CN107450289B - Electrophotographic photoreceptor, process cartridge, and image forming apparatus - Google Patents

Abstract

The invention provides an electrophotographic photoreceptor, a process cartridge and an image forming apparatus. An electrophotographic photoreceptor includes a conductive substrate and a photosensitive layer. The photosensitive layer is one layer. The photosensitive layer contains a charge generator, an electron transporting agent, a hole transporting agent, and a binder resin. The binder resin contains a polycarbonate resin represented by the following general formula (1). The electron transport agent contains a compound represented by the following general formula (2). In the general formula (1), R¹、R²、R³、R⁴、R⁵、R⁶Y, m and n are respectively corresponding to R in the specification¹、R²、R³、R⁴、R⁵、R⁶Y, m and n have the same meaning. In the general formula (2), R⁷And R in the specification⁷Have the same meaning. [ CHEM 1 ]

[ CHEM 2 ]

Description

Electrophotographic photoreceptor, process cartridge, and image forming apparatus

Technical Field

The present invention relates to an electrophotographic photoreceptor (hereinafter, may be referred to as a photoreceptor), a process cartridge, and an image forming apparatus.

Background

The photoreceptor is used in an electrophotographic image forming apparatus. The photoreceptor is provided with a photosensitive layer. The photoreceptor includes a multilayer photoreceptor and a single-layer photoreceptor. The photosensitive layer in the laminated photoreceptor is a charge generation layer having a charge generation function and a charge transport layer having a charge transport function. The photosensitive layer in the single layer type photoreceptor is a one-layer photosensitive layer having a charge generating function and a charge transporting function.

For example, compounds represented by chemical formula (2-11) are known as electron transport materials (electron transporters).

[ CHEM 1 ]

Disclosure of Invention

However, the present inventors have found that the compounds represented by the formula (2-11) are not sufficiently effective in suppressing the occurrence of white spots in formed images.

The present invention has been made in view of the above problems, and an object thereof is to provide a photoreceptor which can suppress the occurrence of white spots in a formed image. Further, it is an object of the present invention to provide a process cartridge and an image forming apparatus, which are capable of suppressing the occurrence of white spots in a formed image by providing the above-described photoreceptor to the process cartridge and the image forming apparatus.

The electrophotographic photoreceptor of the present invention includes a conductive substrate and a photosensitive layer. The photosensitive layer is a layer. The photosensitive layer contains a charge generator, an electron transporting agent, a hole transporting agent, and a binder resin. The binder resin contains a polycarbonate resin represented by the following general formula (1). The electron transport agent contains a compound represented by the following general formula (2).

[ CHEM 2 ]

In the general formula (1), R¹、R²、R⁵And R⁶Independently of each other, represents: a halogen atom, a C1-C6 alkyl group having 1 or more halogen atoms, a C1-C6 alkoxy group having 1 or more halogen atoms, a C6-C14 aryl group having 1 or more halogen atoms, a hydrogen atom, a C1-C6 alkyl group, a C1-C6 alkoxy group, or a C6-C14 aryl group. R¹、R²、R⁵And R⁶Represents: a halogen atom, a C1-C6 alkyl group having 1 or more halogen atoms, a C1-C6 alkoxy group having 1 or more halogen atoms, or a C6-C14 aryl group having 1 or more halogen atoms. R³And R⁴Independently of each other, represents: a hydrogen atom, an optionally substituted C1-C6 alkyl group, an optionally substituted C1-C6 alkoxy group or an optionally substituted C6-C14 aryl group. Y represents: a single bond, optionally substituted C2-C18 alkylene (cycloalkylene), optionally substituted C5-C15 cycloalkylene (cycloalkylalkylene), optionally substituted C5-C15 cycloalkylene (cycloalkylalkylene), -S-, -SO-, -O-or-CO-. m and n are independent of each other and satisfy the following equations (i) and (ii).

m+n＝1.0…(i)

0.0＜m≤1.0…(ii)

In the present specification, the term "optionally substituted" means that the number of substituents is 0 or 1 or more.

[ CHEM 3 ]

In the general formula (2), R⁷Represents: a C1-C8 alkyl group having 1 or more halogen atoms, a C3-C10 cycloalkyl group having 1 or more halogen atoms, a C6-C14 aryl group having 1 or more halogen atoms and which may have a C1-C6 alkyl group, a 5-to 14-membered heterocyclic group having 1 or more halogen atoms, or a C7-C20 aralkyl group having 1 or more halogen atoms.

The process cartridge of the present invention includes the electrophotographic photoreceptor.

An image forming apparatus of the present invention includes: an electrophotographic photoreceptor, a charging section, an exposure section, a developing section, and a transfer section. The charging section charges a surface of the electrophotographic photoreceptor. The exposure section exposes the surface of the charged electrophotographic photoreceptor to form an electrostatic latent image on the surface of the electrophotographic photoreceptor. The developing section develops the electrostatic latent image into a toner image. The transfer section transfers the toner image from the electrophotographic photoreceptor to a recording medium. When the transfer portion transfers the toner image from the electrophotographic photoreceptor to the recording medium, the electrophotographic photoreceptor is held in contact with the recording medium. The electrophotographic photoreceptor is the above electrophotographic photoreceptor.

According to the photoreceptor of the present invention, the occurrence of white spots on a formed image can be suppressed. Further, according to the process cartridge and the image forming apparatus of the present invention, by providing the photoreceptor, it is possible to suppress the occurrence of white spots in the formed image.

Drawings

Fig. 1(a), 1(b), and 1(c) are partial sectional views each showing an example of a photoreceptor according to an embodiment of the present invention.

Fig. 2 is a diagram for explaining a method of measuring the charge amount of calcium carbonate after the photosensitive layer and calcium carbonate are rubbed.

Fig. 3 is a diagram showing an example of the configuration of an image forming apparatus including a photoreceptor according to an embodiment of the present invention.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments in any way. The present invention can be implemented with appropriate modifications within the intended scope. Note that, although the description thereof may be omitted as appropriate, the gist of the present invention is not limited thereto.

Hereinafter, the compound and its derivatives may be collectively referred to by adding "class" to the compound name. When a "class" is added to a compound name to indicate a polymer name, the repeating unit indicating the polymer is derived from the compound or a derivative thereof. The reactions represented by the reaction equations (R-1) to (R-4) may be referred to as reactions (R-1) to (R-4), respectively.

Unless otherwise specified, the halogen atoms, C1-C6 alkyl groups, C1-C6 alkoxy groups and C6-C14 aryl groups have the following meanings.

For example, the halogen atom (halo) is a fluorine atom (fluoro group), a chlorine atom (chloro group), a bromine atom (bromo group), or an iodine atom (iodo group).

The C1-C6 alkyl group is linear or branched and unsubstituted. Examples of the C1-C6 alkyl group include: methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, pentyl, isopentyl, neopentyl or hexyl.

The C1-C6 alkoxy group is linear or branched and unsubstituted. Examples of the C1-C6 alkoxy group include: methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, tert-butoxy, pentoxy, isopentoxy, neopentoxy or hexoxy.

C6-C14 aryl is, for example, C6-C14 aromatic monocyclic hydrocarbon, C6-C14 aromatic condensed bicyclic hydrocarbon or C6-C14 aromatic condensed tricyclic hydrocarbon. Examples of the C6-C14 aryl group include: phenyl, naphthyl, anthryl or phenanthryl.

<1 > photoreceptor

The photoreceptor according to the present embodiment includes a conductive substrate and a photosensitive layer. The binder resin contained in the photosensitive layer contains a polycarbonate resin represented by general formula (1) (hereinafter, sometimes referred to as polycarbonate resin (1)). The electron transport agent contained in the photosensitive layer contains a compound represented by general formula (2) (hereinafter, sometimes referred to as compound (2)). The photosensitive layer contains the polycarbonate resin (1) and the compound (2), and thereby white spots can be suppressed from being generated in the formed image. The reason is presumed as follows.

For ease of understanding, one reason why a self-point is generated on the formed image will be described. In image formation, when a recording medium (e.g., paper) comes into contact with a photoreceptor, minute components (e.g., paper dust) of the recording medium sometimes adhere to the surface of the photoreceptor. After the fine components of the recording medium adhere to the surface of the photoreceptor, the fine components may block light that exposes the photoreceptor in an exposure step for image formation. In a portion where light to be used for exposure is blocked by a fine component, the surface potential of the photoreceptor is difficult to be lowered. Since the toner is hard to adhere to a portion where the surface potential is insufficiently lowered, white spots are generated on the formed image.

In image formation, when a recording medium (e.g., paper) comes into contact with a photoreceptor, a minute component (e.g., paper dust) of the recording medium rubs against the photoreceptor, and the minute component is sometimes charged to a negative polarity or a positive polarity lower than a desired value. However, the photosensitive layer of the photoreceptor of the present embodiment contains the polycarbonate resin (1) and the compound (2). The polycarbonate resin (1) has a large electronegativity due to the halogen atom. The compound (2) also has a halogen atom and thus has a large electronegativity. The fine component is brought into contact with the photoreceptor of the present embodiment, and when the photoreceptor containing the polycarbonate resin (1) and the compound (2) having a large electronegativity rubs against the fine component, the fine component can be charged to a positive polarity equal to or higher than a desired value. In the charging step of image formation, when the surface of the photoreceptor is positively charged, the surface of the photoreceptor, which is positively charged, is electrically repelled by the positive-polarity fine component charged to a desired value or more. When the charge amount of the fine component is a positive value, the electric repulsion with the surface of the photoreceptor is large. This makes it difficult for the fine components to adhere to the surface of the photoreceptor. As a result, the occurrence of white spots in the formed image can be suppressed.

Further, it is difficult to greatly increase the content of the binder resin and the content of the electron transporting agent in the photosensitive layer because the photoreceptor is made to exhibit its function as a photoreceptor. In the photoreceptor of the present embodiment, the polycarbonate resin (1) having a halogen atom and the compound (2) having a halogen atom are contained in the photosensitive layer, whereby the proportion of the halogen atom in the photosensitive layer can be increased. As a result, the minute component of the recording medium can be charged to a positive polarity equal to or higher than a desired value, and the occurrence of white spots in the formed image can be suppressed satisfactorily.

Hereinafter, the structure of the photoreceptor 1 will be described with reference to fig. 1. Fig. 1 is a sectional view showing an example of a photoreceptor 1 according to the present embodiment.

For example, as shown in fig. 1(a), the photoreceptor 1 includes a conductive substrate 2 and a photosensitive layer 3. The photosensitive layer 3 is one layer. The photosensitive layer 3 is a monolayer type photosensitive layer. The photoreceptor 1 is a single-layer type photoreceptor.

As shown in fig. 1(b), the photoreceptor 1 may include a conductive substrate 2, a photosensitive layer 3, and an intermediate layer 4 (undercoat layer). The intermediate layer 4 is provided between the conductive substrate 2 and the photosensitive layer 3. As shown in fig. 1(a), the photosensitive layer 3 may be directly provided on the conductive substrate 2, or as shown in fig. 1(b), the photosensitive layer 3 may be indirectly provided on the conductive substrate 2 via the intermediate layer 4.

As shown in fig. 1(c), the photoreceptor 1 may include a conductive substrate 2, a photosensitive layer 3, and a protective layer 5. The protective layer 5 is provided on the photosensitive layer 3.

The thickness of the photosensitive layer 3 is not particularly limited as long as the photosensitive layer can sufficiently function. The thickness of the photosensitive layer 3 is preferably 5 μm to 100 μm, and more preferably 10 μm to 50 μm.

In order to suppress the occurrence of white spots on the formed image, the photosensitive layer 3 is preferably disposed as the outermost surface layer of the photoreceptor 1. For the same reason, the photoreceptor 1 is preferably a positively-charged single-layer type photoreceptor. The structure of the photoreceptor 1 is described above with reference to fig. 1.

<1-1. photosensitive layer >

The photosensitive layer contains a charge generating agent, an electron transporting agent, a hole transporting agent, and a binder resin in one layer. The photosensitive layer may contain additives as necessary. Hereinafter, the charge generating agent, the electron transporting agent, the hole transporting agent, the binder resin, and the additive will be described.

(Binder resin)

The binder resin contained in the photosensitive layer contains a polycarbonate resin (1). In the photosensitive layer, the polycarbonate resin (1) serves as a binder resin. The polycarbonate resin (1) is represented by the following general formula (1).

[ CHEM 4 ]

First, for R in the general formula (1)¹、R²、R⁵And R⁶The description is given. In the general formula (1), R¹、R²、R⁵And R⁶Independently of each other, represents: a halogen atom, a C1-C6 alkyl group having 1 or more halogen atoms, a C1-C6 alkoxy group having 1 or more halogen atoms, a C6-C14 aryl group having 1 or more halogen atoms, a hydrogen atom, a C1-C6 alkyl group, a C1-C6 alkoxy group, or a C6-C14 aryl group. R¹、R²、R⁵And R⁶Represents: a halogen atom, a C1-C6 alkyl group having 1 or more halogen atoms, a C1-C6 alkoxy group having 1 or more halogen atoms, or a C6-C14 aryl group having 1 or more halogen atoms. Thus, the polycarbonate resin (1) necessarily contains a halogen atom.

R¹、R²、R⁵And R⁶The halogen atom (halo) represented is preferably a chlorine atom (chloro group) or a fluorine atom (fluoro group).

At R¹、R²、R⁵Or R⁶When it represents a C1-C6 alkyl group having 1 or more halogen atoms, the C1-C6 alkyl group is preferably a C1-C3 alkyl group, and more preferably a methyl group. The halogen atom of the C1-C6 alkyl group is preferably a chlorine group or a fluorine group. The number of halogen atoms in the C1-C6 alkyl group is preferably 1 to 3. R¹、R²、R⁵And R⁶The C1-C6 alkyl group having 1 or more halogen atoms represented is preferably a C1-C3 alkyl group having 1 or more and 3 or less halogen atoms, and more preferably a trifluoromethyl group.

At R¹、R²、R⁵Or R⁶When it represents a C1-C6 alkoxy group having 1 or more halogen atoms, the C1-C6 alkoxy group is preferably a C1-C3 alkoxy group. The halogen atom of the C1-C6 alkoxy group is preferably a chlorine group or a fluorine group. The number of halogen atoms in the C1-C6 alkoxy group is preferably 1 to 3. R¹、R²、R⁵And R⁶The C1-C6 alkoxy group having 1 or more halogen atoms represented is preferably a C1-C3 alkoxy group having 1 or more and 3 or less halogen atoms.

At R¹、R²、R⁵Or R⁶When the aryl group represents a C6-C14 aryl group having 1 or more halogen atoms, the C6-C14 aryl group is preferably a C6-C14 aromatic monocyclic hydrocarbon group, and more preferably a phenyl group. The halogen atom of the C6-C14 aryl group is preferably a chlorine group or a fluorine group, and more preferably a fluorine group. The number of halogen atoms in the C6-C14 aryl group is preferably 1 to 3, more preferably 1. R¹、R²、R⁵And R⁶The C6-C14 aryl group having 1 or more halogen atoms is preferably a C6-C14 aryl group having 1 or more and 3 or less halogen atoms, more preferably a C6-C14 aromatic monocyclic hydrocarbon group having 1 or more and 3 or less halogen atoms, still more preferably a fluorophenyl group, and particularly preferably a p (p) fluorophenyl group.

R¹、R²、R⁵And R⁶The C1-C6 alkyl group represented is preferably a C1-C3 alkyl group, more preferably a methyl group.

R¹、R²、R⁵And R⁶The C1-C6 alkoxy group represented is preferably a C1-C3 alkoxy group.

R¹、R²、R⁵And R⁶The C6-C14 aryl group is preferably a C6-C14 aromatic monocyclic hydrocarbon group, and more preferably a phenyl group.

R¹And R²The bonding position of (3) is not particularly limited. R relative to the oxygen atom to which the phenyl group is bonded¹Bonded to the ortho or para position of the phenyl group. R relative to the oxygen atom to which the phenyl group is bonded²Also bonded to the ortho or para position of the phenyl group. R relative to the oxygen atom to which the phenyl group is bonded¹And R²Are preferably bound to the ortho position of the phenyl group.

To suppress the generation of white spots on the formed image, R¹、R²、R⁵And R⁶Preferably: each independently represents a halogen atom, a C1-C6 alkyl group having 1 or more halogen atoms, a C6-C14 aryl group having 1 or more halogen atoms, a hydrogen atom or a C1-C6 alkyl group, R¹、R²、R⁵And R⁶At least one of them represents a halogen atom, a C1-C6 alkyl group having 1 or more halogen atoms, or a C6-C14 aryl group having 1 or more halogen atoms.

In a preferred example of suppressing the occurrence of white spots in the formed image, R is¹And R²All represent a hydrogen atom, R⁵And R⁶One or both of them represent a C1-C6 alkyl group having 1 or more halogen atoms or a C6-C14 aryl group having 1 or more halogen atoms.

In another preferred embodiment for suppressing the occurrence of white spots in the formed image, R¹And R²All represent halogen atoms, R⁵And R⁶Both represent C1-C6 alkyl groups.

In order to suppress the occurrence of white spots in the formed image, the polycarbonate resin (1) preferably has a large number of halogen atoms. The number of halogen atoms in the polycarbonate resin (1) is preferably 1 to 6, more preferably 2 to 6, and particularly preferably 6.

Next, for R in the general formula (1)³And R⁴The description is given. In the general formula (1), R³And R⁴Independently of each other, represents: a hydrogen atom, an optionally substituted C1-C6 alkyl group, an optionally substituted C1-C6 alkoxy group or an optionally substituted C6-C14 aryl group.

R³And R⁴The C1-C6 alkyl group represented is preferably a C1-C3 alkyl group. R³And R⁴The C1-C6 alkyl group may have a substituent. The substituent of the C1-C6 alkyl group is preferably not a halogen atom. Examples of the substituent having a C1-C6 alkyl group are a C1-C6 alkoxy group or a C6-C14 aryl group. The number of the substituents of the C1-C6 alkyl group is, for example, 1 to 3.

R³And R⁴The C1-C6 alkoxy group represented is preferably a C1-C3 alkoxy group. R³And R⁴The C1-C6 alkoxy group may have a substituent. The substituent of the C1-C6 alkoxy group is preferably not a halogen atom. Examples of the substituent having the C1-C6 alkoxy group are a C1-C6 alkoxy group or a C6-C14 aryl group. The number of the substituents of the C1-C6 alkoxy group is, for example, 1 to 3.

R³And R⁴The C6-C14 aryl group is preferably a C6-C14 aromatic monocyclic hydrocarbon group, and more preferably a phenyl group. R³And R⁴The C6-C14 aryl group may have a substituent. The substituent of the C6-C14 aryl group is preferably not a halogen atom. Examples of the substituent of the C6-C14 aryl group are a C1-C6 alkyl group, a C1-C6 alkoxy group, or a C6-C14 aryl group. The number of the substituents of the C6-C14 aryl group is, for example, 1 to 3.

R³And R⁴The bonding position of (3) is not particularly limited. R relative to the oxygen atom to which the phenyl group is bonded³Bonded to the ortho or para position of the phenyl group. R relative to the oxygen atom to which the phenyl group is bonded⁴Also bonded to the ortho or para position of the phenyl group. R relative to the oxygen atom to which the phenyl group is bonded³And R⁴Are preferably bound to the ortho position of the phenyl group.

To suppress the generation of white spots on the formed image, R³And R⁴Both preferably represent hydrogen atoms.

Next, Y in the general formula (1) will be explained. In the general formula (1), Y represents: a single bond, optionally substituted C2-C18 alkylene (cycloalkylene), optionally substituted C5-C15 cycloalkylene (cycloalkylalkylene), optionally substituted C5-C15 cycloalkylene (cycloalkylalkylene), -S-, -SO-, -O-or-CO-.

The C2-C18 alkylene (alkylene) group represented by Y is a linear or branched divalent group having 1 bond to each carbon atom at both ends of the alkyl group. Examples of C2-C18 alkylene (alkylene) include: 1, 2-ethylene, n-propylene, methyl-1, 2-ethylene, n-butylene, methyl-1, 2-propylene, dimethyl-1, 2-ethylene, ethyl-1, 2-ethylene, 1, 5-pentylene, 1, 6-hexylene, 1, 7-heptylene, 1, 8-octylene, 1, 9-nonylene, 1, 10-decylene, 1, 11-undecylene, 1, 12-dodecylene, 1, 13-tridecylene, 1, 14-tetradecylene, 1, 15-pentadecylene, 1, 16-hexadecylene, 1, 17-heptadecylene, or 1, 18-octadecylene. C2-C18 alkylene (alkylene) is preferably C2-C6 alkylene (alkylene). The C2-C18 alkylene (alkylene) group represented by Y may have a substituent. The substituent of the C2-C18 alkylene (alkylene) is preferably not a halogen atom. Examples of the substituent having C2-C18 alkylene (alkylene) are C1-C6 alkoxy or phenyl. The number of the substituents of the C2-C18 alkylene (alkylene) group is, for example, 1 to 3.

C2-C18 alkylene (alkylene) is represented by the following general formula. In the following general formula, R³¹、R³²、R³³And R³⁴Each independently represents a hydrogen atom or a C1-C16 alkyl group. r represents a binding bond. t represents an integer of 1 to 17 inclusive. When t represents 1, R³¹、R³²、R³³And R³⁴The total number of carbon atoms of each group is 0 to 16. When t represents an integer of 2 to 17 inclusive, R³¹、R³²A plurality of R³³And a plurality of R³⁴The total number of carbon atoms of each group is 0 to 16.

[ CHEM 5 ]

The C5-C15 cycloalkylene (cycloakylene) group represented by Y is a divalent group having 1 bond each at 2 carbon atoms among carbon atoms forming the cycloalkane. Examples of C5-C15 cycloalkylene (cycloakylene) are: cyclopentylene (cyclopropenylene), cyclohexylene (cyclophenylene), cycloheptylene (cyclophenylene), cyclooctylene (cyclophenylene), cyclononylene (cyclophenylene), cyclodecylene (cyclodecylene), cycloundecylene (cycloundecylene), cyclododecylene (cyclododecylene), cyclotridecylene (cyclotridecylene), cyclotetradecylene (cyclotetradecylene), or cyclopentadecylene (cyclopentadecylene). C5-C15 cycloalkylene (cycloalkylene) is preferably C5-C7 cycloalkylene (cycloalkylene). The C5-C15 cycloalkylene (cycloakylene) group represented by Y may have a substituent. The substituent of the C5-C15 cycloalkylene (cycloalkylene) group is preferably not a halogen atom. Examples of the substituent which the C5-C15 cycloalkylene (cycloalkylene) has are a C1-C6 alkyl group, a C1-C6 alkoxy group, or a phenyl group. The number of the substituents of the C5-C15 cycloalkylene (cycloalkylene) group is, for example, 1 or more and 3 or less.

C5-C15 cycloalkylene (cycloakylene) is represented by the following general formula. In the following general formula, r represents a bond. Of the u, 1 represents a bond and the others represent a hydrogen atom. w represents an integer of 1 to 11 inclusive.

[ CHEM 6 ]

The C5-C15 cycloalkylene (cycloakylidine) represented by Y is a divalent group having 2 bonds to 1 of the carbon atoms forming the cycloalkane. Examples of C5-C15 cycloalkylene (cycloakylidine) are: cyclopentylene (cyclopropenylene), cyclohexylene (cyclophenylene), cycloheptylene (cyclophenylene), cyclooctylene (cyclophenylene), cyclononylene (cyclophenylene), cyclodecylene (cyclodecylene), cycloundecylene (cycloundecylene), cyclododecylene (cyclododecylene), cyclotridecylene (cyclodecylene), cyclotetradecylene (cyclotetradecylene), or cyclopentadecylene (cyclopropenylene). C5-C15 cycloalkylene (cycloalkylidene) is preferably C5-C7 cycloalkylene (cycloalkylidene), more preferably cyclohexylene (cyclohexylidene). The C5-C15 cycloalkylene (cycloakylidine) represented by Y may have a substituent. The substituent of the C5-C15 cycloalkylene (cycloalkylidene) group is preferably not a halogen atom. Examples of the substituent which the C5-C15 cycloalkylene (cycloalkylidene) group has are a C1-C6 alkyl group, a C1-C6 alkoxy group, or a phenyl group. The number of substituents of the C5-C15 cycloalkylene (cycloalkylidene) group is, for example, 1 or more and 3 or less.

C5-C15 cycloalkylene (cycloakylidine) is represented by the following general formula. In the general formula, s represents an integer of 1 to 11. r represents a binding bond. s preferably represents an integer of 1 to 3, more preferably 2.

[ CHEM 7 ]

In order to suppress the occurrence of white spots in the formed image, Y preferably represents C5-C15 cycloalkylene (cycloakylidine), more preferably C5-C7 cycloalkyl (cycloakylidine), and particularly preferably cyclohexylene (cycloakylidine).

Next, m and n in the general formula (1) will be explained. The polycarbonate resin (1) is composed of a repeating structural unit represented by the following general formula (5) (hereinafter, sometimes referred to as a repeating unit (5)) and a repeating structural unit represented by the following general formula (6) (hereinafter, sometimes referred to as a repeating unit (6)). The polycarbonate resin (1) is a copolymer of the repeating unit (5) and the repeating unit (6). In addition, R in the general formula (5)¹、R²、R⁵And R⁶Each of which is identical with R in the general formula (1)¹、R²、R⁵And R⁶Have the same meaning. R in the general formula (6)³、R⁴And Y are each independently of R in the formula (1)³、R⁴And Y have the same meaning.

[ CHEM 8 ]

[ CHEM 9 ]

M in the general formula (1) represents: the ratio (mole fraction) of the amount (mole number) of the substance of the repeating unit (5) to the total amount (mole number) of the repeating units (5) and (6) in the polycarbonate resin (1). N in the general formula (1) represents: the ratio (mole fraction) of the amount (mole number) of the substance of the repeating unit (6) to the total amount (mole number) of the repeating units (5) and (6) in the resin (1).

In the general formula (1), m and n are independent of each other and satisfy the following expressions (i) and (ii). m represents a number greater than 0.0. Since m is not 0.0, the polycarbonate resin (1) necessarily contains the repeating unit (5). On the other hand, the polycarbonate resin (1) may or may not contain the repeating unit (6). For example, when m is 1.0, n is 0.0. When m is 1.0, the polycarbonate resin (1) contains only the repeating unit (5). When m is 1.0, the polycarbonate resin (1) does not contain the repeating unit (6).

m+n＝1.0…(i)

0.0＜m≤1.0…(ii)

In the formula (ii), 0.2. ltoreq. m.ltoreq.0.8 is preferable, 0.3. ltoreq. m.ltoreq.0.7 is more preferable, and 0.4. ltoreq. m.ltoreq.0.6 is particularly preferable. When m is 0.2 or more, the occurrence of white spots in the formed image is easily suppressed. It can be considered that: when m is 0.8 or less, the solubility of the polycarbonate resin (1) in the solvent contained in the coating liquid for photosensitive layer can be improved. It can also be considered that: when m is 0.8 or less, the oil cracking resistance of the photosensitive layer can be improved. In addition, oil cracking refers to: a phenomenon of cracking of the photoreceptor surface occurs in the case where grease or other grease on a finger adheres to the photoreceptor surface (e.g., photosensitive layer).

When m is not 1.0 and the polycarbonate resin (1) has the repeating unit (6), the polycarbonate resin (1) may be a random copolymer in which the repeating unit (5) and the repeating unit (6) are randomly copolymerized. Alternatively, the polycarbonate resin (1) may be an alternating copolymer in which the repeating unit (5) and the repeating unit (6) are alternately copolymerized. Alternatively, the polycarbonate resin (1) may be a periodic copolymer in which 1 or more repeating units (5) and 1 or more repeating units (6) are periodically copolymerized. Alternatively, the polycarbonate resin (1) may be a block copolymer obtained by copolymerizing a block comprising a plurality of repeating units (5) and a block comprising a plurality of repeating units (6).

Preferable examples of the general formula (1) include the following general formula (1-A), (1-B), (1-C) or (1-D).

[ CHEM 10 ]

M in the formula (1-A)_AAnd n_AHave the same meanings as m and n in the general formula (1), respectively. M in the formula (1-B)_BIs 1.0. M in the formula (1-C)_CAnd n_CHave the same meanings as m and n in the general formula (1), respectively. M in the formula (1-D)_DAnd n_DHave the same meanings as m and n in the general formula (1), respectively. M in the formula (1-A)_AM in the formula (1-C)_CAnd m in the formula (1-D)_DThe preferable example of (2) is the same as the preferable example of m in the general formula (1). N in the general formula (1-A)_AN in the general formula (1-C)_CAnd n in the general formula (1-D)_DThe preferable example of (2) is the same as the preferable example of n in the general formula (1).

A more preferable example of the polycarbonate resin (1) is a polycarbonate resin represented by the following chemical formula (1-1), (1-2), (1-3) or (1-4).

[ CHEM 11 ]

[ CHEM 12 ]

[ CHEM 13 ]

[ CHEM 14 ]

The viscosity average molecular weight of the polycarbonate resin (1) is preferably 25,000 or more, more preferably 25,000 or more and 52,500 or less. When the viscosity average molecular weight of the polycarbonate resin (1) is 25,000 or more, the abrasion resistance of the photoreceptor is easily improved. When the viscosity average molecular weight of the polycarbonate resin (1) is 52,500 or less, the polycarbonate resin (1) is easily dissolved in a solvent at the time of forming a photosensitive layer, and the viscosity of the coating liquid for photosensitive layer does not become too high. As a result, the photosensitive layer is easily formed.

The method for producing the polycarbonate resin (1) is not particularly limited as long as the polycarbonate resin (1) can be produced. Examples of the method for producing the polycarbonate resin (1) include: a method of polycondensing a diol compound constituting a repeating unit of the polycarbonate resin (1) with phosgene (i.e., a phosgene method). More specifically, for example, there is a method of polycondensing a diol compound represented by the following general formula (7), a diol compound represented by the following general formula (8), and phosgene. In addition, R in the general formula (7)¹、R²、R³And R⁴Are respectively connected with R in the general formula (1)¹、R²、R³And R⁴Have the same meaning. R in the general formula (8)³、R⁴And Y is independently from R in the formula (1)³、R⁴And X have the same meaning. Other examples of the method for producing the polycarbonate resin (1) include: a process for the transesterification of a diol compound with diphenyl carbonate.

[ CHEM 15 ]

[ CHEM 16 ]

The photosensitive layer may contain only the polycarbonate resin (1) as a binder resin. The photosensitive layer may contain a binder resin other than the polycarbonate resin (1) (hereinafter, sometimes referred to as another binder resin) in addition to the polycarbonate resin (1). Examples of other binder resins include: a thermoplastic resin other than a polycarbonate resin, a thermosetting resin, or a photocurable resin. Examples of thermoplastic resins other than polycarbonate resins are: polyarylate resin, styrene-butadiene copolymer, styrene-acrylonitrile copolymer, styrene-maleic acid copolymer, acrylic polymer, styrene-acrylic acid copolymer, polyethylene resin, ethylene-vinyl acetate copolymer, chlorinated polyethylene resin, polyvinyl chloride resin, polypropylene resin, ionomer resin, vinyl chloride-vinyl acetate copolymer, alkyd resin, polyamide resin, polyurethane resin, polysulfone resin, diallyl phthalate resin, ketone resin, polyvinyl butyral resin, polyester resin, or polyether resin. Examples of thermosetting resins are: silicone resin, epoxy resin, phenol resin, urea resin, or melamine resin. Examples of the photocurable resin are: epoxy acrylates (acrylic acid adducts of epoxy compounds) or polyurethane-acrylates (acrylic acid adducts of polyurethane compounds). One of these binder resins may be used alone, or two or more thereof may be used in combination.

The content of the polycarbonate resin (1) is preferably 80% by mass or more, more preferably 90% by mass or more, and particularly preferably 100% by mass, based on the total mass of the binder resins. The total mass of the binder resins is the sum of the mass of the polycarbonate resin (1) and the mass of the other binder resins.

(Electron transport agent)

The electron transport agent contained in the photosensitive layer contains the compound (2). In the photosensitive layer, the compound (2) functions as an electron-transporting agent. The compound (2) is represented by the following general formula (2). The compound (2) is a malononitrile derivative.

[ CHEM 17 ]

In the general formula (2), R⁷Represents: C1-C8 alkyl having 1 or more halogen atoms; C3-C10 cycloalkyl having 1 or more halogen atoms; a C6-C14 aryl group having 1 or more halogen atoms and may have a C1-C6 alkyl group; a heterocyclic group having 1 or more halogen atoms and 5 or more and 14 or less members; or C7-C20 aralkyl having 1 or more halogen atoms.

R in the general formula (2)⁷The C1-C8 alkyl group is linear or branched. Examples of the C1-C8 alkyl group include: methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, pentyl, isopentyl, neopentyl, hexyl, heptyl, or octyl. The C1-C8 alkyl group is preferably a C1-C6 alkyl group, more preferably a C3-C5 alkyl group, still more preferably an n-propyl group, an n-butyl group or a neopentyl group, and particularly preferably an n-butyl group. R⁷The C1-C8 alkyl group represented has 1 or more halogen atoms. R⁷The halogen atom of the C1-C8 alkyl group is preferably a chlorine group or a fluorine group, and more preferably a chlorine group. The number of halogen atoms in the C1 to C8 alkyl group represented by R7 is preferably 1 or 2, and more preferably 1.

R⁷Examples of the C3-C10 cycloalkyl group include: cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, or cyclodecyl. C3-C10 cycloalkyl has more than 1 halogen atom. R⁷The halogen atom of the C3-C10 cycloalkyl group is preferably a chlorine group or a fluorine group. R⁷The number of halogen atoms in the C3-C10 cycloalkyl group is preferably 1 or 2.

R⁷The C6-C14 aryl group represented is preferably a phenyl group. R⁷The C6-C14 aryl group represented has 1 or more halogen atoms. R⁷The halogen atom of the C6-C14 aryl group is preferably a chlorine group or a fluorine group, and more preferably a chlorine group. R⁷The number of halogen atoms in the C6-C14 aryl groupPreferably 1 or 2. In addition to halogen atoms, C6-C14 aryl groups may also have C1-C6 alkyl groups.

R⁷The heterocyclic group having 5 to 14 members as represented contains at least 1 hetero atom other than carbon atoms. The hetero atom is 1 or more atoms selected from the group consisting of a nitrogen atom, a sulfur atom and an oxygen atom. Examples of the heterocyclic group having 5 to 14 members include: a 5-or 6-membered monocyclic heterocyclic group containing 1 or more and 3 or less heteroatoms other than carbon atoms; a heterocyclic group in which 2 such monocyclic heterocyclic rings are condensed; a heterocyclic group in which such a monocyclic heterocyclic ring is condensed with a 5-or 6-membered monocyclic hydrocarbon ring; a heterocyclic group in which 3 of such monocyclic heterocyclic rings are condensed; a heterocyclic group in which 2 such monocyclic heterocyclic rings are condensed with 1 5-or 6-membered monocyclic hydrocarbon ring; or a heterocyclic group in which 1 such monocyclic heterocyclic ring is condensed with 2 5-or 6-membered monocyclic hydrocarbon rings. Specific examples of the heterocyclic group having 5 to 14 members include: piperidinyl, piperazinyl, (2-or 3-) morpholinyl, thiophenyl, furanyl, pyrrolyl, imidazolyl, pyrazolyl, isothiazolyl, isoxazolyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, furazanyl, pyranyl, pyridyl, pyridazinyl, pyrimidinyl, pyrazinyl, indolyl, 1H-indazolyl, isoindolyl, benzopyranyl, quinolinyl, isoquinolinyl, purinyl, pteridinyl, triazolyl, tetrazolyl, 4H-quinolizinyl, naphthyridinyl, benzofuranyl, 1, 3-benzodioxolyl, benzoxazolyl, benzothiazolyl, benzimidazolyl, carbazolyl, phenanthridinyl, acridinyl, phenazinyl, or phenanthrolinyl. The heterocyclic group having 5 to 14 members is preferably a 5-or 6-membered monocyclic heterocyclic group containing 1 to 3 hetero atoms (preferably nitrogen atoms) other than carbon atoms, and more preferably a pyridyl group. R⁷The heterocyclic group having 5 to 14 members has 1 to more halogen atoms. R⁷The halogen atom of the heterocyclic group having 5 to 14 members is preferably a chlorine group or a fluorine group. R⁷The number of halogen atoms in the 5-to 14-membered heterocyclic group is preferably 1 or 2.

R⁷C7-C20 aralkyl radicalIs a C1-C6 alkyl group bonded to a C6-C14 aryl group. The C7-C20 aralkyl group is preferably a C1-C6 alkyl group bonded to a phenyl group, more preferably a phenylmethyl (benzyl) or phenylethyl group. R⁷The C7-C20 aralkyl group represented has 1 or more halogen atoms. R⁷The halogen atom in the C7-C20 aralkyl group is preferably a chlorine group or a fluorine group. R⁷The number of halogen atoms in the C7-C20 aralkyl group is preferably 1 or 2.

In the general formula (2), the general formula-COOR⁷The bonding position (substitution position) of the group represented by "is not particularly limited. General formula-COOR⁷The group represented by "may be bonded to any of the 1-, 2-, 3-and 4-positions in the following chemical formula. General formula-COOR⁷The group represented by "is preferably bonded to the 1-, 2-or 4-position in the following chemical formula, and more preferably bonded to the 1-or 4-position.

[ CHEM 18 ]

In order to suppress the generation of white spots on the formed image, R7 preferably represents: C1-C8 alkyl having 1 or 2 halogen atoms; or C7-C20 aralkyl having 1 or 2 halogen atoms.

In order to suppress the occurrence of white spots in the formed image, the compound (2) preferably has a large number of halogen atoms. The number of halogen atoms in the polycarbonate resin (2) is preferably 1 or 2, and more preferably 2.

Specific examples of the compound (2) are compounds represented by the following chemical formulae (2-1) to (2-10) (hereinafter, sometimes referred to as compounds (2-1) to (2-10)). Among them, the compounds (2-1), (2-5) and (2-10) are preferred.

[ CHEM 19 ]

For example, the compound (2) can be produced by the following reactions (R-1) and (R-2) or the likeAnd (5) manufacturing. In addition to these reactions, appropriate steps may be included as necessary. In the reaction equations of the reactions (R-1) and (R-2), R⁷And R in the general formula (2)⁷Have the same meaning. The compounds represented by the following chemical formulae (a), (B), (C) and (D) may be referred to as compounds (a), (B), (C) and (D), respectively.

[ CHEM 20 ]

In the reaction (R-1), 1 molar equivalent of the compound (A) is reacted with 1 molar equivalent of the compound (B) to obtain 1 molar equivalent of the compound (C). It is preferable to add 1 to 5 moles of the compound (B) to 1 mole of the compound (a). The reaction temperature of the reaction (R-1) is preferably 80 ℃ to 150 ℃. The reaction time of the reaction (R-1) is preferably 2 hours or more and 10 hours or less.

The reaction (R-1) may be carried out in the presence of a catalyst. The catalyst is, for example, an acid catalyst, more specifically, for example, p-toluenesulfonic acid, camphorsulfonic acid or pyridinium p-toluenesulfonate. One of these catalysts may be used alone, or two or more of them may be used in combination. The amount of the catalyst to be added is small relative to 1 mole of the compound (a), and specifically preferably 0.01 mole or more and 0.5 mole or less.

The reaction (R-1) may be carried out in a solvent. Examples of the solvent include: ethers (specifically, tetrahydrofuran, diethyl ether or dioxane), halogenated hydrocarbons (specifically, dichloromethane, chloroform or dichloroethane) or aromatic hydrocarbons (specifically, benzene or toluene).

In the reaction (R-2), 1 molar equivalent of the compound (C) is reacted with 1 molar equivalent of the compound (D, malononitrile), to obtain 1 molar equivalent of the compound (2). It is preferable to add 1 to 5 moles of the compound (D) to 1 mole of the compound (C). The reaction temperature of the reaction (R-2) is preferably 40 ℃ to 120 ℃. The reaction time of the reaction (R-2) is preferably 1 hour to 10 hours.

The reaction (R-2) may be carried out in the presence of a catalyst. The catalyst is, for example, a base catalyst, more specifically, piperidine or piperazine.

The reaction (R-2) may be carried out in a solvent. The solvent is, for example, a polar solvent, more specifically, methanol, ethanol, n-propanol, acetone or dioxane.

If necessary, the reaction product obtained by the reaction (R-2) can be purified to isolate the target compound (2). As the purification method, a well-known method is suitably employed. For example, purification can be performed by crystallization or silica gel column chromatography. For example, chloroform is used as a solvent for purification.

The photosensitive layer may contain only the compound (2) as an electron transporting agent. The photosensitive layer may contain an electron-transporting agent other than the compound (2) (hereinafter, sometimes referred to as another electron-transporting agent) in addition to the compound (2). Examples of other electron transport agents are: quinone compounds, imide compounds, hydrazone 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 or dibromomaleic anhydride. Examples of quinone compounds are: a diphenoquinone compound, an azoquinone compound, an anthraquinone compound, a naphthoquinone compound, a nitroanthraquinone compound or a dinitroanthraquinone compound. One of the other electron-transporting agents may be used alone, or two or more of them may be used in combination.

The content of the compound (2) is preferably 80% by mass or more, more preferably 90% by mass or more, and particularly preferably 100% by mass, based on the total mass of the electron transporting agent.

The content of the compound (2) as the electron transport agent is preferably 20 parts by mass or more and 40 parts by mass or less with respect to 100 parts by mass of the binder resin. When the content of the compound (2) is 20 parts by mass or more per 100 parts by mass of the binder resin, the electrical characteristics (particularly, sensitivity characteristics) of the photoreceptor are easily improved. When the content of the compound (2) is 40 parts by mass or less with respect to 100 parts by mass of the binder resin, the compound (2) is easily dissolved in a solvent for forming a photosensitive layer, and a uniform photosensitive layer is easily formed.

(frictional electrification amount of calcium carbonate)

The charge amount of calcium carbonate (hereinafter, may be referred to as the charge amount of calcium carbonate) after the photosensitive layer and calcium carbonate are rubbed is preferably + 7.0. mu.C/g or more. Calcium carbonate is a main component of paper powder, which is an example of a minute component of a recording medium. When the charge amount of calcium carbonate is + 7.0. mu.C/g or more, the fine components of the recording medium may be positively charged after the photoreceptor rubs against the fine components of the recording medium. In the charging step of image formation, when the surface of the photoreceptor is positively charged, the surface of the photoreceptor positively charged is electrically repelled by the fine components of the recording medium positively charged. Thus, the fine components of the recording medium are less likely to adhere to the surface of the photoreceptor. As a result, the occurrence of white spots in the formed image can be further suppressed. The amount of charge of calcium carbonate is preferably + 7.0. mu.C/g to + 15.0. mu.C/g, more preferably + 9.0. mu.C/g to + 15.0. mu.C/g, and particularly preferably + 9.0. mu.C/g to + 13.5. mu.C/g.

Hereinafter, a method of measuring the charge amount of calcium carbonate after the photosensitive layer 3 and calcium carbonate are rubbed will be described with reference to fig. 2. The charged amount of calcium carbonate was measured by performing the first step, the second step, the third step, and the fourth step. In the first step, two photosensitive layers 3 are prepared. One photosensitive layer 3 is a first photosensitive layer 30. The other photosensitive layer 3 is a second photosensitive layer 32. The first photosensitive layer 30 and the second photosensitive layer 32 are circular with a diameter of 3 cm. In the second step, 0.007g of calcium carbonate was placed on top of the first photosensitive layer 30. Thereby, the calcium carbonate layer 24 made of calcium carbonate is formed. Next, a second photosensitive layer 32 is placed on the calcium carbonate layer 24. In the third step, the second photosensitive layer 32 is fixed at a temperature of 23 ℃ and a relative humidity of 50% RH, and the first photosensitive layer 30 is rotated at a rotation speed of 60rpm for 60 seconds. Thereby, calcium carbonate contained in the calcium carbonate layer 24 is rubbed between the first photosensitive layer 30 and the second photosensitive layer 32 to charge the calcium carbonate. In the fourth step, the charged calcium carbonate is attracted by using a charge amount measuring device. The total quantity of electricity Q and the mass M of the calcium carbonate sucked were measured using a charge measuring device, and the charge amount of the calcium carbonate was calculated according to the formula "charge amount Q/M". In addition, the charge amount of calcium carbonate was measured specifically by the method in examples. The method for measuring the charge amount of calcium carbonate after the photosensitive layer 3 and calcium carbonate are rubbed is described above with reference to fig. 2.

(hole transport agent)

For example, the photosensitive layer contains a hole transporting agent. Examples of the hole-transporting agent include: triphenylamine derivatives, diamine derivatives (e.g., N ' -tetraphenylbenzidine derivatives, N ' -tetraphenylphenylenediamine derivatives, N ' -tetraphenylnaphthylenediamine derivatives, N ' -tetraphenylphenylenediamine (N, N ' -tetraphenylphenylenediamine) derivatives or bis (aminophenylvinyl) benzene derivatives), oxadiazole compounds (e.g., 2, 5-bis (4-methylaminophenyl) -1, 3, 4-oxadiazole), styrene compounds (e.g., 9- (4-diethylaminostyryl) anthracene), carbazole compounds (e.g., polyvinylcarbazole), organopolysiloxane compounds, pyrazoline compounds (e.g., 1-phenyl-3- (p-dimethylaminophenyl) pyrazoline), A hydrazone compound, an indole compound, an oxazole compound, an isoxazole compound, a thiazole compound, a thiadiazole compound, an imidazole compound, a pyrazole compound or a triazole compound. The hole-transporting agent may be used alone in 1 kind or in combination of two or more kinds.

The hole transporting agent preferably contains a compound represented by the following general formula (3) (hereinafter, sometimes referred to as compound (3)) or a compound represented by the following general formula (4) (hereinafter, sometimes referred to as compound (4)). The hole-transporting agent is preferably the compound (3) in order to suppress the occurrence of white spots on the formed image. First, the compound (3) will be described.

[ CHEM 21 ]

In the general formula (3), R⁸、R⁹、R¹⁰、R¹¹、R¹²、R¹³、R¹⁴、R¹⁵、R¹⁶、R¹⁷、R¹⁸And R¹⁹Independently of each other, represents: a hydrogen atom, a C1-C6 alkyl group or a C1-C6 alkoxy group.

By containing the compound (2) as an electron transporting agent and the compound (3) as a hole transporting agent in the photosensitive layer, the occurrence of white spots in a formed image can be suppressed without impairing the electrical characteristics (particularly sensitivity characteristics) of the photosensitive layer. Also, it can be considered that: by containing the polycarbonate resin (1) and the compound (3) in the photosensitive layer, the occurrence of oil cracking in the photosensitive layer can be suppressed. R of the Compound (3)⁸～R¹⁹Is not a conjugated group such as an alkenyl group or an aryl group, and thus the molecular weight of the compound (3) is relatively small. It can be considered that: by combining the compound (3) having such a chemical structure with the polycarbonate resin (1) and containing the same in the photosensitive layer, the compound (3) is made to fill in voids (fine voids) in the photosensitive layer.

R⁸～R¹⁹The C1-C6 alkyl group is preferably a C1-C3 alkyl group, more preferably a methyl group or an ethyl group, and particularly preferably a methyl group.

R⁸～R¹⁹The C1-C6 alkoxy group is preferably a C1-C3 alkoxy group, more preferably a methoxy group or an ethoxy group, and particularly preferably a methoxy group.

In the general formula (3), R is used for suppressing the occurrence of white spots in the formed image⁸～R¹⁹Each independently preferably represents a hydrogen atom or a C1-C6 alkyl group, more preferably a hydrogen atom, a methyl group, an ethyl group, a methoxy group or an ethoxy group, and particularly preferably a hydrogen atom or a methyl group.

In the general formula (3), R is preferably selected for suppressing the occurrence of white spots on the formed image⁸And R¹¹Are the same radicals. Preferably R⁹And R¹²Are the same radicals. Preferably R¹⁰And R¹³Are the sameAnd (4) a base.

In the general formula (3), R is used for suppressing the occurrence of white spots in the formed image¹⁴～R¹⁹Preferably represents a hydrogen atom.

Specific examples of the compound (3) are compounds represented by the following chemical formulae (3-1) to (3-4) (hereinafter, sometimes referred to as compounds (3-1) to (3-4)). Among them, the compound (3-1) is preferred.

[ CHEM 22 ]

[ CHEM 23 ]

[ CHEM 24 ]

[ CHEM 25 ]

Next, the compound (4) will be explained.

[ CHEM 26 ]

In the general formula (4), R²⁰～R²⁵Independently of one another, represents a C1-C6 alkyl group, a C1-C6 alkoxy group or a C6-C14 aryl group. R²⁰～R²⁵Each preferably represents a C1-C6 alkyl group, more preferably a C1-C3 alkyl group, and particularly preferably a methyl group or an ethyl group.

In the general formula (4), a, b, c and d are each independently an integer of 0 to 5. In the case where a represents an integer of 2 to 5, a plurality of R bonded to the same phenyl group²⁰May be the same or different from each other. In the case where b represents an integer of 2 to 5, a plurality of R bonded to the same phenyl group²¹May be the same or different from each other. In the case where c represents an integer of 2 to 5, a plurality of R bonded to the same phenyl group²²May be the same or different from each other. In the case where d represents an integer of 2 to 5, a plurality of R bonded to the same phenyl group²³May be the same or different from each other. a and b each preferably represent 0. c and d are each independently an integer of 1 to 5, preferably 2.

R²⁰～R²³The bonding position of (3) is not particularly limited. R²⁰～R²³Each of which may be bonded at any one of ortho-, meta-and para-positions to the phenyl group. R²²And R²³Each preferably bound to the ortho position of the phenyl group.

In the general formula (4), e and f are independent and each represents an integer of 0 to 4. In the case where e represents an integer of 2 or more and 4 or less, a plurality of R's bound to the same phenylene group²⁴May be the same or different from each other. In the case where f represents an integer of 2 to 4, a plurality of R bonded to the same phenylene group²⁵May be the same or different from each other. e and f each preferably represent 0.

R²⁴And R²⁵The bonding position of (3) is not particularly limited. R²⁴And R²⁵Each of which may be bonded at any one of (located at) ortho-and meta-positions with respect to the nitrogen atom to which the phenylene group is bonded.

A specific example of the compound (4) is a compound represented by the following chemical formula (4-1) (hereinafter, sometimes referred to as the compound (4-1)).

[ CHEM 27 ]

When the photosensitive layer contains the compound (3) as the hole transporting agent, the content of the compound (3) is preferably 80% by mass or more, more preferably 90% by mass or more, and particularly preferably 100% by mass, based on the total mass of the hole transporting agents.

When the photosensitive layer contains the compound (4) as the hole transporting agent, the content of the compound (4) is preferably 80% by mass or more, more preferably 90% by mass or more, and particularly preferably 100% by mass, based on the total mass of the hole transporting agents.

The content of the hole transporting agent contained in the photosensitive layer is preferably 40 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the binder resin contained in the photosensitive layer.

(Charge generating agent)

The photosensitive layer contains a charge generating agent. The charge generating agent is not particularly limited as long as it is a charge generating agent for a photoreceptor. Examples of the charge generating agent include: phthalocyanine pigments, perylene pigments, disazo pigments, trisazo pigments, dithione-pyrrolopyrrole (dithioketo-pyrrozole) pigments, metal-free naphthalocyanine pigments, metal naphthalocyanine pigments, squaric acid pigments, indigo pigments, azulene pigments, cyanine pigments, powders of inorganic photoconductive materials (e.g., selenium-tellurium, selenium-arsenic, cadmium sulfide, or amorphous silicon), pyran pigments, anthanthrone pigments, triphenylmethane pigments, threne pigments, toluidine pigments, pyrazoline pigments, or quinacridone pigments. One kind of charge generating agent may be used alone, or two or more kinds may be used in combination.

Examples of the phthalocyanine pigments include: no metal phthalocyanine or metal phthalocyanine. The metal-free phthalocyanine is represented by the chemical formula (CGM-1). Examples of the metal phthalocyanine include: oxytitanium phthalocyanine, hydroxygallium phthalocyanine or chlorogallium phthalocyanine. The phthalocyanine pigment may be crystalline or amorphous. The crystal shape (for example, α -type, β -type, Y-type, V-type, or II-type) of the phthalocyanine pigment is not particularly limited, and phthalocyanine pigments having various crystal shapes can be used.

[ CHEM 28 ]

Examples of the metal-free phthalocyanine include: an X-type crystal of metal-free phthalocyanine (hereinafter, sometimes referred to as X-type metal-free phthalocyanine). Examples of the crystal of oxytitanium phthalocyanine include: an α -type, β -type or Y-type crystal of oxytitanium phthalocyanine (hereinafter, sometimes referred to as α -type, β -type or Y-type oxytitanium phthalocyanine). Examples of the crystal of hydroxygallium phthalocyanine include a V-type crystal of hydroxygallium phthalocyanine. Examples of the crystal of chlorogallium phthalocyanine include type II crystal of chlorogallium phthalocyanine.

For example, in a digital optical image forming apparatus (for example, a laser printer or a facsimile machine using a light source such as a semiconductor laser), a photoreceptor having sensitivity in a wavelength region of 700nm or more is preferably used. In view of having a high quantum yield in a wavelength region of 700nm or more, a phthalocyanine-based pigment is preferable as the charge generating agent, and metal-free phthalocyanine or oxytitanium phthalocyanine is more preferable, and X-type metal-free phthalocyanine or Y-type oxytitanium phthalocyanine is further preferable, and X-type metal-free phthalocyanine is particularly preferable.

For the photoreceptor used in an image forming apparatus using a short-wavelength laser light source (for example, a laser light source having a wavelength of 350nm to 550 nm), an anthraquinone-based pigment is preferably used as the charge generating agent.

The content of the charge generating agent is preferably 0.1 part by mass or more and 50 parts by mass or less, and more preferably 1 part by mass or more and 30 parts by mass or less, with respect to 100 parts by mass of the binder resin contained in the photosensitive layer.

(additives)

The photosensitive layer may contain additives as necessary. Examples of additives include: degradation inhibitors (e.g., antioxidants, radical scavengers, singlet quenchers, or ultraviolet absorbers), softening agents, surface modifiers, extenders, thickeners, dispersion stabilizers, waxes, acceptors, donors, surfactants, plasticizers, sensitizers, or leveling agents. Examples of the antioxidant include: hindered phenols (e.g., di-t-butyl-p-cresol), hindered amines, p-phenylenediamine, arylalkanes, hydroquinones, spirochromans (spirochromans), spiroindanones (spiroindanones), or derivatives thereof; organic sulfur compounds or organic phosphorus compounds.

<1-2. conductive substrate >

The conductive substrate is not particularly limited as long as it can be used as a conductive substrate of a photoreceptor. The conductive substrate may be formed of a conductive material at least on the surface portion. An example of the conductive substrate is a conductive substrate formed of a conductive material. Another example of the conductive substrate is a conductive substrate coated with a conductive material. Examples of the conductive material include: aluminum, iron, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, or brass. These conductive materials may be used alone, or two or more of them may be used in combination (for example, as an alloy). Among these conductive materials, aluminum or an aluminum alloy is preferable because of good charge transfer from the photosensitive layer to the conductive substrate.

The shape of the conductive substrate can be appropriately selected in accordance with the structure of the image forming apparatus. Examples of the shape of the conductive substrate include: sheet-like or drum-like. The thickness of the conductive substrate may be appropriately selected depending on the shape of the conductive substrate.

<1-3. intermediate layer >

For example, the intermediate layer (undercoat layer) contains inorganic particles and a resin (resin for intermediate layer) used in the intermediate layer. It can be considered that: the presence of the intermediate layer allows smooth current flow to be generated when the photoreceptor is exposed, while maintaining an insulating state to such an extent that leakage current can be suppressed, thereby suppressing an increase in resistance.

Examples of the inorganic particles include: particles of a metal (e.g., aluminum, iron, or copper), a metal oxide (e.g., titanium dioxide, aluminum oxide, zirconium oxide, tin oxide, or zinc oxide), or a non-metal oxide (e.g., silicon dioxide). One of these inorganic particles may be used alone, or two or more of these inorganic particles may be used in combination.

The resin for the intermediate layer is not particularly limited as long as it is a resin that can be used to form the intermediate layer. The intermediate layer may also contain additives. Examples of the additive of the intermediate layer are the same as those of the photosensitive layer.

<1-4 > method for producing photoreceptor

For example, the photoreceptor is manufactured as follows. The photoreceptor is produced by applying a coating liquid for a photosensitive layer on a conductive substrate and drying the coating liquid. The coating liquid for photosensitive layer is prepared by dissolving or dispersing a charge generating agent, an electron transporting agent, a hole transporting agent, a binder resin, and components (for example, additives) added as needed in a solvent.

The solvent contained in the coating liquid for photosensitive layer is not particularly limited as long as it can dissolve or disperse each component contained in the coating liquid. Examples of the solvent include: alcohols (e.g., methanol, ethanol, isopropanol, or butanol), aliphatic hydrocarbons (e.g., n-hexane, octane, or cyclohexane), aromatic hydrocarbons (e.g., benzene, toluene, or xylene), halogenated hydrocarbons (e.g., dichloromethane, dichloroethane, carbon tetrachloride, or chlorobenzene), ethers (e.g., dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, or propylene glycol monomethyl ether), ketones (e.g., acetone, methyl ethyl ketone, or cyclohexanone), esters (e.g., ethyl acetate or methyl acetate), dimethyl formaldehyde, dimethyl formamide, or dimethyl sulfoxide. One of these solvents may be used alone, or two or more of them may be used in combination. In order to improve the workability in manufacturing the photoreceptor, it is preferable to use a non-halogenated solvent (a solvent other than halogenated hydrocarbon) as the solvent.

The coating liquid is prepared by mixing and dispersing the respective components into a solvent. For the mixing or dispersing operation, for example, it is possible to use: bead mills, roller mills, ball mills, attritors, paint shakers or ultrasonic dispersers.

In order to improve the dispersibility of each component, for example, a surfactant may be contained in the coating liquid for photosensitive layer.

The method of coating with the coating liquid for photosensitive layer is not particularly limited as long as the method can uniformly coat the coating liquid on the conductive substrate. Examples of the coating method include: dip coating, spray coating, spin coating or bar coating.

The method for drying the coating liquid for photosensitive layer is not particularly limited as long as it is a method capable of evaporating the solvent in the coating liquid. For example, a method of performing heat treatment (hot air drying) using a high-temperature dryer or a reduced-pressure dryer is given. For example, the heat treatment conditions are a temperature of 40 ℃ to 150 ℃ and a time of 3 minutes to 120 minutes.

The method for producing the photoreceptor may further include one or both of a step of forming an intermediate layer and a step of forming a protective layer, as necessary. In the step of forming the intermediate layer and the step of forming the protective layer, a known method is appropriately selected.

<2. image Forming apparatus >

Next, referring to fig. 3, an image forming apparatus 100 according to the present embodiment will be described, in which the image forming apparatus 100 includes a photoreceptor 1. Fig. 3 shows an example of the configuration of the image forming apparatus 100.

The image forming apparatus 100 is not particularly limited as long as it is an electrophotographic image forming apparatus. For example, the image forming apparatus 100 may be a monochrome image forming apparatus or a color image forming apparatus. When the image forming apparatus 100 is a color image forming apparatus, the image forming apparatus 100 employs, for example, a tandem system. The following description will be given taking an example of a tandem image forming apparatus 100.

The image forming apparatus 100 includes: image forming units 40a, 40b, 40c, and 40 d; and a transfer belt 50 and a fixing section 52. Hereinafter, each of the image forming units 40a, 40b, 40c, and 40d is described as the image forming unit 40 without distinction.

The image forming unit 40 includes: the photoreceptor 1, a charging section 42, an exposure section 44, a developing section 46, and a transfer section 48. The photoreceptor 1 is disposed at the center of the image forming unit 40. The photoreceptor 1 is provided to be rotatable in the arrow direction (counterclockwise direction). Around the photoreceptor 1, a charging section 42, an exposure section 44, a development section 46, and a transfer section 48 are provided in this order from the upstream side in the rotation direction of the photoreceptor 1 with respect to the charging section 42. The image forming unit 40 may further include one or both of a cleaning unit (not shown) and a discharging unit (not shown). The cleaning section and the charge removing section are provided between the transfer section 48 and the charging section 42, for example.

The charging section 42 charges the surface of the photoreceptor 1. The charging unit 42 is of a non-contact type or a contact type. Examples of the non-contact type charging unit 42 include a corotron charger and a grid charger. Examples of the contact type charging section 42 are a charging roller and a charging brush.

The image forming apparatus 100 may include a charging roller as the charging unit 42. When the surface of the photoreceptor 1 is charged, the charging roller contacts the photoreceptor 1. In a case where a fine component (e.g., paper dust) of the recording medium P (e.g., paper) adheres to the surface of the photoreceptor 1, the charging roller in contact presses the fine component against the surface of the photoreceptor 1. Thus, the fine component is easily adhered to the surface of the photoreceptor 1. However, the image forming apparatus 100 includes the photoreceptor 1, and the photoreceptor 1 can suppress the occurrence of white spots due to the adhesion of fine components. Therefore, in the image forming apparatus 100, even if the charging roller is used as the charging section 42, the fine component is less likely to adhere to the surface of the photoreceptor 1, and the occurrence of white spots in the formed image can be suppressed.

The charging section 42 preferably charges the surface of the photoreceptor 1 with a positive polarity. The recording medium P may be charged to a positive polarity after the photoreceptor 1 of the present embodiment is brought into contact with the recording medium P and rubbed. After the surface of the photoreceptor 1 is charged to a positive polarity by the charging section 42, the surface of the photoreceptor 1 is electrically repelled from the recording medium P charged to a positive polarity by friction. As a result, fine components (e.g., paper dust) of the recording medium P are less likely to adhere to the surface of the photoreceptor 1, and the occurrence of white spots in the formed image can be suppressed well.

The exposure section 44 exposes the surface of the charged photoreceptor 1. Thereby, an electrostatic latent image is formed on the surface of the photoreceptor 1. Based on image data input into the image forming apparatus 100, an electrostatic latent image is formed.

The developing portion 46 supplies toner to the electrostatic latent image formed on the photoreceptor 1. Thereby, the electrostatic latent image is developed into a toner image. The photoreceptor 1 corresponds to an image bearing member for bearing a toner image.

The developing section 46 can develop the electrostatic latent image into a toner image while contacting the photoreceptor 1. That is, the image forming apparatus 100 can adopt a so-called contact development system. When a fine component (for example, paper dust) of the recording medium P adheres to the surface of the photoreceptor 1, the developing portion 46 in contact presses the fine component against the surface of the photoreceptor 1. Thus, the fine component is easily adhered to the surface of the photoreceptor 1. However, the image forming apparatus 100 includes the photoreceptor 1, and the photoreceptor 1 can suppress the occurrence of white spots due to the adhesion of fine components. Therefore, even if the image forming apparatus 100 employs the contact development method, the fine component is less likely to adhere to the surface of the photoreceptor 1, and the occurrence of white spots on the formed image can be suppressed.

The developing unit 46 can clean the surface of the photoreceptor 1. That is, the image forming apparatus 100 can adopt a so-called cleanerless system. The developing section 46 can remove components (hereinafter, sometimes referred to as "residual components") remaining on the surface of the photoreceptor 1. An example of a residual component is a toner component, more specifically, a toner or a free external additive. Another example of the residual component is a non-toner component, more specifically, a minute component (e.g., paper dust) of the recording medium P. In the image forming apparatus 100 employing the cleanerless system, the residual components on the surface of the photoreceptor 1 are not scraped off by a cleaning portion (e.g., a cleaning blade). Therefore, in general, in the image forming apparatus 100 adopting the cleanerless system, residual components tend to remain on the surface of the photoreceptor 1. However, the photoreceptor 1 according to the present embodiment can suppress the occurrence of white spots due to the adhesion of fine components. Therefore, in the image forming apparatus 100 including the photoreceptor 1, even if the cleanerless system is adopted, residual components, particularly fine components (for example, paper dust) of the recording medium P, are less likely to remain on the surface of the photoreceptor 1. As a result, the image forming apparatus 100 can suppress the occurrence of white spots in the formed image.

In order to efficiently clean the surface of the photoreceptor 1 by the developing unit 46, the following conditions (a) and (b) are preferably satisfied.

Condition (a): in the contact development method, a difference in rotational speed (rotational speed) is provided between the photoreceptor 1 and the developing unit 46.

Condition (b): the surface potential of the photoreceptor 1 and the potential of the developing bias satisfy the following expressions (b-1) and (b-2)

0(V) < potential of developing bias (V) < surface potential of unexposed region (V) … (b-1) of photoreceptor 1

Potential of developing bias (V) > surface potential of exposed region of photoreceptor 1 (V) > 0(V) … (b-2)

As shown in condition (a), when the contact development method is employed and a rotation speed difference is provided between the photosensitive member 1 and the developing portion 46, the surface of the photosensitive member 1 contacts the developing portion 46, and the adhering components on the surface of the photosensitive member 1 are removed by friction with the developing portion 46. The rotation speed of the developing unit 46 is preferably higher than the rotation speed of the photoreceptor 1.

In the condition (b), it is assumed that the development method is a reversal development method. In order to improve the electrical characteristics (particularly, sensitivity characteristics) of the photoreceptor 1 (i.e., single-layer type photoreceptor), it is preferable that the charging polarity of the toner, the surface potential of the unexposed area of the photoreceptor 1, the surface potential of the exposed area of the photoreceptor 1, and the potential of the developing bias are all positive. Further, after the transfer section 48 transfers the toner image from the photoreceptor 1 onto the recording medium P, the surface potential of the unexposed area and the surface potential of the exposed area of the photoreceptor 1 are measured before the charging section 42 charges the surface of the photoreceptor 1 for the next round.

When the formula (b-1) of the condition (b) is satisfied, the electrostatic repulsive force acting between the toner remaining on the photoreceptor 1 (hereinafter, sometimes referred to as the remaining toner) and the unexposed area of the photoreceptor 1 is larger than the electrostatic repulsive force acting between the remaining toner and the developing unit 46. Accordingly, the residual toner in the unexposed area of the photoreceptor 1 moves from the surface of the photoreceptor 1 to the developing section 46, and is then recovered.

When the formula (b-2) of the condition (b) is satisfied, the electrostatic repulsive force acting between the residual toner and the exposed region of the photoreceptor 1 is smaller than the electrostatic repulsive force acting between the residual toner and the developing portion 46. Accordingly, the residual toner in the exposed region of the photoreceptor 1 is retained on the surface of the photoreceptor 1. The toner held on the exposed area of the photoreceptor 1 is directly used in image formation.

The transfer belt 50 conveys the recording medium P between the photoreceptor 1 and the transfer section 48. The transfer belt 50 is an endless belt. The transfer belt 50 is provided to be rotatable in an arrow direction (clockwise direction).

The transfer section 48 transfers the toner image developed by the developing section 46 from the photoreceptor 1 to the recording medium P. When the toner image is transferred from the photoreceptor 1 to the recording medium P by the transfer portion 48, the photoreceptor 1 is kept in contact with the recording medium P. That is, the image forming apparatus 100 employs a so-called direct transfer system. The transfer portion 48 is, for example, a transfer roller.

Toner images of several colors (for example, four colors of black, cyan, magenta, and yellow) are sequentially superimposed on the recording medium P on the transfer belt 50 by the image forming units 40a to 40 d. In the case where image forming apparatus 100 is a monochrome image forming apparatus, image forming apparatus 100 includes image forming unit 40a, and image forming units 40b to 40d are omitted.

The fixing portion 52 heats and/or pressurizes the unfixed toner image transferred onto the recording medium P by the transfer portion 48. For example, the fixing section 52 is a heating roller and/or a pressure roller. The toner image is fixed to the recording medium P by heating and/or pressurizing the toner image. As a result, an image is formed on the recording medium P.

<3. Process Cartridge >

Next, with continued reference to fig. 3, a process cartridge including the photoreceptor 1 in the present embodiment will be described. The process cartridge corresponds to each of the image forming units 40a to 40 d. The processing box is provided with a photosensitive body 1. The process cartridge may further include at least one of a charging section 42, an exposure section 44, a developing section 46, and a transfer section 48 in addition to the photoreceptor 1. The process cartridge may further include one or both of a cleaning device (not shown) and a static eliminator (not shown). The process cartridge is designed to be detachable with respect to the image forming apparatus 100. Therefore, the process cartridge is easy to handle, and when the sensitivity characteristics and the like of the photoreceptor 1 deteriorate, the process cartridge including the photoreceptor 1 can be replaced easily and quickly.

[ examples ] A method for producing a compound

The present invention will be described in more detail with reference to examples. However, the present invention is not limited in any way to the scope of the examples.

<1. materials for photoreceptors >

The following binder resin, charge generator, hole transporting agent and electron transporting agent were prepared as materials for forming a photosensitive layer of the photoreceptor.

<1-1. Binder resin >

The polycarbonate resins (1-1) to (1-4) described in the embodiment were prepared as binder resins. The viscosity-average molecular weights of the polycarbonate resins (1-1) to (1-4) were 50000.

Polycarbonate resins (1-5) to (1-7) were prepared as comparative binder resins. The polycarbonate resins (1-5) to (1-7) are represented by the following chemical formulas (1-5) to (1-7), respectively. The viscosity-average molecular weight of the polycarbonate resins (1-5) to (1-7) was 50000. In addition, the subscripts of the repeating units in the formulae (1-5) to (1-7) represent the mole fractions of the respective repeating units. The subscript "1.0" in the chemical formulas (1-5) and (1-7) indicates that the polycarbonate resins (1-5) and (1-7) each consist of only the recurring units with the subscript.

[ CHEM 29 ]

[ CHEM 30 ]

[ CHEM 31 ]

<1-2. Charge generating agent >

X-type metal-free phthalocyanine is prepared as a charge generating agent.

<1-3. hole transporting agent >

Compounds (3-1) and (4-1) described in the embodiments were prepared as hole transporters.

<1-4. Electron transporting agent >

The compounds (2-1), (2-5) and (2-10) described in the embodiments were prepared as electron-transporting agents. Specifically, compounds (2-1), (2-5) and (2-10) were synthesized by the following methods.

(production of Compound (2-1))

Compound (2-1) is produced according to the following reactions (R-3) and (R-4). The compounds represented by the chemical formulae (A-1), (B-1), (C-1) and (D) in the following reaction equations are sometimes referred to as compounds (A-1), (B-1), (C-1) and (D), respectively.

[ CHEM 32 ]

In the reaction (R-3), the compound (A-1) is reacted with the compound (B-1) to obtain the compound (C-1). Specifically, 2.24g (0.010 mol) of the compound (A-1), 3.26g (0.030 mol) of the compound (B-1) and toluene (100mL) were charged into a flask to dissolve the contents of the flask. In the flask, p-toluenesulfonic acid (0.001 mol) was added. The flask was set on a Dean-Stark apparatus. The contents of the flask were refluxed at 90 ℃ for 5 hours while dehydrating. The contents of the resulting flask were subjected to reduced pressure treatment to evaporate the toluene. Ion-exchanged water was added to the mixture evaporated under reduced pressure, and extraction was performed with chloroform. After drying the obtained organic layer, the organic layer was subjected to a reduced pressure treatment to evaporate chloroform. As a result, Compound (C-1) was obtained as a crude product. The yield of the compound (C-1) was 2.84g, and the yield of the compound (C-1) from the compound (A-1) was 90 mol%.

In the reaction (R-4), the compound (C-1) is reacted with the compound (D, malononitrile) to obtain the compound (2-1). Specifically, 1.57g (0.005 mol) of the compound (C-1) and 0.66g (0.010 mol) of the compound (D) were added to methanol (100mL) to obtain a methanol solution. To the methanol solution was added 0.08g (0.001 mol) of piperidine to obtain a mixture. The mixture was stirred at 80 ℃ for 3 hours while being refluxed. Next, the mixture was added to ion-exchanged water (200mL), a solid was precipitated, and the solid was removed by filtration. The obtained solid was purified by silica gel column chromatography using chloroform as a developing agent. As a result, Compound (2-1) was obtained. The yield of the compound (2-1) was 1.45g, and the yield of the compound (2-1) from the compound (C-1) was 80 mol%.

(production of Compound (2-5))

The reaction (R-3) was carried out in the same manner as in the production of the compound (C-1) except that the following was changed. 3.26g (0.030 mol) of the compound (B-1) added in the production of the compound (C-1) was changed to 5.31g (0.030 mol) of the compound (B-5). As a result, compound (C-5) was obtained instead of compound (C-1). The yield of the compound (C-5) was 3.26g, and the yield of the compound (C-5) from the compound (A-1) was 85 mol%. The compounds (B-5) and (C-5) are compounds represented by the following chemical formulae (B-5) and (C-5), respectively.

[ CHEM 33 ]

[ CHEM 34 ]

Next, the reaction (R-4) was carried out in the same manner as in the production of the compound (2-1) except that the following was changed. 1.57g (0.005 mol) of the compound (C-1) added in the production of the compound (2-1) was changed to 1.92g (0.005 mol) of the compound (C-5). As a result, compound (2-5) was obtained instead of compound (2-1). The yield of the compound (2-5) was 1.73g, and the yield of the compound (2-5) from the compound (C-5) was 80 mol%.

(production of Compound (2-10))

The reaction (R-3) was carried out in the same manner as in the production of the compound (C-1) except that the following points were changed. 2.24g (0.010 mol) of the compound (A-1) added in the production of the compound (C-1) was changed to 2.24g (0.010 mol) of the compound (A-10). 3.26g (0.030 mol) of the compound (B-1) added in the production of the compound (C-1) was changed to 3.84g (0.030 mol) of the compound (B-10). As a result, compound (C-10) was obtained in place of compound (C-1). The yield of the compound (C-10) was 2.81g, and the yield of the compound (C-10) from the compound (A-1) was 84 mol%. The compounds (A-10), (B-10) and (C-10) are represented by the following chemical formulae (A-10), (B-10) and (C-10), respectively.

[ CHEM 35 ]

[ CHEM 36 ]

[ CHEM 37 ]

Next, the reaction (R-4) was carried out in the same manner as in the production of the compound (2-1) except that the following procedure was changed. 1.57g (0.005 mol) of the compound (C-1) added in the production of the compound (2-1) was changed to 1.67g (0.005 mol) of the compound (C-10). As a result, compound (2-10) was obtained in place of compound (2-1). The yield of the compound (2-10) was 1.76g, and the yield of the compound (2-10) from the compound (C-10) was 92 mol%.

Then, use¹H-NMR (proton Nuclear magnetic resonance Spectroscopy), on Compound (2-1) produced¹H-NMR spectrum was measured. The magnetic field strength was set at 300 MHz. Deuterated chloroform (CDCl) was used₃) As a solvent. Tetramethylsilane (TMS) was used as an internal standard. Process for producing Compound (2-1)¹The chemical shift values of the H-NMR spectrum were as follows. According to measurement¹The chemical shift value in the H-NMR spectrum confirmed that the compound (2-1) was obtained. In addition, the same applies to the compounds (2-5) and (2-10), and it was confirmed that the compounds (2-5) and (2-10) were obtained.

Compound (2-1):¹H-NMR(300MHz，CDCl₃)＝8.53(dd，1H)，8.39(d，1H)，8.18(d，1H)，7.85(dd，1H)，7.49(dt，1H)，7.35(t，1H)，7.34(dt，1H)，4.45(t，2H)，3.63(t，2H)，1.90-2.07(m，4H).

compounds represented by the following chemical formulas (2-11) and (2-12) (hereinafter, sometimes referred to as compounds (2-11) and (2-12)) were prepared as electron transporters for comparison.

[ CHEM 38 ]

[ CHEM 39 ]

<2 > production of photoreceptor

The photoreceptors (P-1) to (P-19) were produced using the materials forming the photosensitive layer.

<2-1 > production of photoreceptor (P-1)

In a container, 2 parts by mass of X-type metal-free phthalocyanine as a charge generating agent, 55 parts by mass of a compound (3-1) as a hole transporting agent, 35 parts by mass of a compound (2-1) as an electron transporting agent, 100 parts by mass of a polycarbonate resin (1-1) as a binder resin, and 700 parts by mass of tetrahydrofuran as a solvent were placed. The contents of the vessel were mixed using a ball mill for 12 hours to disperse the material into the solvent. Thus, a coating liquid for photosensitive layer was obtained. The coating liquid for photosensitive layer was applied on an aluminum drum support (diameter 30mm, total length 238.5mm) as a conductive substrate by a dip coating method. The coating liquid for photosensitive layer applied was dried with hot air at 120 ℃ for 80 minutes. Thus, a photosensitive layer (film thickness: 30 μm) was formed in one layer on the conductive substrate. As a result, photoreceptor (P-1) was obtained.

<2-2 > production of photoreceptors (P-2) to (P-19) >

Photoreceptors (P-2) to (P-19) were manufactured by the same method as that for the photoreceptor (P-1) except that the following points were changed. The polycarbonate resin (1-1) used as a binder resin in the production of the photoreceptor (P-1) was changed to a binder resin of the type shown in Table 1. The compound (2-1) used as an electron-transporting agent in the production of the photoreceptor (P-1) was changed to an electron-transporting agent of the type shown in Table 1. The compound (3-1) used as the hole-transporting agent in the production of the photoreceptor (P-1) was changed to the hole-transporting agent of the type shown in Table 1.

<3. evaluation of sensitivity characteristics >

The sensitivity characteristics of each of the manufactured photoreceptors (P-1) to (P-19) were evaluated. The sensitivity characteristics were evaluated in an environment at a temperature of 23 ℃ and a relative humidity of 50% RH. First, the surface of the photoreceptor was charged to +600V using a drum sensitivity tester (manufactured by GENTEC corporation). Then, monochromatic light (wavelength of 780nm, half-width of 20nm, light energy of 1.5. mu.J/cm) was extracted from the white light of the halogen lamp using a band-pass filter²). The extracted monochromatic light is irradiated to the surface of the photoreceptor. The surface potential of the photoreceptor after 0.5 second from the end of the irradiation was measured. The measured surface potential was taken as the post-exposure potential (V)_L(ii) a Unit: + V). Measured post-exposure potential (V) of photoreceptor_L) Shown in table 1. In addition, post-exposure potential (V)_L) The smaller the absolute value of (a) is, the more excellent the sensitivity characteristics of the photoreceptor are.

<4. evaluation of triboelectric charging Property >

The triboelectric chargeability of each of the produced photoreceptors (P-1) to (P-19) was evaluated.

Hereinafter, referring again to fig. 2, a method of measuring the charge amount of calcium carbonate after the photosensitive layer 3 and calcium carbonate are rubbed will be described. The charge amount of calcium carbonate was measured by the first step, the second step, the third step, and the fourth step described below. In the measurement of the electrification amount of calcium carbonate, the jig 10 is used.

The jig 10 includes: a first base 12, a rotary shaft 14, a rotary drive section 16 (e.g., a motor), and a second base 18. The rotation driving unit 16 rotates the rotation shaft 14. The rotary shaft 14 rotates about the rotation axis S of the rotary shaft 14. The first base 12 is integrated with the rotary shaft 14 and rotates about the rotation axis S. The second base 18 is fixed and does not rotate.

(first step)

In the first step, two photosensitive layers 3 are prepared. Hereinafter, one photosensitive layer 3 is referred to as a first photosensitive layer 30, and the other photosensitive layer 3 is referred to as a second photosensitive layer 32. First, a first film 20 is prepared, and the first film 20 includes a first photosensitive layer 30 having a film thickness L1 of 30 μm. Further, a second film 22 is prepared, and the second film 22 includes a second photosensitive layer 32 having a film thickness L2 of 30 μm. Specifically, overhead projector (OHP) films are used as the first film 20 and the second film 22. The first film 20 and the second film 22 are both circular in shape with a diameter of 3 cm. On each of the first film 20 and the second film 22, a coating liquid for photosensitive layer used in the production of the photoreceptor (P-1) was coated. The coating liquid for the photosensitive layer applied was dried with hot air at 120 ℃ for 80 minutes. As a result, the first film 20 having the first photosensitive layer 30 and the second film 22 having the second photosensitive layer 32 are obtained.

(second step)

In the second step, 0.007g of calcium carbonate was placed on top of the first photosensitive layer 30. Thereby, the calcium carbonate layer 24 made of calcium carbonate is formed on the first photosensitive layer 30. Next, a second photosensitive layer 32 is placed on the calcium carbonate layer 24. The specific operation of the second step is as follows.

First, the first film 20 is fixed to the first base 12 using a double-sided tape. 0.007g of calcium carbonate was placed on the first photosensitive layer 30 of the first film 20. Thereby, the calcium carbonate layer 24 made of calcium carbonate is formed on the first photosensitive layer 30. The second film 22 is fixed to the second base 18 using double-sided tape so that the calcium carbonate layer 24 is in contact with the second photosensitive layer 32. Thus, the first base 12, the first film 20, the first photosensitive layer 30, the calcium carbonate layer 24, the second photosensitive layer 32, the second film 22, and the second base 18 are placed in this order from the bottom up. The centers of the first base 12, the first film 20, the first photosensitive layer 30, the second photosensitive layer 32, the second film 22, and the second base 18 are placed to pass through the rotation axis S.

(third step)

In the third step, the second photosensitive layer 32 is fixed at a temperature of 23 ℃ and a relative humidity of 50% RH, and the first photosensitive layer 30 is rotated at a rotation speed of 60rpm for 60 seconds. Specifically, the rotation driving unit 16 drives the rotary shaft 14, the first base 12, the first film 20, and the first photosensitive layer 30 to rotate around the rotation axis S at a rotation speed of 60rpm for 60 seconds. Thereby, calcium carbonate contained in the calcium carbonate layer 24 is rubbed between the first photosensitive layer 30 and the second photosensitive layer 32 to charge the calcium carbonate.

(fourth step)

In the fourth step, the calcium carbonate charged in the third step is taken out of the jig 10, and is sucked by using a charge measuring device (suction type small-sized charge measuring device, "MODEL 212 HS" manufactured by TREK corporation). The total quantity of electricity Q (unit: + μ C) and the mass M (unit: g) of the calcium carbonate adsorbed were measured using a charge quantity measuring device. The charge amount of calcium carbonate (triboelectric charge amount, unit: + μ C/g) was calculated according to the formula "charge amount ═ Q/M".

The triboelectric chargeability of each of the photoreceptors (P-2) to (P-19) was evaluated by the same method as that for the photoreceptor (P-1) except that the following changes were made. In the first step, the coating liquid for photosensitive layer used in the production of the photoreceptor (P-1) is replaced with each of the coating liquids for photosensitive layer used in the production of the photoreceptors (P-2) to (P-19).

The calculated charge amount of calcium carbonate for each of the photoreceptors (P-1) to (P-19) is shown in Table 1. The larger positive value of the charge amount of calcium carbonate indicates that calcium carbonate is more likely to be positively charged with respect to the first photosensitive layer 30 and the second photosensitive layer 32.

<5. evaluation of image characteristics >

The image characteristics of each of the manufactured photoreceptors (P-1) to (P-19) were evaluated. The evaluation of the image characteristics was carried out at a temperature of 32.5 ℃ and a relative humidity of 80% RH. An image forming apparatus (a changer of "monochrome printer FS-1300D" manufactured by Kyowa office information systems Co., Ltd.) was used as an evaluation device. Specifically, the non-contact development system is modified to the contact development system. The scraper cleaning mode is changed into a cleaner-free mode. The grid tube charger is modified into a charging roller. In the image forming apparatus, the direct transfer method is adopted, and the charging polarity of the charging section is positive. "Beijing porcelain office information system brand paper VM-A4" (A4 size) sold by Beijing porcelain office information system corporation was used as the recording medium. In the evaluation of the evaluation apparatus, a one-component developer (test production sample) was used.

Using an evaluation apparatus, image I (image with print coverage of 1%) was continuously printed on 20000 recording media at a photoreceptor rotation speed of 168 mm/sec. Next, image II (black solid image of a4 size) was printed on 1 recording medium. The recording medium on which the image II was formed was visually observed, and the number of white dots appearing in the image II was counted. The more minute components (e.g., paper dust) of the recording medium adhere to the photoreceptor, the more white dots in the image II are likely to be formed. The number of white dots appearing within image II is shown in table 1.

In Table 1, HTM, ETM and V_LRespectively represent a hole transporting agent, an electron transporting agent, and a post-exposure potential.

[ TABLE 1 ]

The photosensitive layers of the photoreceptors (P-1) to (P-12) and (P-18) are one photosensitive layer containing a charge generator, an electron transporting agent, a hole transporting agent and a binder resin. The binder resin contains a polycarbonate resin (1), specifically a polycarbonate resin (1-1), (1-2), (1-3) or (1-4). The electron transporting agent contains a compound (2), specifically a compound (2-1), (2-5) or (2-10). Therefore, as is clear from Table 1, the photoreceptors (P-1) to (P-12) and (P-18) formed images had a small number of white dots, and the occurrence of white dots was suppressed. In addition, in these photoreceptors, the occurrence of white spots on the formed image is suppressed without impairing the electrical characteristics (particularly, sensitivity characteristics) of the photoreceptor.

On the other hand, the photosensitive layers of the photoreceptors (P-13) to (P-15) do not contain the polycarbonate resin (1) and the compound (2). The photosensitive layer of the photoreceptor (P-16) does not contain the compound (2). The photosensitive layer of the photoreceptor (P-17) does not contain the polycarbonate resin (1). The photosensitive layer of the photoreceptor (P-19) does not contain the compound (2). Therefore, as is clear from Table 1, the photoreceptors (P-13) to (P-17) and (P-19) had a large number of white spots on the formed image, which caused a white spot problem.

As is clear from the above, the photoreceptor according to the present invention suppresses the occurrence of white spots on the formed image. It is also known that the process cartridge and the image forming apparatus according to the present invention suppress the generation of white spots on the formed image.

Claims (9)

1. An electrophotographic photoreceptor comprising a conductive substrate and a photosensitive layer,

the photosensitive layer is a layer containing a charge generating agent, an electron transporting agent, a hole transporting agent and a binder resin,

the binder resin contains a polycarbonate resin represented by the following general formula (1),

the electron transporting agent contains a compound represented by the following general formula (2),

[ CHEM 1 ]

In the general formula (1) described above,

R¹、R²、R⁵and R⁶Independently of one another, represents a halogen atom, a C1-C6 alkyl group having 1 or more halogen atoms, a C6-C14 aryl group having 1 or more halogen atoms, a hydrogen atom or a C1-C6 alkyl group,

R¹、R²、R⁵and R⁶At least one of them represents a halogen atom, a C1-C6 alkyl group having 1 or more halogen atoms, or a C6-C14 aryl group having 1 or more halogen atoms,

R³and R⁴All represent a hydrogen atom, and are,

y represents a C5-C15 cycloalkylene group,

m and n are independent of each other and satisfy the following formulas (i) and (ii),

m+n＝1.0…(i)

0.0＜m＜1.0…(ii)

[ CHEM 2 ]

In the general formula (2), R⁷Represents:

C1-C8 alkyl having 1 or more halogen atoms;

C3-C10 cycloalkyl having 1 or more halogen atoms;

a C6-C14 aryl group having 1 or more halogen atoms and may have a C1-C6 alkyl group;

a heterocyclic group having 1 or more halogen atoms and 5 or more and 14 or less members; or

C7-C20 aralkyl having 1 or more halogen atoms.

2. The electrophotographic photoreceptor according to claim 1,

the charge amount of the calcium carbonate after the friction between the photosensitive layer and the calcium carbonate is more than +7.0 mu C/g.

3. The electrophotographic photoreceptor according to claim 1 or 2,

the charge amount of the calcium carbonate after the friction between the photosensitive layer and the calcium carbonate is more than +9.0 mu C/g and less than +15.0 mu C/g.

4. The electrophotographic photoreceptor according to claim 1 or 2,

the general formula (1) is the following general formula (1-A), (1-C) or (1-D),

[ CHEM 3 ]

In the general formula (1-A), m_AAnd n_AAre independent of each other and satisfy the mathematical formulam_A+n_A1.0 and the mathematical formula 0.0 < m_A＜1.0，

M in the general formula (1-C)_CAnd n_CAre independent of each other and satisfy the mathematical formula m_C+n_C1.0 and the mathematical formula 0.0 < m_C＜1.0，

In the general formula (1-D), m_DAnd n_DAre independent of each other and satisfy the mathematical formula m_D+n_D1.0 and the mathematical formula 0.0 < m_D＜1.0。

5. The electrophotographic photoreceptor according to claim 1 or 2,

in the general formula (2), R⁷Represents a C1-C8 alkyl group having 1 or 2 halogen atoms, or a C7-C20 aralkyl group having 1 or 2 halogen atoms.

6. The electrophotographic photoreceptor according to claim 1 or 2,

the hole-transporting agent contains a compound represented by the following general formula (3),

[ CHEM 4 ]

In the general formula (3), R⁸、R⁹、R¹⁰、R¹¹、R¹²、R¹³、R¹⁴、R¹⁵、R¹⁶、R¹⁷、R¹⁸And R¹⁹Each independently represents a hydrogen atom, a C1-C6 alkyl group or a C1-C6 alkoxy group.

7. The electrophotographic photoreceptor according to claim 6,

in the general formula (3), R⁸、R⁹、R¹⁰、R¹¹、R¹²、R¹³、R¹⁴、R¹⁵、R¹⁶、R¹⁷、R¹⁸And R¹⁹Each independently represents a hydrogen atom or C1-C6 alkyl.

8. A kind of processing box is disclosed, which comprises a box body,

the electrophotographic photoreceptor according to claim 1 or 2.

9. An image forming apparatus includes:

an electrophotographic photoreceptor;

a charging section that charges a surface of the electrophotographic photoreceptor;

an exposure section that exposes the surface of the electrophotographic photoreceptor charged to form an electrostatic latent image on the surface of the electrophotographic photoreceptor;

a developing section that develops the electrostatic latent image into a toner image; and

a transfer section for transferring the toner image from the electrophotographic photoreceptor to a recording medium,

it is characterized in that the preparation method is characterized in that,

the electrophotographic photoreceptor is held in contact with the recording medium when the transfer section transfers the toner image from the electrophotographic photoreceptor to the recording medium,

the electrophotographic photoreceptor according to claim 1 or 2.

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