CN116719212A

CN116719212A - Electrophotographic photoreceptor, process cartridge, and image forming apparatus

Info

Publication number: CN116719212A
Application number: CN202310203790.2A
Authority: CN
Inventors: 佐佐木知也; 桥本考平; 藤井亮介; 小林纮子; 冈崎有杜; 成田幸介
Original assignee: Fujifilm Business Innovation Corp
Current assignee: Fujifilm Business Innovation Corp
Priority date: 2022-03-07
Filing date: 2023-03-06
Publication date: 2023-09-08

Abstract

An electrophotographic photoreceptor comprising a conductive substrate, an undercoat layer disposed on the conductive substrate, and a layered photosensitive layer having a charge generation layer and a charge transport layer disposed on the undercoat layer, wherein the charge transport layer contains a charge transport material and a polyester resin, and when the average thickness of the charge transport layer is set to As (μm) and the average thickness of the undercoat layer is set to Bs (μm), 27.ltoreq.As.ltoreq.50, 10.ltoreq.Bs.ltoreq.40, and 0.70.ltoreq.As/Bs.ltoreq.4.80 are satisfied.

Description

Electrophotographic photoreceptor, process cartridge, and image forming apparatus

Technical Field

The invention relates to an electrophotographic photoreceptor, a process cartridge, and an image forming apparatus.

Background

Patent document 1 discloses a layered positively charged electrophotographic photoreceptor in which a charge transport layer and a charge generation layer are layered on a conductive support, wherein the total amount of residual solvents contained in the charge generation layer and the charge transport layer is 50 μg/cm ² Hereinafter, the mass ratio of the electron transport material to the hole transport material in the charge generation layer is in the range of 5:1 to 4:2, the film thickness of the charge transport layer is in the range of 3 μm to 40 μm, the film thickness of the charge generation layer is in the range of 3 μm to 40 μm, and the moisture content of the charge generation layer and the charge transport layer as a whole is in the range of 0.05% by mass to 1.5% by mass.

Patent document 2 discloses an electrophotographic photoreceptor in which an undercoat layer, a charge generation layer, and a charge transport layer are laminated on a conductive substrate, wherein the thickness of the undercoat layer is 4 μm or more and the thickness of the charge transport layer is 20 μm or less, and a relationship of V/d 40 or less is established between the thickness d (μm) of the charge transport layer and the absolute value V (Volt) of the surface potential of the charged electrophotographic photoreceptor.

Patent document 3 discloses an electrophotographic photoreceptor in which a lower coating layer contains metal oxide particles, and strength of 5×10 is applied at 23±2℃ ⁴ Volume resistivity ρ at (V/cm) electric field is 1×10 ⁷ (Ω·cm) or more and less than 2×10 ⁸ In the range of (Ω·cm), the layer thickness of the undercoating is in the range of 10 to 40 μm, and the layer thickness of the photosensitive layer is in the range of 30 to 50 μm.

Patent document 1: japanese patent application laid-open No. 2015-212837

Patent document 2: japanese patent laid-open No. 2000-314976

Patent document 3: japanese patent laid-open No. 2020-115195

Disclosure of Invention

The object of the present invention is to provide an electrophotographic photoreceptor in which double images and color dots are less likely to occur in images than an electrophotographic photoreceptor having a layered photosensitive layer and a ratio of an average thickness As of a charge transport layer to an average thickness Bs of an under coat layer of less than 0.70 or more than 4.80, or an electrophotographic photoreceptor having a single-layer photosensitive layer and a ratio of an average thickness At of a single-layer photosensitive layer to an average thickness Bt of an under coat layer of less than 0.70 or more than 4.80.

Specific means for solving the above problems include the following means.

< 1 > an electrophotographic photoreceptor comprising a conductive substrate, an undercoat layer disposed on the conductive substrate, and a laminated photosensitive layer having a charge generation layer and a charge transport layer disposed on the undercoat layer,

the charge transport layer contains a charge transport material and a polyester resin,

when the average thickness of the charge transport layer is set to As (μm) and the average thickness of the undercoating layer is set to Bs (μm), 27.ltoreq.As.ltoreq.50, 10.ltoreq.Bs.ltoreq.40, and 0.70.ltoreq.As/Bs.ltoreq.4.80 are satisfied.

< 2 > the electrophotographic photoreceptor described in < 1 > which satisfies 0.87.ltoreq.As/Bs.ltoreq.3.42.

< 3 > the electrophotographic photoreceptor according to < 1 > or < 2 >, wherein the polyester resin comprises a polyester resin (1) having a dicarboxylic acid unit (a) represented by formula (a) and a diol unit (B) represented by formula (B).

The electrophotographic photoreceptor according to < 4 > to < 3 >, wherein the dicarboxylic acid unit (A) represented by the formula (A) contains at least one selected from the group consisting of a dicarboxylic acid unit (A1) represented by the formula (A1), a dicarboxylic acid unit (A2) represented by the formula (A2), a dicarboxylic acid unit (A3) represented by the formula (A3), and a dicarboxylic acid unit (A4) represented by the formula (A4).

< 5 > according to < 3 > or < 4 > wherein the glycol unit (B) represented by the formula (B) contains at least one selected from the group consisting of a glycol unit (B1) represented by the formula (B1), a glycol unit (B2) represented by the formula (B2), a glycol unit (B3) represented by the formula (B3), a glycol unit (B4) represented by the formula (B4), a glycol unit (B5) represented by the formula (B5), a glycol unit (B6) represented by the formula (B6), a glycol unit (B7) represented by the formula (B7), and a glycol unit (B8) represented by the formula (B8).

< 6 > an electrophotographic photoreceptor comprising a conductive substrate, an undercoat layer disposed on the conductive substrate, and a single-layer photosensitive layer disposed on the undercoat layer,

the single-layer photosensitive layer contains a charge transport material and a polyester resin,

when the average thickness of the single-layer photosensitive layer is set to be At (μm) and the average thickness of the undercoating layer is set to be Bt (μm), 27 At or less than or equal to 50, 10 At or less than or equal to 40, and 0.70 At/Bt or less than or equal to 4.80 are satisfied.

< 7 > the electrophotographic photoreceptor described in < 6 > which satisfies 0.87.ltoreq.at/bt.ltoreq.3.42.

< 8 > the electrophotographic photoreceptor according to < 6 > or < 7 >, wherein the polyester resin comprises a polyester resin (1) having a dicarboxylic acid unit (A) represented by formula (A) and a diol unit (B) represented by formula (B).

The electrophotographic photoreceptor according to < 9 > to < 8 >, wherein the dicarboxylic acid unit (A) represented by the formula (A) contains at least one selected from the group consisting of a dicarboxylic acid unit (A1) represented by the formula (A1), a dicarboxylic acid unit (A2) represented by the formula (A2), a dicarboxylic acid unit (A3) represented by the formula (A3), and a dicarboxylic acid unit (A4) represented by the formula (A4).

< 10 > according to < 8 > or < 9 > wherein the glycol unit (B) represented by the formula (B) contains at least one selected from the group consisting of a glycol unit (B1) represented by the formula (B1), a glycol unit (B2) represented by the formula (B2), a glycol unit (B3) represented by the formula (B3), a glycol unit (B4) represented by the formula (B4), a glycol unit (B5) represented by the formula (B5), a glycol unit (B6) represented by the formula (B6), a glycol unit (B7) represented by the formula (B7), and a glycol unit (B8) represented by the formula (B8).

A process cartridge comprising an electrophotographic photoreceptor as defined in any one of < 1 > to < 10 >,

the process cartridge is attached to and detached from the image forming apparatus.

< 12 > an image forming apparatus, comprising:

an electrophotographic photoreceptor of any one of < 1 > to < 10 >;

A charging unit that charges a surface of the electrophotographic photoreceptor;

an electrostatic latent image forming unit that forms an electrostatic latent image on the charged electrophotographic photosensitive body surface;

a developing unit that develops an electrostatic latent image formed on a surface of the electrophotographic photoreceptor with a developer containing a toner to form a toner image; a kind of electronic device with high-pressure air-conditioning system

And a transfer unit for transferring the toner image to the surface of the recording medium.

Effects of the invention

According to the invention of < 1 >, < 3 >, < 4 > or < 5 >, there is provided an electrophotographic photoreceptor in which ghost images and color spots are less likely to occur in an image than an electrophotographic photoreceptor having a laminated photosensitive layer and in which the ratio As/Bs of the average thickness As of the charge transport layer to the average thickness Bs of the undercoat layer is less than 0.70 or more than 4.80.

According to the invention of < 2 >, there is provided an electrophotographic photoreceptor in which ghost images and color spots are less likely to occur in an image than an electrophotographic photoreceptor having a laminated photosensitive layer and in which the ratio As/Bs of the average thickness As of the charge transport layer to the average thickness Bs of the undercoating layer is less than 0.87 or exceeds 3.42.

According to the invention of < 6 >, < 8 >, < 9 > or < 10 >, there is provided an electrophotographic photoreceptor in which ghost images and color spots are less likely to occur in an image than an electrophotographic photoreceptor having a single-layer type photosensitive layer and having a ratio At of the average thickness At of the single-layer type photosensitive layer to the average thickness Bt of the under coat layer of less than 0.70 or more than 4.80.

According to the invention of < 7 > there is provided an electrophotographic photoreceptor in which double images and color points are less likely to occur in an image than an electrophotographic photoreceptor having a single-layer type photosensitive layer and in which the ratio At/Bt of the average thickness At of the single-layer type photosensitive layer to the average thickness Bt of the under coat layer is less than 0.87 or exceeds 3.42.

According to the invention of < 11 > there is provided a process cartridge which is less likely to cause double images and color spots in images than in the case where the ratio As/Bs of the average thickness As of the charge transport layer to the average thickness Bs of the under coat layer in the electrophotographic photoreceptor is less than 0.70 or more than 4.80 or the ratio At/Bt of the average thickness At of the single-layer type photosensitive layer to the average thickness Bt of the under coat layer is less than 0.70 or more than 4.80.

According to the invention of < 12 > there is provided an image forming apparatus in which double images and color dots are less likely to occur in an image than in the case where the ratio As/Bs of the average thickness As of the charge transport layer to the average thickness Bs of the under coat layer in the electrophotographic photoreceptor is less than 0.70 or more than 4.80 or the ratio At/Bt of the average thickness At of the single-layer type photosensitive layer to the average thickness Bt of the under coat layer is less than 0.70 or more than 4.80.

Drawings

Embodiments of the present invention will be described in detail with reference to the following drawings.

Fig. 1 is a partial cross-sectional view showing an example of the layer structure of an electrophotographic photoreceptor according to embodiment 1;

fig. 2 is a partial cross-sectional view showing an example of the layer structure of the electrophotographic photoreceptor according to embodiment 2;

fig. 3 is a schematic configuration diagram showing an example of the image forming apparatus according to the present embodiment;

fig. 4 is a schematic configuration diagram showing another example of the image forming apparatus according to the present embodiment;

fig. 5 is a schematic view of an image formed for evaluating image quality in the embodiment.

Detailed Description

Hereinafter, embodiments of the present invention will be described. The description and examples are illustrative of the embodiments and are not intended to limit the scope of the embodiments.

In the present invention, the numerical range shown by the use of "to" indicates a range in which numerical values before and after the use of "to" are included as a minimum value and a maximum value, respectively.

In the numerical ranges described in stages in the present invention, the upper limit or the lower limit described in one numerical range may be replaced with the upper limit or the lower limit of the numerical range described in other stages. In the numerical ranges described in the present invention, the upper limit or the lower limit of the numerical range may be replaced with the values shown in the examples.

In the present invention, the term "process" is included in the present term, and the purpose of the process can be achieved not only in a separate process but also in a case where the process cannot be clearly distinguished from other processes.

In the present invention, when the embodiment is described with reference to the drawings, the structure of the embodiment is not limited to the structure shown in the drawings. The sizes of the components in the drawings are conceptual, and the relative relationship between the sizes of the components is not limited thereto.

In the present invention, each component may also contain a plurality of corresponding substances. In the present invention, when the amounts of the respective components in the composition are mentioned, when a plurality of substances corresponding to the respective components are present in the composition, the total amount of the plurality of substances present in the composition is represented unless otherwise specified.

In the present invention, a plurality of types of particles corresponding to the respective components may be contained. When a plurality of particles corresponding to each component are present in the composition, the particle size of each component indicates a value regarding a mixture of the plurality of particles present in the composition unless otherwise specified.

In the present invention, unless otherwise specified, alkyl groups include straight-chain, branched-chain and cyclic groups.

In the present invention, regarding the organic group, aromatic ring, linking group, alkyl group, aryl group, aralkyl group, alkoxy group, aryloxy group, hydrogen atom in the group may be substituted with halogen atom.

< electrophotographic photoreceptor >)

The present invention provides embodiments 1 and 2 as electrophotographic photoreceptors (hereinafter also referred to as "photoreceptors").

The photoreceptor according to embodiment 1 includes a conductive substrate, an undercoating layer disposed on the conductive substrate, and a laminated photosensitive layer having a charge generation layer and a charge transport layer disposed on the undercoating layer. The charge transport layer of the photoreceptor according to embodiment 1 contains a charge transport material and a polyester resin.

The photoreceptor according to embodiment 1 may further include another layer (for example, an intermediate layer). In the photoreceptor according to embodiment 1, for example, the charge transport layer is preferably a surface layer.

The photoreceptor according to embodiment 2 includes a conductive substrate, an undercoating layer disposed on the conductive substrate, and a single-layer photosensitive layer disposed on the undercoating layer. The single-layer photosensitive layer of the photoreceptor according to embodiment 2 contains a charge transport material and a polyester resin.

The photoreceptor according to embodiment 2 may further include another layer (for example, an intermediate layer). In the photoreceptor according to embodiment 2, for example, the single-layer photosensitive layer is preferably a surface layer.

Fig. 1 is a partial cross-sectional view schematically showing an example of the layer structure of the photoreceptor according to embodiment 1. The photoreceptor 10A shown in fig. 1 has a laminated photosensitive layer. The photoreceptor 10A has a structure in which a lower coating layer 2, a charge generation layer 3, and a charge transport layer 4 are laminated in this order on a conductive substrate 1, and the charge generation layer 3 and the charge transport layer 4 constitute a photosensitive layer 5 (so-called function-separated photosensitive layer). The photoreceptor 10A may have an intermediate layer (not shown) between the undercoating layer 2 and the charge generation layer 3.

Fig. 2 is a partial cross-sectional view schematically showing an example of the layer structure of the photoreceptor according to embodiment 2. The photoreceptor 10B shown in fig. 2 has a single-layer type photosensitive layer. The photoreceptor 10B has a structure in which the undercoating 2 and the photosensitive layer 5 are laminated in this order on the conductive base 1. The photoreceptor 10B may have an intermediate layer (not shown) between the undercoating 2 and the photosensitive layer 5.

Hereinafter, when description is given of matters common to embodiment 1 and embodiment 2, these two modes are collectively referred to as this embodiment. When a common item in the charge transport layer and the single-layer photosensitive layer is described, the two layers are collectively referred to as a photosensitive layer.

The photoreceptor according to the present embodiment has the following structure, and thus, ghost images and color dots are less likely to occur in an image.

The average thickness As of the charge transport layer in embodiment 1 and the average thickness At of the single-layer photosensitive layer in embodiment 2 are 27 μm to 50 μm.

Since the charge transport layer or the single-layer photosensitive layer contains a polyester resin, if the average thickness As or the average thickness At is less than 27 μm, color spots are liable to occur (insulation is liable to be broken). From this viewpoint, the average thickness As or the average thickness At is 27 μm or more, for example, 31 μm or more, more preferably 35 μm or more, and still more preferably 37 μm or more.

Since the charge transport layer or the single-layer photosensitive layer contains a polyester resin, ghost images tend to occur if the average thickness As or the average thickness At exceeds 50 μm. From this viewpoint, the average thickness As or the average thickness At is 50 μm or less, for example, preferably 48 μm or less, more preferably 46 μm or less, and still more preferably 45 μm or less.

The average thickness Bs of the undercoating layer in embodiment 1 and the average thickness Bt of the undercoating layer in embodiment 2 are 10 μm or more and 40 μm or less.

If the average thickness Bs or the average thickness Bt is smaller than 10 μm, fine foreign matters generated in the image forming apparatus may pierce the photoconductor to leak current and generate color spots. From this viewpoint, the average thickness Bs or the average thickness Bt is 10 μm or more, for example, 14 μm or more, more preferably 18 μm or more, and still more preferably 20 μm or more.

If the average thickness Bs or the average thickness Bt exceeds 40 μm, ghost images tend to occur (charges tend to accumulate). From this viewpoint, the average thickness Bs or the average thickness Bt is 40 μm or less, for example, 36 μm or less, more preferably 32 μm or less, and still more preferably 30 μm or less.

The ratio As/Bs of the average thickness As of the charge transport layer to the average thickness Bs of the under coat layer in embodiment 1 and the ratio At/Bt of the average thickness At of the single-layer photosensitive layer to the average thickness Bt of the under coat layer in embodiment 2 are 0.70 or more and 4.80 or less.

Since the charge transport layer or the single-layer photosensitive layer contains a polyester resin, if the ratio As/Bs or the ratio At/Bt is less than 0.70, the stability of the residual potential is deteriorated. From this viewpoint, the ratio As/Bs or the ratio At/Bt is 0.70 or more, for example, preferably 0.87 or more, more preferably 1.10 or more, and still more preferably 1.24 or more.

Since the charge transport layer or the single-layer photosensitive layer contains a polyester resin, if the ratio As/Bs or the ratio At/Bt exceeds 4.80, the stability of the residual potential is deteriorated. From this viewpoint, the ratio As/Bs or the ratio At/Bt is 4.80 or less, for example, preferably 3.42 or less, more preferably 2.50 or less, and still more preferably 2.20 or less.

In embodiment 1, the average thickness As of the charge transport layer and the average thickness Bs of the undercoating are calculated by measuring the layer thickness by an eddy current film thickness meter at 10 equally in the axial direction of the photoreceptor and at 40 equally divided (90 ° intervals) in the circumferential direction into four parts in total, and performing arithmetic average.

In embodiment 2, the average thickness At of the single-layer photosensitive layer and the average thickness Bt of the undercoating are obtained in the same manner after the above-described "charge transport layer" is replaced with "single-layer photosensitive layer".

The polyester resin contained in the photosensitive layer and each layer of the photosensitive body will be described in detail below.

[ polyester resin (1) ]

As the polyester resin as the binder resin of the photosensitive layer, for example, polyester resin (1) having at least dicarboxylic acid unit (a) and diol unit (B) is preferable. The polyester resin (1) may contain dicarboxylic acid units other than the dicarboxylic acid unit (a). The polyester resin (1) may contain other glycol units than the glycol unit (B).

The dicarboxylic acid unit (a) is a structural unit represented by the following formula (a).

[ chemical formula 1]

(A)

In formula (A), ar ^A1 Ar and Ar ^A2 Each independently is an aromatic ring which may have a substituent, L ^A Is a single bond or a divalent linking group, n ^A1 0, 1 or 2.

Ar ^A1 The aromatic ring of (a) may be any of monocyclic ring and polycyclic ring. Examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring, and benzene rings and naphthalene rings are preferable.

Ar ^A1 The hydrogen atom on the aromatic ring of (a) may be substituted with an alkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, a halogen atom or the like. As Ar ^A1 The substituent when the aromatic ring is substituted is preferably, for example, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

Ar ^A2 The aromatic ring of (a) may be any of monocyclic ring and polycyclic ring. Examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring, and benzene rings and naphthalene rings are preferable.

Ar ^A2 The hydrogen atom on the aromatic ring of (a) may be substituted with an alkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, a halogen atom or the like. As Ar ^A2 The substituent when the aromatic ring is substituted is preferably, for example, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

When L ^A When the divalent linking group is used, examples of the divalent linking group include an oxygen atom, a sulfur atom and a-C (Ra) ¹ )(Ra ² ) -. Here, ra ¹ Ra (Ra) ² Each independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms, or Ra ¹ And (3) with Ra (Ra) ² May be bonded to form a cyclic alkyl group.

Ra ¹ Ra (Ra) ² The alkyl group having 1 to 10 carbon atoms may be any of linear, branched, and cyclic. The carbon number of the alkyl group is, for example, preferably 1 to 6, more preferably 1 to 4, and still more preferably 1 or 2.

Ra ¹ Ra (Ra) ² The aryl group having 6 to 12 carbon atoms may be a single ring or a multiple ring. The number of carbon atoms of the aryl group is, for example, preferably 6 or more and 10 or less, and more preferably 6.

Ra ¹ Ra (Ra) ² The alkyl group in the aralkyl group having 7 to 20 carbon atoms may be any of a straight chain, a branched chain, and a cyclic group. The number of carbon atoms of the alkyl group in the aralkyl group having 7 to 20 carbon atoms is, for example, preferably 1 to 4, more preferably 1 to 3, and still more preferably 1 or 2.

Ra ¹ Ra (Ra) ² The aryl group in the aralkyl group having 7 to 20 carbon atoms may be a single ring or a multiple ring. The number of carbon atoms of the aryl group is, for example, preferably 6 or more and 10 or less, and more preferably 6.

The dicarboxylic acid unit (a) preferably includes at least one selected from the group consisting of a dicarboxylic acid unit (A1) represented by the following formula (A1), a dicarboxylic acid unit (A2) represented by the following formula (A2), a dicarboxylic acid unit (A3) represented by the following formula (A3), and a dicarboxylic acid unit (A4) represented by the following formula (A4), for example. The dicarboxylic acid unit (a) more preferably contains at least one selected from the group consisting of a dicarboxylic acid unit (A2), a dicarboxylic acid unit (A3) and a dicarboxylic acid unit (A4), and further preferably contains a dicarboxylic acid unit (A2), for example.

[ chemical formula 2]

(A1)

In formula (A1), n ¹⁰¹ Is an integer of 0 to 4 inclusive, n ¹⁰¹ Ra of ¹⁰¹ Each independently represents an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkane having 1 to 6 carbon atomsAn oxy group.

n ¹⁰¹ For example, 0, 1 or 2 is preferable, 0 or 1 is more preferable, and 0 is still more preferable.

[ chemical formula 3]

(A2)

In formula (A2), n ²⁰¹ N is as follows ²⁰² Each independently is an integer of 0 to 4, n ²⁰¹ Ra of ²⁰¹ N is as follows ²⁰² Ra of ²⁰² Each independently represents an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

n ²⁰¹ For example, 0, 1 or 2 is preferable, 0 or 1 is more preferable, and 0 is still more preferable.

n ²⁰² For example, 0, 1 or 2 is preferable, 0 or 1 is more preferable, and 0 is still more preferable.

[ chemical formula 4]

(A3)

In formula (A3), n ³⁰¹ N is as follows ³⁰² Each independently is an integer of 0 to 4, n ³⁰¹ Ra of ³⁰¹ N is as follows ³⁰² Ra of ³⁰² Each independently represents an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

n ³⁰¹ For example, 0, 1 or 2 is preferable, 0 or 1 is more preferable, and 0 is still more preferable.

n ³⁰² For example, 0, 1 or 2 is preferable, 0 or 1 is more preferable, and 0 is still more preferable.

[ chemical formula 5]

(A4)

In formula (A4), n ⁴⁰¹ Is an integer of 0 to 6, n ⁴⁰¹ Ra of ⁴⁰¹ Each independently represents an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

n ⁴⁰¹ For example, an integer of 0 to 4 is preferable, 0, 1 or 2 is more preferable, and 0 is still more preferable.

Ra of formula (A1) ¹⁰¹ Ra of formula (A2) ²⁰¹ Ra (Ra) ²⁰² Ra of formula (A3) ³⁰¹ Ra (Ra) ³⁰² And Ra of formula (A4) ⁴⁰¹ The specific mode and preferred mode are the same, so that Ra will be as follows ¹⁰¹ 、Ra ²⁰¹ 、Ra ²⁰² 、Ra ³⁰¹ 、Ra ³⁰² Ra (Ra) ⁴⁰¹ Collectively referred to as "Ra".

The alkyl group having 1 to 10 carbon atoms in Ra may be any of linear, branched, and cyclic. The carbon number of the alkyl group is, for example, preferably 1 to 6, more preferably 1 to 4, and still more preferably 1 or 2.

Examples of the straight-chain alkyl group having 1 to 10 carbon atoms include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, and n-decyl.

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

Examples of the cyclic alkyl group having 3 to 10 carbon atoms include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl and polycyclic (for example, bicyclic, tricyclic and spirocyclic) alkyl groups in which these monocyclic alkyl groups are linked.

The aryl group having 6 to 12 carbon atoms related to Ra may be any of monocyclic and polycyclic. The number of carbon atoms of the aryl group is, for example, preferably 6 or more and 10 or less, and more preferably 6.

Examples of the aryl group having 6 to 12 carbon atoms include phenyl, biphenyl, 1-naphthyl, and 2-naphthyl.

The alkyl group in the alkoxy group having 1 to 6 carbon atoms related to Ra may be any of linear, branched, and cyclic. The number of carbon atoms of the alkyl group in the alkoxy group having 1 to 6 carbon atoms is, for example, preferably 1 to 4 carbon atoms, more preferably 1 to 3 carbon atoms, and still more preferably 1 or 2 carbon atoms.

Examples of the straight-chain alkoxy group having 1 to 6 carbon atoms include methoxy, ethoxy, n-propoxy, n-butoxy, n-pentyloxy and n-hexyloxy.

Examples of the branched alkoxy group having 3 to 6 carbon atoms include an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, an isopentyloxy group, a neopentyloxy group, a tert-pentyloxy group, an isohexyloxy group, a Zhong Ji oxy group, a tert-hexyloxy group and the like.

Examples of the cyclic alkoxy group having 3 to 6 carbon atoms include cyclopropyloxy group, cyclobutoxy group, cyclopentyloxy group, cyclohexyloxy group and the like.

The dicarboxylic acid units (A1-1) to (A1-9) are specifically exemplified below as the dicarboxylic acid unit (A1). The dicarboxylic acid unit (A1) is not limited thereto.

[ chemical formula 6]

The dicarboxylic acid units (A2-1) to (A2-3) are specifically exemplified below as the dicarboxylic acid unit (A2). The dicarboxylic acid unit (A2) is not limited thereto.

[ chemical formula 7]

The dicarboxylic acid units (A3-1) to (A3-2) are specifically exemplified below as the dicarboxylic acid unit (A3). The dicarboxylic acid unit (A3) is not limited thereto.

[ chemical formula 8]

The dicarboxylic acid units (A4-1) to (A4-3) are specifically exemplified below as the dicarboxylic acid unit (A4). The dicarboxylic acid unit (A4) is not limited thereto.

[ chemical formula 9]

The dicarboxylic acid unit (A) preferably contains at least one selected from the group consisting of (A1-1), (A1-7), (A2-3), (A3-2) and (A4-3) of the above specific examples, more preferably contains at least one selected from the group consisting of (A2-3), (A3-2) and (A4-3), and still more preferably contains at least (A2-3).

The mass ratio of the total of the dicarboxylic acid units (A1) to (A4) in the polyester resin (1) is, for example, preferably 15% by mass or more and 60% by mass or less.

When the total mass ratio of the dicarboxylic acid units (A1) to (A4) is 15 mass% or more, the abrasion resistance of the photosensitive layer is good. From this viewpoint, the total mass ratio of the dicarboxylic acid units (A1) to (A4) is, for example, more preferably 20 mass% or more, and still more preferably 25 mass% or more.

When the total mass ratio of the dicarboxylic acid units (A1) to (A4) is 60 mass% or less, peeling of the photosensitive layer can be suppressed. From this viewpoint, the total mass ratio of the dicarboxylic acid units (A1) to (A4) is, for example, preferably 55 mass% or less, and more preferably 50 mass% or less.

The dicarboxylic acid units (A1) to (A4) contained in the polyester resin (1) may be one kind or two or more kinds.

Examples of the dicarboxylic acid unit (a) other than the dicarboxylic acid units (A1) to (A4) include aliphatic dicarboxylic acid (for example, oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, alkenylsuccinic acid, adipic acid, sebacic acid) units, alicyclic dicarboxylic acid (for example, cyclohexanedicarboxylic acid) units, and lower (for example, 1 to 5 carbon atoms) alkyl ester units thereof. These dicarboxylic acid units contained in the polyester resin (1) may be one kind or two or more kinds.

The dicarboxylic acid unit (a) contained in the polyester resin (1) may be one kind or two or more kinds.

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

[ chemical formula 10]

(B)

In formula (B), ar ^B1 Ar and Ar ^B2 Each independently is an aromatic ring which may have a substituent, L ^B Is a single bond, an oxygen atom, a sulfur atom or-C (Rb) ¹ )(Rb ² )-，n ^B1 0, 1 or 2.Rb (Rb) ¹ Rb ² Each independently represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms, rb ¹ With Rb ² May be bonded to form a cyclic alkyl group.

Ar ^B1 The aromatic ring of (a) may be any of monocyclic ring and polycyclic ring. Examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring, and benzene rings and naphthalene rings are preferable.

Ar ^B1 The hydrogen atom on the aromatic ring of (a) may be substituted with an alkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, a halogen atom or the like. As Ar ^B1 The substituent when the aromatic ring is substituted is preferably, for example, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

Ar ^B2 The aromatic ring of (a) may be any of monocyclic ring and polycyclic ring. Examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring, and benzene rings and naphthalene rings are preferable.

Ar ^B2 The hydrogen atom on the aromatic ring of (a) may be substituted with an alkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, a halogen atom or the like. As Ar ^B2 The substituent when the aromatic ring is substituted is preferably, for example, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

Rb ¹ Rb ² The alkyl group having 1 to 20 carbon atoms may be any of linear, branched, and cyclic. The carbon number of the alkyl group is, for example, preferably 1 to 18, more preferably 1 to 14, still more preferably 1 to 10.

Rb ¹ Rb ² The aryl group having 6 to 12 carbon atoms may be a single ring or a multiple ring. The number of carbon atoms of the aryl group is, for example, preferably 6 or more and 10 or less, and more preferably 6.

Rb ¹ Rb ² The alkyl group in the aralkyl group having 7 to 20 carbon atoms may be any of a straight chain, a branched chain, and a cyclic group. The number of carbon atoms of the alkyl group in the aralkyl group having 7 to 20 carbon atoms is, for example, preferably 1 to 4, more preferably 1 to 3, and still more preferably 1 or 2.

Rb ¹ Rb ² The aryl group in the aralkyl group having 7 to 20 carbon atoms may be a single ring or a multiple ring. The number of carbon atoms of the aryl group is, for example, preferably 6 or more and 10 or less, and more preferably 6.

The diol unit (B) preferably includes at least one selected from the group consisting of a diol unit (B1) represented by the following formula (B1), a diol unit (B2) represented by the following formula (B2), a diol unit (B3) represented by the following formula (B3), a diol unit (B4) represented by the following formula (B4), a diol unit (B5) represented by the following formula (B5), a diol unit (B6) represented by the following formula (B6), a diol unit (B7) represented by the following formula (B7), and a diol unit (B8) represented by the following formula (B8), for example.

The diol unit (B) more preferably contains at least one selected from the group consisting of a diol unit (B1) represented by the following formula (B1), a diol unit (B2) represented by the formula (B2), a diol unit (B4) represented by the formula (B4), a diol unit (B5) represented by the formula (B5) and a diol unit (B6) represented by the formula (B6), for example,

further preferably, the composition comprises at least one selected from the group consisting of a diol unit (B1) represented by the following formula (B1), a diol unit (B2) represented by the formula (B2), a diol unit (B5) represented by the formula (B5) and a diol unit (B6) represented by the formula (B6),

still more preferably, at least one selected from the group consisting of a diol unit (B1) represented by the following formula (B1), a diol unit (B2) represented by the formula (B2) and a diol unit (B6) represented by the formula (B6),

It is most preferable to include at least one selected from the group consisting of a diol unit (B1) represented by the following formula (B1) and a diol unit (B2) represented by the formula (B2).

[ chemical formula 11]

(B1)

In formula (B1), rb ¹⁰¹ Is branched alkyl group having 4 to 20 carbon atoms, rb ²⁰¹ Is hydrogen atom or alkyl group with carbon number of 1-3, rb ⁴⁰¹ 、Rb ⁵⁰¹ 、Rb ⁸⁰¹ Rb ⁹⁰¹ Each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

Rb ¹⁰¹ The number of carbon atoms of the branched alkyl group having 4 to 20 carbon atoms is, for example, preferably 4 to 16 carbon atoms, more preferably 4 to 12 carbon atoms, and still more preferably 4 to 8 carbon atoms. As Rb ¹⁰¹ Specific examples of (a) include isobutyl, sec-butyl, tert-butyl, isopentyl, neopentyl, tert-pentyl, isohexyl, sec-hexyl, tert-hexyl, isoheptyl, sec-heptyl, tert-heptyl, isooctyl, sec-octyl, tert-octyl, isononyl, sec-nonyl, tert-nonyl, isodecyl, zhong Guiji, tert-decyl, isododecyl, sec-dodecyl, tert-tetradecyl, tert-pentadecyl and the like.

[ chemical formula 12]

(B2)/>

In formula (B2), rb ¹⁰² Is a linear alkyl group having 4 to 20 carbon atoms, rb ²⁰² Is hydrogen atom or alkyl group with carbon number of 1-3, rb ⁴⁰² 、Rb ⁵⁰² 、Rb ⁸⁰² Rb ⁹⁰² Each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

Rb ¹⁰² The number of carbon atoms of the linear alkyl group having 4 to 20 carbon atoms is, for example, preferably 4 to 16 carbon atoms, more preferably 4 to 12 carbon atoms, and still more preferably 4 to 8 carbon atoms. As Rb ¹⁰² Specific examples of (a) include n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, tridecyl, n-tetradecyl, n-pentadecyl, n-heptadecyl, n-octadecyl, n-nonadecyl, and n-eicosyl.

[ chemical formula 13]

(B3)

In formula (B3), rb ¹¹³ Rb ²¹³ Each independently represents a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom, d is an integer of 7 to 15 inclusive, or Rb ⁴⁰³ 、Rb ⁵⁰³ 、Rb ⁸⁰³ Rb ⁹⁰³ Each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

Rb ¹¹³ Rb ²¹³ The number of carbon atoms of the linear alkyl group having 1 to 3 carbon atoms is preferably 1 or 2, more preferably 1. Specific examples of the group include methyl, ethyl and n-propyl.

Rb ¹¹³ Rb ²¹³ The alkyl group in the alkoxy group having 1 to 4 carbon atoms may be any of a straight chain, a branched chain, and a cyclic one. The number of carbon atoms of the alkyl group in the alkoxy group having 1 to 4 carbon atoms is, for example, preferably 1 to 3 carbon atoms, more preferably 1 or 2 carbon atoms, and still more preferably 1 carbon atom. Specific examples of the group include methoxy, ethoxy, n-propoxy, n-butoxy, isopropoxy, isobutoxy, sec-butoxy, tert-butoxy, cyclopropoxy, and cyclobutoxy.

As Rb ¹¹³ Rb ²¹³ Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

[ chemical formula 14]

(B4)

In formula (B4), rb ¹⁰⁴ Rb ²⁰⁴ Each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, or Rb ⁴⁰⁴ 、Rb ⁵⁰⁴ 、Rb ⁸⁰⁴ Rb ⁹⁰⁴ Each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

Rb ¹⁰⁴ The alkyl group having 1 to 3 carbon atoms may be any of linear, branched, and cyclic. The number of carbon atoms of the alkyl group is, for example, preferably 1 or 2, more preferably 1. As Rb ¹⁰⁴ Specific examples of (a) include methyl, ethyl, n-propyl, isopropyl and cyclopropyl.

[ chemical formula 15]

(B5)

In the formula (B5), ar ¹⁰⁵ Is aryl group with 6-12 carbon atoms or aralkyl group with 7-20 carbon atoms, rb ²⁰⁵ Is hydrogen atom or alkyl group with carbon number of 1-3, rb ⁴⁰⁵ 、Rb ⁵⁰⁵ 、Rb ⁸⁰⁵ Rb ⁹⁰⁵ Each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

Ar ¹⁰⁵ The aryl group having 6 to 12 carbon atoms may be a single ring or a multiple ring. The number of carbon atoms of the aryl group is, for example, preferably 6 or more and 10 or less, and more preferably 6.

Ar ¹⁰⁵ The alkyl group in the aralkyl group having 7 to 20 carbon atoms may be any of a straight chain, a branched chain, and a cyclic group. The number of carbon atoms of the alkyl group in the aralkyl group having 7 to 20 carbon atoms is, for example, preferably 1 to 4, more preferably 1 to 3, and still more preferably 1 or 2.Ar (Ar) ¹⁰⁵ The aryl group in the aralkyl group having 7 to 20 carbon atoms may be a single ring or a multiple ring. The number of carbon atoms of the aryl group is, for example, preferably 6 or more and 10 or less, and more preferably 6. Examples of the aralkyl group having 7 to 20 carbon atoms include benzyl, phenylethyl, phenylpropyl, 4-phenylbutyl, phenylpentyl, phenylhexyl, phenylheptyl, phenyloctyl, phenylnonyl, naphthylmethyl, naphthylethyl, anthracenylmethyl, phenyl-cyclopentylmethyl and the like.

[ chemical formula 16]

(B6)

In formula (B6), rb ¹¹⁶ Rb ²¹⁶ Each independently represents a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom, e is an integer of 4 to 6, or Rb ⁴⁰⁶ 、Rb ⁵⁰⁶ 、Rb ⁸⁰⁶ Rb ⁹⁰⁶ Each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

Rb ¹¹⁶ Rb ²¹⁶ The number of carbon atoms of the straight-chain alkyl group having 1 to 3 carbon atoms is preferably 1 or 2,more preferably 1. Specific examples of the group include methyl, ethyl and n-propyl.

Rb ¹¹⁶ Rb ²¹⁶ The alkyl group in the alkoxy group having 1 to 4 carbon atoms may be any of a straight chain, a branched chain, and a cyclic one. The number of carbon atoms of the alkyl group in the alkoxy group having 1 to 4 carbon atoms is, for example, preferably 1 to 3 carbon atoms, more preferably 1 or 2 carbon atoms, and still more preferably 1 carbon atom. Specific examples of the group include methoxy, ethoxy, n-propoxy, n-butoxy, isopropoxy, isobutoxy, sec-butoxy, tert-butoxy, cyclopropoxy, and cyclobutoxy.

As Rb ¹¹⁶ Rb ²¹⁶ Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

[ chemical formula 17]

(B7)

In formula (B7), rb ⁴⁰⁷ 、Rb ⁵⁰⁷ 、Rb ⁸⁰⁷ Rb ⁹⁰⁷ Each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

[ chemical formula 18]

(B8)

In formula (B8), rb ⁴⁰⁸ 、Rb ⁵⁰⁸ 、Rb ⁸⁰⁸ Rb ⁹⁰⁸ Each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom.

Rb of formula (B1) ²⁰¹ Rb of formula (B2) ²⁰² Rb of formula (B4) ²⁰⁴ And Rb of formula (B5) ²⁰⁵ The specific mode and preferred mode of (a) are the same, so Rb will be described below ²⁰¹ 、Rb ²⁰² 、Rb ²⁰⁴ Rb ²⁰⁵ Collectively referred to as "Rb ²⁰⁰ "to illustrate.

Rb ²⁰⁰ The alkyl group having 1 to 3 carbon atoms may be any of linear, branched, and cyclic. The number of carbon atoms of the alkyl group is, for example, preferably 1 or 2, more preferably 1.

Examples of the alkyl group having 1 to 3 carbon atoms include methyl, ethyl, n-propyl, isopropyl and cyclopropyl.

Rb of formula (B1) ⁴⁰¹ Rb of formula (B2) ⁴⁰² Rb of formula (B3) ⁴⁰³ Rb of formula (B4) ⁴⁰⁴ Rb of formula (B5) ⁴⁰⁵ Rb of formula (B6) ⁴⁰⁶ Rb of formula (B7) ⁴⁰⁷ And Rb of formula (B8) ⁴⁰⁸ The specific mode and preferred mode of (a) are the same, so Rb will be described below ⁴⁰¹ 、Rb ⁴⁰² 、Rb ⁴⁰³ 、Rb ⁴⁰⁴ 、Rb ⁴⁰⁵ 、Rb ⁴⁰⁶ 、Rb ⁴⁰⁷ Rb ⁴⁰⁸ Collectively referred to as "Rb ⁴⁰⁰ "to illustrate.

Rb ⁴⁰⁰ The alkyl group having 1 to 4 carbon atoms may be any of linear, branched, and cyclic. The number of carbon atoms of the alkyl group is, for example, preferably 1 to 3, more preferably 1 or 2, and still more preferably 1.

Examples of the straight-chain alkyl group having 1 to 4 carbon atoms include methyl, ethyl, n-propyl and n-butyl.

Examples of the branched alkyl group having 3 or 4 carbon atoms include isopropyl, isobutyl, sec-butyl and tert-butyl.

Examples of the cyclic alkyl group having 3 or 4 carbon atoms include cyclopropyl and cyclobutyl.

Rb ⁴⁰⁰ The alkyl group in the alkoxy group having 1 to 6 carbon atoms may be any of a straight chain, a branched chain, and a cyclic one. The number of carbon atoms of the alkyl group in the alkoxy group having 1 to 6 carbon atoms is, for example, preferably 1 to 4 carbon atoms, more preferably 1 to 3 carbon atoms, and still more preferably 1 or 2 carbon atoms.

As Rb ⁴⁰⁰ Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

Rb of formula (B1) ⁵⁰¹ Rb of formula (B2) ⁵⁰² Rb of formula (B3) ⁵⁰³ Rb of formula (B4) ⁵⁰⁴ Rb of formula (B5) ⁵⁰⁵ Rb of formula (B6) ⁵⁰⁶ Rb of formula (B7) ⁵⁰⁷ And Rb of formula (B8) ⁵⁰⁸ The specific mode and preferred mode of (a) are the same, so Rb will be described below ⁵⁰¹ 、Rb ⁵⁰² 、Rb ⁵⁰³ 、Rb ⁵⁰⁴ 、Rb ⁵⁰⁵ 、Rb ⁵⁰⁶ 、Rb ⁵⁰⁷ Rb ⁵⁰⁸ Collectively referred to as "Rb ⁵⁰⁰ "to illustrate.

Rb ⁵⁰⁰ The alkyl group having 1 to 4 carbon atoms may be any of linear, branched, and cyclic. The number of carbon atoms of the alkyl group is, for example, preferably 1 to 3, more preferably 1 or 2, and still more preferably 1.

Rb ⁵⁰⁰ The alkyl group in the alkoxy group having 1 to 6 carbon atoms may be any of a straight chain, a branched chain, and a cyclic one. The number of carbon atoms of the alkyl group in the alkoxy group having 1 to 6 carbon atoms is, for example, preferably 1 to 4, more preferably 1 to 3, still more preferably 1 or 2 。

As Rb ⁵⁰⁰ Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

Rb of formula (B1) ⁸⁰¹ Rb of formula (B2) ⁸⁰² Rb of formula (B3) ⁸⁰³ Rb of formula (B4) ⁸⁰⁴ Rb of formula (B5) ⁸⁰⁵ Rb of formula (B6) ⁸⁰⁶ Rb of formula (B7) ⁸⁰⁷ And Rb of formula (B8) ⁸⁰⁸ The specific mode and preferred mode of (a) are the same, so Rb will be described below ⁸⁰¹ 、Rb ⁸⁰² 、Rb ⁸⁰³ 、Rb ⁸⁰⁴ 、Rb ⁸⁰⁵ 、Rb ⁸⁰⁶ 、Rb ⁸⁰⁷ Rb ⁸⁰⁸ Collectively referred to as "Rb ⁸⁰⁰ "to illustrate.

Rb ⁸⁰⁰ The alkyl group having 1 to 4 carbon atoms may be any of linear, branched, and cyclic. The number of carbon atoms of the alkyl group is, for example, preferably 1 to 3, more preferably 1 or 2, and still more preferably 1.

Rb ⁸⁰⁰ The alkyl group in the alkoxy group having 1 to 6 carbon atoms may be a straight chain or branched chainEither of a ring shape and a ring shape. The number of carbon atoms of the alkyl group in the alkoxy group having 1 to 6 carbon atoms is, for example, preferably 1 to 4 carbon atoms, more preferably 1 to 3 carbon atoms, and still more preferably 1 or 2 carbon atoms.

As Rb ⁸⁰⁰ Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

Rb of formula (B1) ⁹⁰¹ Rb of formula (B2) ⁹⁰² Rb of formula (B3) ⁹⁰³ Rb of formula (B4) ⁹⁰⁴ Rb of formula (B5) ⁹⁰⁵ Rb of formula (B6) ⁹⁰⁶ Rb of formula (B7) ⁹⁰⁷ And Rb of formula (B8) ⁹⁰⁸ The specific mode and preferred mode of (a) are the same, so Rb will be described below ⁹⁰¹ 、Rb ⁹⁰² 、Rb ⁹⁰³ 、Rb ⁹⁰⁴ 、Rb ⁹⁰⁵ 、Rb ⁹⁰⁶ 、Rb ⁹⁰⁷ Rb ⁹⁰⁸ Collectively referred to as "Rb ⁹⁰⁰ "to illustrate.

Rb ⁹⁰⁰ The alkyl group having 1 to 4 carbon atoms may be any of linear, branched, and cyclic. The number of carbon atoms of the alkyl group is, for example, preferably 1 to 3, more preferably 1 or 2, and still more preferably 1.

Rb ⁹⁰⁰ The alkyl group in the alkoxy group having 1 to 6 carbon atoms may be any of a straight chain, a branched chain, and a cyclic one. The number of carbon atoms of the alkyl group in the alkoxy group having 1 to 6 carbon atoms is, for example, preferably 1 to 4 carbon atoms, more preferably 1 to 3 carbon atoms, and still more preferably 1 or 2 carbon atoms.

As Rb ⁹⁰⁰ Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

Specific examples of the diol units (B1) are the diol units (B1-1) to (B1-6). The diol unit (B1) is not limited thereto.

[ chemical formula 19]

Specific examples of the diol units (B2) are the diol units (B2-1) to (B2-11). The diol unit (B2) is not limited thereto.

[ chemical formula 20]

Specific examples of the diol units (B3) are the diol units (B3-1) to (B3-4). The diol unit (B3) is not limited thereto.

[ chemical formula 21]

Specific examples of the diol units (B4) are the diol units (B4-1) to (B4-7). The diol unit (B4) is not limited thereto.

[ chemical formula 22]

Specific examples of the diol units (B5) are the diol units (B5-1) to (B5-6). The diol unit (B5) is not limited thereto.

[ chemical formula 23]

Specific examples of the diol units (B6) are the diol units (B6-1) to (B6-4). The diol unit (B6) is not limited thereto.

[ chemical formula 24]

Specific examples of the diol units (B7) are the diol units (B7-1) to (B7-3). The diol unit (B7) is not limited thereto.

[ chemical formula 25]

Specific examples of the diol units (B8) are the diol units (B8-1) to (B8-3). The diol unit (B8) is not limited thereto.

[ chemical formula 26]

The diol units (B) contained in the polyester resin (1) may be one kind or two or more kinds.

The mass ratio of the diol unit (B) in the polyester resin (1) is, for example, preferably 25 mass% or more and 80 mass% or less.

When the mass ratio of the diol unit (B) is 25% by mass or more, peeling of the photosensitive layer can be suppressed. From this viewpoint, the mass ratio of the diol unit (B) is, for example, more preferably 30 mass% or more, and still more preferably 35 mass% or more.

When the mass ratio of the diol unit (B) is 80% by mass or less, the abrasion resistance can be improved while maintaining the solubility in a coating liquid for forming a photosensitive layer. From this viewpoint, the mass ratio of the diol unit (B) is, for example, more preferably 75 mass% or less, and still more preferably 70 mass% or less.

Examples of the diol unit other than the diol unit (B) include an aliphatic diol (e.g., ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butylene glycol, hexylene glycol, neopentyl glycol) unit and an alicyclic diol (e.g., cyclohexanediol, cyclohexanedimethanol, hydrogenated bisphenol a) unit. These diol units contained in the polyester resin (1) may be one kind or two or more kinds.

The terminal of the polyester resin (1) may be sealed or modified by a capping agent, a molecular weight regulator, or the like used in the production. Examples of the blocking agent or the molecular weight regulator include monophenols, monoacylchlorides, monoalcohols, and monocarboxylic acids.

Examples of the monophenols include phenol, o-cresol, m-cresol, p-cresol, o-ethylphenol, m-ethylphenol, p-ethylphenol, o-propylphenol, m-propylphenol, p-propylphenol, o-t-butylphenol, m-t-butylphenol, p-t-butylphenol, pentylphenol, hexylphenol, octylphenol, nonylphenol, 2, 6-dimethylphenol derivatives, 2-methylphenol derivatives, o-phenylphenol, m-phenylphenol, p-phenylphenol, o-methoxyphenol, m-methoxyphenol, p-methoxyphenol, 2,3, 5-trimethylphenol, 2,3, 6-trimethylphenol, 2, 3-xylenol, 2, 4-xylenol, 2, 5-xylenol, 2, 6-xylenol, 3, 4-xylenol, 3, 5-xylenol, 2-phenyl-2- (4-hydroxyphenyl) propane, 2-phenyl-2- (2-hydroxyphenyl) propane.

Examples of the monobasic acid chloride include monofunctional acid halides such as benzoyl chloride, benzoin chloride, methylsulfonyl chloride, phenyl chloroformate, acetyl chloride, butyryl chloride, octanoyl chloride, benzoyl chloride, benzenesulfonyl chloride and phenylphosphonyl chloride, and their substituents.

Examples of the monohydric alcohol include methanol, ethanol, n-propanol, isopropanol, n-butanol, 2-butanol, pentanol, hexanol, dodecanol, stearyl alcohol, benzyl alcohol, and phenethyl alcohol.

Examples of the monocarboxylic acid include acetic acid, propionic acid, octanoic acid, cyclohexane carboxylic acid, benzoic acid, methylbenzoic acid, phenylacetic acid, p-tert-butylbenzoic acid, and p-methoxyphenylacetic acid.

The weight average molecular weight of the polyester resin (1) is, for example, preferably 3 to 30 ten thousand, more preferably 4 to 25 ten thousand, and even more preferably 5 to 20 ten thousand.

The molecular weight of the polyester resin (1) is a molecular weight in terms of polystyrene as measured by GPC (gel permeation chromatography). GPC was used as eluent with tetrahydrofuran.

The polyester resin (1) is obtained by polycondensation or the like of a monomer imparting a dicarboxylic acid unit (a) and a monomer imparting a diol unit (B) and, if necessary, other monomers by a conventional method. Examples of the method of polycondensation of the monomer include interfacial polymerization, solution polymerization, and melt polymerization. The interfacial polymerization method is a polymerization method for obtaining a polyester by mixing a dicarboxylic acid halide dissolved in an organic solvent that is not compatible with water and a diol dissolved in an aqueous alkali solution. Examples of the interfacial polymerization method include Japanese patent publication No. W.M.EARECKSON, J.Poly.Sci., XL399 and Japanese patent publication No. 40-1959 in 1959. The interfacial polymerization method is faster than the solution polymerization method, and therefore can suppress hydrolysis of dicarboxylic acid halide, and as a result, a polyester resin having a high molecular weight can be obtained.

[ conductive matrix ]

Examples of the conductive substrate include a metal plate, a metal drum, and a metal belt, each of which includes a metal (aluminum, copper, zinc, chromium, nickel, molybdenum, vanadium, indium, gold, platinum, and the like) or an alloy (stainless steel, and the like). Further, examples of the conductive substrate include conductive compounds (e.g., conductive polymers, indium oxide, etc.); papers coated, vapor deposited or laminated with metals (e.g., aluminum, palladium, gold, etc.) or alloys; a resin film; a belt, etc. As used herein, "conductive" means having a volume resistivity of less than 1X 10 ¹³ Ω·cm。

When the electrophotographic photoreceptor is used in a laser printer, the surface of the conductive substrate is preferably roughened to 0.04 μm or more and 0.5 μm or less, for example, by the center line average roughness Ra, in order to suppress interference fringes generated when the laser beam is irradiated. When incoherent light is used for the light source, it is not particularly necessary to prevent roughening of interference fringes, but it is preferable to lengthen the lifetime because occurrence of defects caused by irregularities on the surface of the conductive substrate is suppressed.

Examples of the roughening method include wet polishing by suspending a polishing agent in water and blowing the polishing agent onto a conductive substrate, centerless polishing by pressing the conductive substrate against a rotating grinding wheel and continuously performing grinding, and anodic oxidation.

As a roughening method, there is also mentioned a method in which a conductive or semiconductive powder is dispersed in a resin without roughening the surface of a conductive substrate to form a layer on the surface of the conductive substrate, and roughening is performed by particles dispersed in the layer.

Roughening treatment by anodic oxidation is a treatment of forming an oxide film on the surface of a conductive substrate made of metal (for example, aluminum) by anodic oxidation in an electrolyte solution with the conductive substrate as an anode. Examples of the electrolyte solution include sulfuric acid solution and oxalic acid solution. However, the porous anodic oxide film formed by anodic oxidation has chemical activity in its original state, is easily contaminated, and also has a large variation in resistance due to the environment. Therefore, for example, it is preferable to perform a pore sealing treatment of the porous anodic oxide film to change to a more stable hydrous oxide by blocking micropores of the oxide film by volume expansion caused by water and reaction in pressurized water vapor or boiling water (a metal salt such as nickel may be added).

The film thickness of the anodic oxide film is preferably, for example, 0.3 μm or more and 15 μm or less. If the film thickness is within the above range, the barrier property against injection tends to be exerted, and the residual potential increase due to repeated use tends to be suppressed.

The conductive substrate may be subjected to treatment with an acidic treatment liquid or boehmite treatment.

The treatment with the acidic treatment liquid is performed, for example, as follows. First, an acidic treatment liquid containing phosphoric acid, chromic acid, and fluoric acid is prepared. The mixing ratio of phosphoric acid, chromic acid, and fluoric acid in the acidic treatment liquid may be, for example, in the range of 10 mass% or more and 11 mass% or less, chromic acid in the range of 3 mass% or more and 5 mass% or less, fluoric acid in the range of 0.5 mass% or more and 2 mass% or less, and the concentration of the total amount of acids in the ranges of 13.5 mass% or more and 18 mass% or less. The treatment temperature is preferably, for example, 42℃to 48 ℃. The film thickness of the coating film is preferably, for example, 0.3 μm or more and 15 μm or less.

The boehmite treatment is performed, for example, by immersing in pure water at 90 ℃ or more and 100 ℃ or less for 5 minutes to 60 minutes or by contacting in heated steam at 90 ℃ or more and 120 ℃ or less for 5 minutes to 60 minutes. The film thickness of the coating film is preferably, for example, 0.1 μm or more and 5 μm or less. The anode may be further oxidized by using an electrolyte solution having a low solubility of a coating such as adipic acid, boric acid, borate, phosphate, phthalate, maleate, benzoate, tartrate, citrate, or the like.

[ under coating ]

The under coat is, for example, a layer containing inorganic particles and a binder resin.

Examples of the inorganic particles include powder resistance (volume resistivity) of 1×10 ² Omega cm or more and 1X 10 ¹¹ Inorganic particles having an omega cm or less.

Among them, the inorganic particles having the above-mentioned resistance value may be, for example, metal oxide particles such as tin oxide particles, titanium oxide particles, zinc oxide particles, and zirconium oxide particles, and particularly preferably zinc oxide particles.

The specific surface area of the inorganic particles by BET method is, for example, 10m ² And/g above.

The volume average particle diameter of the inorganic particles may be, for example, 50nm to 2000nm (for example, preferably 60nm to 1000 nm).

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

The inorganic particles may be subjected to surface treatment. The inorganic particles may be mixed with two or more kinds of particles having different surface treatments or particles having different particle diameters.

Examples of the surface treatment agent include silane coupling agents, titanate coupling agents, aluminum coupling agents, and surfactants. In particular, for example, a silane coupling agent is preferable, and a silane coupling agent having an amino group is more preferable.

Examples of the silane coupling agent having an amino group include 3-aminopropyl triethoxysilane, N-2- (aminoethyl) -3-aminopropyl trimethoxysilane, N-2- (aminoethyl) -3-aminopropyl methyldimethoxysilane, and N, N-bis (2-hydroxyethyl) -3-aminopropyl triethoxysilane, but are not limited thereto.

The silane coupling agent may be used in combination of two or more. For example, a silane coupling agent having an amino group may be used in combination with other silane coupling agents. Examples of the other silane coupling agent include vinyltrimethoxysilane, 3-methacryloxypropyl-tris (2-methoxyethoxy) silane, 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyl trimethoxysilane, vinyltriacetoxy silane, 3-mercaptopropyl trimethoxysilane, 3-aminopropyl triethoxysilane, N-2- (aminoethyl) -3-aminopropyl trimethoxysilane, N-2- (aminoethyl) -3-aminopropyl methyldimethoxysilane, N-bis (2-hydroxyethyl) -3-aminopropyl triethoxysilane, and 3-chloropropyltrimethoxysilane, but are not limited thereto.

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

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

Here, from the viewpoint of improving the long-term stability of the electrical characteristics and the carrier blocking property, the lower coating layer preferably contains an electron-accepting compound (acceptor compound) together with the inorganic particles, for example.

Examples of the electron-accepting compound include quinone compounds such as chloranil and tetrabromo-p-benzoquinone; tetracyano terephthalquinone dimethane compounds; fluorenone compounds such as 2,4, 7-trinitrofluorenone and 2,4,5, 7-tetranitro-9-fluorenone; oxadiazole compounds such as 2- (4-biphenyl) -5- (4-tert-butylphenyl) -1,3, 4-oxadiazole, 2, 5-bis (4-naphthyl) -1,3, 4-oxadiazole, and 2, 5-bis (4-diethylaminophenyl) -1,3, 4-oxadiazole; xanthones; thiophene compounds; diphenoquinone compounds such as 3,3', 5' -tetra-t-butyldiphenoquinone; benzophenone compounds; and electron transporting substances.

In particular, as the electron-accepting compound, for example, a compound having an anthraquinone structure is preferable. As the compound having an anthraquinone structure, for example, a hydroxyanthraquinone compound, an aminoanthraquinone compound, an aminohydroxyanthraquinone compound, and the like are preferable, and specifically, for example, anthraquinone, alizarin, quinizarine, anthramagenta, rhodoxanthin, and the like are preferable.

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

Examples of the method for attaching the electron-accepting compound to the surface of the inorganic particle include a dry method and a wet method.

The dry method is, for example, a method in which an electron-accepting compound is directly added dropwise or an electron-accepting compound dissolved in an organic solvent is added dropwise while stirring the inorganic particles by a mixer or the like having a large shearing force, and the electron-accepting compound is sprayed with dry air or nitrogen gas to adhere the electron-accepting compound to the surfaces of the inorganic particles. When the electron accepting compound is added dropwise or sprayed, it is preferable to conduct the process at a temperature equal to or lower than the boiling point of the solvent, for example. After dropping or spraying the electron accepting compound, sintering may be performed at 100 ℃ or higher. The sintering is not particularly limited as long as it is at a temperature and for a time at which electrophotographic characteristics can be obtained.

The wet method is a method in which inorganic particles are dispersed in a solvent by, for example, a stirrer, ultrasonic waves, a sand mill, an attritor, a ball mill, or the like, and an electron-accepting compound is added to the solvent, stirred or dispersed, and then the solvent is removed to attach the electron-accepting compound to the surfaces of the inorganic particles. The solvent removal method removes the solvent, for example, by filtration or evaporation. After removal of the solvent, sintering may also be performed at temperatures above 100 ℃. The sintering is not particularly limited as long as it is at a temperature and for a time at which electrophotographic characteristics can be obtained. In the wet method, the moisture contained in the inorganic particles can be removed before the electron-accepting compound is added, and examples thereof include a method of removing the inorganic particles in a solvent while stirring and heating the inorganic particles, and a method of removing the inorganic particles by azeotroping the inorganic particles with the solvent.

The electron-accepting compound may be attached before or after the surface treatment with the surface treatment agent is performed on the inorganic particles, or the electron-accepting compound may be attached and the surface treatment with the surface treatment agent may be performed simultaneously.

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

Examples of the binder resin used for the under coat layer include known polymer compounds such as acetal resins (for example, polyvinyl butyral), polyvinyl alcohol resins, polyvinyl acetal resins, casein resins, polyamide resins, cellulose resins, gelatin, polyurethane resins, polyester resins, unsaturated polyester resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinyl acetate resins, vinyl chloride-vinyl acetate-maleic anhydride resins, silicone-alkyd resins, urea resins, phenolic resins, phenol-formaldehyde resins, melamine resins, urethane resins, alkyd resins, and epoxy resins; zirconium chelate compounds; a titanium chelate compound; an aluminum chelate compound; a titanium alkoxide compound; an organic titanium compound; known materials such as silane coupling agents.

Examples of the binder resin used for the under coat layer include a charge-transporting resin having a charge-transporting group, a conductive resin (e.g., polyaniline) and the like.

Among them, the binder resin used for the lower coat layer is preferably a resin of which the upper layer is insoluble in a coating solvent, and particularly preferably a thermosetting resin selected from urea resins, phenol-formaldehyde resins, melamine resins, urethane resins, unsaturated polyester resins, alkyd resins, epoxy resins, and the like; a resin obtained by a reaction between a curing agent and at least one resin selected from the group consisting of polyamide resins, polyester resins, polyether resins, methacrylic resins, acrylic resins, polyvinyl alcohol resins and polyvinyl acetal resins.

When two or more kinds of these binder resins are used in combination, the mixing ratio thereof is set as required.

Various additives may be contained in the under coat layer in order to improve electrical characteristics, improve environmental stability, and improve image quality.

Examples of the additive include known materials such as electron-transporting pigments including polycyclic condensates and azo compounds, zirconium chelate compounds, titanium chelate compounds, aluminum chelate compounds, titanium alkoxide compounds, organic titanium compounds, and silane coupling agents. As described above, the silane coupling agent is used for the surface treatment of the inorganic particles, but may be added as an additive to the under coat layer.

Examples of the silane coupling agent used as the additive include vinyltrimethoxysilane, 3-methacryloxypropyl-tris (2-methoxyethoxy) silane, 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyl trimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyl trimethoxysilane, 3-aminopropyl triethoxysilane, N-2- (aminoethyl) -3-aminopropyl trimethoxysilane, N-2- (aminoethyl) -3-aminopropyl methyldimethoxysilane, N-bis (2-hydroxyethyl) -3-aminopropyl triethoxysilane, and 3-chloropropyltrimethoxysilane.

Examples of the zirconium chelate compound include zirconium butoxide, zirconium ethylacetoacetate, zirconium triethanolamine, zirconium butacetylacetonate, zirconium ethylacetoacetate butoxide, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octoate, zirconium naphthenate, zirconium laurate, zirconium stearate, zirconium isostearate, zirconium methacrylate butoxide, zirconium stearate butoxide, zirconium isostearate butoxide, and the like.

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

Examples of the aluminum chelate compound include aluminum isopropoxide, aluminum monobutyloxide diisopropoxide, aluminum butoxide, aluminum diisopropoxide of ethyl diacetoacetate, aluminum tris (ethyl acetoacetate), and the like.

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

The lower coating layer may have a vickers hardness of 35 or more, for example.

In order to suppress the interference moire image, the surface roughness (ten-point average roughness) of the lower coating layer may be adjusted to, for example, 1/(4 n) (n is the refractive index of the upper layer) to 1/2 of the exposure laser wavelength λ used.

In order to adjust the surface roughness, resin particles or the like may be added to the lower coating layer. Examples of the resin particles include silicone resin particles and crosslinked polymethyl methacrylate resin particles. Also, in order to adjust the surface roughness, the surface of the under-coating layer may be polished. Examples of the polishing method include polishing, sand blasting, wet polishing, and grinding.

The formation of the undercoating is not particularly limited, and a known formation method can be used, but for example, the formation of a coating film of a coating liquid for undercoating in which the above-mentioned components are added to a solvent is performed by drying the coating film and heating it as necessary.

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

Specific examples of the solvents include usual organic solvents such as methanol, ethanol, n-propanol, isopropanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, dichloromethane, chloroform, chlorobenzene, and toluene.

Examples of the method for dispersing inorganic particles in the preparation of the coating liquid for forming the lower coating layer include known methods such as a roll mill, a ball mill, a vibration ball mill, an attritor, a sand mill, a colloid mill, and a paint shaker.

Examples of the method of applying the coating liquid for forming the under coat layer to the conductive substrate include usual methods such as a blade coating method, a bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, and a curtain coating method.

The average thickness of the undercoating layer is, for example, preferably 14 μm or more and 36 μm or less, more preferably 18 μm or more and 32 μm or less, still more preferably 20 μm or more and 30 μm or less.

[ intermediate layer ]

An intermediate layer may also be provided between the under-coating layer and the photosensitive layer.

The intermediate layer is, for example, a layer containing a resin. Examples of the resin used in the intermediate layer include polymer compounds such as acetal resins (e.g., polyvinyl butyral), polyvinyl alcohol resins, polyvinyl acetal resins, casein resins, polyamide resins, cellulose resins, gelatin, polyurethane resins, polyester resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinyl acetate resins, vinyl chloride-vinyl acetate-maleic anhydride resins, silicone-alkyd resins, phenol-formaldehyde resins, and melamine resins.

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

The compounds used in these intermediate layers may be used alone or as a mixture or polycondensate of a plurality of compounds.

Among them, the intermediate layer is preferably a layer containing an organometallic compound containing a zirconium atom or a silicon atom, for example.

The formation of the intermediate layer is not particularly limited, and a known formation method can be used, but for example, the formation of a coating film of the intermediate layer-forming coating liquid in which the above-mentioned components are added to a solvent is performed by drying the coating film and heating if necessary.

As a coating method for forming the intermediate layer, a usual method such as a dip coating method, a push coating method, a wire bar coating method, a spray coating method, a blade coating method, a curtain coating method, or the like can be used.

The thickness of the intermediate layer is preferably set in a range of 0.1 μm or more and 3 μm or less, for example. The intermediate layer may be used as an under-coating.

[ Charge generation layer ]

The charge generation layer is, for example, a layer containing a charge generation material and a binder resin. The charge generation layer may be a vapor deposition layer of the charge generation material. The vapor deposition layer of the charge generating material is suitable for a case where a incoherent light source such as an LED (Light Emitting Diode: light emitting diode) or an organic EL (electroluminescence) image array is used.

Examples of the charge generating material include azo pigments such as disazo and trisazo; condensed ring aromatic pigments such as dibromoanthracenyl ketone; perylene pigments; a pyrrolopyrrole pigment; a phthalocyanine pigment; zinc oxide; trigonal selenium, and the like.

Among them, in order to cope with laser exposure in the near infrared region, for example, a metal phthalocyanine pigment or a metal-free phthalocyanine pigment is preferably used as the charge generating material. Specifically, for example, hydroxygallium phthalocyanine is more preferable; chlorogallium phthalocyanine; dichloro tin phthalocyanine; oxytitanium phthalocyanine.

On the other hand, in order to cope with laser exposure in the near ultraviolet region, for example, a condensed ring aromatic pigment such as dibromoanthracenyl ketone is preferable as the charge generating material; thioindigo pigments; a porphyrazine compound; zinc oxide; trigonal selenium; disazo pigments, and the like.

Even in the case of using an incoherent light source such as an LED or an organic EL image array having a light emission center wavelength in the range of 450nm or more and 780nm or less, the above-described charge generating material can be used, but from the viewpoint of resolution, when a photosensitive layer is used with a thin film of 20 μm or less, the electric field intensity in the photosensitive layer becomes high, and charge is reduced by charge injection from a matrix, so that an image defect called a black dot is liable to occur. This is remarkable when a charge generating material that easily generates dark current in a p-type semiconductor such as trigonal selenium or phthalocyanine pigment is used.

In contrast, when an n-type semiconductor such as a condensed aromatic pigment, a perylene pigment, or an azo pigment is used as the charge generating material, dark current is less likely to occur, and even if the film is formed, an image defect called a black dot can be suppressed. In the determination of n-type, a semiconductor that is more likely to flow as a carrier than holes, electrons, is n-type by a commonly used time-of-flight method and by determining the polarity of the flowing photocurrent.

The binder resin used for the charge generation layer is selected from a wide range of insulating resins, and the binder resin may be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinyl anthracene, polyvinyl pyrene, and polysilane.

Examples of the binder resin include polyvinyl butyral resin, polyarylate resin (polycondensates of bisphenols and aromatic dicarboxylic acids, etc.), polycarbonate resin, polyester resin, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyamide resin, acrylic resin, polyacrylamide resin, polyvinyl pyridine resin, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol resin, polyvinyl pyrrolidone resin, etc. Here, "insulating" means that the volume resistivity is 1X 10 ¹³ Omega cm or more.

These binder resins may be used singly or in combination of two or more.

The mixing ratio of the charge generating material to the binder resin is preferably in the range of 10:1 to 1:10, for example, in terms of mass ratio.

Other known additives may be contained in the charge generation layer.

The charge generation layer may be formed by a known method, but for example, a coating film of a charge generation layer forming coating liquid in which the above components are added to a solvent is formed, and the coating film is dried and heated as necessary. The formation of the charge generation layer may be performed by vapor deposition of a charge generation material. The formation of the charge generation layer by vapor deposition is particularly suitable for the case of using a condensed aromatic pigment or a perylene pigment as a charge generation material, for example.

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

As a method for dispersing particles (for example, a charge generating material) in the charge generating layer forming coating liquid, for example, a medium dispersing machine such as a ball mill, a vibration ball mill, an attritor, a sand mill, a horizontal sand mill, or a medium-free dispersing machine such as a stirrer, an ultrasonic dispersing machine, a roller mill, or a high-pressure homogenizer can be used. Examples of the high-pressure homogenizer include a collision system in which a dispersion liquid is dispersed by liquid-liquid collision or liquid-wall collision in a high-pressure state, and a penetration system in which a fine flow path is penetrated and dispersed in a high-pressure state.

In this dispersion, it is effective to set the average particle diameter of the charge generating material in the charge generating layer forming coating liquid to 0.5 μm or less, for example, preferably 0.3 μm or less, and more preferably 0.15 μm or less.

Examples of the method of applying the charge generating layer forming coating liquid to the under coat layer (or to the intermediate layer) include usual methods such as a blade coating method, a bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, and a curtain coating method.

The thickness of the charge generation layer is preferably set in a range of, for example, 0.1 μm or more and 5.0 μm or less, and more preferably in a range of 0.2 μm or more and 2.0 μm or less.

[ Charge transport layer ]

The charge transport layer is, for example, a layer containing a charge transport material and a binder resin. The charge transport layer may be a layer comprising a polymeric charge transport material.

Examples of the charge transport material include quinone compounds such as p-benzoquinone, chloranil, tetrabromobenzoquinone, and anthraquinone; tetracyano terephthalates; fluorenone compounds such as 2,4, 7-trinitrofluorenone; an anthrone compound; benzophenone compounds; cyanovinyl compounds; electron-transporting compounds such as vinyl compounds. Examples of the charge transport material include hole transport compounds such as triarylamines, biphenylamines, arylalkanes, aryl-substituted vinyl compounds, stilbenes, anthracene compounds, and hydrazones. These charge transport materials may be used singly or in combination of two or more, but are not limited thereto.

Examples of the polymer charge transport material include known chemical substances having charge transport properties such as poly-N-vinylcarbazole and polysilane. For example, a polyester-based polymer charge transport material is preferable. The polymer charge transport material may be used alone or in combination with a binder resin.

Examples of the charge transport material or the polymer charge transport material include polycyclic aromatic compounds, aromatic nitro compounds, aromatic amine compounds, heterocyclic compounds, hydrazone compounds, styrene compounds, enamine compounds, benzidine compounds, triallylamine compounds (particularly triphenylamine compounds), diamine compounds, oxadiazole compounds, carbazole compounds, organopolysiloxane compounds, pyrazoline compounds, indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, triazole compounds, cyanide compounds, benzofuran compounds, aniline compounds, butadiene compounds, and resins having groups derived from these compounds. Specifically, compounds described in paragraphs 0078 to 0080 of JP-A-2021-117377, paragraphs 0046 to 0048 of JP-A-2019-035900, paragraphs 0052 to 0053 of JP-A-2019-012341, paragraphs 0122 to 0134 of JP-A-2021-071565, paragraphs 0101 to 0110 of JP-A-2021-015223, paragraph 0116 of JP-A-2013-097300, paragraphs 0309 to 0316 of International publication No. 2019/070003, and paragraphs 0103 to 0107 of JP-A-2018-159787 and paragraphs 0102 to 0113 of JP-A-2021-148818, respectively, are mentioned.

From the viewpoint of charge mobility, the charge transport material preferably contains at least one selected from the group consisting of a chemical substance (C1) represented by the following formula (C1), a chemical substance (C2) represented by the formula (C2), a chemical substance (C3) represented by the formula (C3), and a chemical substance (C4) represented by the formula (C4), for example.

[ chemical formula 27]

(C1)

In the formula (C1), ar ^T1 、Ar ^T2 Ar and Ar ^T3 Each independently is aryl, -C ₆ H ₄ -C(R ^T4 )＝C(R ^T5 )(R ^T6 ) or-C ₆ H ₄ -CH＝CH-CH＝C(R ^T7 )(R ^T8 )。R ^T4 、R ^T5 、R ^T6 、R ^T7 R is R ^T8 Each independently is a hydrogen atom, an alkyl group, or an aryl group. When R is ^T5 R is R ^T6 When aryl groups are present, the aryl groups may be bonded to each other by-C (R ⁵¹ )(R ⁵² ) -and/or-C (R ⁶¹ )＝C(R ⁶² ) -divalent groups linked. R is R ⁵¹ 、R ⁵² 、R ⁶¹ R is R ⁶² Each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.

The group in the formula (C1) may be substituted with a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or a substituted amino group substituted with an alkyl group having 1 to 3 carbon atoms.

As the chemical substance (C1), for example, one having at least one aryl group or-C is preferable from the viewpoint of charge mobility ₆ H ₄ -CH＝CH-CH＝C(R ^T7 )(R ^T8 ) More preferably, the chemical substance (C '1) is represented by the following formula (C' 1).

[ chemical formula 28]

In the formula (C' 1), R ^T111 、R ^T112 、R ^T121 、R ^T122 、R ^T131 R is R ^T132 Each independently represents a hydrogen atom, a halogen atom, an alkyl group (for example, an alkyl group having 1 to 3 carbon atoms), an alkoxy group (for example, an alkoxy group having 1 to 3 carbon atoms), a phenyl group, or a phenoxy group. Tj1, tj2, tj3, tk1, tk2, and Tk3 are each independently 0, 1, or 2.

[ chemical formula 29]

(C2)

In the formula (C2), R ^T201 、R ^T202 、R ^T211 R is R ^T212 Each independently represents a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an amino group substituted with an alkyl group having 1 or 2 carbon atoms, an aryl group, -C (R) ^T21 )＝C(R ^T22 )(R ^T23 ) Or-ch=ch-ch=c (R ^T24 )(R ^T25 )。R ^T21 、R ^T22 、R ^T23 、R ^T24 R is R ^T25 Each independently is a hydrogen atom, an alkyl group, or an aryl group. R is R ^T221 R is R ^T222 Each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms or an alkoxy group having 1 to 5 carbon atoms. Tm1, tm2, tn1 and Tn2 are each independently 0, 1 or 2.

The group in the formula (C2) may be substituted with a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or a substituted amino group substituted with an alkyl group having 1 to 3 carbon atoms.

As the chemical substance (C2), for example, from the viewpoint of charge mobility, it is preferable to have at least one alkyl group, aryl group, or-ch=ch-ch=c (R ^T24 )(R ^T25 ) More preferably having at least two alkyl groups, aryl groups or-ch=ch-ch=c (R ^T24 )(R ^T25 ) Is a chemical substance of (a).

[ chemical formula 30]

(C3)

In formula (C3), R ^T301 、R ^T302 、R ^T311 R is R ^T312 Each independently represents a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an amino group substituted with an alkyl group having 1 or 2 carbon atoms, an aryl group, -C (R) ^T31 )＝C(R ^T32 )(R ^T33 ) Or-ch=ch-ch=c (R ^T34 )(R ^T35 )。R ^T31 、R ^T32 、R ^T33 、R ^T34 R is R ^T35 Each independently is a hydrogen atom, an alkyl group, or an aryl group. R is R ^T321 、R ^T322 R is R ^T331 Each independently being a hydrogen atom, a halogenAn atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. To1, to2, tp1, tp2, tq1, tq2, and Tr1 are each independently 0, 1, or 2.

The group in the formula (C3) may be substituted with a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or a substituted amino group substituted with an alkyl group having 1 to 3 carbon atoms.

[ chemical formula 31]

(C4)

In formula (C4), R ^T401 、R ^T402 、R ^T411 R is R ^T412 Each independently represents a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an amino group substituted with an alkyl group having 1 or 2 carbon atoms, an aryl group, -C (R) ^T41 )＝C(R ^T42 )(R ^T43 ) Or-ch=ch-ch=c (R ^T44 )(R ^T45 )。R ^T41 、R ^T42 、R ^T43 、R ^T44 R is R ^T45 Each independently is a hydrogen atom, an alkyl group, or an aryl group. R is R ^T421 、R ^T422 R is R ^T431 Each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms or an alkoxy group having 1 to 5 carbon atoms. Ts1, ts2, tt1, tt2, tu1, tu2, and Tv1 are each independently 0, 1, or 2.

The group in the formula (C4) may be substituted with a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or a substituted amino group substituted with an alkyl group having 1 to 3 carbon atoms.

The content of the charge transport material contained in the charge transport layer is preferably 20 mass% or more and 70 mass% or less with respect to the total mass of the charge transport layer, for example.

The charge transport layer preferably contains at least a polyester resin (1) as a binder resin, for example. The proportion of the polyester resin (1) in the total amount of the binder resin contained in the charge transport layer is, for example, preferably 60 mass% or more, more preferably 70 mass% or more, still more preferably 80 mass% or more, and particularly preferably 90 mass% or more. When the polyester resin (1) is used in combination with another resin, the other resin used in combination is preferably, for example, a polycarbonate resin.

The charge transport layer may contain other binder resins than the polyester resin (1). Examples of the other binder resin include polyester resins other than the polyester resin (1), polycarbonate resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinylidene chloride resins, polystyrene resins, polyvinyl acetate resins, styrene-butadiene copolymers, vinylidene chloride-acrylonitrile copolymers, vinyl chloride-vinyl acetate-maleic anhydride copolymers, silicone resins, silicone alkyd resins, phenol-formaldehyde resins, styrene-alkyd resins, poly-N-vinylcarbazole, polysilane, and the like. One kind or two or more kinds of these binder resins are used singly.

Other known additives may be included in the charge transport layer. Examples of the additives include antioxidants, leveling agents, antifoaming agents, fillers, and viscosity modifiers.

The formation of the charge transport layer is not particularly limited, and a known formation method can be used, but for example, a coating film of a coating liquid for forming a charge transport layer in which the above-mentioned components are added to a solvent is formed, and the coating film is dried and heated as necessary.

Examples of the solvent used for preparing the charge transport layer-forming coating liquid include aromatic hydrocarbons such as benzene, toluene, xylene, and chlorobenzene; ketones such as acetone and 2-butanone; halogenated aliphatic hydrocarbons such as methylene chloride, chloroform and dichloroethane; cyclic or linear ethers such as tetrahydrofuran and diethyl ether. These solvents are used singly or in combination of two or more.

Examples of the coating method for applying the charge transport layer-forming coating liquid to the charge generating layer include usual methods such as a blade coating method, a bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, and a curtain coating method.

The average thickness of the charge transport layer is, for example, preferably 31 μm or more and 48 μm or less, more preferably 35 μm or more and 46 μm or less, and still more preferably 37 μm or more and 45 μm or less.

[ Single-layer photosensitive layer ]

The single-layer photosensitive layer (charge generation/charge transport layer) is a layer containing a charge generation material, a charge transport material, a binder resin, and other additives as necessary. These materials are the same as those described in the charge generation layer and the charge transport layer.

The single-layer photosensitive layer preferably contains at least a polyester resin (1) as a binder resin, for example. The proportion of the polyester resin (1) in the total amount of the binder resin contained in the single-layer photosensitive layer is, for example, preferably 60 mass% or more, more preferably 70 mass% or more, still more preferably 80 mass% or more, and particularly preferably 90 mass% or more. When the polyester resin (1) is used in combination with another resin, the other resin used in combination is preferably, for example, a polycarbonate resin.

In the single-layer photosensitive layer, the content of the charge generating material may be, for example, 0.1 mass% or more and 10 mass% or less, and preferably 0.8 mass% or more and 5 mass% or less, relative to the total solid content.

The content of the charge transport material contained in the single-layer photosensitive layer may be, for example, 40 mass% or more and 60 mass% or less with respect to the total solid content.

The formation method of the single-layer photosensitive layer is the same as that of the charge generation layer or the charge transport layer.

The average thickness of the single-layer photosensitive layer is, for example, preferably from 31 μm to 48 μm, more preferably from 35 μm to 46 μm, and even more preferably from 37 μm to 45 μm.

Protective layer

The protective layer is arranged on the photosensitive layer according to the requirement. The protective layer is provided, for example, for the purpose of preventing chemical changes of the photosensitive layer at the time of charging or further improving the mechanical strength of the photosensitive layer.

Therefore, for example, a layer composed of a cured film (crosslinked film) may be applied to the protective layer. Examples of the layers include the layers 1) and 2) described below.

1) A layer comprising a cured film of a composition containing a charge transport material having a reactive group and a charge transport backbone in the same molecule (i.e., a layer comprising a polymer or a crosslinked body of the charge transport material containing a reactive group)

2) A layer comprising a cured film of a composition comprising a non-reactive charge transport material and a non-charge transport material having no charge transport backbone but having reactive groups (i.e., a layer comprising a non-reactive charge transport material and a polymer or crosslinked body of the non-charge transport material having reactive groups)

Examples of the reactive group of the charge transport material containing a reactive group include a chain-polymerizable group, an epoxy group, -OH, -OR [ wherein R represents an alkyl group ]]、-NH ₂ 、-SH、-COOH、-SiR ^Q1 _3-Qn (OR ^Q2 ) _Qn [ wherein R is ^Q1 Represents a hydrogen atom, an alkyl group or a substituted or unsubstituted aryl group, R ^Q2 Represents a hydrogen atom, an alkyl group or a trialkylsilyl group. Qn represents an integer of 1 to 3]And the like.

The chain-polymerizable group is not particularly limited as long as it is a functional group capable of radical polymerization, and is, for example, a functional group having a group containing at least a carbon double bond. Specifically, examples thereof include a group containing at least one selected from vinyl, vinyl ether, vinyl thioether, phenylvinyl, vinylphenyl, acryl, methacryl, and derivatives thereof. Among them, the chain-polymerizable group is preferably a group containing at least one selected from vinyl, phenylvinyl, vinylphenyl, acryl, methacryl, and derivatives thereof, for example, because of its excellent reactivity.

The charge transporting skeleton of the charge transporting material containing a reactive group is not particularly limited as long as it is a known structure in electrophotographic photoreceptors, and examples thereof include a structure derived from a nitrogen-containing hole transporting compound such as a triarylamine compound, a biphenylamine compound, and a hydrazone compound, and conjugated to a nitrogen atom. Among them, for example, a triarylamine skeleton is preferable.

The charge transport material containing a reactive group, the non-reactive charge transport material, and the non-charge transport material containing a reactive group, each having these reactive groups and a charge transport skeleton, may be selected from known materials.

Other known additives may be included in the protective layer.

The formation of the protective layer is not particularly limited, and a known formation method can be used, but for example, the formation of a coating film of the coating liquid for forming a protective layer, in which the above-mentioned components are added to a solvent, drying the coating film, and if necessary, performing a curing treatment such as heating, is performed.

Examples of the solvent used for preparing the coating liquid for forming the protective layer include aromatic solvents such as toluene and xylene; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester solvents such as ethyl acetate and butyl acetate; ether solvents such as tetrahydrofuran and dioxane; fiber-dissolving solvents such as ethylene glycol monomethyl ether; alcohols solvents such as isopropyl alcohol and butyl alcohol. These solvents are used singly or in combination of two or more.

The coating liquid for forming the protective layer may be a solvent-free coating liquid.

Examples of the method of applying the coating liquid for forming the protective layer to the photosensitive layer (for example, the charge transport layer) include a usual method such as a dip coating method, a push coating method, a wire bar coating method, a spray coating method, a blade coating method, and a curtain coating method.

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

Image forming apparatus, process cartridge

The image forming apparatus according to the present embodiment includes an electrophotographic photoreceptor, a charging unit that charges a surface of the electrophotographic photoreceptor, an electrostatic latent image forming unit that forms an electrostatic latent image on the charged surface of the electrophotographic photoreceptor, a developing unit that develops the electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing toner to form a toner image, and a transfer unit that transfers the toner image to a recording medium surface. The electrophotographic photoreceptor according to the present embodiment is also applicable as an electrophotographic photoreceptor.

The image forming apparatus according to the present embodiment is applied to the following known image forming apparatus: a device provided with a fixing unit for fixing the toner image transferred to the surface of the recording medium; a direct transfer system for directly transferring the toner image formed on the surface of the electrophotographic photoreceptor to a recording medium; an intermediate transfer system for primarily transferring the toner image formed on the surface of the electrophotographic photoreceptor to the surface of the intermediate transfer member and secondarily transferring the toner image transferred to the surface of the intermediate transfer member to the surface of the recording medium; a device provided with a cleaning unit for cleaning the surface of the electrophotographic photoreceptor before charging after transferring the toner image; a device including a static electricity removing unit for irradiating the surface of the electrophotographic photoreceptor with static electricity removing light to remove static electricity after transferring the toner image; and a device provided with an electrophotographic photoreceptor heating member for raising the temperature of the electrophotographic photoreceptor and lowering the relative temperature.

In the case of an intermediate transfer type device, for example, a configuration is applied in which the transfer unit has an intermediate transfer body that transfers a toner image on the surface, a primary transfer unit that primarily transfers the toner image formed on the surface of the electrophotographic photoconductor to the surface of the intermediate transfer body, and a secondary transfer unit that secondarily transfers the toner image transferred to the surface of the intermediate transfer body to the surface of the recording medium.

The image forming apparatus according to the present embodiment may be either a dry development type image forming apparatus or a wet development type image forming apparatus (development type using a liquid developer).

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

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

Fig. 3 is a schematic configuration diagram illustrating an example of an image forming apparatus according to the present embodiment.

As shown in fig. 3, the image forming apparatus 100 according to the present embodiment includes a process cartridge 300 having an electrophotographic photoreceptor 7, an exposure device 9 (an example of an electrostatic latent image forming unit), a transfer device 40 (a primary transfer device), and an intermediate transfer body 50. In the image forming apparatus 100, the exposure device 9 is disposed at a position where the electrophotographic photoreceptor 7 can be exposed from the opening of the process cartridge 300, the transfer device 40 is disposed at a position facing the electrophotographic photoreceptor 7 with the intermediate transfer member 50 interposed therebetween, and a part of the intermediate transfer member 50 is disposed in contact with the electrophotographic photoreceptor 7. Although not shown, there is also a secondary transfer device for transferring the toner image transferred to the intermediate transfer member 50 to a recording medium (e.g., paper). The intermediate transfer member 50, the transfer device 40 (primary transfer device), and the secondary transfer device (not shown) correspond to an example of a transfer unit.

The process cartridge 300 in fig. 3 integrally supports the electrophotographic photoreceptor 7, the charging device 8 (an example of a charging unit), the developing device 11 (an example of a developing unit), and the cleaning device 13 (an example of a cleaning unit) in a housing. The cleaning device 13 has a cleaning blade (an example of a cleaning member) 131, and the cleaning blade 131 is disposed in contact with the surface of the electrophotographic photoreceptor 7. The cleaning member may be a fibrous member of conductivity or insulation other than the cleaning blade 131, and may be used alone or in combination with the cleaning blade 131.

Fig. 3 shows an example of an image forming apparatus including a fibrous member 132 (in the form of a roller) for supplying the lubricant 14 to the surface of the electrophotographic photoreceptor 7 and a fibrous member 133 (in the form of a flat brush) for assisting cleaning, but these are arranged as necessary.

Hereinafter, each configuration of the image forming apparatus according to the present embodiment will be described.

Charging device-

As the charging device 8, for example, a contact type charger using a conductive or semiconductive charging roller, a charging brush, a charging film, a charging rubber blade, a charging hose, or the like can be used. Further, a roller charger of a noncontact type, a scorotron charger using corona discharge, a charger known per se such as a corotron charger, or the like may be used.

Exposure apparatus

The exposure device 9 includes, for example, an optical system device that exposes light such as semiconductor laser light, LED light, liquid crystal shutter light, or the like to a predetermined pattern on the surface of the electrophotographic photoreceptor 7. The wavelength of the light source is set to be within the spectral sensitivity region of the electrophotographic photoreceptor. Near infrared light having an oscillation wavelength around 780nm is the main stream as the wavelength of semiconductor lasers. However, the wavelength is not limited to this, and a laser having an oscillation wavelength in a range of 400nm to 450nm may be used as the oscillation wavelength laser or the blue laser in the 600nm band. In addition, a surface-emission type laser source capable of outputting multiple light beams to form a color image is also effective.

Development device

As the developing device 11, for example, a conventional developing device that develops with or without contacting a developer can be cited. The developing device 11 is not particularly limited as long as it has the above-described function, and may be selected according to the purpose. For example, a known developer having a function of adhering a one-component developer or a two-component developer to the electrophotographic photoreceptor 7 using a brush, a roller, or the like is exemplified. Among them, for example, a developer using a developing roller for holding a developer on a surface is preferable.

The developer used in the developing device 11 may be a single-component developer containing a single toner or a two-component developer containing a toner and carriers. The developer may be magnetic or non-magnetic. These developers are known developers.

Cleaning device

The cleaning device 13 may be a cleaning blade type device having a cleaning blade 131. Besides the cleaning scraper mode, a brush cleaning mode and a developing and cleaning mode can be adopted.

Transfer device

Examples of the transfer device 40 include a contact transfer charger using a belt, a roller, a film, a rubber blade, or the like; grid corona tube transfer charger utilizing corona discharge; corotron transfer charger and the like are known per se.

Intermediate transfer body

As the intermediate transfer member 50, a belt-shaped transfer member (intermediate transfer belt) including polyimide, polyamideimide, polycarbonate, polyarylate, polyester, rubber, or the like to which the semiconductive property is imparted can be used. Further, as an intermediate transfer member, a roller-shaped transfer member may be used in addition to the belt-shaped transfer member.

Fig. 4 is a schematic configuration diagram showing another example of the image forming apparatus according to the present embodiment.

The image forming apparatus 120 shown in fig. 4 is a tandem-type multicolor image forming apparatus in which four process cartridges 300 are mounted. In the image forming apparatus 120, four process cartridges 300 are arranged in an array on the intermediate transfer member 50, respectively, and one electrophotographic photoreceptor is used for one color. The image forming apparatus 120 has the same configuration as the image forming apparatus 100 except for the tandem system.

Examples

Embodiments of the invention will be described in detail below with reference to examples, but the embodiments of the invention are not limited to these examples.

In the following description, unless otherwise specified, "parts" and "%" are mass references.

In the following description, unless otherwise specified, synthesis, processing, production, and the like are performed at room temperature (25 ℃.+ -. 3 ℃).

Preparation of binding resin for photosensitive layer

[ polyester resin (1) ]

Polyester resins (1-1) to (1-9) were prepared. The units and compositions constituting the polyester resins are shown in tables 1 and 2.

The "structural unit to composition ratio" (for example, A2-3:50) is shown in tables 1 and 2. The composition ratio is mol% of each of the dicarboxylic acid units and the diol units.

A2-3 and the like described in tables 1 and 2 and the like are specific examples of the dicarboxylic acid unit (A) described above.

The examples of the diol unit (B) described above are B1-4 and the like shown in Table 1 and Table 2.

Production of photoreceptor having laminated photosensitive layer

Example S1

Formation of the under-coating

An aluminum cylindrical tube having an outer diameter of 30mm, a length of 250mm and a wall thickness of 1mm was prepared as a conductive base.

Zinc oxide (average particle diameter 70nm, specific surface area 15m ² Prepared per g, TAYCA CORPORATION) 100 parts and 500 parts of toluene were mixed and stirred, and a silane coupling agent (trade name: KBM603, shin-Etsu chemical Co., ltd., N-2- (aminoethyl) -3-aminopropyl trimethoxysilane) 1.3 parts, was stirred for 2 hours. Then, toluene was distilled under reduced pressure, and sintered at 120℃for 3 hours to obtain zinc oxide surface-treated with a silane coupling agent.

110 parts of zinc oxide subjected to surface treatment and 500 parts of tetrahydrofuran were mixed and stirred, and a solution of 0.6 part of alizarin dissolved in 50 parts of tetrahydrofuran was added thereto and stirred at 50℃for 5 hours. Then, the solid component was filtered off by filtration under reduced pressure, and dried under reduced pressure at 60℃to obtain alizarin-imparted zinc oxide.

Mixing 60 parts of zinc oxide to be added with alizarin and a curing agent (blocked isocyanate, trade name: SUM)IDUR3175, sumika Bayer Urethane co., ltd.) 13.5 parts of a butyral resin (trade name: S-LEC BM-1,SEKISUI CHEMICAL CO, LTD. Co.) 15 parts of a solution of 100 parts dissolved in 68 parts of methyl ethyl ketone and 5 parts of methyl ethyl ketone were usedAnd dispersed by a sand mill for 2 hours to obtain a dispersion. To the dispersion was added 0.005 part of dioctyltin dilaurate and 4 parts of silicone resin particles (trade name: tospin 145, momentive performance Materials Inc.) as a catalyst, to obtain a coating liquid for forming a lower coating layer. The coating liquid for forming the undercoating was applied to the outer peripheral surface of the conductive substrate by dip coating, and dried and cured at 170 ℃ for 40 minutes to form the undercoating. The average thickness Bs of the undercoating is shown in table 1.

Formation of a Charge generating layer

A mixture composed of 15 parts of hydroxygallium phthalocyanine (having diffraction peaks at positions of at least 7.5 °, 9.9 °, 12.5 °, 16.3 °, 18.6 °, 25.1 ° and 28.3 ° in terms of a Bragg angle (2θ.+ -. 0.2 ℃) using X-ray diffraction spectrum of Cukα characteristic X-rays), 10 parts of a vinyl chloride/vinyl acetate copolymer resin (trade name: VMCH, manufactured by Nippon Unicar Company Limited) as a binder resin, and 200 parts of n-butyl acetate was dispersed by a sand mill for 4 hours using glass beads having a diameter of 1 mm. To the dispersion was added 175 parts of n-butyl acetate and 180 parts of methyl ethyl ketone, and the mixture was stirred to obtain a charge generation layer forming coating liquid. The charge generation layer forming coating liquid was dip-coated on the undercoating layer, and dried at room temperature (25 ℃.+ -. 3 ℃) to form a charge generation layer having an average thickness of 0.18. Mu.m.

Formation of a Charge transport layer

60 parts of a polyester resin (1-1) as a binder resin and 40 parts of CTM-1 as a charge transport material were dissolved in 270 parts of tetrahydrofuran and 30 parts of toluene to obtain a coating liquid for forming a charge transport layer. The charge transport layer was formed by dip-coating a charge generation layer with a coating liquid for forming a charge transport layer and drying at 145 ℃ for 30 minutes. The average thickness As of the charge transport layer is shown in table 1.

[ chemical formula 32]

Examples S2 to S20 and comparative examples SC1 to SC11

Each photoreceptor was produced in the same manner As in example S1 except that the average thickness Bs of the under coat layer, the type of binder resin of the charge transport layer, the type of charge transport material of the charge transport layer, and the average thickness As of the charge transport layer were changed to the specifications described in table 1. The charge transport materials CTM-2 to CTM-5 are the following compounds. The polycarbonate resin PC-1 is a resin composed of the following repeating units.

Example S21

A photoreceptor was produced in the same manner as in example S4 except that alizarin was changed to 2,3, 4-trihydroxybenzophenone in the formation of the undercoating layer of example S4.

Example S22

In the formation of the undercoating of example S4, zinc oxide (average particle diameter 70nm, specific surface area 15m ² A photoreceptor was produced in the same manner as in example S4 except that the composition (produced by/g, TAYCA CORPORATION) was changed to titanium oxide (produced by MT-500B, average particle diameter: 35nm,TAYCA CORPORATION).

[ chemical formula 33]

[ chemical formula 34]

Production of photosensitive body having Single-layer photosensitive layer

[ photoreceptor T1]

Formation of the under-coating

60 parts of zinc oxide to which alizarin was added, 13.5 parts of a curing agent (blocked isocyanate, trade name: SUMIDUR3175, sumika Bayer Urethane Co., ltd.) and 15 parts of a butyral resin (trade name: S-LEC BM-1,SEKISUI CHEMICAL CO, LTD.) were mixed, 100 parts of a solution in 68 parts of methyl ethyl ketone and 5 parts of methyl ethyl ketone, and usedAnd dispersed by a sand mill for 2 hours to obtain a dispersion. To the dispersion was added 0.005 part of dioctyltin dilaurate and 4 parts of silicone resin particles (trade name: tospin 145, momentive performance Materials Inc.) as a catalyst, to obtain a coating liquid for forming a lower coating layer. The coating liquid for forming the undercoating was applied to the outer peripheral surface of the conductive substrate by dip coating, and dried and cured at 170 ℃ for 40 minutes to form the undercoating. The average thickness Bt of the undercoating is reported in table 2.

Formation of a monolayer photosensitive layer

52.75 parts of a polyester resin (1-1) as a binder resin, 52.75 parts of a V-type hydroxygallium phthalocyanine (having diffraction peaks at positions of at least 7.3 DEG, 16.0 DEG, 24.9 DEG and 28.0 DEG in terms of Bragg angle (2θ.+ -. 0.2 DEG) using X-ray diffraction spectrum of Cukα characteristic) as a charge generating material, 7.8 parts of an electron transporting material, namely ETM-1, 38.2 parts of a charge transporting material, namely CTM-1 (mass ratio of ETM-1 to CTM-1: 17:83), 175 parts of tetrahydrofuran as a solvent and 75 parts of toluene were mixed, and a coating liquid for forming a photosensitive layer was obtained by dispersing the mixture for 4 hours using glass beads having a diameter of 1mm by a sand mill. The coating liquid for forming a photosensitive layer was dip-coated on the undercoating layer, and dried and cured at 110 ℃ for 40 minutes to form a single-layer photosensitive layer. The average thickness At of the single-layer photosensitive layer is shown in table 2.

[ chemical formula 35]

[ photoreceptors T2 to T8, photoreceptors TC1 to TC7]

Each photoreceptor was produced in the same manner as photoreceptor T1 except that the average thickness Bt of the under coat layer, the type of binder resin of the single-layer type photosensitive layer, and the average thickness At of the single-layer type photosensitive layer were changed to the specifications described in table 2.

< photoreceptor and evaluation of Performance of image Forming apparatus >)

The photoreceptors of each example and each comparative example were mounted on an image forming apparatus docu centrecolor500 made of FUJIFILM Business Innovation, and 30 ten thousand images shown in fig. 5 (an image having a region with 5 empty characters "G" in a black image with an image density of 100% and a region with a black halftone image with an image density of 40%) were continuously output on A4 paper in an environment with a temperature of 24 ℃ and a relative humidity of 55%. The last 10 sheets were compared with the naked eye, and the ghost and color point (black point) were classified as follows. The results are shown in tables 1 to 2.

Ghost (ghost) imaging

A: there is no concentration change in the character "G".

B: the change in density is perceived in the character "G", but is acceptable in practical use.

C: the character "G" has a density change, which is not acceptable in practical use.

Color point (black dot)

A: color point is not generated

B: color point generation in 1 or 2 sheets

C: color point generation in more than 3

[ stability of residual potential ]

The photoreceptors of each example and each comparative example were mounted on the image forming apparatus, and 60 ten thousand solid images with an image density (area coverage) of 100% were continuously output on A4 paper. Wherein, the 1 st to 30 th ten thousand sheets are continuously output under the environment of 28 ℃ and the relative humidity of 85%, and the 30 th ten thousand to 1 st ten thousand sheets are continuously output under the environment of 10 ℃ and the relative humidity of 15%.

In the image formation described above, the residual potential on the surface of the photoreceptor after outputting the 1 st sheet and after outputting 60 ten thousand sheets is measured, and the difference in absolute value (the absolute value of the residual potential after outputting 60 ten thousand sheets—the absolute value of the residual potential after outputting 1 sheet) is obtained, and is set as the rising value of the absolute value of the residual potential. It is classified as follows. The results are shown in tables 1 and 2.

A: an absolute value of the residual potential rising less than 20V

B: the absolute value of the residual potential rises to 20V or more and less than 30V

C: the absolute value of the residual potential rises to 30V or more and less than 40V

D: the absolute value of the residual potential rises to 40V or more and less than 50V

E: the absolute value of the residual potential was increased by 50V or more (Table 1)

TABLE 2

The present invention includes the following modes.

(1)

An electrophotographic photoreceptor comprising a conductive substrate, an undercoat layer disposed on the conductive substrate, and a laminated photosensitive layer having a charge generation layer and a charge transport layer disposed on the undercoat layer,

(2)

The electrophotographic photoreceptor according to (1), which satisfies 0.87.ltoreq.As/Bs.ltoreq.3.42.

(3)

The electrophotographic photoreceptor according to (1) or (2), wherein,

the polyester resin comprises a polyester resin (1) having a dicarboxylic acid unit (A) represented by formula (A) and a diol unit (B) represented by formula (B).

(4)

The electrophotographic photoreceptor according to (3), wherein,

the dicarboxylic acid unit (a) represented by the formula (a) contains at least one selected from the group consisting of a dicarboxylic acid unit (A1) represented by the formula (A1), a dicarboxylic acid unit (A2) represented by the formula (A2), a dicarboxylic acid unit (A3) represented by the formula (A3), and a dicarboxylic acid unit (A4) represented by the formula (A4).

(5)

The electrophotographic photoreceptor according to (3) or (4), wherein,

the diol unit (B) represented by the formula (B) contains a diol unit selected from the group consisting of those represented by the formula (B1)

(B1) At least one of the group consisting of a diol unit (B2) represented by the formula (B2), a diol unit (B3) represented by the formula (B3), a diol unit (B4) represented by the formula (B4), a diol unit (B5) represented by the formula (B5), a diol unit (B6) represented by the formula (B6), a diol unit (B7) represented by the formula (B7), and a diol unit (B8) represented by the formula (B8).

(6)

An electrophotographic photoreceptor comprising a conductive substrate, an undercoat layer disposed on the conductive substrate, and a single-layer photosensitive layer disposed on the undercoat layer,

(7)

The electrophotographic photoreceptor according to (6), which satisfies 0.87. Ltoreq.at/bt.ltoreq.3.42.

(8)

The electrophotographic photoreceptor according to (6) or (7), wherein,

(9)

The electrophotographic photoreceptor according to (8), wherein,

(10)

The electrophotographic photoreceptor according to (8) or (9), wherein,

(11)

A process cartridge comprising the electrophotographic photoreceptor according to any one of (1) to (10),

(12)

An image forming apparatus includes:

(1) The electrophotographic photoreceptor of any one of (10);

According to the invention As recited in (1), (3), (4) or (5), there is provided an electrophotographic photoreceptor in which double images and color points are less likely to occur in an image than an electrophotographic photoreceptor which is provided with a laminated photosensitive layer and in which the ratio As/Bs of the average thickness As of the charge transport layer to the average thickness Bs of the undercoat layer is less than 0.70 or more than 4.80.

According to the invention As recited in (2), there is provided an electrophotographic photoreceptor in which ghost images and color spots are less likely to occur in an image than an electrophotographic photoreceptor which is provided with a laminated photosensitive layer and in which the ratio As/Bs of the average thickness As of the charge transport layer to the average thickness Bs of the undercoating layer is less than 0.87 or exceeds 3.42.

According to the invention as recited in (6), (8), (9) or (10), there is provided an electrophotographic photoreceptor in which double images and color points are less likely to occur in an image than an electrophotographic photoreceptor having a single-layer type photosensitive layer and in which the ratio At/Bt of the average thickness At of the single-layer type photosensitive layer to the average thickness Bt of the under coat layer is less than 0.70 or more than 4.80.

According to the invention as recited in item (7), there is provided an electrophotographic photoreceptor in which double images and color points are less likely to occur in an image than an electrophotographic photoreceptor which has a single-layer type photosensitive layer and in which the ratio At/Bt of the average thickness At of the single-layer type photosensitive layer to the average thickness Bt of the under coat layer is less than 0.87 or exceeds 3.42.

According to the invention As recited in (11), there is provided a process cartridge which is less likely to cause double image and color point in an image, compared with the case where the ratio As/Bs of the average thickness As of the charge transport layer to the average thickness Bs of the under coat layer in the electrophotographic photoreceptor is less than 0.70 or more than 4.80 or the ratio At/Bt of the average thickness At of the single-layer type photosensitive layer to the average thickness Bt of the under coat layer is less than 0.70 or more than 4.80.

According to the invention As recited in (12), there is provided an image forming apparatus in which ghost and color dots are less likely to occur in an image in comparison with the case where the ratio As/Bs of the average thickness As of the charge transport layer to the average thickness Bs of the under coat layer in the electrophotographic photoreceptor is less than 0.70 or more than 4.80 or the ratio At/Bt of the average thickness At of the single-layer type photosensitive layer to the average thickness Bt of the under coat layer is less than 0.70 or more than 4.80.

The foregoing embodiments of the invention have been presented for purposes of illustration and description. In addition, the embodiments of the present invention are not all inclusive and exhaustive, and do not limit the invention to the disclosed embodiments. It is evident that various modifications and changes will be apparent to those skilled in the art to which the present invention pertains. The embodiments were chosen and described in order to best explain the principles of the invention and its application. Thus, other persons skilled in the art can understand the present invention by various modifications that are assumed to be optimized for the specific use of the various embodiments. The scope of the invention is defined by the following claims and their equivalents.

Symbol description

1-conductive substrate, 2-undercoating, 3-charge generating layer, 4-charge transporting layer, 5-photosensitive layer, 10A-photoreceptor, 10B-photoreceptor.

7-electrophotographic photoreceptor, 8-charging device, 9-exposing device, 11-developing device, 13-cleaning device, 14-lubricant, 40-transfer device, 50-intermediate transfer body, 100-image forming device, 120-image forming device, 131-cleaning blade, 132-fibrous member (roll shape), 133-fibrous member (flat brush shape), 300-process cartridge.

Claims

1. An electrophotographic photoreceptor comprising a conductive substrate, an undercoat layer disposed on the conductive substrate, and a laminated photosensitive layer having a charge generation layer and a charge transport layer disposed on the undercoat layer,

2. The electrophotographic photoreceptor according to claim 1, which satisfies 0.87.ltoreq.As/Bs.ltoreq.3.42.

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

the polyester resin comprises a polyester resin (1) having a dicarboxylic acid unit (A) represented by the following formula (A) and a diol unit (B) represented by the formula (B),

[ chemical formula 1]

(A)

(B)

In formula (A), ar ^A1 Ar and Ar ^A2 Each independently is an aromatic ring which may have a substituent, L ^A Is a single bond or a divalent linking group, n ^A1 Is 0, 1 or 2,

in formula (B), ar ^B1 Ar and Ar ^B2 Each independently is an aromatic ring which may have a substituent, L ^B Is a single bond, an oxygen atom, a thiogenSon or-C (Rb) ¹ )(Rb ² )-，n ^B1 0, 1 or 2, rb ¹ Rb ² Each independently represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms, rb ¹ With Rb ² May be bonded to form a cyclic alkyl group.

4. The electrophotographic photoreceptor according to claim 3, wherein,

the dicarboxylic acid unit (A) represented by the formula (A) contains at least one selected from the group consisting of a dicarboxylic acid unit (A1) represented by the formula (A1), a dicarboxylic acid unit (A2) represented by the formula (A2), a dicarboxylic acid unit (A3) represented by the formula (A3) and a dicarboxylic acid unit (A4) represented by the formula (A4) described below,

[ chemical formula 2]

(A1)

(A2)

(A3)

(A4)

In formula (A1), n ¹⁰¹ Is an integer of 0 to 4 inclusive, n ¹⁰¹ Ra of ¹⁰¹ Each independently represents an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms,

in formula (A2), n ²⁰¹ N is as follows ²⁰² Each independently is an integer of 0 to 4, n ²⁰¹ Ra of ²⁰¹ N is as follows ²⁰² Ra of ²⁰² Each independently represents an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms,

in formula (A3), n ³⁰¹ N is as follows ³⁰² Each independently is an integer of 0 to 4, n ³⁰¹ Ra of ³⁰¹ N is as follows ³⁰² Ra of ³⁰² Each independently represents an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms,

5. The electrophotographic photoreceptor according to claim 3 or 4, wherein,

the diol unit (B) represented by the formula (B) contains at least one selected from the group consisting of a diol unit (B1) represented by the formula (B1), a diol unit (B2) represented by the formula (B2), a diol unit (B3) represented by the formula (B3), a diol unit (B4) represented by the formula (B4), a diol unit (B5) represented by the formula (B5), a diol unit (B6) represented by the formula (B6), a diol unit (B7) represented by the formula (B7) and a diol unit (B8) represented by the formula (B8) described below,

[ chemical formula 3]

(B1)

(B2)

(B3)

(B4)

[ chemical formula 4]

(B5)

(B6)

(B7)

(B8)

In formula (B1), rb ¹⁰¹ Is branched alkyl group having 4 to 20 carbon atoms, rb ²⁰¹ Is hydrogen atom or alkyl group with carbon number of 1-3, rb ⁴⁰¹ 、Rb ⁵⁰¹ 、Rb ⁸⁰¹ Rb ⁹⁰¹ Each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom,

in formula (B2), rb ¹⁰² Is a linear alkyl group having 4 to 20 carbon atoms, rb ²⁰² Is hydrogen atom or alkyl group with carbon number of 1-3, rb ⁴⁰² 、Rb ⁵⁰² 、Rb ⁸⁰² Rb ⁹⁰² Each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom,

in formula (B3), rb ¹¹³ Rb ²¹³ Each independently represents a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom, d is an integer of 7 to 15 inclusive, or Rb ⁴⁰³ 、Rb ⁵⁰³ 、Rb ⁸⁰³ Rb ⁹⁰³ Are each independently a hydrogen atom, a carbon number of 1 or more and 4The following alkyl group, an alkoxy group having 1 to 6 carbon atoms or a halogen atom,

in formula (B4), rb ¹⁰⁴ Rb ²⁰⁴ Each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, or Rb ⁴⁰⁴ 、Rb ⁵⁰⁴ 、Rb ⁸⁰⁴ Rb ⁹⁰⁴ Each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom,

in the formula (B5), ar ¹⁰⁵ Is aryl group with 6-12 carbon atoms or aralkyl group with 7-20 carbon atoms, rb ²⁰⁵ Is hydrogen atom or alkyl group with carbon number of 1-3, rb ⁴⁰⁵ 、Rb ⁵⁰⁵ 、Rb ⁸⁰⁵ Rb ⁹⁰⁵ Each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom,

in formula (B6), rb ¹¹⁶ Rb ²¹⁶ Each independently represents a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom, e is an integer of 4 to 6, or Rb ⁴⁰⁶ 、Rb ⁵⁰⁶ 、Rb ⁸⁰⁶ Rb ⁹⁰⁶ Each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom,

in formula (B7), rb ⁴⁰⁷ 、Rb ⁵⁰⁷ 、Rb ⁸⁰⁷ Rb ⁹⁰⁷ Each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom,

6. An electrophotographic photoreceptor comprising a conductive substrate, an undercoat layer disposed on the conductive substrate, and a single-layer photosensitive layer disposed on the undercoat layer,

when the average thickness of the single-layer photosensitive layer is set to At (μm), the average thickness of the undercoating layer is set to Bt (μm) _m ) When the ratio of the catalyst to the catalyst is 27-50, 10-40 and 0.70-4.80.

7. The electrophotographic photoreceptor according to claim 6, which satisfies 0.87. Ltoreq.at/bt.ltoreq.3.42.

8. The electrophotographic photoreceptor according to claim 6 or 7, wherein,

the polyester resin comprises a polyester resin (1) having a dicarboxylic acid unit (A) represented by the following formula (A) and a diol unit (B) represented by the following formula (B),

[ chemical formula 5]

(A)

(B)

in formula (B), ar ^B1 Ar and Ar ^B2 Each independently is an aromatic ring which may have a substituent, L ^B Is a single bond, an oxygen atom, a sulfur atom or-C (Rb) ¹ )(Rb ² )-，n ^B1 0, 1 or 2, rb ¹ Rb ² Each independently represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms, rb ¹ With Rb ² May be bonded to form a cyclic alkyl group.

9. The electrophotographic photoreceptor according to claim 8, wherein,

[ chemical formula 6]

(A1)

(A2)

(A3)

(A4)

in formula (A3), n ³⁰¹ N is as follows ³⁰² Each independently is an integer of 0 to 4, n ³⁰¹ Ra of ³⁰¹ N is as follows ³⁰² Ra of ³⁰² Are each independently an alkyl group having 1 to 10 carbon atoms or more and a C6 to 12 carbon atoms or moreLower aryl or alkoxy having 1 to 6 carbon atoms,

10. The electrophotographic photoreceptor according to claim 8 or 9, wherein,

[ chemical formula 7]

(B1)

(B2)

(B3)

(B4)

[ chemical formula 8]

(B5)

(B6)

iB7

(B8)

in formula (B3), rb ¹¹³ Rb ²¹³ Each independently represents a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom, d is an integer of 7 to 15 inclusive, or Rb ⁴⁰³ 、Rb ⁵⁰³ 、Rb ⁸⁰³ Rb ⁹⁰³ Each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom,

11. A process cartridge provided with the electrophotographic photoreceptor as claimed in any one of claim 1 to 10,

12. An image forming apparatus includes:

the electrophotographic photoreceptor of any one of claims 1 to 10;