, under high temperature and high humidity conditions of 32°C and 85% RH, image I was printed on 10,000 sheets of paper using the evaluation machine. Next, under low temperature and low humidity conditions of 10°C and 15% RH, image I was printed on 10,000 sheets of paper using the evaluation machine. After printing under low temperature and low humidity conditions, the evaluation machine was left to stand for 2 hours. Next, under low temperature and low humidity conditions, a solid image (image with 100% image density) was printed on a single sheet of paper using an evaluation machine. Afterward, the film thickness T2 of the photosensitive layer of the photoreceptor was measured. Then, the amount of abrasion (T1-T2, unit: μm), which is the change in the film thickness of the photosensitive layer before and after printing, was determined. The measured abrasion amounts are shown in Table 1. The criteria for judging the abrasion resistance of the photoreceptor are shown below.

[0215] (Abrasion resistance standards) Good: The amount of wear is 0.5 μm or less. Defective: The amount of wear exceeds 0.5 μm.

[0216] <Image sequence> To evaluate the suppression of image flow in the formed image, a modified color multifunction printer (Taskalfa 356ci, manufactured by Kyocera Document Solutions Inc.) that had been modified to be negatively charged was used as the evaluation machine. This evaluation machine was equipped with a charging roller made of epichlorohydrin resin with dispersed conductive carbon. The development method of this evaluation machine was a two-component development method. This evaluation machine was equipped with a cleaning blade, a friction roller, and a static eliminator. Cyan toner was filled into the toner cartridge of the evaluation machine.

[0217] Image flow in the formed image was evaluated under high temperature and high humidity conditions of 32°C and 80% RH relative humidity. A single-layer photoreceptor was mounted in the evaluation machine. Using the evaluation machine, Image II (a character image with an image density of 1.6%) was printed on one sheet of paper. The dots constituting the characters in the printed Image II were observed using a microscope. The image flow in the formed image was then judged according to the following criteria. A judgment of A indicated that the occurrence of image flow in the formed image was suppressed. A judgment of B or C indicated that the occurrence of image flow in the formed image was not suppressed. The judgment results are shown in Table 3.

[0218] (Image flow criteria) A: All the dots that should appear within the microscope field of view are printed on it. B: Some of the dots that should appear in the microscope field of view are missing, but the number of missing dots is less than half. C: Of the total dots that should appear in the microscope field of view, some dots are missing, and the number of missing dots is more than half.

[0219] [Table 1]

[0220] [Table 2]

[0221] [Table 3]

[0222] The terms used in Tables 1 to 3 are as follows. Note that the amounts (in parts by mass) shown in the "Compounds for Resin Formation" column of Table 1 represent the solid content (in parts by mass) of the compound used to form the halogen-containing resin. Compounds for resin formation: Compounds for forming halogen-containing resins. Part: Mass part %:mass% Halogen ratio: Predetermined halogen ratio Hardness: Martens hardness HTM: Hole transport agent HTM content: The percentage of hole transporter relative to the mass of the charge transport layer. Unit content: The mass ratio of repeating units derived from the relevant compound to the mass of the halogen-containing resin. Actual: Example Comparison: Comparative Example

[0223] As shown in Table 1, the predetermined halogen ratio of the protective layer of the stacked photoreceptors (P-B1) to (P-B2) was less than 2% by mass. As shown in Table 3, the image flow judgment of the stacked photoreceptors (P-B1) to (P-B2) was B or C, indicating that the occurrence of image flow in the formed image was not suppressed.

[0224] As shown in Table 1, the predetermined halogen content of the protective layer of the multilayer photoreceptor (P-B3) is over 20% by mass, and the Martens hardness of the protective layer is 280 N / mm². 2 The value was less than 0.5 μm. As shown in Table 3, the wear of the stacked photoreceptor (P-B3) was greater than 0.5 μm, indicating poor wear resistance.

[0225] As shown in Table 1, the Martens hardness of the protective layer of the stacked photoreceptor (P-B4) to (P-B5) is 280 N / mm². 2 The values ​​were less than 0.5 μm. As shown in Table 3, the wear of the stacked photoreceptors (P-B4) to (P-B5) was greater than 0.5 μm, indicating poor wear resistance.

[0226] As shown in Table 1, the Martens hardness of the protective layer of the stacked photoreceptor (P-B6) is 450 N / mm². 2 The result was "B". As shown in Table 3, the image flow of the stacked photoreceptor (P-B6) was judged as "B", indicating that the occurrence of image flow was not suppressed in the formed image.

[0227] As shown in Table 1, the stacked photoreceptor (P-B7) lacked a protective layer. The wear of the stacked photoreceptor (P-B7) exceeded 0.5 μm, indicating poor wear resistance.

[0228] As shown in Table 1, the predetermined halogen content of the protective layer of the stacked photoreceptors (P-A1) to (P-A9) is 2% by mass or more and 20% by mass or less, and the Martens hardness of the protective layer is 280 N / mm². 2 More than 450N / mm 2 The following results were obtained. As shown in Table 3, the image flow of the stacked photoreceptors (P-A1) to (P-A9) was rated A, indicating that the occurrence of image flow in the formed image was suppressed. As shown in Table 3, the wear amount of the stacked photoreceptors (P-A1) to (P-A9) was 0.5 μm or less, indicating good wear resistance. Furthermore, the stacked photoreceptors (P-A1) to (P-A9) also exhibited good initial sensitivity characteristics.

[0229] [Manufacturing of single-layer photoreceptors] A single-layer photoreceptor (P-C1) was manufactured using the following method. The composition of this single-layer photoreceptor is shown in Table 4, which will be described later. The mass ratio of repeating units derived from the corresponding compounds to the mass of the halogen-containing resin composed of the compounds shown in Table 4 is shown in Table 5, which will be described later.

[0230] <Manufacturing of single-layer photoreceptor (P-C1)> (Formation of a single-layer photosensitive layer) Mixture b was obtained by mixing 2.85 parts by mass of Y-type titanyl phthalocyanine, 60.00 parts by mass of hole transporter (HT-2), 30.00 parts by mass of hole transporter (HT-3), 30.00 parts by mass of electron transporter (ET-1), 30.00 parts by mass of electron transporter (ET-6), 70.00 parts by mass of bisphenol Z-type polycarbonate resin, 0.02 parts by mass of leveling agent, and 500.00 parts by mass of tetrahydrofuran using a rod-shaped sonic oscillator for 20 minutes. As the bisphenol Z-type polycarbonate resin, "Yupizeta PCZ-200" (viscosity-average molecular weight 21,500, glass transition temperature 174°C) manufactured by Mitsubishi Gas Chemical Company, Inc. was used. Dimethyl silicone oil ("KF96-50CS" manufactured by Shin-Etsu Chemical Co., Ltd.) was used as the leveling agent. The resulting mixture b was filtered using a 5 μm mesh filter to obtain a coating solution for a single-layer photosensitive layer. Next, the coating solution for the single-layer photosensitive layer was applied to a conductive substrate by dip coating. An aluminum drum-shaped support was used as the conductive substrate. The applied coating solution for the single-layer photosensitive layer was dried at 110°C for 60 minutes to form a single-layer photosensitive layer (film thickness: 25 μm) on the conductive substrate.

[0231] (Formation of a protective layer) The protective layer of the single-layer photoreceptor (P-C1) was formed in the same manner as the protective layer of the multilayer photoreceptor (P-A1), except that the compounds for forming the halogen-containing resin shown in Table 4 were used, and the protective layer coating solution was applied to the single-layer photoreceptor layer instead of the charge transport layer.

[0232] [Measurement of single-layer photoreceptor] The predetermined halogen ratio and Martens hardness of a single-layer photoreceptor (P-C1) were measured using the same method as for multilayer photoreceptors. The measurement results are shown in Table 4.

[0233] [Evaluation of single-layer photoreceptors] The initial sensitivity characteristics, wear resistance, and image distortion of the single-layer photoreceptor (P-C1) were evaluated using the following method.

[0234] <Initial Sensitivity Characteristics> The sensitivity characteristics of the single-layer photoreceptor were evaluated using the same method as for evaluating the sensitivity characteristics of the multilayer photoreceptor, except that the surface of the photoreceptor was charged to +550V instead of -550V. The measured VL (unit: +V) is shown in Table 6.

[0235] <Abrasion Resistance> The abrasion resistance of the single-layer photoreceptor was evaluated using the same method as for evaluating the abrasion resistance of the stacked photoreceptor, except that the evaluation machine was changed from a color printer (OKI DATA Corporation's "C711dn") to a modified color multifunction printer (Kyocera Document Solutions Corporation's "Taskalfa 356ci"). The measured abrasion amounts are shown in Table 6.

[0236] <Image sequence> Except for restoring the negative charge of the evaluation unit to a positive charge, the image flow of the single-layer photoreceptor was evaluated using the same method as for evaluating the image flow of the stacked photoreceptor. The results are shown in Table 6.

[0237] [Table 4]

[0238] [Table 5]

[0239] [Table 6]

[0240] The terms "resin-forming compound," "parts," "%," "halogen ratio," "hardness," "HTM," "unit content," and "actual" used in Tables 4 to 6 have the same meaning as the terms explained in Tables 1 to 3. Note that the amounts (unit: parts by mass) shown in the "resin-forming compound" column of Table 4 represent the solid content (unit: parts by mass) of the compound used to form the halogen-containing resin. Furthermore, the "HTM content" in Table 4 indicates the content of the hole transporter relative to the mass of the single-layer photosensitive layer.

[0241] As shown in Table 4, the predetermined halogen content of the protective layer of the single-layer photoreceptor (P-C1) is 2% by mass or more and 20% by mass or less, and the Martens hardness of the protective layer is 280 N / mm². 2 More than 450N / mm 2 The following results were obtained. As shown in Table 6, the image flow of the single-layer photoreceptor (P-C1) was rated A, indicating that image flow was suppressed in the formed image. As shown in Table 6, the wear amount of the single-layer photoreceptor (P-C1) was 0.5 μm or less, indicating good wear resistance. Furthermore, the single-layer photoreceptor (P-C1) also exhibited good initial sensitivity characteristics.

[0242] From the above, it has been shown that the photoreceptor of the present invention, which includes stacked photoreceptors (P-A1) to (P-A9) and single-layer photoreceptor (P-C1), has excellent wear resistance and can suppress the occurrence of image flow in the formed image. Furthermore, because such a photoreceptor is provided, it is determined that the process cartridge and image forming apparatus of the present invention have excellent wear resistance of the photoreceptor and can suppress the occurrence of image flow in the formed image. [Industrial applicability]

[0243] The photoreceptor and process cartridge according to the present invention can be used in an image forming apparatus. The image forming apparatus according to the present invention can be used to form an image on a recording medium.

Claims

1. An electrophotographic photoreceptor comprising a conductive substrate, a photosensitive layer, and a protective layer, The photosensitive layer contains a charge generating agent and a hole transporting agent, The protective layer is the outermost layer of the electrophotographic photoreceptor and contains a resin having halogen groups. The mass ratio of halogen atoms contained in the protective layer to the mass of the protective layer is 2% by mass or more and 20% by mass or less. The Martens hardness of the aforementioned protective layer is 280 N / mm². ２ 450N / mm or more ２ The following: The resin comprises a first repeating unit, a second repeating unit, and a third repeating unit. The first repeating unit does not have the halogen group, The second repeating unit has the halogen group and does not have a siloxane bond-containing group. The third repeating unit is an electrophotographic photoreceptor having the halogen group and the siloxane bond-containing group.

2. The mass ratio of the second repeating unit to the mass of the resin is 3.0% by mass or more and 42.0% by mass or less. The electrophotographic photoreceptor according to claim 1, wherein the mass ratio of the third repeating unit to the mass of the resin is 1.0% by mass or more and 45.0% by mass or less.

3. The electrophotographic photoreceptor according to claim 1, wherein the second repeating unit includes a repeating unit derived from a compound represented by formula (EB-1). 【Chemistry 1】 (In the above formula (EB-1), R １ represents the group represented by formula (b1), and R ２ (This represents a hydrogen atom or a methyl group.) 【Chemistry 2】 (In formula (b1) above, m represents 0 or 1, n represents an integer between 1 and 3, R ３ (where * represents a hydrogen atom or a fluorine atom, and * represents a bonding bond.)

4. The electrophotographic photoreceptor according to claim 1, wherein the third repeating unit includes repeating units derived from a fluorosilicone-modified acrylic polymer having a vinyl group.

5. The electrophotographic photoreceptor according to claim 1, wherein the first repeating unit includes a repeating unit derived from a compound represented by formula (EA-3) and a repeating unit derived from a compound represented by formula (EA-4). 【Transformation 3】

6. The electrophotographic photoreceptor according to claim 1, wherein the thickness of the protective layer is 1 μm or more and 4 μm or less.

7. The electrophotographic photoreceptor according to claim 1, wherein the hole transport agent contained in the photosensitive layer comprises at least one of the compounds represented by formulas (1) and (2). 【Chemistry 4】 (In the above formula (1), R ４１ , R ４２ , R ４３ , R ４４ , R ４５ , and R ４６ each independently represents an alkyl group having 1 to 8 carbon atoms or a phenyl group, and R ４７ and R ４８ each independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a phenyl group, and e １ , e ２ , e ３ , and e ４ each independently represents an integer of 0 or more and 5 or less, and e ５ and e ６ each independently represents an integer of 0 or more and 4 or less, In the above formula (2), R ５０ , R ５１ , and R ５４ Each independently represents an alkyl group having 1 to 8 carbon atoms, or a phenyl group, R ５２ , and R ５３ Each independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a phenyl group which may be substituted with an alkyl group having 1 to 8 carbon atoms, and f ３ , f ４ , and f ５ Each of these independently represents an integer between 0 and 5 (inclusive).

8. The electrophotographic photoreceptor according to claim 1, wherein the charge generating agent contained in the photosensitive layer comprises titanylphthalocyanine.

9. The photosensitive layer includes a charge generation layer and a charge transport layer. The charge generating layer contains the charge generating agent, The charge transport layer contains the hole transport agent, The electrophotographic photoreceptor according to claim 1, wherein the content of the hole transporter in the charge transport layer is 40% by mass or more relative to the mass of the charge transport layer.

10. At least one selected from the group consisting of a charging device, an exposure device, a developing device, a transfer device, a cleaning member, a friction roller, and a static elimination device, A process cartridge comprising an electrophotographic photoreceptor as described in claim 1.

11. Image carrier and, A charging device for charging the surface of the image carrier, An exposure apparatus for exposing the surface of the charged image carrier to form an electrostatic latent image on the surface of the image carrier, A developing apparatus that supplies toner to the surface of the image carrier and develops the electrostatic latent image as a toner image, The system comprises a transfer device for transferring the toner image from the image carrier to the transfer target, An image forming apparatus wherein the image carrier is the electrophotographic photoreceptor described in claim 1.

12. A cleaning member for collecting the toner adhering to the surface of the image carrier, A friction roller for rubbing the surface of the image carrier, and A static elimination device for removing static electricity from the surface of the image carrier. The image forming apparatus according to claim 11, further comprising at least one selected from the group consisting of the following.

13. The image forming apparatus according to claim 11, wherein the charging device is a charging roller.

14. The image forming apparatus according to claim 11, wherein the developing apparatus supplies the toner, which has been charged by friction with the carrier, to the surface of the image carrier.

Images