JP7634518B2 - Polycarbonate copolymer, coating liquid, electrophotographic photoreceptor, method for producing polycarbonate copolymer, and electric device - Google Patents

Description

The present invention relates to a polycarbonate copolymer, a coating liquid, an electrophotographic photoreceptor, a method for producing a polycarbonate copolymer, and an electrical device.

Polycarbonate resins have excellent mechanical, thermal, and electrical properties. Therefore, polycarbonate resins have been used as materials for molded products and the like in various industrial fields. In recent years, polycarbonate resins have been widely used in the field of functional products by utilizing the optical properties and the like of polycarbonate resins in addition to the above-mentioned properties. With the expansion of such applications and fields, the performance required for polycarbonate resins has also become more diverse.
Such demands on polycarbonate resins may not be met sufficiently by polycarbonate resins obtained by simply polycondensing conventional raw materials (e.g., 2,2-bis(4-hydroxyphenyl)propane, 1,1-bis(4-hydroxyphenyl)cyclohexane, etc.) Therefore, polycarbonate copolymers having various chemical structures have been proposed according to the applications and required properties.

One example of a product that utilizes the electrical and optical properties of polycarbonate resin is an electrophotographic photoreceptor that uses polycarbonate resin as a binder resin for functional materials such as charge generating materials and charge transport materials.

An electrophotographic photoreceptor is required to have predetermined sensitivity, electrical characteristics and optical characteristics according to the electrophotographic process.
In addition, since various operations (e.g., corona charging, toner development, transfer onto paper, cleaning treatment, etc.) are repeatedly performed on the surface of the photosensitive layer of the electrophotographic photoreceptor, at least one of an electrical external force and a mechanical external force is applied each time these operations are performed. Therefore, in order to maintain the image quality of electrophotography over a long period of time, the photosensitive layer provided on the surface of the electrophotographic photoreceptor is required to have durability against these external forces.

In recent years, with the introduction of various printer systems, it is known that wear of electrophotographic photoconductors occurs due to various factors (wear modes). Known wear of electrophotographic photoconductors includes mechanical wear (for example, fatigue wear, etc.) and electrical wear caused by discharge deterioration due to a charging roller, etc.
Therefore, there is a demand for binder resins that are effective against wear that occurs in the above-mentioned wear mode.

Conventionally, polycarbonate resins made from raw materials such as 2,2-bis(4-hydroxyphenyl)propane or 2,2-bis(4-hydroxyphenyl)cyclohexane have been used as binder resins for photoreceptors, but they were not sufficient in terms of durability. Therefore, various methods have been used to meet the demand for high durability of binder resins for photoreceptors. Copolymer polycarbonate is known as an effective technology for improving the wear resistance of the photosensitive layer of an electrophotographic photoreceptor.

For example, Patent Document 1 describes a polycarbonate copolymer obtained by polycondensation of biphenol, which has a rigid skeleton, and a bischloroformate oligomer derived from a dihydric phenol compound having a monomer number of about dimer to tetramer. It describes that the copolymerization ratio of the biphenol component in the polycarbonate copolymer is close to 25 mol%.

Furthermore, Patent Documents 2 and 3 disclose a polycarbonate copolymer obtained by polycondensation of a bischloroformate oligomer derived from a dihydric phenol compound having a monomer to dimer structure, and a dihydric phenol compound containing biphenol or the like. It discloses that the copolymerization ratio of biphenol or the like in the polycarbonate copolymer is close to 50 mol %.

Furthermore, Patent Document 4 describes an electrophotographic photoreceptor containing a specific charge generating material and a specific polycarbonate resin in a photosensitive layer, and describes that the specific polycarbonate resin is a polycarbonate copolymer having repeating units containing a terphenyl skeleton or an anthracene skeleton, which are more rigid than biphenol, and repeating units containing a bisphenol skeleton.

Furthermore, Patent Document 5 describes a polycarbonate copolymer having structural units containing a p-terphenyl skeleton.

Japanese Patent Application Publication No. 4-179961 JP 2011-26574 A JP 2011-26575 A Japanese Patent Application Publication No. 9-43882 Japanese Patent Application Publication No. 6-56982

The polycarbonate copolymer described in Patent Document 1 is produced by copolymerizing a bisphenol Z skeleton, which has good solubility, with biphenol, which has good abrasion resistance. The polycarbonate copolymer is produced using a raw material in which the number of oligomers is about dimer to tetramer. Therefore, the copolymerization ratio of the biphenol component in the polycarbonate copolymer is limited to about 23 mol%, and the abrasion resistance is insufficient.

The polycarbonate copolymers described in Patent Documents 2 and 3 are produced from raw materials with a reduced number of oligomers. Therefore, the copolymerization ratio of the biphenol skeleton in the polycarbonate copolymer is improved to 25 mol% to 47 mol%. However, even the polycarbonate copolymers described in Patent Documents 2 and 3 do not have sufficient abrasion resistance to meet the need for high durability against mechanical deterioration that occurs when using toner containing a large amount of external additives.

The polycarbonate copolymers described in Patent Documents 4 and 5 contain a terphenyl skeleton, which is more rigid than biphenol etc. and is expected to improve durability. However, the structure and composition of these polycarbonate copolymers are not optimized for applications requiring abrasion resistance, and the abrasion resistance is insufficient.
Furthermore, when the polycarbonate copolymer is used by dissolving it in an organic solvent, the polycarbonate copolymer is required to have good solubility in the organic solvent.

The object of the present invention is to provide a polycarbonate copolymer having excellent abrasion resistance and good solubility in organic solvents, a method for producing the polycarbonate copolymer, a coating liquid using the polycarbonate copolymer, an electrophotographic photoreceptor using the polycarbonate copolymer, and an electrical device using the electrophotographic photoreceptor.

The polycarbonate copolymer according to one embodiment of the present invention has a repeating unit A represented by the following general formula (1) and a repeating unit B represented by the following general formula (2), and is obtained from at least one of a bischloroformate oligomer represented by the following general formula (1A) and a bischloroformate oligomer represented by the following general formula (2A),
The average number of monomers _n1 of the bischloroformate oligomer represented by the general formula (1A) is 1.0 or more and 1.3 or less,
The average number of monomers _n2 of the bischloroformate oligomer represented by the general formula (2A) is 1.0 or more and 1.3 or less.

In the general formula (1), Ar ¹ is a group represented by the following general formula (3):
In the general formula (2), ^Ar2 is a group represented by the following general formula (4):

[In the general formulas (3) and (4),
R ¹¹ to R ¹⁸ and R ²¹ to R ²⁸ each independently represent a hydrogen atom or a substituent;
R ¹¹ to R ¹⁸ and R ²¹ to R ²⁸ as substituents each independently represent
an unsubstituted alkyl group having 1 to 2 carbon atoms;
an unsubstituted fluoroalkyl group having 1 to 2 carbon atoms;
an unsubstituted alkoxy group having 1 to 2 carbon atoms,
R ¹⁹ and R ²⁰ each independently represent a hydrogen atom or a substituent;
R ¹⁹ and R ²⁰ as substituents each independently represent
an unsubstituted alkyl group having 1 to 2 carbon atoms;
^X2 and ^X3 each independently represent
CR ¹⁰⁰ or a nitrogen atom;
^R100 is,
a hydrogen atom or an unsubstituted alkyl group having 1 to 2 carbon atoms;
^X1 is
a group represented by -CR ³ R ⁴ -,
a substituted or unsubstituted cycloalkylidene group having 5 to 6 carbon atoms,
a substituted or unsubstituted bicyclohydrocarbon diyl group having 7 to 10 carbon atoms, or a substituted or unsubstituted tricyclohydrocarbon diyl group having 10 to 16 carbon atoms,
^R3 and ^R4 each independently represent a hydrogen atom or a substituent;
^R3 and ^R4 as substituents each independently represent
an unsubstituted alkyl group having 1 to 3 carbon atoms;
an unsubstituted fluoroalkyl group having 1 to 3 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 12 ring carbon atoms,
provided that when R ¹⁹ and R ²⁰ are hydrogen atoms, any one or more of R ¹¹ to R ¹⁴ are substituents, and any one or more of R ¹⁵ to R ¹⁸ are substituents;
When R ¹¹ to R ¹⁸ are hydrogen atoms, R ¹⁹ and R ²⁰ are substituents.

In the general formula (1A), Ar ¹ is a group represented by the general formula (3), n ₁ represents the average number of monomers,
In the general formula (2A), ^Ar2 is a group represented by the general formula (4), and _n2 represents the average number of monomers.

In a method for producing a polycarbonate copolymer according to one embodiment of the present invention, a polycarbonate copolymer is produced by the following synthesis reaction (CS1), (CS2) or (CS3).
(CS1) A bischloroformate oligomer represented by the following general formula (1A) and a dihydric phenolic compound represented by the following general formula (6) are subjected to interfacial polycondensation in the presence of an acid binder.
(CS2) A bischloroformate oligomer represented by the following general formula (2A) and a dihydric phenolic compound represented by the following general formula (5) are subjected to interfacial polycondensation in the presence of an acid binder.
(CS3) A bischloroformate oligomer represented by the following general formula (1A) is mixed with a bischloroformate oligomer represented by the following general formula (2A), and the mixture of the bischloroformate oligomer represented by the following general formula (1A) and the bischloroformate oligomer represented by the following general formula (2A) is subjected to interfacial polycondensation with a dihydric phenolic compound represented by the following general formula (5) or a dihydric phenolic compound represented by the following general formula (6).

[In the general formulas (1A) and (5), Ar ¹ is a group represented by the following general formula (3), and in the general formulas (2A) and (6), Ar ² is a group represented by the following general formula (4):
In the general formula (1A), _n1 represents the average number of monomers and is 1.0 to 1.3,
In the general formula (2A), _n2 represents the average number of monomers and is 1.0 to 1.3.

[In the general formulas (3) and (4),
R ¹¹ to R ¹⁸ and R ²¹ to R ²⁸ each independently represent a hydrogen atom or a substituent;
R ¹¹ to R ¹⁸ and R ²¹ to R ²⁸ as substituents each independently represent
an unsubstituted alkyl group having 1 to 2 carbon atoms;
an unsubstituted fluoroalkyl group having 1 to 2 carbon atoms;
an unsubstituted alkoxy group having 1 to 2 carbon atoms,
R ¹⁹ and R ²⁰ each independently represent a hydrogen atom or a substituent;
R ¹⁹ and R ²⁰ as substituents each independently represent
an unsubstituted alkyl group having 1 to 2 carbon atoms;
^X2 and ^X3 each independently represent
CR ¹⁰⁰ or a nitrogen atom;
^R100 is,
a hydrogen atom or an unsubstituted alkyl group having 1 to 2 carbon atoms;
^X1 is
a group represented by -CR ³ R ⁴ -,
a substituted or unsubstituted cycloalkylidene group having 5 to 6 carbon atoms,
a substituted or unsubstituted bicyclohydrocarbon diyl group having 7 to 10 carbon atoms, or a substituted or unsubstituted tricyclohydrocarbon diyl group having 10 to 16 carbon atoms,
^R3 and ^R4 each independently represent a hydrogen atom or a substituent;
^R3 and ^R4 as substituents each independently represent
an unsubstituted alkyl group having 1 to 3 carbon atoms;
an unsubstituted fluoroalkyl group having 1 to 3 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 12 ring carbon atoms,
provided that when R ¹⁹ and R ²⁰ are hydrogen atoms, any one or more of R ¹¹ to R ¹⁴ are substituents, and any one or more of R ¹⁵ to R ¹⁸ are substituents;
When R ¹¹ to R ¹⁸ are hydrogen atoms, R ¹⁹ and R ²⁰ are substituents.

The coating fluid according to one embodiment of the present invention contains the polycarbonate copolymer according to one embodiment of the present invention and an organic solvent.
An electrophotographic photoreceptor according to an embodiment of the present invention contains the polycarbonate copolymer according to an embodiment of the present invention.
An electrophotographic photoreceptor according to one aspect of the present invention includes a substrate and a photosensitive layer provided on the substrate, the photosensitive layer including the polycarbonate copolymer according to one aspect of the present invention.
An electrical device according to an aspect of the present invention includes the electrophotographic photoreceptor according to an aspect of the present invention.

According to the present invention, it is possible to provide a polycarbonate copolymer having excellent abrasion resistance and good solubility in organic solvents, a method for producing the polycarbonate copolymer, a coating liquid using the polycarbonate copolymer, an electrophotographic photoreceptor using the polycarbonate copolymer, and an electrical device using the electrophotographic photoreceptor.

As a result of extensive research, the present inventors have found that a polycarbonate copolymer having excellent abrasion resistance can be obtained by using, as a raw material, at least one of a bischloroformate oligomer having a p-terphenyl skeleton (a bischloroformate oligomer derived from a repeating unit A represented by general formula (1)) and a bischloroformate oligomer having a bisphenol skeleton (a bischloroformate oligomer derived from a repeating unit B represented by general formula (2)), and have completed the present invention. The bischloroformate oligomer having a p-terphenyl skeleton and the bischloroformate oligomer having a bisphenol skeleton both have an average number of monomers adjusted to be 1.0 or more and 1.3 or less, that is, a low number of monomers.
The inventors have also determined that excellent wear resistance is related to good yield stress and elastic power.
Furthermore, the present inventors have found that by using at least one of a bischloroformate oligomer having a p-terphenyl skeleton and a bischloroformate oligomer having a bisphenol skeleton as a raw material, it is possible to obtain a polycarbonate copolymer that has good solubility in organic solvents, can suppress crystallization, and can suppress clouding of the solution due to crystallization, even when the copolymer contains a relatively high proportion of a highly crystalline and rigid p-terphenyl skeleton.

Example 10 of Patent Document 2 (JP 2011-26574 A) and the like describes a polycarbonate copolymer obtained by reacting a low-mer bischloroformate oligomer having a divalent aromatic group of bisphenol Z with a biphenol monomer. The polycarbonate copolymer of the present embodiment has better abrasion resistance and also has better yield stress and elastic power related to abrasion than the polycarbonate copolymer described in Patent Document 2 (JP 2011-26574 A).
Furthermore, as described above, even when the polycarbonate copolymer of the present embodiment contains a relatively high proportion of the highly crystalline and rigid p-terphenyl skeleton, it has good solubility in organic solvents, can suppress crystallization, and can suppress clouding of the solution due to crystallization. Therefore, the polycarbonate copolymer of the present embodiment has good abrasion resistance even when used for electrophotographic photoreceptors, and electrophotographic photoreceptors using the polycarbonate copolymer can exhibit good electrophotographic characteristics.

Hereinafter, a polycarbonate copolymer according to one embodiment of the present invention (hereinafter, the polycarbonate copolymer may be simply referred to as a "PC copolymer"), a coating liquid using the PC copolymer, an electrophotographic photoreceptor using the PC copolymer, and an electrical device using the electrophotographic photoreceptor will be described in detail.
In this specification, a numerical range expressed using "to" means a range including the numerical value before "to" as the lower limit and the numerical value after "to" as the upper limit.

[Structure of PC copolymer]
The PC copolymer of the present embodiment has a repeating unit A represented by the following general formula (1) and a repeating unit B represented by the following general formula (2), and is obtained using at least one of a bischloroformate oligomer represented by the following general formula (1A) and a bischloroformate oligomer represented by the following general formula (2A) as a raw material:
The average number of monomers _n1 of the bischloroformate oligomer represented by the general formula (1A) is 1.0 or more and 1.3 or less.
The average number of monomers _n2 of the bischloroformate oligomer represented by the general formula (2A) is 1.0 or more and 1.3 or less.

(In the general formula (1), Ar ¹ is a group represented by the following general formula (3), and in the general formula (2), Ar ² is a group represented by the following general formula (4). * indicates a bonding position.)

[In the general formulas (3) and (4),
R ¹¹ to R ¹⁸ and R ²¹ to R ²⁸ each independently represent a hydrogen atom or a substituent;
R ¹¹ to R ¹⁸ and R ²¹ to R ²⁸ as substituents each independently represent
an unsubstituted alkyl group having 1 to 2 carbon atoms;
an unsubstituted fluoroalkyl group having 1 to 2 carbon atoms;
an unsubstituted alkoxy group having 1 to 2 carbon atoms,
R ¹⁹ and R ²⁰ each independently represent a hydrogen atom or a substituent;
R ¹⁹ and R ²⁰ as substituents each independently represent
an unsubstituted alkyl group having 1 to 2 carbon atoms;
^X2 and ^X3 each independently represent
CR ¹⁰⁰ or a nitrogen atom;
^R100 is,
a hydrogen atom or an unsubstituted alkyl group having 1 to 2 carbon atoms;
^X1 is
a group represented by -CR ³ R ⁴ -,
a substituted or unsubstituted cycloalkylidene group having 5 to 6 carbon atoms,
a substituted or unsubstituted bicyclohydrocarbon diyl group having 7 to 10 carbon atoms, or a substituted or unsubstituted tricyclohydrocarbon diyl group having 10 to 16 carbon atoms,
^R3 and ^R4 each independently represent a hydrogen atom or a substituent;
^R3 and ^R4 as substituents each independently represent
an unsubstituted alkyl group having 1 to 3 carbon atoms;
an unsubstituted fluoroalkyl group having 1 to 3 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 12 ring carbon atoms,
provided that when R ¹⁹ and R ²⁰ are hydrogen atoms, any one or more of R ¹¹ to R ¹⁴ are substituents, and any one or more of R ¹⁵ to R ¹⁸ are substituents;
When R ¹¹ to R ¹⁸ are hydrogen atoms, R ¹⁹ and R ²⁰ are substituents. * indicates the bonding position.]

In the general formula (1A), Ar ¹ is a group represented by the general formula (3), n ₁ represents the average number of monomers,
In the general formula (2A), ^Ar2 is a group represented by the general formula (4), and _n2 represents the average number of monomers.

In this specification addendum, hydrogen atoms include isotopes with different numbers of neutrons, namely protium, deuterium, and tritium.

In the general formulas (3) and (4), examples of the alkyl group having 1 to 2 carbon atoms constituting R ¹¹ to R ²⁰ , R ²¹ to R ²⁸ and R ¹⁰⁰ include a methyl group and an ethyl group, with a methyl group being preferred.
In the general formulas (3) and (4), the fluoroalkyl group having 1 to 2 carbon atoms constituting R ¹¹ to R ¹⁸ and R ²¹ to R ²⁸ includes the above-mentioned alkyl group having 1 to 2 carbon atoms substituted with one or more fluorine atoms, and is preferably a perfluoroalkyl group, such as a trifluoromethyl group.
In the general formulae (3) and (4), examples of the alkoxy group having 1 to 2 carbon atoms constituting R ¹¹ to R ¹⁸ and R ²¹ to R ²⁸ include a methoxy group and an ethoxy group.

In the general formulas (3) and (4), the alkyl group having 1 to 3 carbon atoms constituting ^R3 and ^R4 includes a linear alkyl group or a branched alkyl group. Examples of the alkyl group include a methyl group, an ethyl group, and various propyl groups. A methyl group is preferable.
In the general formulas (3) and (4), examples of the fluoroalkyl group having 1 to 3 carbon atoms constituting ^R3 and ^R4 include the above-mentioned alkyl group having 1 to 3 carbon atoms substituted with one or more fluorine atoms. Preferred are perfluoroalkyl groups, such as a trifluoromethyl group.
In the general formulae (3) and (4), examples of the aryl group having 6 to 12 ring carbon atoms constituting R ³ and R ⁴ include a phenyl group, a biphenyl group, and a naphthyl group.

In the general formulas (3) and (4), examples of the cycloalkylidene group having 5 to 6 carbon atoms constituting X ¹ include a cyclopentylidene group, a cyclohexylidene group, and a 3,5,5-trimethylcyclohexylidene group.

The bicyclohydrocarbon diyl group refers to a divalent group derived by removing two hydrogen atoms from a bicyclohydrocarbon.
In the general formulas (3) and (4), examples of the bicyclohydrocarbon diyl group having 7 to 10 carbon atoms constituting ^X1 include divalent groups derived from any one of decahydronaphthalene (bicyclo[4.4.0]decane), norbornane (bicyclo[2.2.1]heptane), bornane, bicyclo[4.2.0]octane, bicyclo[4.3.0]nonane, bicyclo[3.3.1]nonane, and perhydroazulene.

The tricyclohydrocarbon diyl group refers to a divalent group derived by removing two hydrogen atoms from a tricyclohydrocarbon.
In the general formulas (3) and (4), examples of the tricyclohydrocarbon diyl group having 10 to 16 carbon atoms constituting ^X1 include divalent groups derived from any of perhydroanthracene, 10,10-dimethyl-2,3,4,4a,5,6,7,8,8a,9,9a,10a-dodecahydro-1H-anthracene, perhydrofluorene, tricyclo[8.5.0.0 ^2,8 ]pentadecane, exo-tricyclo[5.5.5.0 ^2,6 ]decane, and endo-tricyclo[5.5.5.0 ^2,6 ]decane.

In the present specification, examples of the substituent in the case of "substituted or unsubstituted" include at least one group selected from the group consisting of aryl groups having 6 to 12 ring carbon atoms (e.g., phenyl, biphenyl, naphthyl, etc.), heteroaryl groups having 5 to 12 ring atoms (e.g., pyridyl, etc.), alkyl groups having 1 to 20 carbon atoms (e.g., methyl, ethyl, n-propyl, isopropyl, etc.), fluoroalkyl groups having 1 to 20 carbon atoms (e.g., fluoromethyl and difluoromethyl groups), alkoxy groups having 1 to 20 carbon atoms (e.g., methoxy and ethoxy groups), and halogen atoms. Examples of halogen atoms include fluorine atoms, chlorine atoms, and bromine atoms.
In this specification, the substituent in the case of "substituted or unsubstituted" may be further substituted with at least one group selected from the group consisting of an aryl group having 6 to 12 ring carbon atoms, a heteroaryl group having 5 to 12 ring atoms, an alkyl group having 1 to 20 carbon atoms, a fluoroalkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, and a halogen atom.

In the PC copolymer of this embodiment, the abundance ratio represented by Ar ¹ /(Ar ¹ +Ar ² ) is preferably 30 mol % or more and 55 mol % or less, more preferably 35 mol % or more and 45 mol % or less, and even more preferably 38 mol % or more and 43 mol % or less.
When the abundance ratio represented by Ar ¹ /(Ar ¹ +Ar ² ) is 30 mol % or more, the effect of improving the wear resistance is easily achieved.
When the abundance ratio represented by Ar ¹ /(Ar ¹ +Ar ² ) is 55 mol % or less, crystallization of the highly regular p-terphenyl structure is unlikely to occur, and a decrease in solubility in organic solvents is suppressed.
The above mol % is a value expressed as a percentage of the molar copolymer composition. The molar copolymer composition can be measured from a nuclear magnetic resonance spectrum, specifically, by the method described in the Examples.

In the PC copolymer of this embodiment, the abundance ratio represented by ^Ar2 /( ^Ar1 + ^Ar2 ) is preferably 45 mol% or more and 70 mol% or less, more preferably 55 mol% or more and 65 mol% or less, and even more preferably 57 mol% or more and 62 mol% or less.
When the abundance ratio represented by Ar ² /(Ar ¹ +Ar ² ) is 45 mol % or more, crystallization of the highly regular p-terphenyl structure is unlikely to occur, and a decrease in solubility in organic solvents is suppressed.
When the abundance ratio represented by Ar ² /(Ar ¹ +Ar ² ) is 70 mol % or less, the effect of improving the wear resistance is easily achieved.

In the PC copolymer of the present embodiment, in the general formula (3), ^X2 and ^X3 each independently are preferably ^CR100 , and more preferably CH.

In the PC copolymer of this embodiment, in general formula (4), X ¹ is preferably a group represented by -CR ³ R ⁴ - or a substituted or unsubstituted cycloalkylidene group having 5 to 6 carbon atoms, and more preferably a substituted or unsubstituted cycloalkylidene group having 5 to 6 carbon atoms.
When X ¹ is a group represented by -CR ³ R ⁴ -, it is preferable that R ³ and R ⁴ each independently represent an unsubstituted alkyl group having 1 to 3 carbon atoms.

In the PC copolymer of this embodiment, it is preferable that R ¹¹ to R ¹⁸ and R ²¹ to R ²⁸ each independently represent a hydrogen atom or an unsubstituted alkyl group having 1 to 2 carbon atoms.

In the PC copolymer of this embodiment, R ¹¹ and R ¹⁶ are preferably the same.
In the PC copolymer of this embodiment, R ¹² and R ¹⁵ are preferably the same.
In the PC copolymer of this embodiment, R ¹³ and R ¹⁸ are preferably the same.
In the PC copolymer of this embodiment, R ¹⁴ and R ¹⁷ are preferably the same.
In the PC copolymer of this embodiment, R ¹⁹ and R ²⁰ are preferably the same.
In the PC copolymer of this embodiment, ^X2 and ^X3 are preferably the same.

In the PC copolymer of this embodiment, R ²¹ and R ²⁶ are preferably the same.
In the PC copolymer of this embodiment, R ²² and R ²⁵ are preferably the same.
In the PC copolymer of this embodiment, R ²³ and R ²⁸ are preferably the same.
In the PC copolymer of this embodiment, R ²⁴ and R ²⁷ are preferably the same.
In the PC copolymer of this embodiment, ^R3 and ^R4 are preferably different from each other.

As a PC copolymer having a repeating unit A represented by the general formula (1) and a repeating unit B represented by the general formula (2), one represented by the following general formula (100) is preferred.

In the general formula (100), a represents the molar copolymer ratio in the repeating unit A, and b represents the molar copolymer ratio in the repeating unit B.
a is Ar ¹ /(Ar ¹ +Ar ² ) and b is Ar ² /(Ar ¹ +Ar ² ).
The abundance ratio Ar ¹ /(Ar ¹ +Ar ² ) is expressed as the molar percentage of Ar ¹ .
The molar copolymerization ratio Ar ¹ /(Ar ¹ +Ar ² ) is represented by the molar fraction of Ar ¹ .
The same applies to the abundance ratio and molar copolymerization ratio of ^Ar2 .

In the general formula (100), the repeating units are not necessarily consecutive.
The PC copolymer represented by the general formula (100) may be either an alternating copolymer or a random copolymer.

In the PC copolymer of this embodiment, in the general formula (1), Ar ¹ is preferably a divalent group derived from any one of 2,5-bis(4-hydroxyphenyl)-3,6-dimethylpyrazine, 2',5'-dimethyl-[1,1';4',1'']terphenyl-4,4''-diol, and 3,3''-dimethyl-4,4''-dihydroxy-p-terphenyl.
The divalent group derived from 2,5-bis(4-hydroxyphenyl)-3,6-dimethylpyrazine is a group represented by the following general formula (3-1). The divalent group derived from 2',5'-dimethyl-[1,1';4',1'']terphenyl-4,4''-diol is a group represented by the following general formula (3-2). 3,3''-dimethyl-4,4''-dihydroxy-p-terphenyl is a group represented by the following general formula (3-3).

In the PC copolymer of this embodiment, Ar ¹ may be, for example, a group represented by the following general formulae (3-1) to (3-4), in which * indicates a bonding position.

In the PC copolymer of the present embodiment, in the general formula (2), Ar ² is preferably a group represented by the following general formula (4A).

(In the general formula (4A), R ²¹ to R ²⁸ each independently have the same definition as R ²¹ to R ²⁸ in the general formula (4). * indicates a bonding position.)

In the PC copolymer of this embodiment, ^Ar2 may be, for example, a group represented by the following general formulae (4-1) to (4-6), in which * indicates a bonding position.

The PC copolymer of this embodiment uses, as a raw material, at least one _of the bischloroformate oligomer represented by the general formula (1A) having an average number of repeat units _n1 in the range of 1.0 to 1.3 and the bischloroformate oligomer represented by the general formula (2A) having an average number of repeat units n2 in the range of 1.0 to 1.3, so that even when the PC copolymer has a highly crystalline ^Ar1 skeleton, the triad fraction of the AAA triad (a structural unit AAA consisting of three consecutive repeat units A lined up) in the PC copolymer can be suppressed to 5 mol % or less. As a result, crystallization of the PC copolymer can be suppressed, and the PC copolymer can have good solubility in organic solvents.

Here, a description will be given of triplets and triplet fractions.
In the PC copolymer of the present embodiment, structural units ABA, BAA, AAA, AAB, BBA, BAB, ABB, and BBB each constituted by three consecutive repeating units A represented by general formula (1) or three consecutive repeating units B represented by general formula (2) are defined as a triad.
The number of moles of each triad relative to the total number of moles of all triads (ABA, BAA, AAA, AAB, BBA, BAB, ABB, and BBB) expressed as a percentage is defined as the triad fraction.
For example, in the chain of repeating units A and B shown below, in addition to ABA and BAA enclosed in a square, there are a total of eight triads represented by AAA, AAB, BBA, BAB, ABB, and BBB. In this chain, the number of moles of each triad out of the total number of moles of the eight triads expressed as a percentage is the triad fraction.

Diads and diad fractions can be explained in the same way as triads and triad fractions.
In the PC copolymer of the present embodiment, the structural units AA, BB, AB, and BA each composed of two consecutive repeating units A represented by the general formula (1) or two consecutive repeating units B represented by the general formula (2) are defined as a diad.
The number of moles of each diad relative to the total number of moles of all diads (AA, BB, AB, and BA) is defined as the diad fraction, expressed as a percentage.
For example, in the chain of repeating units A and B shown below, in addition to AA and BB enclosed in ellipses, there are a total of four diads represented by AB and BA. In this chain, the diad fraction is the percentage of the number of moles of each diad out of the total number of moles of the four diads.

For example, when the PC copolymer of the present embodiment has repeating units A and B represented by the following general formula, the 4-position carbon represented by α, β, γ, and δ in the following general formula shows a specific shift value in the ¹³ C-NMR spectrum due to the influence of the left and right skeletons. In the case of the following general formula, it is influenced by the left and right A skeletons. This makes it possible to know the percentage of each of the triad patterns represented by ABA, BAA, AAA, AAB, BBA, BAB, ABB, and BBB contained.
The ¹³ C-NMR spectrum is measured, for example, under the following measurement conditions.

( ^13C -NMR Spectrum Measurement Conditions)
Apparatus: Bruker Japan Co., Ltd. (AVANCE III HD 500)
(5mmφ TCI cryoprobe used)
_Solvent : _CD2Cl2
Measurement concentration (sample amount/solvent amount): 50 mg/mL
- Number of times of accumulation: 1024 times (about 1 hour)

In the PC copolymer of the present embodiment, when the structural units ABA, BAA, AAA, AAB, BBA, BAB, ABB, and BBB each constituted by three consecutive repeating units A represented by the general formula (1) or three consecutive repeating units B represented by the general formula (2) are defined as a triad, the percentage of the number of moles of the triad represented by AAA to the total number of moles of the total eight types of triads represented by ABA, BAA, AAA, AAB, BBA, BAB, ABB, and BBB (triad fraction) is preferably 3 mol % or less, more preferably 2 mol % or less, and even more preferably 1 mol % or less.
When the percentage of the number of moles of the triads represented by AAA (triad fraction) is 3 mol % or less, the crystallinity of the resin decreases and the solubility in organic solvents increases, which results in improved compatibility with charge transport materials and the like, and further improved wear resistance and electrical properties of the photoreceptor.

In the PC copolymer of the present embodiment, when the structural units AA, BB, AB, and BA each constituted by two consecutively arranged repeating units A represented by the general formula (1) or two consecutively arranged repeating units B represented by the general formula (2) are defined as a diad, the percentage of the number of moles of the diad represented by AA to the total number of moles of the four types of diads represented by AA, BB, AB, and BA (diad fraction) is preferably 5 mol % or less, more preferably 3 mol % or less, and even more preferably 1 mol % or less.
When the percentage of the number of moles of diads represented by AA (diad fraction) is 5 mol % or less, the crystallinity of the resin is reduced and the solubility in organic solvents is improved, which results in improved compatibility with charge transport materials and the like, and improved wear resistance and electrical properties of the photoreceptor.

It is preferable that the PC copolymer of the present embodiment dissolves in THF (tetrahydrofuran) at a solid content concentration of 10 mass %, and the haze value of the solution is 3% or less.
The HAZE value is more preferably 2% or less, and further preferably 1% or less.
When the HAZE value is 3% or less, a PC copolymer having excellent transparency can be obtained.
The HAZE value can be measured by the method described in the Examples below.

The PC copolymer of this embodiment preferably has a yield stress of 70% or more at a tensile speed of 1 mm/min in a tensile test.
The yield stress is more preferably 72% or more, and further preferably 75% or more.
When the yield stress is 70% or more, a PC copolymer having improved abrasion resistance can be obtained.
The yield stress can be measured by the method described in the Examples below.

The PC copolymer of this embodiment preferably has a Martens hardness of 160 MPa or more when the load is set to 0.6 N in a nanoindentation test.
The Martens hardness is more preferably 170 MPa or more, and further preferably 180 MPa or more.
When the Martens hardness is 160 MPa or more, this not only contributes to improvement of abrasion resistance, but also provides a PC copolymer with good toner adhesion resistance when used as a binder resin for a photoreceptor.
The Martens hardness can be measured by the method described in the Examples below.

The PC copolymer of this embodiment preferably has an elastic power of 46% or more when a load is set to 0.6 N in an indentation test.
The elastic power is more preferably 47% or more, and further preferably 48% or more.
When the elastic power is 46% or more, a PC copolymer having improved abrasion resistance can be obtained.
The elastic power can be measured by the method described in the Examples below.

A film sample is obtained by dissolving 2 g of the PC copolymer of this embodiment in methylene chloride and casting the resulting solution on a PET film. The cast surface of the film sample is then contacted with an abrasive wheel carrying a load of 500 g and rotated 2,000 times, after which the mass loss of the film sample is preferably 3.0 mg or less.
The mass loss is more preferably 2.5 mg or less, and even more preferably 2.0 mg or less.
When the mass loss is 3.0 mg or less, a PC copolymer having improved abrasion resistance can be obtained.
The mass loss can be measured by the method described in the Examples below.

In this embodiment, the reduced viscosity [η _SP /C] of the PC copolymer is the value at 20° C. of a methylene chloride solution of the PC copolymer having a concentration of 0.5 g/dL.
The reduced viscosity [η _SP /C] of the PC copolymer of this embodiment is preferably 0.1 dL/g to 5 dL/g, more preferably 0.2 dL/g to 3 dL/g, and even more preferably 0.3 dL/g to 2.5 dL/g.
When the PC copolymer has a reduced viscosity [η _SP /C] of 0.1 dL/g or more, sufficient abrasion resistance can be obtained when used as an electrophotographic photoreceptor or the like.
When the reduced viscosity [η _SP /C] of the PC copolymer is 5 dL/g or less, an appropriate coating viscosity can be maintained when a molded article such as an electrophotographic photoreceptor is produced from the coating liquid, and the productivity of the molded article such as an electrophotographic photoreceptor can be increased.
The reduced viscosity can be measured by the method described in the Examples below.

In terms of improving electrical properties, the PC copolymer of this embodiment preferably has chain ends blocked with a monovalent aromatic group or a monovalent fluorine-containing aliphatic group.
The monovalent aromatic group may be a group that contains an aliphatic group, such as an alkyl group.
The monovalent fluorine-containing aliphatic group may be a group containing an aromatic group.
In addition, the monovalent aromatic group and the monovalent fluorine-containing aliphatic group may have a substituent added thereto, such as an alkyl group, a halogen atom, and an aryl group. These substituents may have a further substituent added thereto, such as an alkyl group, a halogen atom, and an aryl group. In addition, when there are a plurality of substituents, these substituents may be bonded to each other to form a ring.

The monovalent aromatic group constituting the chain end preferably contains an aryl group having a carbon number of 6 to 12. Examples of such aryl groups include a phenyl group and a biphenyl group.
Examples of the substituent added to the aromatic group and the substituent added to the alkyl group added to the aromatic group include halogen atoms such as fluorine atom, chlorine atom, and bromine atom. Examples of the substituent added to the aromatic group include alkyl groups having 1 to 20 carbon atoms. This alkyl group may be a group to which a halogen atom has been added as described above, or may be a group to which an aryl group has been added.

Examples of the monovalent fluorine-containing aliphatic group constituting the chain end include monovalent groups derived from fluorine-containing alcohols.

As the fluorine-containing alcohol, a fluorine-containing alcohol in which a plurality of fluoroalkyl chains each having 2 to 6 carbon atoms are linked together via ether bonds and in which the total number of fluorine atoms is 13 to 19 is preferred. If the total number of fluorine atoms is 13 or more, sufficient water repellency and oil repellency can be exhibited. On the other hand, if the total number of fluorine atoms is 19 or less, a decrease in reactivity during polymerization can be suppressed, and the mechanical strength, surface hardness, heat resistance, etc. of the obtained PC copolymer can be improved.
Furthermore, the monovalent fluorine-containing aliphatic group is preferably a monovalent group derived from a fluorine-containing alcohol having two or more ether bonds. By using such a fluorine-containing alcohol, the dispersibility of the PC copolymer in the coating liquid is improved, the wear resistance of the molded body and the electrophotographic photoreceptor is improved, and the surface lubricity, water repellency and oil repellency after wear can be maintained.

Alternatively, the fluorine-containing alcohol is preferably a fluorine-containing alcohol represented by the following general formula (30) or (31), a fluorine-containing alcohol such as 1,1,1,3,3,3-hexafluoro-2-propanol, or a fluorine-containing alcohol via an ether bond represented by the following general formula (32), (33), or (34).

H(CF ₂ ) _n1 CH ₂ OH...(30)
F( _CF2 ) _{m1 CH2OH} ...(31)

In the general formula (30), n1 is an integer from 1 to 12, and in the general formula (31), m1 is an integer from 1 to 12.

F-(CF ₂ ) _n ³¹ -OCF ₂ CH ₂ -OH...(32)
F-(CF ₂ CF ₂ ) _n ³² -(CF ₂ CF ₂ O) _n ³³ -CF ₂ CH ₂ OH...(33)
C(R) ₃ -(CF ₂ ) _n ³⁵ -O-(CF ₂ CF ₂ O) _n ³⁴ -CF ₂ CH ₂ OH...(34)

In the general formula (32), ⁿ³¹ is an integer of 1 to 10, and preferably an integer of 5 to 8.
In the general formula (33), n ³² is an integer of 0 to 5, and preferably an integer of 0 to 3. n ³³ is an integer of 1 to 5, and preferably an integer of 1 to 3.
In the general formula (34), n ³⁴ is an integer of 1 to 5, and preferably an integer of 1 to 3. n ³⁵ is an integer of 0 to 5, and preferably an integer of 0 to 3. R is _CF3 or F.

In this embodiment, in terms of improving electrical properties and abrasion resistance, it is preferable that the chain ends of the PC copolymer are blocked with a monovalent group derived from a phenol represented by the following general formula (9) or a monovalent group derived from a fluorine-containing alcohol represented by the following general formula (10).

In the above general formula (9), R ₁₀ represents an alkyl group having 1 to 10 carbon atoms or a fluoroalkyl group having 1 to 10 carbon atoms;
In the above general formula (10), _Rf represents a perfluoroalkyl group having 5 or more carbon atoms and 11 or more fluorine atoms, or a perfluoroalkyloxy group represented by the following general formula (11).

In the general formula (11), R _f2 is a linear or branched perfluoroalkyl group having 1 to 6 carbon atoms, and m is an integer of 1 to 3.

[Production method of PC copolymer]
A method for producing a PC copolymer will be described below by taking the PC copolymer represented by the above general formula (100) as an example.

The PC copolymer of this embodiment can be suitably obtained, for example, by the following synthesis reaction (CS1), (CS2) or (CS3).
(CS1) A bischloroformate oligomer represented by the following general formula (1A) and a dihydric phenolic compound represented by the following general formula (6) are subjected to interfacial polycondensation in the presence of an acid binder.
(CS2) A low-mer bischloroformate oligomer represented by the following general formula (2A) and a dihydric phenol compound represented by the following general formula (5) are subjected to interfacial polycondensation in the presence of an acid binder.
(CS3) A bischloroformate oligomer having a low molecular weight represented by the following general formula (1A) is mixed with a bischloroformate oligomer having a low molecular weight represented by the following general formula (2A), and the mixture of the bischloroformate oligomer represented by the following general formula (1A) and the bischloroformate oligomer represented by the following general formula (2A) is subjected to interfacial polycondensation with a dihydric phenolic compound represented by the following general formula (5) or a dihydric phenolic compound represented by the following general formula (6):

The above synthesis reactions (CS1) to (CS3) of PC copolymer are carried out in the presence of at least one of an end-capping agent and a branching agent, if necessary.

In the general formulae (1A) and (5), Ar ¹ is a group represented by the general formula (3). In the general formulae (2A) and (6), Ar ² is a group represented by the general formula (4).

In the general formula (1A), _n1 represents the average number of monomers of the bischloroformate oligomer. The average number of monomers, _n1 , is 1.0 or more and 1.3 or less, preferably 1.0 or more and 1.2 or less, and more preferably 1.0 or more and 1.1 or less.
In the general formula (2A), _n2 represents the average number of monomers of the bischloroformate oligomer. The average number of monomers _n2 is 1.0 or more and 1.3 or less, preferably 1.0 or more and 1.2 or less, and more preferably 1.0 or more and 1.1 or less.
The PC copolymer of this embodiment can _be easily produced by using, as a raw material, at least one of the bischloroformate oligomer represented by the general formula (1A) in which the average number of monomers _n1 is in the range of 1.0 or more and 1.3 or less, and the bischloroformate oligomer represented by the general formula (2A) in which the average number of monomers n2 is in the range of 1.0 or more and 1.3 or less.
The average number of monomers _n1 and _n2 can be calculated by the methods described in the Examples below.

For example, even if a bischloroformate oligomer represented by the general formula (2A) having an average number of monomers _n2 of 1.0 is reacted with a comonomer, for example, a terphenyl compound represented by the general formula (5) in a molar ratio of 1:1, it may be difficult to achieve an abundance ratio of ^Ar1 ( ^Ar1 /( ^Ar1 + ^Ar2 )) of 50 mol%.
This is because, during the reaction of the ^Ar2 oligomer (the bischloroformate oligomer represented by the general formula (2A)) formed with the monomer containing ^Ar1 (the terphenyl compound represented by the general formula (5)), the chloroformate group at the end of the ^Ar2 oligomer reacts with a base present in the reaction system to become a hydroxyl group, which may undergo polycondensation with the ^Ar2 oligomer having a chlorine terminal.

In addition, by using at least one of the bischloroformate oligomer represented by the general formula (1A) having an average number of repeat units _n1 in the range of 1.0 to 1.3 and the bischloroformate oligomer represented by the general formula ( _2A ) having an average number of repeat units n2 in the range of 1.0 to ^1.3 as a raw material, the triad fraction of the triad AAA (a structural unit AAA consisting of three consecutive repeat units A) in the PC copolymer can be suppressed to 5 mol % or less even in the case of a highly crystalline Ar 1 skeleton, as described above. As a result, crystallization of the PC copolymer can be suppressed, and the PC copolymer can have good solubility in organic solvents.

The bischloroformate oligomer represented by the general formula (1A) used in the method for producing the PC copolymer of this embodiment is derived from the terphenyl compound represented by the general formula (5).
The bischloroformate oligomer represented by the general formula (2A) used in the method for producing the PC copolymer of this embodiment is derived from a dihydric phenol compound represented by the general formula (6).

(Monomer represented by general formula (5))
The monomer (terphenyl compound) represented by the above general formula (5) which is the raw material for Ar ¹ , which is a structural unit of the PC copolymer of this embodiment, will be described below.
Examples of the monomer (terphenyl compound) represented by the general formula (5) include 2,5-bis(3-dimethyl-4-hydroxyphenyl)-pyrazine, 2,5-bis(3-diethyl-4-hydroxyphenyl)-pyrazine, 2,5-bis(4-hydroxyphenyl)-3,6-dimethylpyrazine, 2,5-bis(4-hydroxyphenyl)-3,6-diethylpyrazine, 2',5'-dimethyl-[1,1';4',1'']terphenyl-4,4''-diol, 2',5'-diethyl-[1,1';4',1'']terphenyl-4,4''-diol, 3,3''-dimethyl-4,4''-dihydroxy-p-terphenyl, 3,3''-diethyl-4,4''-dihydroxy-p-terphenyl, 2,5-bis(3-diethyl-4,4''-dihydroxy-p-terphenyl, trifluoromethyl-4-hydroxyphenyl)-pyrazine, 2,5-bis(3-ditetrafluoroethyl-4-hydroxyphenyl)-pyrazine, 2,5-bis(4-hydroxyphenyl)-3,6-ditrifluoromethylpyrazine, 2,5-bis(4-hydroxyphenyl)-3,6-ditetrafluoroethylpyrazine, 2',5'-ditrifluoromethyl-[1,1';4',1'']terphenyl-4,4''-diol, 2',5'-ditetrafluoroethyl-[1,1';4',1'']terphenyl-4,4''-diol, 3,3''-ditrifluoromethyl-4,4''-dihydroxy-p-terphenyl, 3,3''-ditetrafluoroethyl-4,4''-dihydroxy-p-terphenyl, and the like.

Among these, 2,5-bis(3-dimethyl-4-hydroxyphenyl)-pyrazine, 2',5'-dimethyl-[1,1';4',1'']terphenyl-4,4''-diol, and 3,3''-dimethyl-4,4''-dihydroxy-p-terphenyl are preferred as terphenyl compounds because they give PC copolymers with excellent mechanical properties. They are also preferred because they give good coating fluids when used as PC copolymers for electrophotographic photoreceptors. These compounds may be used alone or in combination of two or more.

From the viewpoint of abrasion resistance, these terphenyl compounds are preferably dihydric phenol monomers whose homopolymers have a solubility in methylene chloride of 2% by mass or less and which crystallize during the polycarbonate synthesis reaction by the interfacial polycondensation method, making it substantially impossible to synthesize homopolymers having a number average molecular weight of 10,000 or more.
Whether the solubility in methylene chloride is 2% by mass or less can be confirmed by immersing 2 parts by mass of a solid homopolymer having an organic solvent content of 500 ppm by mass or less and a viscosity average molecular weight in the range of 15,000 to 30,000 inclusive in 98 parts by mass of methylene chloride at room temperature (25° C.), leaving it for 24 hours, performing solid-liquid separation, and drying the solid side to determine whether the mass loss is 0.04 parts by mass or more.

(Monomer represented by general formula (6))
The dihydric phenol compound (comonomer) represented by the general formula (6) that serves as the raw material for ^Ar2 , which is a structural unit of the PC copolymer of this embodiment, will be described below.
The dihydric phenol compound represented by the general formula (6) includes a bisphenol compound. Specifically, for example, 1,1-bis(3-methyl-4-hydroxyphenyl)ethane, 1,1-bis(4-hydroxyphenyl)ethane, 1,2-bis(4-hydroxyphenyl)ethane, 2,2-bis(3-methyl-4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)butane, 1,1-bis(4-hydroxyphenyl)cyclopentane, 1,1-bis(3-methyl-4-hydroxyphenyl)cyclopentane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 1,1-bis(3-methyl-4-hydroxyphenyl)cyclohexane, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, bis(3-methyl-4-hydroxyphenyl)methane, 2,2-bis(4-hydroxyphenyl)propane, 1,1-bis(4-hydroxyphenyl)-1,1-diphenylmethane, 1,1-bis(4-hydroxyphenyl)-1-furan, phenylethane, 1,1-bis(4-hydroxyphenyl)-1-phenylmethane, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, 2,2-bis(3-methyl-4-hydroxyphenyl)propane, 1,1-bis(3-ethyl-4-hydroxyphenyl)cyclohexane, 2,2-bis(3-trifluoromethyl-4-hydroxyphenyl)ethane, 2,2-bis(3-pentafluoroethyl-4-hydroxyphenyl)ethane, 2,2-bis(2-methyl-4-hydroxyphenyl)propane, 2,2-bis(3-trifluoromethyl-4-hydroxyphenyl)propane, 2,2-bis(3-pentafluoroethyl-4-hydroxyphenyl)propane, 1,1-bis(3-trifluoromethyl-4-hydroxyphenyl)cyclohexane, and 1,1-bis(3-pentafluoroethyl-4-hydroxyphenyl)cyclohexane.

Among these bisphenol compounds, 2,2-bis(4-hydroxyphenyl)butane, 1,1-bis(4-hydroxyphenyl)ethane, 1,1-bis(4-hydroxyphenyl)cyclohexane, and 1,1-bis(3-methyl-4-hydroxyphenyl)cyclohexane are preferred in that they give PC copolymers that are excellent in abrasion resistance and solubility in organic solvents. They are also preferred because they give good coating fluids when used as PC copolymers for electrophotographic photoreceptors. These bisphenol compounds may be used alone or in combination of two or more.

(End-capping agent)
In the method for producing a PC copolymer according to this embodiment, the end-capping agent that generates the chain ends can be, for example, a monovalent carboxylic acid or a derivative thereof, or a monovalent phenol. For example, p-tert-butyl-phenol, p-phenylphenol, p-cumylphenol, p-perfluorononylphenol, p-(perfluorononylphenyl)phenol, p-(perfluorohexyl)phenol, p-tert-perfluorobutylphenol, perfluorooctylphenol, perfluorohexylphenol, 1-(p-hydroxybenzyl)perfluorodecane, p-[2-(1H,1H-perfluorotridodecyloxy)-1,1,1,3,3,3-hexafluoropropyl]phenol, 3,5-bis(perfluorohexyloxycarbonyl)phenol, p-hydroxybenzoic acid perfluorododecyl, p-(1H,1H-perfluorooctyloxy)phenol, 2H,2H,9H-perfluorononanoic acid, and 1,1,1,3,3,3-tetrafluoro-2-propanol can be mentioned.

As an end-capping agent for generating a chain end, a fluorine-containing alcohol represented by the above general formula (30) or (31), or a monovalent fluorine-containing alcohol such as 1,1,1,3,3,3-hexafluoro-2-propanol is also preferably used. It is also preferable to use a fluorine-containing alcohol via an ether bond represented by the above general formula (32), (33), or (34).

As the end-capping agent for generating the chain end, it is preferable to use, among these, a monohydric phenol represented by the general formula (9) or a monohydric fluorine-containing alcohol represented by the general formula (10) in terms of improving electrical properties and abrasion resistance.

As the monohydric phenol represented by the general formula (9), for example, p-tert-butyl-phenol, p-perfluorononylphenol, p-perfluorohexylphenol, p-tert-perfluorobutylphenol, and p-perfluorooctylphenol are preferably used. That is, in this embodiment, it is preferable that the chain ends are blocked with an end blocking agent selected from the group consisting of p-tert-butyl-phenol, p-perfluorononylphenol, p-perfluorohexylphenol, p-tert-perfluorobutylphenol, and p-perfluorooctylphenol.

Examples of the fluorine-containing alcohol via an ether bond represented by the general formula (10) include the following compounds. That is, the chain end of this embodiment may be preferably blocked with a terminal blocking agent selected from any one of the following fluorine-containing alcohols.

As the monovalent phenol that is the end-capping agent, a compound in which a monovalent organic siloxane-modified phenyl group is converted into a monovalent phenol can also be suitably used.
An example of the monovalent organosiloxane-modified phenyl group is a group represented by the following formula (9).

In the above general formula (9), Z is a hydrocarbon group having 2 to 6 carbon atoms. It is preferably an alkylene group, and more preferably a methylene group having 2 to 4 repeating units.
R ⁴¹ is an aliphatic hydrocarbon group having 1 to 6 carbon atoms, preferably an alkyl group having 1 to 6 carbon atoms.
R ⁴² to R ⁴⁵ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 12 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 12 ring carbon atoms.
R ⁴⁶ to R ⁴⁹ are each independently a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms or a substituted or unsubstituted aryl group having 6 to 12 ring carbon atoms.
Examples of the substituted or unsubstituted alkyl group having 1 to 12 carbon atoms and the substituted or unsubstituted aryl group having 6 to 12 ring carbon atoms include the groups exemplified as ^R3 and ^R4 in the general formulae (3) and (4). The alkyl group is preferably a methyl group. The aryl group is preferably a phenyl group.
n is an integer from 2 to 600, and indicates the average number of repeating units when the polymer has a molecular weight distribution.

Examples of monovalent organosiloxane-modified phenyl groups include the following groups:

In an electrophotographic photoreceptor using a PC copolymer having a monovalent organosiloxane-modified phenyl group as a binder resin, adhesion of foreign matter such as toner can be reduced.
When the PC copolymer of the present embodiment has a monovalent organosiloxane-modified phenyl group, the proportion of the monovalent organosiloxane-modified phenyl group is preferably 0.01% by mass or more, more preferably 50% by mass or less, even more preferably 0.1% by mass or more and 20% by mass or less, and particularly preferably 0.5% by mass or more and 10% by mass or less, based on the total mass of the PC copolymer.

The proportion of the terminal blocking agent added is preferably 0.05 mol% or more and 30 mol% or less, more preferably 0.1 mol% or more and 10 mol% or less, expressed as the molar percentage (copolymerization composition ratio) of the copolymerization composition of repeating unit A, repeating unit B, and the chain end. When the proportion of the terminal blocking agent added is 30 mol% or less, a decrease in mechanical strength can be suppressed. When the proportion of the terminal blocking agent added is 0.05 mol% or more, a decrease in moldability can be suppressed.

In addition, the branching agent that can be used in the method for producing a PC copolymer of this embodiment is not particularly limited. Specific examples of branching agents include phloroglucin, pyrogallol, 4,6-dimethyl-2,4,6-tris(4-hydroxyphenyl)-2-heptene, 2,6-dimethyl-2,4,6-tris(4-hydroxyphenyl)-3-heptene, 2,4-dimethyl-2,4,6-tris(4-hydroxyphenyl)heptane, 1,3,5-tris(2-hydroxyphenyl)benzene, 1,3,5-tris(4-hydroxyphenyl)benzene, 1,1,1-tris(4-hydroxyphenyl)ethane, tris(4-hydroxyphenyl)phenylmethane, 2,2-bis[4,4-bis(4-hydroxyphenyl)cyclohexyl]propane, 2,4-bis[2-bis(4- 2,6-bis(2-hydroxy-5-methylbenzyl)-4-methylphenol, 2-(4-hydroxyphenyl)-2-(2,4-dihydroxyphenyl)propane, tetrakis(4-hydroxyphenyl)methane, tetrakis[4-(4-hydroxyphenylisopropyl)phenoxy]methane, 2,4-dihydroxybenzoic acid, trimesic acid, cyanuric acid, 3,3-bis(3-methyl-4-hydroxyphenyl)-2-oxo-2,3-dihydroindole, 3,3-bis(4-hydroxyaryl)oxindole, 5-chloroisatin, 5,7-dichloroisatin, and 5-bromoisatin.

The proportion of the branching agent added is preferably 30 mol% or less, more preferably 5 mol% or less, in terms of copolymer composition ratio. When the proportion of the branching agent added is 30 mol% or less, the deterioration of moldability can be suppressed.

In the case of carrying out interfacial polycondensation, examples of the acid binder include alkali metal hydroxides (e.g., sodium hydroxide, potassium hydroxide, lithium hydroxide, cesium hydroxide, etc.), alkaline earth metal hydroxides (e.g., magnesium hydroxide, calcium hydroxide, etc.), weak alkali metal acid salts (e.g., sodium carbonate, potassium carbonate, calcium acetate, etc.), weak alkaline earth metal acid salts, and organic bases (e.g., pyridine, etc.).
When performing interfacial polycondensation, the preferred acid binder is an alkali metal hydroxide such as sodium hydroxide, potassium hydroxide, and calcium hydroxide, and an alkaline earth metal hydroxide. These acid binders can also be used as a mixture. The proportion of the acid binder used can be appropriately adjusted in consideration of the stoichiometric ratio (equivalent) of the reaction. Specifically, one equivalent or an excess of the acid binder can be used per mole of the total hydroxyl groups of the dihydric phenol as the raw material, and preferably one or more and ten or less equivalents of the acid binder can be used.

The solvent used in the method for producing the PC copolymer of this embodiment is not problematic as long as it exhibits a certain level of solubility in the obtained copolymer. Suitable examples of the solvent include aromatic hydrocarbons (e.g., toluene, xylene, etc.), halogenated hydrocarbons (e.g., methylene chloride, chloroform, 1,1-dichloroethane, 1,2-dichloroethane, 1,1,1-trichloroethane, 1,1,2-trichloroethane, 1,1,1,2-tetrachloroethane, 1,1,2,2-tetrachloroethane, pentachloroethane, and chlorobenzene, etc.), ketones (e.g., cyclohexanone, acetone, and acetophenone, etc.), and ethers (tetrahydrofuran and 1,4-dioxane, etc.). These solvents may be used alone or in combination of two or more. Furthermore, the interfacial polycondensation reaction may be carried out using two solvents that are not miscible with each other.

The catalyst used in the method for producing a PC copolymer of the present embodiment is not particularly limited. For example, tertiary amines (e.g., trimethylamine, triethylamine, tributylamine, N,N-dimethylcyclohexylamine, pyridine, N,N-diethylaniline, N,N-dimethylaniline, etc.), quaternary ammonium salts (e.g., trimethylbenzylammonium chloride, triethylbenzylammonium chloride, tributylbenzylammonium chloride, trioctylmethylammonium chloride, tetrabutylammonium chloride, tetrabutylammonium bromide, etc.), and quaternary phosphonium salts (e.g., tetrabutylphosphonium chloride, tetrabutylphosphonium bromide, etc.) are suitable.
Furthermore, if necessary, a small amount of an antioxidant such as sodium sulfite or a hydrosulfite salt may be added to the reaction system of the PC copolymer of this embodiment.

The method for producing the PC copolymer of this embodiment can be carried out in various ways other than the above-mentioned method for producing the PC copolymer. For example, a terphenyl compound represented by the general formula (5) is reacted with phosgene or the like to produce a bischloroformate oligomer having a low number of monomers represented by the general formula (1A). Then, a method can be adopted in which the bischloroformate oligomer is reacted with a dihydric phenolic compound represented by the general formula (6) in the presence of a mixture of the solvent and an alkaline aqueous solution of an acid binder. This method is preferable in that the abundance ratio represented by Ar ¹ /(Ar ¹ +Ar ² ) in the PC copolymer can be adjusted to a preferred range.

A method for producing a bischloroformate oligomer having an _n1 value in the range of 1.0 or more and 1.3 or a bischloroformate oligomer having an _n2 value in the range of 1.0 or more and 1.3 or less in the general formula (1A) is shown in detail in the Production Examples described later, but is roughly as follows.
First, the terphenyl compound represented by the general formula (5) or the dihydric phenolic compound represented by the general formula (6) is suspended in a hydrophobic solvent such as methylene chloride, and phosgene is further added to form a first solution. Meanwhile, a tertiary amine such as triethylamine is dissolved in a hydrophobic solvent such as methylene chloride to form a second solution, which is then added dropwise to the first solution to react at a temperature below room temperature (25° C.). The third solution containing the resulting reaction mixture is washed with hydrochloric acid and pure water to obtain an organic layer containing a polycarbonate oligomer with a low monomer number.
The dropping temperature and the reaction temperature are usually from 0° C. to 70° C., and preferably from 5° C. to 65° C. The dropping time and the reaction time are both usually from 15 minutes to 4 hours, and preferably from 30 minutes to 3 hours.
The average number of monomers _n1 and _n2 of the bischloroformate oligomer thus obtained, represented by the general formula (1A) or (2A), are each independently 1.0 or more and 1.3 or less, preferably 1.0 or more and 1.2 or less, and more preferably 1.0 or more and 1.1 or less.
Use of the bischloroformate oligomer produced by this production method is preferable in that the washing step during the production of a PC copolymer can be simplified.

A dihydric phenolic compound (monomer) represented by the general formula (6) is added to the organic layer containing the thus obtained low-mer bischloroformate oligomer represented by the general formula (1A) and reacted. Alternatively, a dihydric phenolic compound (monomer) represented by the general formula (5) is added to the organic layer containing the low-mer bischloroformate oligomer represented by the general formula (2A) and reacted.

The reaction temperature is preferably 0°C or higher and 150°C or lower, more preferably 5°C or higher and 40°C or lower, and further preferably 10°C or higher and 25°C or lower.
The reaction pressure may be reduced, normal, or increased, but is usually preferably normal pressure or the autogenous pressure of the reaction system. The reaction time depends on the reaction temperature, but is usually from 0.5 minutes to 10 hours, preferably from 1 minute to 3 hours.

In this reaction, the terphenyl compound represented by the general formula (5) or the dihydric phenol compound represented by the general formula (6) is preferably added as an aqueous solution or an organic solvent solution. There is no particular restriction on the order of addition. In addition, catalysts, end-capping agents, branching agents, etc. can be added in the above production method as necessary either during the production of the bischloroformate oligomer or during the subsequent high molecular weight reaction, or both.

The PC copolymer obtained as described above is a copolymer comprising the repeating unit A represented by the above general formula (1) and the repeating unit B represented by the above general formula (2).
Furthermore, this PC copolymer may contain polycarbonate units having structural units other than the repeating units A and B, or units having a polyester or polyether structure, as long as the achievement of the object of the present invention is not impaired.

The reduced viscosity [η _SP /C] of the obtained PC copolymer can be adjusted to within the above range by various methods, for example, by selecting the reaction conditions, adjusting the amounts of the branching agent and the end-capping agent used, etc. In some cases, the obtained PC copolymer can be appropriately subjected to at least one of physical treatments (e.g., mixing and fractionation) and chemical treatments (e.g., polymer reaction, crosslinking treatment, partial decomposition treatment, etc.) to obtain a PC copolymer with a predetermined reduced viscosity [η _SP /C].
The resulting reaction product (crude product) can be subjected to various post-treatments such as known separation and purification methods to recover a PC copolymer having a desired purity (degree of purification).

[Configuration of Coating Liquid]
The coating liquid of the present embodiment contains at least the PC copolymer of the present embodiment and an organic solvent capable of dissolving or dispersing the PC copolymer. In addition to the PC copolymer and the organic solvent, the coating liquid may contain additives such as low molecular weight compounds, colorants (e.g., dyes and pigments), functional compounds (e.g., charge transport materials, electron transport materials, hole transport materials, and charge generating materials), fillers (e.g., inorganic or organic fillers, fibers, and fine particles), antioxidants, ultraviolet absorbers, and acid scavengers. Examples of substances that may be contained in addition to the PC copolymer include substances contained in the components of the electrophotographic photoreceptor described below. In addition, the coating liquid may contain other resins as long as they do not impair the effects of the present invention, and examples of such resins are listed as examples of the components of the electrophotographic photoreceptor described below. In addition, the organic solvent used in the present embodiment may be used alone or in combination with a plurality of solvents, taking into consideration the solubility, dispersibility, viscosity, evaporation rate, chemical stability, and stability against physical changes of the PC copolymer of the present embodiment and other materials. Examples of such resins are listed as examples of the components of the electrophotographic photoreceptor described below.

The concentration of the PC copolymer component in the coating liquid of this embodiment may be an appropriate viscosity according to the use of the coating liquid. The concentration of the PC copolymer component in the coating liquid is preferably 0.1% by mass or more and 40% by mass or less, more preferably 1% by mass or more and 35% by mass or less, and even more preferably 5% by mass or more and 30% by mass or less. If the concentration of the PC copolymer component in the coating liquid is 40% by mass or less, the viscosity does not become too high and the coating property is good. If it is 0.1% by mass or more, the viscosity can be kept at an appropriate level and a homogeneous film can be obtained. In addition, the concentration is appropriate for shortening the drying time after coating and easily achieving the target film thickness.

The PC copolymer of this embodiment has good compatibility with the charge transport material, and is not likely to cause whitening or gelation even when dissolved in the organic solvent. Therefore, the coating liquid of this embodiment containing the PC copolymer and an organic solvent can suppress whitening or gelation of the PC polymer component for a long period of time even when it further contains a charge transport material, and can be stored stably. In addition, when the photosensitive layer of an electrophotographic photoreceptor is formed using this coating liquid (coating liquid containing a charge transport material), the photosensitive layer can be suppressed from crystallizing, and an excellent electrophotographic photoreceptor can be produced that does not cause defects in image quality.
When the coating liquid of the present embodiment contains a PC copolymer and a charge transport material, the ratio of the PC copolymer to the charge transport material in the coating liquid is usually 20:80 to 80:20, preferably 30:70 to 70:30, in terms of mass ratio.
In the coating liquid of this embodiment, the PC copolymer of this embodiment may be used alone or in combination of two or more kinds.

The coating liquid of the present embodiment is usually suitably used for forming the charge transport layer of a multi-layer electrophotographic photoreceptor, the photosensitive layer of which includes at least a charge generation layer and a charge transport layer. In addition, by further adding the charge generation material to the coating liquid, the coating liquid can also be used for forming the photosensitive layer of a single-layer electrophotographic photoreceptor.
In addition, the coating liquid of the present embodiment has excellent moldability, and is therefore suitable for use in forming a molded body.
Furthermore, when a molded article is formed using the coating liquid of the present embodiment, crystallization of the molded article can be suppressed, resulting in a molded article with high transparency.

[Configuration of Molded Product]
At least one of the PC copolymer of this embodiment and the coating liquid of this embodiment can be used to form a molded body.
The molded article may be, for example, an optical member, and examples of the optical member may include, for example, an electrophotographic photoreceptor and an optical lens. In addition, when the substrate is in the form of a film, the laminated film as one embodiment of the molded article may be applied, for example, as a film for in-mold molding and a decorative film. In addition, the laminated film may be applied as a film for touch panels used in liquid crystal and organic EL displays, optical films such as optical compensation films and anti-reflection films, and conductive films.
A molded article containing the PC copolymer of this embodiment is resistant to whitening and has excellent transparency, as well as excellent mechanical strength such as abrasion resistance and electrical strength.

[Configuration of Electrophotographic Photoreceptor]
The electrophotographic photoreceptor of the present embodiment contains the PC copolymer of the present embodiment.
An electrophotographic photoreceptor according to one embodiment has a substrate and a photosensitive layer provided on the substrate, and the photosensitive layer contains the PC copolymer of this embodiment.
The electrophotographic photoreceptor of this embodiment may be any electrophotographic photoreceptor, including various known types of electrophotographic photoreceptors, so long as the PC copolymer of this embodiment is used in the photosensitive layer. However, it is preferred that the photosensitive layer is a laminated type electrophotographic photoreceptor having at least one charge generation layer and at least one charge transport layer, or a single-layer type electrophotographic photoreceptor having a charge generation material and a charge transport material in one layer.

The PC copolymer may be used in any part of the photosensitive layer, but in order to fully exert the effects of this embodiment, it is preferable to use it as a binder resin for a charge transport material in a charge transport layer or as a binder resin for a single photosensitive layer. It is also preferable to use it not only in the photosensitive layer but also in a surface protective layer. In the case of a multi-layered electrophotographic photoreceptor having two charge transport layers, it is preferable to use it in one of the charge transport layers.
In the electrophotographic photoreceptor of the present embodiment, the PC copolymer of the present embodiment may be used alone or in combination of two or more. If desired, other binder resin components such as polycarbonates may be contained within a range that does not impair the object of the present embodiment. Furthermore, additives such as antioxidants may be contained.

The electrophotographic photoreceptor of this embodiment has a photosensitive layer on a conductive substrate. When the photosensitive layer has a charge generation layer and a charge transport layer, the charge transport layer may be laminated on the charge generation layer, or conversely, the charge generation layer may be laminated on the charge transport layer. The photosensitive layer may also contain a charge generation material and a charge transport material simultaneously in one layer. Furthermore, a conductive or insulating protective film may be formed on the surface layer as necessary. By using the PC copolymer of this embodiment in the surface layer, an electrophotographic photoreceptor with excellent wear resistance can be obtained.
Furthermore, intermediate layers such as an adhesive layer for improving adhesion between layers or a blocking layer for blocking charges may be formed.

As the conductive substrate material used in the electrophotographic photoreceptor of this embodiment, various materials such as known materials can be used. Specifically, plates, drums, and sheets made of aluminum, nickel, chromium, palladium, titanium, molybdenum, indium, gold, platinum, silver, copper, zinc, brass, stainless steel, lead oxide, tin oxide, indium oxide, ITO (indium tin oxide: tin-doped indium oxide) or graphite, glass, cloth, paper, and plastic films, sheets, or seamless belts that have been treated to be conductive by coating by vapor deposition, sputtering, or painting, and metal drums that have been treated to be metal oxidized by electrode oxidation, etc. can be used.

The charge generation layer has at least a charge generation material. This charge generation layer can be obtained by forming a layer of the charge generation material on the substrate as the base by vacuum deposition or sputtering, or by forming a layer of the charge generation material bound to the substrate as the base using a binder resin. Various methods, including known methods, can be used to form a charge generation layer using a binder resin. Usually, for example, a suitable method is to apply a coating liquid in which the charge generation material is dispersed or dissolved together with the binder resin in an appropriate solvent onto a substrate as the base, and then dry it to obtain a wet molded body.

As the charge generating material in the charge generating layer, various known materials can be used. Specific compounds include selenium alone (e.g., amorphous selenium, trigonal selenium, etc.), selenium alloys (e.g., selenium-tellurium, etc.), selenium compounds or selenium-containing compositions (e.g., As ₂ Se ₃ , etc.), inorganic materials consisting of elements of Groups 12 and 16 of the periodic table (for example, zinc oxide, CdS-Se, etc.), oxide-based semiconductors (for example, titanium oxide, etc.), silicon-based materials (for example, amorphous silicon, etc.), metal-free phthalocyanine pigments (for example, τ-type metal-free phthalocyanine, χ-type metal-free phthalocyanine, etc.), metal phthalocyanine pigments (for example, α-type copper phthalocyanine, β-type copper phthalocyanine, γ-type copper phthalocyanine, ε-type copper phthalocyanine, X-type copper phthalocyanine, A-type titanyl phthalocyanine, B-type titanyl phthalocyanine, C-type titanyl phthalocyanine, D-type titanyl phthalocyanine, E-type titanyl phthalocyanine, F-type titanyl phthalocyanine, G-type titanyl phthalocyanine, H-type titanyl phthalocyanine, K-type titanyl phthalocyanine, L-type titanyl phthalocyanine, M-type titanyl phthalocyanine, Examples of the charge generating material include phthalocyanine, N-type titanyl phthalocyanine, Y-type titanyl phthalocyanine, oxo-titanyl phthalocyanine, titanyl phthalocyanine that exhibits a strong diffraction peak at a Bragg angle 2θ of 27.3±0.2 degrees in an X-ray diffraction diagram, and gallium phthalocyanine, etc.), cyanine dyes, anthracene pigments, bisazo pigments, pyrene pigments, polycyclic quinone pigments, quinacridone pigments, indigo pigments, perylene pigments, pyrylium dyes, squalium pigments, anthanthrone pigments, benzimidazole pigments, azo pigments, thioindigo pigments, quinoline pigments, lake pigments, oxazine pigments, dioxazine pigments, triphenylmethane pigments, azulenium dyes, triarylmethane dyes, xanthine dyes, thiazine dyes, thiapyrylium dyes, polyvinylcarbazole, and bisbenzimidazole pigments. These compounds can be used alone or in combination of two or more compounds as the charge generating material. Among these charge generating substances, preferred charge generating substances include those specifically described in JP-A-11-172003.

The charge transport layer can be obtained as a wet molded body by forming a layer in which a charge transport material is bound with a binder resin on a substrate serving as a base.
The binder resin for the charge generating layer or charge transport layer is not particularly limited, and various known resins can be used. Specifically, for example, polystyrene, polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, polyvinyl acetal, alkyd resin, acrylic resin, polyacrylonitrile, polycarbonate, polyurethane, epoxy resin, phenol resin, polyamide, polyketone, polyacrylamide, butyral resin, polyester resin, vinylidene chloride-vinyl chloride copolymer, methacrylic resin, styrene-butadiene copolymer, vinylidene chloride-acrylonitrile copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin, melamine resin, polyether resin , benzoguanamine resin, epoxy acrylate resin, urethane acrylate resin, poly-N-vinyl carbazole, polyvinyl butyral, polyvinyl formal, polysulfone, casein, gelatin, polyvinyl alcohol, ethyl cellulose, nitrocellulose, carboxy-methyl cellulose, vinylidene chloride-based polymer latex, acrylonitrile-butadiene copolymer, vinyltoluene-styrene copolymer, soybean oil-modified alkyd resin, nitrated polystyrene, polymethylstyrene, polyisoprene, polythiocarbonate, polyarylate, polyhaloarylate, polyallyl ether, polyvinyl acrylate, and polyester acrylate.
These may be used alone or in combination of two or more. As the binder resin in the charge generating layer and/or the charge transport layer, it is preferable to use the PC copolymer of the present embodiment described above.

The charge transport layer can be formed by any of various known methods, but a preferred method is to apply a coating liquid in which a charge transport material is dispersed or dissolved in a suitable solvent together with the PC copolymer of this embodiment onto a substrate as a given base, and then dry the resulting coating liquid to obtain a wet molded body. The blending ratio of the charge transport material and the PC copolymer used to form the charge transport layer is preferably 20:80 to 80:20 by mass, more preferably 30:70 to 70:30.
In the charge transport layer, the PC copolymer of the present embodiment may be used alone or in combination with two or more kinds. In addition, other binder resins may be used in combination with the PC copolymer of the present embodiment within a range that does not impair the object of the present embodiment.

The thickness of the charge transport layer thus formed is usually about 5 μm to 100 μm, preferably 10 μm to 50 μm, and more preferably 15 μm to 35 μm. If the thickness is 5 μm or more, the initial charging potential does not decrease, and if it is 100 μm or less, the deterioration of the electrophotographic characteristics can be prevented.
As the charge transport material that can be used together with the PC copolymer of the present embodiment, various known compounds can be used. As such compounds, for example, carbazole compounds, indole compounds, imidazole compounds, oxazole compounds, pyrazole compounds, oxadiazole compounds, pyrazoline compounds, thiadiazole compounds, aniline compounds, hydrazone compounds, aromatic amine compounds, aliphatic amine compounds, stilbene compounds, fluorenone compounds, butadiene compounds, quinone compounds, quinodimethane compounds, thiazole compounds, triazole compounds, imidazolone compounds, imidazolidine compounds, bisimidazolidine compounds, oxazolone compounds, benzothiazole compounds, benzimidazole compounds, quinazoline compounds, benzofuran compounds, acridine compounds, phenazine compounds, poly-N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, polyvinylacridine, poly-9-vinylphenylanthracene, pyrene-formaldehyde resin, ethylcarbazole resin, or polymers having these structures in the main chain or side chain, etc. are preferably used. These compounds may be used alone or in combination of two or more.
Among these charge transporting substances, the compounds specifically exemplified in JP-A-11-172003 and the charge transporting substances represented by the following structures are particularly preferably used.

In addition, in the electrophotographic photoreceptor of this embodiment, it is preferable to use the PC copolymer of this embodiment as a binder resin in at least one of the charge generation layer and the charge transport layer.

In the electrophotographic photoreceptor of this embodiment, a commonly used undercoat layer can be provided between the conductive substrate and the photosensitive layer. For this undercoat layer, for example, fine particles (e.g., titanium oxide, aluminum oxide, zirconia, titanic acid, zirconic acid, lanthanum lead, titanium black, silica, lead titanate, barium titanate, tin oxide, indium oxide, silicon oxide, etc.), polyamide resin, phenolic resin, casein, melamine resin, benzoguanamine resin, polyurethane resin, epoxy resin, cellulose, nitrocellulose, polyvinyl alcohol, and polyvinyl butyral resin can be used. In addition, the binder resin or the PC copolymer of this embodiment can be used as the resin used in this undercoat layer. These fine particles and resins can be used alone or in various mixtures. When used as a mixture, it is preferable to use inorganic fine particles and resin in combination because a film with good smoothness is formed.

The thickness of the undercoat layer is from 0.01 μm to 10 μm, preferably from 0.1 μm to 7 μm. When the thickness is 0.01 μm or more, the undercoat layer can be formed uniformly, and when the thickness is 10 μm or less, deterioration of electrophotographic properties can be suppressed.
In addition, a known blocking layer that is commonly used can be provided between the conductive substrate and the photosensitive layer. The same resin as the binder resin can be used as the blocking layer. The PC copolymer of this embodiment can also be used. The thickness of this blocking layer is 0.01 μm or more and 20 μm or less, preferably 0.1 μm or more and 10 μm or less. If the thickness is 0.01 μm or more, the blocking layer can be formed uniformly, and if the thickness is 20 μm or less, the deterioration of electrophotographic properties can be suppressed.

Furthermore, in the electrophotographic photoreceptor of this embodiment, a protective layer may be laminated on the photosensitive layer. The same type of resin as the binder resin may be used for this protective layer. It is particularly preferable to use the PC copolymer of this embodiment. The thickness of this protective layer is 0.01 μm or more and 20 μm or less, preferably 0.1 μm or more and 10 μm or less. This protective layer may contain the charge generating material, the charge transport material, additives, metals and their oxides, nitrides, or salts, alloys, carbon black, and conductive materials such as organic conductive compounds.

Furthermore, to improve the performance of this electrophotographic photoreceptor, the charge generation layer and charge transport layer may contain binders, plasticizers, curing catalysts, fluidity imparting agents, pinhole control agents, and spectral sensitivity sensitizers (sensitizing dyes). In addition, various chemical substances, antioxidants, surfactants, anti-curl agents, leveling agents, and other additives may be added to prevent an increase in residual potential, a decrease in charging potential, and a decrease in sensitivity due to repeated use.

Examples of the binder include silicone resin, polyamide resin, polyurethane resin, polyester resin, epoxy resin, polyketone resin, polycarbonate copolymer, polystyrene resin, polymethacrylate resin, polyacrylamide resin, polybutadiene resin, polyisoprene resin, melamine resin, benzoguanamine resin, polychloroprene resin, polyacrylonitrile resin, ethyl cellulose resin, nitrocellulose resin, urea resin, phenol resin, phenoxy resin, polyvinyl butyral resin, formal resin, vinyl acetate resin, vinyl acetate/vinyl chloride copolymer resin, and polyester carbonate resin. At least one of a thermosetting resin and a photocurable resin can also be used. In any case, there is no particular restriction as long as the resin is electrically insulating and can form a film under normal conditions and does not impair the effects of the present invention.

Specific examples of the plasticizer include biphenyl, chlorinated biphenyl, o-terphenyl, halogenated paraffin, dimethylnaphthalene, dimethyl phthalate, dibutyl phthalate, dioctyl phthalate, diethylene glycol phthalate, triphenyl phosphate, diisobutyl adipate, dimethyl sebacate, dibutyl sebacate, butyl laurate, methylphthalyl ethyl glycolate, dimethyl glycol phthalate, methylnaphthalene, benzophenone, polypropylene, polystyrene, and fluorohydrocarbons.

Specific examples of the curing catalyst include methanesulfonic acid, dodecylbenzenesulfonic acid, and dinonylnaphthalenedisulfonic acid. Examples of the flowability imparting agent include Modaflow and Acronal 4F. Examples of the pinhole control agent include benzoin and dimethyl phthalate. It is preferable to use these plasticizers, curing catalysts, flowability imparting agents, and pinhole control agents in an amount of 5% by mass or less relative to the charge transport material.

In addition, when a sensitizing dye is used, suitable spectral sensitivity sensitizers include, for example, triphenylmethane dyes (e.g., methyl violet, crystal violet, night blue, and Victoria blue), acridine dyes (e.g., erythrosine, rhodamine B, rhodamine 3R, acridine orange, and flapeocine), thiazine dyes (e.g., methylene blue and methylene green), oxazine dyes (capri blue and meldola blue), cyanine dyes, merocyanine dyes, styryl dyes, pyrylium salt dyes, and thiopyrylium salt dyes.

An electron-accepting substance can be added to the photosensitive layer for the purpose of improving sensitivity, reducing residual potential, reducing fatigue during repeated use, etc. Specific examples include succinic anhydride, maleic anhydride, dibromomaleic anhydride, phthalic anhydride, tetrachlorophthalic anhydride, tetrabromophthalic anhydride, 3-nitrophthalic anhydride, 4-nitrophthalic anhydride, pyromellitic anhydride, mellitic anhydride, tetracyanoethylene, tetracyanoquinodimethane, o-dinitrobenzene, m-dinitrobenzene, 1,3,5-trinitrobenzene, p-nitrobenzonitrile, picryl chloride, quinone chlorimide, chloranil, bromanil, benzoquinone, 2,3-dichlorobenzoquinone, dichlorodicyanoparabenzoquinone, naphthoquinone, diphenoquinone, tropoquinone, anthraquinone, 1-chloroanthraquinone, dinitroanthraquinone, 4-nitrobenzophenone, 4,4'-dinitro Compounds having a large electron affinity, such as benzophenone, 4-nitrobenzalmalondinitrile, α-cyano-β-(p-cyanophenyl)ethyl acrylate, 9-anthracenylmethylmalondinitrile, 1-cyano-(p-nitrophenyl)-2-(p-chlorophenyl)ethylene, 2,7-dinitrofluorenone, 2,4,7-trinitrofluorenone, 2,4,5,7-tetranitrofluorenone, 9-fluorenylidene-(dicyanomethylenemalononitrile), polynitro-9-fluorenylidene-(dicyanomethylenemalononitrile), picric acid, o-nitrobenzoic acid, p-nitrobenzoic acid, 3,5-dinitrobenzoic acid, pentafluorobenzoic acid, 5-nitrosalicylic acid, 3,5-dinitrosalicylic acid, phthalic acid, and mellitic acid, are preferred. These compounds may be added to either the charge generation layer or the charge transport layer, and the blending ratio is from 0.01 parts by weight to 200 parts by weight, preferably from 0.1 parts by weight to 50 parts by weight, based on 100 parts by weight of the charge generation substance or the charge transport substance.

In addition, to improve the surface properties, tetrafluoroethylene resin, trifluorochloroethylene resin, tetrafluoroethylene hexafluoropropylene resin, vinyl fluoride resin, vinylidene fluoride resin, difluorodichloroethylene resin, copolymers thereof, and fluorine-based graft polymers may be used. The blending ratio of these surface modifiers is 0.1% by mass or more and 60% by mass or less, preferably 5% by mass or more and 40% by mass or less, relative to the binder resin. If the blending ratio is 0.1% by mass or more, the surface durability and surface energy reduction, etc., of the surface modification are sufficient, and if it is 60% by mass or less, there is no deterioration in electrophotographic properties.

The antioxidant is preferably, for example, a hindered phenol-based antioxidant, an aromatic amine-based antioxidant, a hindered amine-based antioxidant, a sulfide-based antioxidant, an organic phosphoric acid-based antioxidant, etc. The blending ratio of these antioxidants is usually 0.01% by mass to 10% by mass, preferably 0.1% by mass to 2% by mass, based on the charge transport material.
As specific examples of such antioxidants, the compounds represented by the chemical formulas [Chemical formula 94] to [Chemical formula 101] described in the specification of JP-A-11-172003 are suitable.
These antioxidants may be used alone or in combination of two or more. They may be added not only to the photosensitive layer but also to the surface protective layer, undercoat layer and blocking layer.

Specific examples of the solvent used in forming at least one of the charge generating layer and the charge transport layer include aromatic solvents (e.g., benzene, toluene, xylene, and chlorobenzene), ketones (e.g., acetone, methyl ethyl ketone, and cyclohexanone), alcohols (e.g., methanol, ethanol, and isopropanol), esters (e.g., ethyl acetate and ethyl cellosolve), halogenated hydrocarbons (e.g., carbon tetrachloride, carbon tetrabromide, chloroform, dichloromethane, tetrachloroethane, etc.), ethers (e.g., tetrahydrofuran, dioxolane, and dioxane, etc.), sulfoxides (e.g., dimethyl sulfoxide, etc.), and amides (e.g., dimethylformamide, diethylformamide, etc.). These solvents may be used alone or in combination of two or more.

The photosensitive layer of the single-layer electrophotographic photoreceptor can be easily formed by using the charge generating material, charge transport material, and additives, and applying the PC copolymer of this embodiment as a binder resin. As the charge transport material, it is preferable to add at least one of the hole transport material and the electron transport material described above. As the electron transport material, the electron transport material exemplified in JP-A-2005-139339 can be preferably applied.
The application of each layer can be carried out using various types of application equipment such as known equipment. Specifically, for example, an applicator, a spray coater, a bar coater, a tip coater, a roll coater, a dip coater, a doctor blade, or the like can be used.

The thickness of the photosensitive layer in the electrophotographic photoreceptor is 5 μm to 100 μm, preferably 10 μm to 50 μm, and more preferably 15 μm to 35 μm. If it is 5 μm or more, it is possible to prevent the initial potential from becoming low, and if it is 100 μm or less, it is possible to suppress the deterioration of electrophotographic characteristics. The ratio of the charge generating material to the binder resin used in the manufacture of the electrophotographic photoreceptor is 1:99 to 30:70 by mass, preferably 3:97 to 15:85. The ratio of the charge transport material to the binder resin is 10:90 to 80:20 by mass, preferably 30:70 to 70:30.

The electrophotographic photoreceptor thus obtained uses the PC copolymer of this embodiment, and therefore can prevent the coating liquid from becoming cloudy during the preparation of the photosensitive layer, and can also prevent gelation. In addition, since the photosensitive layer contains the PC copolymer of this embodiment as a binder resin, the photoreceptor has excellent durability (abrasion resistance) and excellent electrical properties (charging properties), and maintains excellent electrophotographic properties over a long period of time, and is suitable for use in various electrophotographic fields, such as copiers (monochrome, multicolor, full-color; analog, digital), printers (laser, LED, liquid crystal shutter), facsimiles, plate-making machines, and devices having multiple functions.

In addition, when using the electrophotographic photoreceptor of this embodiment, corona discharge (corotron, scorotron), contact charging (charging roll, charging brush), etc. are used for charging. Examples of charging methods include DC charging method and AC/DC superimposed charging method in which AC is superimposed. In addition, any of halogen lamps, fluorescent lamps, lasers (semiconductor, He-Ne), LED, and photoreceptor internal exposure methods may be used for exposure. For development, dry development methods and wet development methods such as cascade development, two-component magnetic brush development, one-component insulating toner development, and one-component conductive toner development are used. For transfer, for example, electrostatic transfer methods (for example, corona transfer, roller transfer, and belt transfer), pressure transfer methods, and adhesive transfer methods are used. For fixing, for example, heat roller fixing, radiant flash fixing, open fixing, and pressure fixing are used. Furthermore, for cleaning and de-electrification, for example, brush cleaners, magnetic brush cleaners, electrostatic brush cleaners, magnetic roller cleaners, and blade cleaners are used. In addition, a cleanerless method may be adopted. As the resin for the toner, for example, styrene resin, styrene-acrylic copolymer resin, polyester, epoxy resin, and cyclic hydrocarbon polymer can be used. The shape of the toner may be spherical or irregular. Toner controlled to a certain shape (for example, spheroidal or potato-shaped) can also be used. The toner may be any of pulverized toner, suspension polymerized toner, emulsion polymerized toner, chemically granulated toner, and ester elongation toner.

[Configuration of Electrical Equipment]
The electrical device of the present embodiment has the electrophotographic photoreceptor of the present embodiment (for example, a photoreceptor drum using the electrophotographic photoreceptor of the present embodiment), and examples of such electrical devices include copiers and printers such as laser printers.
Since the electrical device of the present embodiment has the electrophotographic photoreceptor of the present embodiment, which has excellent abrasion resistance, the frequency of replacing the photoreceptor drum and the like is reduced, which is a great cost advantage.

[Modifications of the embodiment]
The present invention is not limited to the above-described embodiment, and any modifications and improvements that can achieve the object of the present invention are included in the present invention.

Next, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples and various modifications and applications are possible without departing from the spirit of the present invention.

[Production Example: Preparation of Oligomer]
<Production Example 1: Synthesis of bisphenol Z oligomer (bischloroformate)>
56.6 kg (224 mol) of 1,1-bis(4-hydroxyphenyl)cyclohexane (bisphenol Z) was suspended in 1080 L of methylene chloride, and 66.0 kg (667 mol) of phosgene was added thereto to dissolve it. A solution of 44.0 kg (435 mol) of triethylamine dissolved in 120 L of methylene chloride was added dropwise to the suspension at 2.2°C to 17.8°C over 2 hours and 50 minutes. After stirring for 30 minutes at 17.9°C to 19.6°C, 900 L of methylene chloride was distilled off at 14°C to 20°C. 210 L of pure water, 1.2 kg of concentrated hydrochloric acid, and 450 g of hydrosulfite were added to the remaining liquid for washing. Then, washing was repeated five times with 210 L of pure water to obtain a methylene chloride solution of bisphenol Z oligomer having a chloroformate group at the molecular end.
The chloroformate concentration of the obtained solution was 1.14 mol/L, the solid concentration was 0.22 kg/L, and the average number of monomers was 1.02. Hereinafter, the raw material obtained in Production Example 1 is referred to as Z-CF.
The raw material Z-CF is a bischloroformate oligomer represented by the general formula (2A).

The average number of monomers (n ₂ ) was calculated using the following formula.
Average number of molecules (n ₂ )=1+(Mav-M1)/M2...(Math. 1)
(In the formula (Math. 1), Mav is (2×1000/(CF value)), M2 is (M1−98.92), M1 is the molecular weight of the bischloroformate compound when n ₂ =1 in general formula (2A), the CF value (N/kg) is (CF value/concentration), the CF value (N) is the number of chlorine atoms in the bischloroformate compound represented by general formula (2A) contained in 1 L of reaction solution, and the concentration (kg/L) is the amount of solids obtained by concentrating 1 L of reaction solution. Here, 98.92 is the total atomic weight of two chlorine atoms, one oxygen atom, and one carbon atom that are eliminated by polycondensation of the bischloroformate compounds.)

<Production Example 2: Synthesis of bisphenol CZ oligomer (bischloroformate)>
A solution of 199.4 g (1.97 mol) of triethylamine diluted with 460 mL of methylene chloride was added dropwise to a mixture of 266 g (0.897 mol) of 1,1-bis(3-methyl-4-hydroxyphenyl)cyclohexane (bisphenol CZ), 1058 mL of methylene chloride, and 187 g (1.89 mol) of phosgene at 13°C to 16°C over 3 hours and 6 minutes. The reaction mixture was stirred at 14°C to 16°C for 1 hour and 38 minutes. The reaction mixture was washed with 5.0 mL of concentrated hydrochloric acid and 200 mL of pure water. Thereafter, washing with water was repeated until the aqueous layer became neutral, and a methylene chloride solution of bisphenol C oligomer having a chloroformate group at the molecular end was obtained.
The resulting solution had a chloroformate concentration of 1.01 mol/L, a solid concentration of 0.22 kg/L, and an average number of monomers of 1.10. Hereinafter, the raw material obtained in Production Example 2 is referred to as CZ-CF.
The raw material CZ-CF is a bischloroformate oligomer represented by the general formula (2A).

<Production Example 3: Synthesis of dimethyl-p-terphenyl oligomer (bischloroformate)>
250 g (0.861 mol) of 3,3″-dimethyl-4,4″-dihydroxy-p-terphenyl was suspended in 1000 mL of methylene chloride, and 179 g (1.81 mol) of phosgene was added thereto to dissolve it. A solution of 192.3 g (1.90 mol) of triethylamine dissolved in 500 mL of methylene chloride was added dropwise to the suspension at 13° C. to 17° C. over 2 hours and 50 minutes. After stirring for 30 minutes at 14° C. to 16° C., 850 mL of methylene chloride was distilled off at 14° C. to 20° C. The remaining liquid was washed with 210 mL of pure water and 5.0 ml of concentrated hydrochloric acid. Thereafter, washing with water was repeated until the aqueous layer became neutral, and a methylene chloride solution of dimethyl-p-terphenyl oligomer having a chloroformate group at the molecular end was obtained.
The resulting solution had a chloroformate concentration of 1.14 mol/L, a solid concentration of 0.17 kg/L, and an average number of monomers of 1.03. Hereinafter, the raw material obtained in Production Example 3 is referred to as MpT-CF.
The raw material MpT-CF is a bischloroformate oligomer represented by the general formula (1A).

The average number of monomers (n ₁ ) was determined in the same manner as the above-mentioned average number of monomers (n ₂ ).

<Production Example 4: Synthesis of PC oligomer of bisphenol Z>
120.0 g (0.448 mol) of 1,1-bis(4-hydroxyphenyl)cyclohexane (bisphenol Z) was added to an alkaline solution prepared by dissolving 46 g (1.15 mol) of sodium hydroxide and 64 g (1.14 mol) of potassium hydroxide in 1.24 L of pure water, and 0.64 L of methylene chloride was mixed and stirred. Under cooling to 5° C., 69 g of phosgene gas was blown into the liquid at a rate of 15 g/hr until the pH became 9 or less.
Next, after stopping the introduction of phosgene gas, the atmosphere was replaced with nitrogen and the reaction liquid was adjusted with hydrochloric acid to a pH of 7 to 9. This reaction liquid was allowed to stand and separated to obtain a methylene chloride solution of an oligomer having a chloroformate group at the molecular end.
The chloroformate concentration of the obtained solution was 0.52 mol/L, the solid concentration was 0.220 kg/L, and the average number of monomers was 2.70. Hereinafter, the raw material obtained in Production Example 4 is referred to as PCOCH.

Example 1
(Production of PC copolymer)
Into a reaction vessel equipped with a mechanical stirrer, stirring blades, and baffles, the raw material Z-CF (bischloroformate oligomer, average polymerization number: 1.02) (155 mL) obtained in Production Example 1 and methylene chloride (332 mL) were poured. To this was added p-tert-butylphenol (0.317 g) as an end-capping agent, and the mixture was stirred so as to be thoroughly mixed. After cooling to a temperature inside the reactor of 15° C., the entire amount of the prepared 2,5-bis(4-hydroxyphenyl)-3,6-dimethylpyrazine solution (solution preparation method: 122 mL of a 2.1 N aqueous potassium hydroxide solution (16.6 g of potassium hydroxide) was prepared, cooled to room temperature (25° C.) or lower, and then 0.25 g of hydrosulfite was added as an antioxidant, and 20.7 g of 2,5-bis(4-hydroxyphenyl)-3,6-dimethylpyrazine was added and completely dissolved) was added to this solution, and 2.0 mL of an aqueous triethylamine solution (7 vol %) was added with stirring, and stirring was continued for 1 hour.
The resulting reaction mixture was diluted with 0.36 L of methylene chloride and 0.03 L of water and washed. The lower layer was separated and further washed once with 0.15 L of water, once with 0.15 L of 0.03 N hydrochloric acid, and three times with 0.1 L of water, in that order. The resulting methylene chloride solution was dropped into warm water at 60°C to 70°C while stirring, and the resulting precipitate was filtered and dried to obtain a PC copolymer (PC-1) having the following structure.

(Identification of PC copolymer)
The PC copolymer (PC-1) thus obtained was dissolved in methylene chloride to prepare a solution having a concentration of 0.5 g/dL, and the reduced viscosity [η _SP /C] at 20° C. was measured to be 1.22 dL/g. The structure and composition of the obtained PC copolymer (PC-1) were analyzed by ¹ H-NMR spectrum and ¹³ C-NMR spectrum, and it was confirmed that the PC copolymer was composed of the following repeating units and composition.
The reduced viscosity was measured using an automatic viscosity measuring device VMR-042 manufactured by Rigo Co., Ltd., using an improved Ubbelohde viscometer for automatic viscosity (RM type).
The measurement conditions for ¹ H-NMR spectrum and ¹³ C-NMR spectrum are as follows.

( ^1H -NMR spectrum measurement conditions)
・Apparatus: JEOL Ltd. (JNM-ECZ400S)
_Solvent : _CD2Cl2
Measurement concentration (sample amount/solvent amount): 1.5 mg/mL
・Number of times: 64 times (approximately 3 min)

( ^13C -NMR Spectrum Measurement Conditions)
Apparatus: Bruker Japan Co., Ltd. (AVANCE III HD 500)
(5mmφ TCI cryoprobe used)
_Solvent : _CD2Cl2
Measurement concentration (sample amount/solvent amount): 50 mg/mL
- Number of times of accumulation: 1024 times (about 1 hour)

a=Ar ¹ /(Ar ¹ +Ar ² )=0.42
b=Ar ² /(Ar ¹ +Ar ² )=0.58

The structure of the general formula (PC-1) was confirmed by the following procedure.
First, an assignment analysis was carried out using ^{the 1} H-NMR spectrum and the ¹³ C-NMR spectrum, and the molar copolymerization ratio a in the repeating unit A and the molar copolymerization ratio b in the repeating unit B were calculated from the integrated intensities according to the following formula.
a=Ar ¹ /(Ar ¹ +Ar ² )...(number A)
b = ^Ar2 / ( ^Ar1 + ^Ar2 ) ... (number B)

(Production of Coating Fluid and Electrophotographic Photoreceptor)
An electrophotographic photoreceptor was manufactured by using a polyethylene terephthalate (PET) resin film on which aluminum metal was vapor-deposited as a conductive substrate, and by sequentially laminating a charge generating layer and a charge transport layer on the surface of the conductive substrate to form a laminated photosensitive layer.
0.5 parts by mass of oxotitanium phthalocyanine was used as the charge generating material, and 0.5 parts by mass of butyral resin was used as the binder resin. These were added to 19 parts by mass of methylene chloride as a solvent, and dispersed in a ball mill. The dispersion was applied to the surface of the conductive substrate film by a bar coater, and dried to form a charge generating layer having a thickness of about 0.5 μm.
Next, 0.5 g of the compound (CTM-1) represented by the following formula (23) as a charge transport material and 0.5 g of the PC copolymer (PC-1) obtained in the above example were dispersed in 10 mL of tetrahydrofuran to prepare a coating liquid, which was then applied onto the charge generation layer with an applicator and dried to form a charge transport layer with a thickness of about 20 μm.

[Evaluation of PC Copolymer and Electrophotographic Photoreceptor]
(Solubility of PC Copolymer)
The solubility of the PC copolymer was evaluated by adding the PC copolymer (PC-1) (1 g) obtained above to THF (9 g), stirring with a shaker for 30 minutes, and visually observing the insoluble parts in the liquid and the degree of turbidity. When the PC copolymer (PC-1) was dissolved and no turbidity was observed, it was rated as "dissolved", when there was an insoluble part, it was rated as "insoluble", and when it became turbid, it was rated as "turbid".

(Transparency (HAZE value) of PC copolymer)
The haze value (%) was measured using the solution used in the evaluation of the solubility of the PC copolymer (a THF solution having a solid content concentration of PC-1 of 10% by mass).
The haze value (%) was measured in accordance with JIS K 7136 (2000). A haze meter (NDH500) manufactured by Nippon Denshoku Industries Co., Ltd. was used as the measuring device. The international standard number corresponding to JIS K 7136 is ISO 14782 (1999). The haze value (%) can also be measured in accordance with ISO 14782 (1999).

(Tensile properties (yield stress) of PC copolymer)
PC copolymer (PC-1) (2.5 g) was added to methylene chloride (20 mL) and stirred with a shaker for 60 minutes, after which the solution was spread in a petri dish with a diameter of 150 mm. It was then air-dried for one day and further dried in a dryer at 100°C for 10 hours. From the dried sample, a film sample of 40 mm x 6 mm (2 mm at the neck) x approximately 90 μm thick was prepared using a punching tool for tensile testing. The yield stress (%) of the PC copolymer (PC-1) was measured using this film sample.
The yield stress (%) was measured using a benchtop tensile tester (EZgraph, manufactured by Shimadzu Corporation) with the tensile speed set at 1 mm/min.

(Martens hardness and elastic power of PC copolymer)
A film sample similar to that used for the tensile properties of the PC copolymer was prepared, and the Martens hardness and elastic power of the PC copolymer (PC-1) were measured using this film sample.
The Martens hardness (MPa) and elastic power (%) were measured by a nanoindentation test.
The Martens hardness (MPa) and the elastic power (%) were measured using a nanoindentation device (ENT-1100a, manufactured by Elionix) with the load set to 0.6 N.

(Wear resistance of PC copolymer and electrophotographic photoreceptor)
[Preparation 1] Preparation of a sample for evaluating the abrasion resistance of the copolymer PC copolymer (PC-1) (2 g) was dissolved in methylene chloride (12 mL) and cast onto a commercially available PET film using an applicator. The film was heated under reduced pressure (100 Pa or less) to remove the solvent, and a film sample of 100 mm x 100 mm x approximately 30 μm thick was obtained.

[Preparation 2] Preparation of a sample for evaluating the wear resistance of a photoreceptor PC copolymer (PC-1) (1 g) and the above CTM-1 (0.67 g) were dissolved in THF (10 mL) and cast onto a commercially available PET film using an applicator. The film was heated under reduced pressure (100 Pa or less) to remove the solvent, and a film sample of 100 mm x 100 mm x approximately 30 μm thick was obtained.

[Evaluation of wear resistance]
The abrasion resistance of the cast surface of the films prepared in the above [Preparation 1] and [Preparation 2] was evaluated using a Suga abrasion tester NUS-ISO-3 (manufactured by Suga Test Instruments Co., Ltd.).
The test conditions were as follows: abrasive paper (manufactured by Suga Test Instruments Co., Ltd., containing alumina particles with a particle size of 3 μm) was placed under a load of 4.9 N and brought into contact with the film surface, and reciprocated 2,000 times to measure the mass loss.

(Charging Characteristics of Electrophotographic Photoreceptor)
Next, the electrophotographic characteristics of the electrophotographic photoreceptor manufactured as described above were measured using a static charge tester CYNTHIA54IM (manufactured by Gentec Co., Ltd.) Under conditions of EV (exposure sensitivity measurement) mode and initial charge amount of −700 V, the initial surface potential V ₀ (V) and the residual potential (initial residual potential V _R (V)) 5 seconds after light irradiation (10 Lux) were measured.

The results of these evaluations are shown in Table 1. For Examples 2 to 5 and Comparative Examples 1 to 4 described below, evaluation samples of the copolymer and photoreceptor were prepared using the PC copolymer obtained in each example instead of the PC copolymer (PC-1), and similar evaluations were performed. The results are also shown in Table 1.

Example 2
Into a reaction vessel equipped with a mechanical stirrer, stirring blades, and baffles, the raw material Z-CF (bischloroformate oligomer, average polymerization number: 1.02) (155 mL) obtained in Production Example 1 and methylene chloride (323 mL) were poured. To this was added p-tert-butylphenol (0.346 g) as an end-capping agent, and the mixture was stirred so as to be thoroughly mixed. After cooling the temperature inside the reactor to 15° C., the entire amount of the prepared 2',5'-dimethyl-[1,1';4',1'']terphenyl-4,4''-diol solution (solution preparation method: 122 mL of 2.1 N potassium hydroxide aqueous solution (16.6 g of potassium hydroxide) was prepared, cooled to room temperature (25° C.) or lower, 0.25 g of hydrosulfite was added as an antioxidant, and 20.5 g of 2',5'-dimethyl-[1,1';4',1'']terphenyl-4,4''-diol was further added and completely dissolved) was added to this solution, and 1.8 mL of a triethylamine aqueous solution (7 vol%) was added with stirring, and stirring was continued for 80 minutes.
The resulting reaction mixture was diluted with 0.36 L of methylene chloride and 0.03 L of water and washed. The lower layer was separated and further washed once with 0.15 L of water, once with 0.15 L of 0.03 N hydrochloric acid, and three times with 0.1 L of water, in that order. The resulting methylene chloride solution was dropped into warm water at 60°C to 70°C while stirring, and the resulting precipitate was filtered and dried to obtain a PC copolymer (PC-2) having the following structure.
The reduced viscosity [η _SP /C] of the PC copolymer (PC-2) at 20° C. was 1.21 dL/g, and the structure was confirmed by NMR to be a PC copolymer consisting of the following repeating units and composition:

a=Ar ¹ /(Ar ¹ +Ar ² )=0.40
b=Ar ² /(Ar ¹ +Ar ² )=0.60

Example 3
Into a reaction vessel equipped with a mechanical stirrer, stirring blades, and baffles, the raw material Z-CF (bischloroformate oligomer, average polymerization number: 1.02) (155 mL) obtained in Production Example 1 and methylene chloride (332 mL) were poured. To this was added p-tert-butylphenol (0.369 g) as an end-capping agent, and the mixture was stirred so as to be thoroughly mixed. After cooling the temperature inside the reactor to 15° C., the entire amount of the prepared 3,3″-dimethyl-4,4″-dihydroxy-p-terphenyl solution (solution preparation method: 122 mL of 2.1 N aqueous potassium hydroxide solution (16.6 g of potassium hydroxide) was prepared, cooled to room temperature (25° C.) or lower, and then 0.18 g of hydrosulfite was added as an antioxidant, and 20.5 g of 3,3″-dimethyl-4,4″-dihydroxy-p-terphenyl was added and completely dissolved) was added to this solution, and 1.8 mL of an aqueous triethylamine solution (7 vol %) was added with stirring, and stirring was continued for 1 hour.
The resulting reaction mixture was diluted with 0.36 L of methylene chloride and 0.03 L of water and washed. The lower layer was separated and further washed once with 0.15 L of water, once with 0.15 L of 0.03 N hydrochloric acid, and three times with 0.1 L of water, in that order. The resulting methylene chloride solution was dropped into warm water at 60°C to 70°C while stirring, and the resulting precipitate was filtered and dried to obtain a PC copolymer (PC-3) having the following structure.
The reduced viscosity [η _SP /C] of the PC copolymer (PC-3) at 20° C. was 1.21 dL/g, and the structure was confirmed by NMR to be a PC copolymer consisting of the following repeating units and composition:

a=Ar ¹ /(Ar ¹ +Ar ² )=0.41
b=Ar ² /(Ar ¹ +Ar ² )=0.59

Example 4
Into a reaction vessel equipped with a mechanical stirrer, stirring blades, and baffles, the raw material MpT-CF (bischloroformate oligomer, average number of monomers: 1.03) (155 mL) obtained in Production Example 3 and methylene chloride (221 mL) were poured. To this, p-tert-butylphenol (0.250 g) was added as an end-capping agent, and the mixture was stirred so as to be thoroughly mixed. After cooling to a temperature inside the reactor of 15°C, the entire amount of the prepared bisphenol Z solution (solution preparation method: 94 mL of 2.7 N potassium hydroxide aqueous solution (19.6 g of potassium hydroxide) was prepared, cooled to room temperature (25°C) or lower, 0.17 g of hydrosulfite was added as an antioxidant, and 19.0 g of bisphenol Z was further added and completely dissolved) was added to this solution, and 1.8 mL of a triethylamine aqueous solution (7 vol%) was added while stirring, and stirring was continued for 1 hour.
The resulting reaction mixture was diluted with 0.26 L of methylene chloride and 0.02 L of water, and washed. The lower layer was separated, and further washed once with 0.11 L of water, once with 0.11 L of 0.03 N hydrochloric acid, and three times with 0.11 L of water, in that order. The resulting methylene chloride solution was dropped into warm water at 60°C to 70°C while stirring, and the resulting precipitate was filtered and dried to obtain a PC copolymer (PC-4) having the following structure.
The reduced viscosity [η _SP /C] of the PC copolymer (PC-4) at 20° C. was 1.21 dL/g, and its structure was confirmed by NMR to be a PC copolymer consisting of the following repeating units and composition:

a=Ar ¹ /(Ar ¹ +Ar ² )=0.51
b=Ar ² /(Ar ¹ +Ar ² )=0.49

Example 5
Into a reaction vessel equipped with a mechanical stirrer, stirring blades, and baffles, the raw material CZ-CF (bischloroformate oligomer, average polymerization number 1.10) (155 mL) obtained in Production Example 2 and methylene chloride (332 mL) were poured. To this was added p-tert-butylphenol (0.3424 g) as an end-capping agent, and the mixture was stirred so as to be thoroughly mixed. After cooling the temperature inside the reactor to 15° C., the entire amount of the prepared 2',5'-dimethyl-[1,1';4',1'']terphenyl-4,4''-diol solution (solution preparation method: 122 mL of 1.9 N potassium hydroxide aqueous solution (14.7 g of potassium hydroxide) was prepared, cooled to room temperature (25° C.) or lower, 0.16 g of hydrosulfite was added as an antioxidant, and 18.2 g of 2',5'-dimethyl-[1,1';4',1'']terphenyl-4,4''-diol was further added and completely dissolved) was added to this solution, and 1.6 mL of a triethylamine aqueous solution (7 vol%) was added with stirring, and stirring was continued for 80 minutes.
The resulting reaction mixture was diluted with 0.2 L of methylene chloride and 0.1 L of water and washed. The lower layer was separated and further washed once with 0.1 L of water, once with 0.1 L of 0.03 N hydrochloric acid, and three times with 0.1 L of water, in that order. The resulting methylene chloride solution was dropped into warm water at 60°C to 70°C with stirring, and the resulting precipitate was filtered and dried to obtain a PC copolymer (PC-5) having the following structure.
The reduced viscosity [η _SP /C] of the PC copolymer (PC-5) at 20° C. was 1.21 dL/g, and its structure was confirmed by NMR to be a PC copolymer consisting of the following repeating units and composition:

a=Ar ¹ /(Ar ¹ +Ar ² )=0.40
b=Ar ² /(Ar ¹ +Ar ² )=0.60

Comparative Example 1
Into a reaction vessel equipped with a mechanical stirrer, stirring blades, and baffles, the raw material Z-CF (bischloroformate oligomer, average number of polymerizations: 1.02) (155 mL) obtained in Production Example 1 and methylene chloride (332 mL) were poured. To this was added p-tert-butylphenol (0.317 g) as an end-capping agent, and the mixture was stirred so as to be thoroughly mixed. After cooling to a temperature inside the reactor of 10° C., the entire amount of the prepared 4,4″-dihydroxy-p-terphenyl solution (solution preparation method: 122 mL of 2.1 N potassium hydroxide aqueous solution (16.6 g of potassium hydroxide) was prepared, cooled to room temperature (25° C.) or lower, 0.16 g of hydrosulfite was added as an antioxidant, and 18.5 g of 4,4″-dihydroxy-p-terphenyl was further added and completely dissolved) was added to this solution, and 1.8 mL of a triethylamine aqueous solution (7 vol%) was added while stirring, and stirring was continued for 80 minutes.
The resulting reaction mixture was diluted with 0.36 L of methylene chloride and 0.03 L of water and washed. The lower layer was separated and further washed once with 0.15 L of water, once with 0.15 L of 0.03 N hydrochloric acid, and three times with 0.15 L of water, in that order. The resulting methylene chloride solution was dropped into warm water at 60°C to 70°C with stirring, and the resulting precipitate was filtered and dried to obtain a PC copolymer (PC-6) having the following structure.
The reduced viscosity [η _SP /C] of the PC copolymer (PC-6) at 20° C. was 1.17 dL/g, and its structure was confirmed by NMR to be a PC copolymer consisting of the following repeating units and composition:

a=Ar ¹ /(Ar ¹ +Ar ² )=0.42
b=Ar ² /(Ar ¹ +Ar ² )=0.58

Comparative Example 2
Into a reaction vessel equipped with a mechanical stirrer, stirring blades, and baffles, the raw material PCOCH (bischloroformate oligomer, average polymerization number 2.70) (155 mL) obtained in Production Example 4 and methylene chloride (322 mL) were poured. To this was added p-tert-butylphenol (0.165 g) as an end-capping agent, and the mixture was stirred so as to be thoroughly mixed. After cooling to 15° C. inside the reactor, the entire amount of the prepared 2,5-bis(4-hydroxyphenyl)-3,6-dimethylpyrazine solution (solution preparation method: 122 mL of a 1.0 N aqueous potassium hydroxide solution (7.6 g of potassium hydroxide) was prepared, cooled to room temperature (25° C.) or lower, and then 0.08 g of hydrosulfite was added as an antioxidant, and 9.4 g of 2,5-bis(4-hydroxyphenyl)-3,6-dimethylpyrazine was further added and completely dissolved) was added to this solution, and 0.8 mL of an aqueous triethylamine solution (7 vol %) was added with stirring, and stirring was continued for 1 hour.
The resulting reaction mixture was diluted with 0.36 L of methylene chloride and 0.03 L of water and washed. The lower layer was separated and further washed once with 0.15 L of water, once with 0.15 L of 0.03 N hydrochloric acid, and three times with 0.15 L of water, in that order. The resulting methylene chloride solution was dropped into warm water at 60°C to 70°C while stirring, and the resulting precipitate was filtered and dried to obtain a PC copolymer (PC-7) having the following structure.
The reduced viscosity [η _SP /C] of the PC copolymer (PC-7) at 20° C. was 1.19 dL/g, and its structure was confirmed by NMR to be a PC copolymer consisting of the following repeating units and composition:

a=Ar ¹ /(Ar ¹ +Ar ² )=0.15
b=Ar ² /(Ar ¹ +Ar ² )=0.85

Comparative Example 3
Into a reaction vessel equipped with a mechanical stirrer, stirring blades, and baffles, the raw material Z-CF (bischloroformate oligomer, average number of monomers: 1.02) (155 mL) obtained in Production Example 1 and methylene chloride (332 mL) were poured. To this, p-tert-butylphenol (0.293 g) was added as an end-capping agent, and the mixture was stirred so as to be thoroughly mixed. After cooling to a temperature inside the reactor of 15°C, the entire amount of the prepared 4,4″-biphenol solution (solution preparation method: 122 mL of 2.1 N potassium hydroxide aqueous solution (16.6 g of potassium hydroxide) was prepared, cooled to room temperature (25°C) or lower, 0.12 g of hydrosulfite was added as an antioxidant, and 13.16 g of 4,4″-biphenol was further added and completely dissolved) was added to this solution, and 1.8 mL of a triethylamine aqueous solution (7 vol%) was added while stirring, and stirring was continued for 1 hour.
The resulting reaction mixture was diluted with 0.36 L of methylene chloride and 0.03 L of water and washed. The lower layer was separated and further washed once with 0.15 L of water, once with 0.15 L of 0.03 N hydrochloric acid, and three times with 0.15 L of water, in that order. The resulting methylene chloride solution was dropped into warm water at 60°C to 70°C with stirring, and the resulting precipitate was filtered and dried to obtain a PC copolymer (PC-8) having the following structure.
The reduced viscosity [η _SP /C] of the PC copolymer (PC-8) at 20° C. was 1.21 dL/g, and the structure was confirmed by NMR to be a PC copolymer consisting of the following repeating units and composition:

Comparative Example 4
According to Example 1 of Japanese Patent No. 3,155,828, a PC copolymer (PC-9) having a 2,2-bis(4-hydroxyphenyl)propane (bisphenol A) content of 85% and a 2,5-bis(4-hydroxyphenyl)-3,6-dimethylpyrazine content of 15% was prepared as follows.
74 g of 2,2-bis(4-hydroxyphenyl)propane was dissolved in 550 mL of 6% aqueous sodium hydroxide solution, and 250 mL of methylene chloride was added. While stirring the resulting solution, phosgene gas was blown into it at a rate of 950 mL/min for 15 minutes under cooling. The reaction solution was allowed to stand and the organic layer was separated to obtain a methylene chloride solution of 2,2-bis(4-hydroxyphenyl)propane oligomers having a degree of polymerization of 2 to 4 and chloroformate groups at the molecular terminals.
A small amount of p-tert-butylphenol and methylene chloride were added as end terminators to the obtained oligomer solution to make the total volume 720 mL, and then mixed with a solution in which 20 g of 2,5-bis(4-hydroxyphenyl)-3,6-dimethylpyrazine was dissolved in 240 mL of 1.5 N potassium hydroxide aqueous solution, and then 5 mL of 5% triethylamine aqueous solution was added and vigorously stirred at room temperature for 1 hour. After adding 1 liter of methylene chloride and 1.5 liters of water to the reaction product and stirring, the aqueous layer was separated, and the organic phase was washed once with 0.01 N hydrochloric acid and three times with water. This organic phase was dropped into methanol, and the resulting precipitate was filtered and dried to obtain a PC copolymer (PC-9) having the following structure.
The reduced viscosity [η _SP /C] of the PC copolymer (PC-9) at 20° C. was 0.89 dL/g, and the structure was confirmed by NMR to be a PC copolymer consisting of the following repeating units and composition:

[Evaluation results]
Table 1 shows the evaluation results of Examples 1 to 5 and Comparative Examples 1 to 4.
Comparing Examples 1 to 5 with Comparative Examples 1 to 4, it was confirmed that the PC copolymers of Examples 1 to 5 had good abrasion resistance and stable solubility in organic solvents. Furthermore, the PC copolymers of Examples 1 to 5 had good resin properties (yield stress, Martens hardness, and elastic power) and were also excellent in transparency.
For example, in Example 1, a low-molecular oligomer having a divalent aromatic group of bisphenol Z (raw material Z-CF) was reacted with 2,5-bis(4-hydroxyphenyl)-3,6-dimethylpyrazine monomer by the production method described herein to obtain a PC copolymer (PC-1) having a copolymerization ratio (mol %) of repeating unit B derived from bisphenol Z to repeating unit A derived from 2,5-bis(4-hydroxyphenyl)-3,6-dimethylpyrazine of repeating unit B: repeating unit A = 58:42. The reduced viscosity was also 1.22 [dL/g].
The PC copolymer (PC-1) of Example 1 has a good yield stress and elastic power related to the wear of the photoreceptor, and also has a good Martens hardness related to the toner filming of the photoreceptor, as shown in the evaluation results, even when compared with a polycarbonate copolymer obtained by reacting a low-mer bischloroformate oligomer having a divalent aromatic group of bisphenol Z with a biphenol monomer (e.g., Example 10 of JP 2011-26574 A). Furthermore, despite containing a relatively high proportion of rigid terphenyl skeletons, the PC copolymer (PC-1) of Example 1 has excellent solubility in organic solvents, can suppress the clouding of the solution due to crystallization, and has good wear resistance and electrophotographic properties even when used as an electrophotographic photoreceptor.
The PC copolymer of Comparative Example 1 was confirmed to have good abrasion resistance, as in Examples 1 to 5, but had poor solubility in THF and was almost insoluble. The PC copolymers of Comparative Examples 2 to 4 had poor resin properties and abrasion resistance compared to Examples 1 to 5, and this effect was also seen in the evaluation of the photoreceptor, where the abrasion resistance of the photoreceptor deteriorated. For this reason, it was found that the abrasion resistance is insufficient for recent high-durability machines.
From the above, it was found that the PC copolymers of Examples 1 to 5 have excellent resin properties, high abrasion resistance, and excellent solubility in organic solvents. Furthermore, Examples 1 to 5 also showed good results in terms of abrasion resistance and electrical properties in the photoreceptor evaluation.

The polycarbonate copolymer of the present invention can be suitably used as a binder resin for the photosensitive layer of an electrophotographic photoreceptor. In addition, a photoreceptor drum made using the electrophotographic photoreceptor of the present invention can be suitably used in electrical equipment such as copiers and printers, including laser printers.

Claims (16)

A polycarbonate copolymer,
The polycarbonate copolymer has a repeating unit A represented by the following general formula (1) and a repeating unit B represented by the following general formula (2), and is obtained from at least one of a bischloroformate oligomer represented by the following general formula (1A) and a bischloroformate oligomer represented by the following general formula (2A),
The average number of monomers _n1 of the bischloroformate oligomer represented by the general formula (1A) is 1.0 or more and 1.3 or less,
The average number of monomers _n2 of the bischloroformate oligomer represented by the general formula (2A) is 1.0 or more and 1.3 or less.
Polycarbonate copolymer.
In the general formula (1), Ar ¹ is a group represented by the following general formula (3):
In the general formula (2), ^Ar2 is a group represented by the following general formula (4):
[In the general formulas (3) and (4),
R ¹¹ to R ¹⁸ and R ²¹ to R ²⁸ each independently represent a hydrogen atom or a substituent;
R ¹¹ to R ¹⁸ and R ²¹ to R ²⁸ as substituents each independently represent
an unsubstituted alkyl group having 1 to 2 carbon atoms;
an unsubstituted fluoroalkyl group having 1 to 2 carbon atoms;
an unsubstituted alkoxy group having 1 to 2 carbon atoms,
R ¹⁹ and R ²⁰ each independently represent a hydrogen atom or a substituent;
R ¹⁹ and R ²⁰ as substituents each independently represent
an unsubstituted alkyl group having 1 to 2 carbon atoms;
^X2 and ^X3 each independently represent
CR ¹⁰⁰ or a nitrogen atom;
^R100 is,
a hydrogen atom or an unsubstituted alkyl group having 1 to 2 carbon atoms;
^X1 is
a group represented by -CR ³ R ⁴ -,
a substituted or unsubstituted cycloalkylidene group having 5 to 6 carbon atoms,
a substituted or unsubstituted bicyclohydrocarbon diyl group having 7 to 10 carbon atoms, or a substituted or unsubstituted tricyclohydrocarbon diyl group having 10 to 16 carbon atoms,
^R3 and ^R4 each independently represent a hydrogen atom or a substituent;
^R3 and ^R4 as substituents each independently represent
an unsubstituted alkyl group having 1 to 3 carbon atoms;
an unsubstituted fluoroalkyl group having 1 to 3 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 12 ring carbon atoms,
provided that when R ¹⁹ and R ²⁰ are hydrogen atoms, any one or more of R ¹¹ to R ¹⁴ are substituents, and any one or more of R ¹⁵ to R ¹⁸ are substituents;
When R ¹¹ to R ¹⁸ are hydrogen atoms, R ¹⁹ and R ²⁰ are substituents.
In the general formula (1A), Ar ¹ is a group represented by the general formula (3), n ₁ represents the average number of monomers,
In the general formula (2A), ^Ar2 is a group represented by the general formula (4), and _n2 represents the average number of monomers. The polycarbonate copolymer according to claim 1,
the abundance ratio represented by Ar ¹ /(Ar ¹ +Ar ² ) is 30 mol % or more and 55 mol % or less,
The abundance ratio represented by Ar ² /(Ar ¹ +Ar ² ) is 45 mol % or more and 70 mol % or less.
Polycarbonate copolymer. The polycarbonate copolymer according to claim 1 or 2,
In the general formula (1), Ar ¹ is
2,5-bis(4-hydroxyphenyl)-3,6-dimethylpyrazine,
a divalent group derived from either 2',5'-dimethyl-[1,1';4',1'']terphenyl-4,4''-diol or 3,3''-dimethyl-4,4''-dihydroxy-p-terphenyl;
Polycarbonate copolymer. The polycarbonate copolymer according to any one of claims 1 to 3,
In the general formula (2), Ar ² is a group represented by the following general formula (4A):
Polycarbonate copolymer.
(In the general formula (4A), R ²¹ to R ²⁸ each independently have the same definition as R ²¹ to R ²⁸ in the general formula (4).) The polycarbonate copolymer according to any one of claims 1 to 4,
R ¹¹ to R ¹⁸ and R ²¹ to R ²⁸ each independently represent
A polycarbonate copolymer that is a hydrogen atom or an unsubstituted alkyl group having 1 to 2 carbon atoms. The polycarbonate copolymer according to any one of claims 1 to 5,
The polycarbonate copolymer is dissolved in THF at a solid content concentration of 10% by mass, and the HAZE value of the solution is 3% or less.
Polycarbonate copolymer. The polycarbonate copolymer according to any one of claims 1 to 6,
The polycarbonate copolymer has a yield stress of 70% or more at a tensile speed of 1 mm/min in a tensile test.
Polycarbonate copolymer. The polycarbonate copolymer according to any one of claims 1 to 7,
The polycarbonate copolymer has a Martens hardness of 160 MPa or more when the load is set to 0.6 N in a nanoindentation test.
Polycarbonate copolymer. The polycarbonate copolymer according to any one of claims 1 to 8,
The polycarbonate copolymer has an elastic power of 46% or more when a load is set to 0.6 N in an indentation test.
Polycarbonate copolymer. The polycarbonate copolymer according to any one of claims 1 to 9 ,
When the structural units AA, BB, AB, and BA each constituted by two consecutive repeating units A represented by the general formula (1) and two consecutive repeating units B represented by the general formula (2) are defined as a diad,
The percentage of the number of moles of the diad represented by AA to the total number of moles of the four types of diads represented by AA, BB, AB, and BA is 5 mol % or less.
Polycarbonate copolymer. The polycarbonate copolymer according to any one of claims 1 to 9 ,
When the structural units ABA, BAA, AAA, AAB, BBA, BAB, ABB, and BBB each constituted by three consecutive repeating units A represented by the general formula (1) and three consecutive repeating units B represented by the general formula (2) are defined as a triad,
the percentage of the number of moles of the triad represented by AAA to the total number of moles of the total eight types of triads represented by ABA, BAA, AAA, AAB, BBA, BAB, ABB, and BBB is 3 mol % or less;
Polycarbonate copolymer. A method for producing a polycarbonate copolymer, comprising producing a polycarbonate copolymer by the following synthesis reaction (CS1), (CS2), or (CS3):
(CS1) A bischloroformate oligomer represented by the following general formula (1A) and a dihydric phenolic compound represented by the following general formula (6) are subjected to interfacial polycondensation in the presence of an acid binder.
(CS2) A bischloroformate oligomer represented by the following general formula (2A) and a dihydric phenolic compound represented by the following general formula (5) are subjected to interfacial polycondensation in the presence of an acid binder.
(CS3) A bischloroformate oligomer represented by the following general formula (1A) is mixed with a bischloroformate oligomer represented by the following general formula (2A), and the mixture of the bischloroformate oligomer represented by the following general formula (1A) and the bischloroformate oligomer represented by the following general formula (2A) is subjected to interfacial polycondensation with a dihydric phenolic compound represented by the following general formula (5) or a dihydric phenolic compound represented by the following general formula (6).
[In the general formulas (1A) and (5), Ar ¹ is a group represented by the following general formula (3), and in the general formulas (2A) and (6), Ar ² is a group represented by the following general formula (4):
In the general formula (1A), _n1 represents the average number of monomers and is 1.0 to 1.3,
In the general formula (2A), _n2 represents the average number of monomers and is 1.0 to 1.3.
[In the general formulas (3) and (4),
R ¹¹ to R ¹⁸ and R ²¹ to R ²⁸ each independently represent a hydrogen atom or a substituent;
R ¹¹ to R ¹⁸ and R ²¹ to R ²⁸ as substituents each independently represent
an unsubstituted alkyl group having 1 to 2 carbon atoms;
an unsubstituted fluoroalkyl group having 1 to 2 carbon atoms;
an unsubstituted alkoxy group having 1 to 2 carbon atoms,
R ¹⁹ and R ²⁰ each independently represent a hydrogen atom or a substituent;
R ¹⁹ and R ²⁰ as substituents each independently represent
an unsubstituted alkyl group having 1 to 2 carbon atoms;
^X2 and ^X3 each independently represent
CR ¹⁰⁰ or a nitrogen atom;
^R100 is,
a hydrogen atom or an unsubstituted alkyl group having 1 to 2 carbon atoms;
^X1 is
a group represented by -CR ³ R ⁴ -,
a substituted or unsubstituted cycloalkylidene group having 5 to 6 carbon atoms,
a substituted or unsubstituted bicyclohydrocarbon diyl group having 7 to 10 carbon atoms, or a substituted or unsubstituted tricyclohydrocarbon diyl group having 10 to 16 carbon atoms,
^R3 and ^R4 each independently represent a hydrogen atom or a substituent;
^R3 and ^R4 as substituents each independently represent
an unsubstituted alkyl group having 1 to 3 carbon atoms;
an unsubstituted fluoroalkyl group having 1 to 3 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 12 ring carbon atoms,
provided that when R ¹⁹ and R ²⁰ are hydrogen atoms, any one or more of R ¹¹ to R ¹⁴ are substituents, and any one or more of R ¹⁵ to R ¹⁸ are substituents;
When R ¹¹ to R ¹⁸ are hydrogen atoms, R ¹⁹ and R ²⁰ are substituents. A coating liquid comprising the polycarbonate copolymer according to any one of claims 1 to 11 and an organic solvent. An electrophotographic photoreceptor comprising the polycarbonate copolymer according to claim 1 . A substrate;
A photosensitive layer provided on the substrate,
The photosensitive layer comprises the polycarbonate copolymer according to claim 1 . An electric device comprising the electrophotographic photoreceptor according to claim 14 or 15 .