JP2014123113A - Electrophotographic photoreceptor, electrophotographic photoreceptor cartridge, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem in which: in order to improve durability of a photoreceptor, it is required to achieve both improvement of mechanical characteristics such as abrasion resistance, and adhesion with a substrate and stabilization of electrical characteristics such as residual potential, sensitivity, and chargeability; and therefore, it has been an object to achieve both improvement of the mechanical characteristics and stabilization of the electrical characteristics without causing an increase in residual potential and deterioration of an image memory.SOLUTION: There is provided an electrophotographic photoreceptor including at least a charge generating layer and a charge transport layer as photosensitive layers on a conductive support, and containing, in the charge transport layer, a metal complex or a metal salt of an aromatic carboxylic acid, and a polyarylate resin to improve adhesion of the photosensitive layers and suppress accumulation of residual potential. Also provided are an image forming apparatus including the electrophotographic photoreceptor exhibiting excellent mechanical characteristics and electrical characteristics, and an electrophotographic photoreceptor cartridge.

Description

The present invention relates to an electrophotographic photosensitive member, an image forming apparatus, and a cartridge used for a copying machine, a printer, and the like. More specifically, in an electrophotographic photoreceptor having at least a charge generation layer and a charge transport layer as a photosensitive layer, the charge transport layer contains a metal complex or metal salt of an aromatic carboxylic acid and a polyarylate resin having a specific repeating structure. Thus, the present invention relates to an electrophotographic photosensitive member, a cartridge, and an image forming apparatus that exhibit improved performance and excellent mechanical characteristics and electrical characteristics by improving adhesion of a photosensitive layer and reducing residual potential.

  The electrophotographic technique is widely used in the fields of copiers, various printers, printing presses and the like because of its excellent immediacy and high quality images. As an electrophotographic photosensitive member that is the core of the electrophotographic technology, an electrophotographic photosensitive member using an organic photoconductive material having advantages such as non-pollution, easy film formation, and easy manufacture (hereinafter simply referred to as “ Also referred to as “photoreceptor”).

  As an electrophotographic photoreceptor using an organic photoconductive material, a so-called dispersion type single-layer photoreceptor in which a photoconductive fine powder is dispersed in a binder resin, a charge generation layer and a charge transport layer are laminated. Multilayer photoreceptors are known. Multilayer photoconductors provide highly efficient charge generating materials and wide and highly safe photoconductors. Also, photoconductors can be easily formed by coating, have high productivity, and are advantageous in terms of cost. For these reasons, they have been developed and put into practical use.

  An electrophotographic photosensitive member using an organic photoconductive material has the above-mentioned advantages, but does not satisfy all the characteristics required for an electrophotographic photosensitive member, and in particular, it is repeatedly used in a copying machine or a printer. However, there is a problem that the photosensitive layer gradually deteriorates. Therefore, it is desired that the damage due to repeated use is small, the sensitivity is high, the residual potential is low, and the electrical characteristics are stable. These characteristics greatly depend on the charge generation material, the charge transport material, the additive, and the binder resin. In particular, when a polyarylate resin is used as the binder resin, it is known that the mechanical properties are excellent.

On the other hand, the residual potential of the electrophotographic photosensitive member is suppressed by containing a metal complex or metal salt of an aromatic carboxylic acid that has been used in the charge transport layer as a conventional toner charge control agent (Patent Documents 1 to 3). It is known that it can be performed (Patent Documents 4 and 5).
In recent years, there has been a demand for further downsizing of an image forming apparatus from the viewpoint of space saving. In this case, in order to reduce the size of the image forming apparatus, a small-diameter type such as 24 mmφ or 30 mmφ is used as the photoreceptor. As the diameter of the photosensitive member is reduced, the internal stress in the photosensitive layer increases, and as a result, the adhesiveness between the support and the photosensitive layer is deteriorated, and defects such as peeling and cracking are likely to occur. In addition, when the photosensitive layer is made thicker to extend the life of the photoreceptor, the internal stress increases and the adhesiveness deteriorates. Therefore, today's electrophotographic photosensitive members are required to have not only wear resistance but also sufficient adhesion.

JP-A-53-127726 JP-A-57-104940 JP 59-79256 A JP-A-3-78753 Japanese Patent No. 5096931

In order to improve the durability of the photoreceptor, it is necessary to achieve both improvement in mechanical properties such as abrasion resistance and adhesion to the substrate, and stabilization of electrical characteristics such as residual potential, sensitivity and chargeability. For this reason, by increasing the binder resin ratio of the photosensitive layer, it is possible to improve the adhesion between the photosensitive layer and the substrate, while increasing the residual potential and causing problems with image memory, it is difficult to achieve both. there were.
In addition, polyarylate resin as a binder resin is excellent in mechanical properties, but has problems of increased residual potential and deteriorated adhesion between the photosensitive layer and the substrate as compared with polycarbonate resin.

In the electrophotographic photoreceptor having at least a charge generation layer and a charge transport layer in the photosensitive layer, the metal complex or metal salt of an aromatic carboxylic acid represented by the following general formula (I) in the charge transport layer, and It has been found that by containing a polyarylate resin, both residual potential and adhesiveness can be improved, and both good electrical characteristics and image characteristics can be achieved. That is, the gist of the present invention resides in the following six points.
(1) In an electrophotographic photosensitive member having at least a charge generation layer and a charge transport layer as a photosensitive layer on a conductive support,
An electrophotographic photoreceptor, wherein the charge transport layer contains a metal complex or metal salt of an aromatic carboxylic acid represented by the following general formula (I), and a polyarylate resin. (Claim 1)
ArCOOH (I)
(In the formula (I), Ar represents an aryl group having 30 or less carbon atoms which may have a substituent.)
(2) The electrophotographic photosensitive member according to (1), wherein the aromatic carboxylic acid represented by the general formula (I) has a structure represented by the following general formula (II) or (III). (Claim 2)

(In the formulas (II) and (III), the substituents R ^{11 to} R ¹³ each independently represent a halogen atom, an alkyl group, an alkoxy group, an amino group, a nitrile group, a nitro group, a carboxyl group, or an aryl group. Ring A represents an aromatic ring having 5 to 10 carbon atoms, a represents an integer of 0 to 2, and b and c represent integers of 0 to 4. However, R ^{11 to} R ¹³ are bonded to each other to form a ring. You may do it.)
(3) The electrophotographic photosensitive member according to (1) or (2), wherein the polyarylate resin is a polyarylate resin having a repeating structure represented by the following general formula [1]. (Claim 3)

(In the general formula [1], Ar ^{1 to} Ar ⁴ may be the same or different and each independently represents an arylene group which may have a substituent. X represents a single bond, an oxygen atom, sulfur. 2 represents a divalent organic residue having an atom, a structure represented by Formula [2], or a structure represented by Formula [3], wherein R ¹ and R ^{2 in} Formula [2] are each independently A hydrogen atom, an alkyl group, an aryl group, or a cycloalkylidene group formed by combining R ¹ and R ^2, and R ³ in the formula [3] represents an alkylene group, an arylene group, or a formula a group represented by [4], an alkylene group and ^{R 4} and ^{R 5} are each independently of the formula [4], .k Ar ⁵ is representative of the arylene group is an integer of 0-5. Y has a single bond, a sulfur atom, an oxygen atom, or a structure represented by the formula [5]. That represents a divalent organic residue. Equation [5] R ⁶ and R ⁷ in each independently represent a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or R ⁶ and R ⁷ and is formed by combining Represents a cycloalkylidene group.)

(4) Any one of (1) to (3), characterized by having an undercoat layer in which metal oxide particles are dispersed in a resin as a blocking layer between the conductive support and the photosensitive layer. 2. The electrophotographic photosensitive member according to item 1. (Claim 4)
(5) The electrophotographic photosensitive member according to any one of (1) to (4), a charging unit for charging the electrophotographic photosensitive member, and exposing the charged electrophotographic photosensitive member to form an electrostatic latent image. An electron comprising: an exposure part to be formed; a developing part for developing an electrostatic latent image formed on the electrophotographic photosensitive member; and a cleaning part for cleaning the electrophotographic photosensitive member. Photoconductor cartridge. (Claim 5)
(6) The electrophotographic photosensitive member according to any one of (1) to (4), a charging unit for charging the electrophotographic photosensitive member, and exposing the charged electrophotographic photosensitive member to form an electrostatic latent image. An image forming apparatus comprising: an exposure portion to be formed; and a developing portion for developing an electrostatic latent image formed on the electrophotographic photosensitive member. (Claim 6)

According to the present invention, in the electrophotographic photoreceptor, the charge transport layer contains the metal complex or metal salt of the aromatic carboxylic acid represented by the above formula (I) and the polyarylate resin, whereby the photoreceptor can be applied to the substrate. In addition to improved adhesion, the residual potential of the electrophotographic photoreceptor can be reduced.
The reason for the improved adhesiveness is that the physical properties of the photosensitive layer are changed by adding the metal complex or metal salt of the aromatic carboxylic acid represented by the formula (I), and the affinity between the photosensitive layer and the substrate is improved. This is probably because of this. At the same time, when the metal complex or metal salt has a charge generation layer / charge transport layer interface or a blocking layer such as a photosensitive layer / substrate interface or an undercoat layer, the charge is transferred at the blocking layer / photosensitive layer interface. In addition, it is considered that it is useful.

1 is a schematic diagram illustrating a main configuration of an embodiment of an image forming apparatus of the present invention. The powder X-ray-diffraction spectrum by CuK (alpha) characteristic X-ray of the oxytitanium phthalocyanine used in Example 1 is shown.

  Hereinafter, the embodiments of the present invention will be described in detail. However, the present invention is not limited to the following descriptions, and can be appropriately modified and implemented without departing from the gist of the present invention.

[Electrophotographic photoreceptor]
Hereinafter, the electrophotographic photoreceptor of the present invention will be described in detail.
<Metal complex or metal salt of aromatic carboxylic acid>
The photosensitive layer in the invention contains a metal complex or metal salt of an aromatic carboxylic acid represented by the following general formula (I) in the charge transport layer.

ArCOOH (I)
In formula (I), Ar represents an aryl group having 30 or less carbon atoms which may have a substituent. The number of carbon atoms of the aryl group is 30 or less, preferably 20 or less, more preferably 15 or less. Specific examples include a phenyl group, a naphthyl group, an anthracenyl group, and a pyrenyl group. From the viewpoint of synthesis, a phenyl group or a naphthyl group is preferable, and a phenyl group is most preferable.

The total number of carbon atoms of the substituent that Ar may have is preferably 30 or less, and preferably 20 or less, and more preferably 10 or less, from the viewpoints of solubility and synthesis. Specific examples include halogen atoms, alkyl groups, alkoxy groups, amino groups, aryl groups, sulfonyl groups, phosphonyl groups, hydroxy groups, nitrile groups, nitro groups, carboxyl groups, and the like. Of these, the effect of reducing the residual potential is better when the aromatic carboxylic acid is more acidic, so a halogen atom, a sulfonyl group, an o-hydroxy group, a nitrile group, a nitro group, and a carboxyl group are preferred, and material safety is improved. An o-hydroxy group is particularly preferable from the viewpoint. Moreover, it is preferable to have an alkyl group from the surface of solubility.
The general formula (I) is preferably an aromatic carboxylic acid having a structure represented by the following general formula (II) or (III).

The substituents R ^{11 to} R ^{13 in} formulas (II) and (III) are each independently a halogen atom, a sulfonyl group, an alkyl group, an alkoxy group, an amino group, a nitrile group, a nitro group, a carboxyl group, or an aryl group. And ring A represents an aromatic ring having 5 to 10 carbon atoms. However, R ^{11 to} R ¹³ may be bonded to each other to form a ring. As R < ¹¹ > -R < ¹³ >, an alkyl group or an alkoxy group is preferable, and an alkyl group is preferable from a soluble viewpoint. As carbon number of an alkyl group or an alkoxy group, it is 6 or less, and 4 or less is preferable. Specific examples of the alkyl group include linear alkyl groups such as methyl, ethyl, and propyl groups, branched alkyl groups such as isopropyl, tertbutyl, and isobutyl groups, and cyclic groups such as cyclohexyl and cyclopentyl groups. Among them, a branched alkyl group is preferable from the viewpoint of solubility, and among them, a tertbutyl group is preferable. a represents an integer of 2 to 0, b and c each represents an integer of 4 to 0, preferably 3 to 0, and more preferably 2 to 0. The substitution position is preferably a para-position or an ortho-position with respect to the hydroxy group for ease of synthesis.

Specific examples of the ring A include benzene, naphthalene, pyrrole, furan, thiophene, indole, and benzofuran, and benzene or naphthalene is preferable because of easy availability of raw materials and synthesis.
The main specific examples of the aromatic carboxylic acid represented by the general formula (I) are shown below, but are not limited thereto.

The metal used may be any metal that forms a metal salt or metal complex with the aromatic carboxylic acid, but Al, Zn, Cr, Co, Ni, and Fe are preferred.
Among these, when polycarbonate or polyarylate is used as the binder resin, it is preferable that the viscosity of the coating solution does not decrease due to the cleavage of the molecular chain, and in that sense, Al is particularly preferable.

The metal complex or metal salt of the present invention can be obtained by a known method such as JL Clark, H. Kao, J. Amer. Chem. Soc. 70.2151, (1948), JP-A-53-127726, It can be synthesized by the method described in JP-A-57-104940 or JP-A-59-79256.
As metal salts, for example, according to JL Clark, H. Kao, J. Amer. Chem. Soc. 70.1511, (1948), a solution of 2 mol of sodium salicylate and a solution of 1 mol of zinc chloride It can be obtained as a white powdery zinc salt by mixing at room temperature and stirring. Other metals such as aromatic carboxylic acids and zinc can also be produced according to this method. It is presumed that the generated zinc salicylate is represented by the following structural formula (A).

In the case of a combination of another aromatic carboxylic acid and another metal such as cobalt, nickel, or iron, a metal salt or a metal complex can be produced according to the above method.
Of these, metal complexes or metal salts having a structure represented by the following general formula (IV) are preferred.

In the formula (IV), R ¹⁴ and R ¹⁵ have the same meaning as R ¹³ and d and e have the same meanings as c. M represents a metal atom, and among these, Al, Zn, Cr, Co, Ni, and Fe are preferable, and Al is particularly preferable for the reasons described above.
As an example of the production of the compound represented by the formula (IV), according to JP-A-53-127726, a methanol solution of 3,5-ditertiarybutylsalicylic acid and an aqueous solution of Cr ₂ (SO ₄ ) ₃ are mixed, By adjusting the pH to 4-5 with an aqueous sodium hydroxide solution and refluxing, a chromium complex is obtained as a pale green precipitate. The generated 3,5-ditertiarybutyl salicylate chromium complex is presumed to be represented by the following structural formula (B).

The ratio of adding the metal complex or metal salt to the charge transport layer of the photosensitive layer is usually 100 parts by weight of the binder resin in order to obtain a sufficient residual potential reduction effect and adhesive improvement effect as a ratio with the binder resin. On the other hand, it is usually 0.001 part by mass or more, preferably 0.005 part by mass or more, more preferably 0.01 part by mass or more. On the other hand, from the viewpoint of preventing the negative effects of dark decay, it is usually 20 parts by mass or less, preferably 10 parts by mass or less, and more preferably 2 parts by mass or less. The salt or complex is preferably an anhydride. This is because the solubility in the organic solvent for adjusting the coating solution is lowered, and the presence of water adversely affects the structural and electrical interactions such as entanglement with the polyarylate resin and the charge transport material.

<Polyarylate resin>
As the polyarylate resin contained in the charge transport layer, one containing a repeating structure represented by the following general formula [1] is particularly preferable. The polyarylate resin can be produced by a known method, for example, with a divalent hydroxyaryl component and a dicarboxylic acid component.

In the general formula [1], Ar ^{1 to} Ar ⁴ may be the same or different, and each independently represents an arylene group which may have a substituent. The arylene group is not particularly limited, but is preferably an arylene group having 6 to 20 carbon atoms, and examples thereof include a phenylene group, a naphthylene group, an anthrylene group, a phenanthrylene group, and a pyrenylene group. Among these, a phenylene group and a naphthylene group are particularly preferable from the viewpoint of production cost. Further, when a phenylene group and a naphthylene group are compared, a phenylene group is more preferable in terms of ease of synthesis in addition to manufacturing cost.

The substituent that may be independently present in the arylene group is not particularly limited, and preferred examples include a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, a condensed polycyclic group, and a halogen group. Considering the mechanical properties as the binder resin for the photosensitive layer and the solubility in the coating solution for forming the photosensitive layer, the aryl group is preferably a phenyl group or a naphthyl group, and the halogen group is a fluorine atom, a chlorine atom, a bromine atom or an iodine atom. The alkoxy group is preferably a methoxy group, an ethoxy group, or a butoxy group. The alkyl group is preferably an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 8 carbon atoms, and 1 to 2 carbon atoms. Are particularly preferable, and specifically, a methyl group is most preferable. The number of substituents for each of Ar ^{1 to} Ar ⁴ is not particularly limited, but is preferably 3 or less, more preferably 2 or less, and particularly preferably 1 or less.

Further, in the general formula [1], Ar ¹ and Ar ² are preferably the same arylene group having the same substituent, and particularly preferably an unsubstituted phenylene group. Ar ³ and Ar ⁴ are preferably the same arylene group, and particularly preferably a phenylene group having a methyl group.

In General Formula [1], X represents a divalent organic residue having a single bond, an oxygen atom, a sulfur atom, a structure represented by Formula [2], or a structure represented by Formula [3]. R ¹ and R ² in the formula [2] each independently represent a hydrogen atom, an alkyl group, or an aryl group, or a cycloalkylidene group formed by combining R ¹ and R ² . Examples of the alkyl group of R ¹ and R ² in the formula [2] include a methyl group, an ethyl group, a propyl group, and a butyl group, and examples of the aryl group include a phenyl group and a naphthyl group. In addition, examples of the cycloalkylidene group formed by combining R ¹ and R ² in the formula [2] include a cyclopentylidene group, a cyclohexylidene group, and a cycloheptylidene group. Furthermore, R ³ in the formula [3] is an alkylene group, an arylene group, or a group represented by the formula [4], and R ⁴ and R ⁵ in the formula [4] are each independently an alkylene group. And Ar ⁵ represents an arylene group. Examples of the alkylene group represented by R ³ in the formula [3] include a methylene group, an ethylene group, and a propylene group. Examples of the arylene group represented by R ³ in the formula [3] include a phenylene group and a terphenylene group. It is done. Specific examples of the group represented by the formula [4] include a group represented by the following formula [6]. Among these, X is preferably an oxygen atom from the viewpoint of wear resistance.

In general formula [1], k is an integer of 0 to 5, preferably an integer of 0 to 1, and most preferably 1 from the viewpoint of wear resistance.
In general formula [1], Y represents a single bond, a sulfur atom, an oxygen atom, or a divalent organic residue having a structure represented by formula [5]. R ⁶ and R ⁷ in the formula [5] each independently represent a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a cycloalkylidene group formed by combining R ⁶ and R ⁷ . Considering the mechanical properties as the binder resin for the photosensitive layer and the solubility in the coating solution for forming the photosensitive layer, the aryl group is preferably a phenyl group or a naphthyl group, and the alkoxy group is preferably a methoxy group, an ethoxy group, or a butoxy group. preferable. Moreover, as an alkyl group, a C1-C10 alkyl group is preferable, More preferably, it is C1-C8, Most preferably, it is C1-2. Considering the simplicity of production of the divalent hydroxyaryl component used in producing the polyarylate resin, Y is a single bond, —O—, —S—, —CH ₂ —, —CH (CH ₃ ) —. , —C (CH ₃ ) ₂ — and cyclohexylidene are preferable, and —CH ₂ —, —CH (CH ₃ ) —, —C (CH ₃ ) ₂ — and cyclohexylidene are particularly preferable. Is —CH ₂ —, —CH (CH ₃ ) —.

In the present invention, the polyarylate resin is preferably a polyarylate resin having a repeating structure represented by the following general formula [7]. In the following general formula [7], Ar ^{16 to} Ar ¹⁹ each independently represent an arylene group which may have a substituent, and R ⁸ represents a hydrogen atom or an alkyl group.

In the general formula [7], Ar ^{16 to} Ar ¹⁹ respectively correspond to the Ar ^{1 to} Ar ⁴ and particularly preferably a phenylene group which may have a substituent. Moreover, as a preferable substituent, it is a hydrogen atom or an alkyl group, Most preferably, it is a methyl group. Further, in the general formula [7], Ar ¹⁸ and Ar ¹⁹ are the same phenylene group having a methyl group, and Ar ¹⁶ and Ar ¹⁷ are particularly preferably phenylene groups having no substituent. R ⁸ represents a hydrogen atom or an alkyl group, and the alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and particularly preferably a methyl group. .
The divalent hydroxyaryl component to be a divalent hydroxyaryl residue in the polyarylate resin is represented by the following general formula [8], but is preferably represented by the following general formula [9].

Ar ³ , Ar ⁴ and Y in the general formula [8] are as described above.

Ar ¹⁸ and Ar ¹⁹ in the general formula [9] independently represent a phenylene group which may have a substituent, and R ⁸ represents a hydrogen atom or a methyl group.
Among these, when R ⁸ in the general formula [9] is a hydrogen atom, bis (4-hydroxyphenyl) methane and (2-hydroxyphenyl) are considered in consideration of the ease of production of the divalent hydroxyaryl component. ) (4-hydroxyphenyl) methane, bis (2-hydroxyphenyl) methane, bis (4-hydroxy-3-methylphenyl) methane, bis (4-hydroxy-3-ethylphenyl) methane are preferred, It is also possible to use a combination of a plurality of hydroxyaryl components.

In addition, when R ⁸ in the general formula [9] is a methyl group, 1,1-bis (4-hydroxyphenyl) ethane, 1- (2-hydroxyphenyl) -1- (4-hydroxyphenyl) ethane 1,1-bis (2-hydroxyphenyl) ethane, 1,1-bis (4-hydroxy-3-methylphenyl) ethane, 1,1-bis (4-hydroxy-3-ethylphenyl)
Ethane is preferred, and a combination of these divalent hydroxyaryl components can also be used.

Although the general formula [9] is included in the general formula [8], the divalent hydroxyaryl component represented by the general formula [8] is bis (4-hydroxy-3, 5-dimethylphenyl) methane, 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, 1,1-bis (4-hydroxy-3,5-dimethylphenyl) cyclohexane, or bis (4 -Hydroxyphenyl) ether, (2-hydroxyphenyl) (4-hydroxyphenyl) ether, bis (2-hydroxyphenyl) ether, bis (4-hydroxy-3-methylphenyl) ether, bis (4-hydroxy-3-) Ethylphenyl) ether is preferred, and a combination of a plurality of these divalent hydroxyaryl components can be used.
The dicarboxylic acid component which is a dicarboxylic acid residue in the polyarylate resin is represented by the following general formula [10].

Ar ¹ , Ar ² , X, and k in the general formula [10] are as described above, and are preferably represented by the following general formula [11].

Ar ¹⁶ and Ar ¹⁷ in the general formula [11] are also as described above, and are preferably phenylene groups which may have a substituent.
Specific examples of the preferred dicarboxylic acid residue include diphenyl ether-2,2′-dicarboxylic acid residue, diphenyl ether-2,3′-dicarboxylic acid residue, diphenyl ether-
Examples include 2,4′-dicarboxylic acid residue, diphenyl ether-3,3′-dicarboxylic acid residue, diphenyl ether-3,4′-dicarboxylic acid residue, diphenyl ether-4,4′-dicarboxylic acid residue. Among these, considering the simplicity of production of the dicarboxylic acid component, diphenyl ether-2,2′-dicarboxylic acid residue, diphenyl ether-2,4′-dicarboxylic acid residue, diphenyl ether-4,4′-dicarboxylic acid Residues are more preferred, and diphenyl ether-4,4′-dicarboxylic acid residues are particularly preferred.

The viscosity average molecular weight of the polyarylate resin is not particularly limited, but is usually 10,000 or more, preferably 15,000 or more, more preferably 20,000 or more, but usually 300,000 or less, preferably 200, 000 or less, more preferably 100,000 or less. If the viscosity average molecular weight is excessively small, the mechanical strength of the photosensitive layer is lowered, which is not practical. On the other hand, if the viscosity average molecular weight is excessively large, it is difficult to apply and form the photosensitive layer to an appropriate film thickness.

<Conductive support>
As the conductive support used for the photoreceptor, for example, metal materials such as aluminum, aluminum alloy, stainless steel, copper, and nickel, and conductive powders such as metal, carbon, and tin oxide are added to impart conductivity. A resin material, a resin, glass, paper, or the like on which a conductive material such as aluminum, nickel, or ITO (indium tin oxide) is deposited or applied on the surface is mainly used. As a form, a drum shape, a sheet shape, a belt shape or the like is used. A conductive material having an appropriate resistance value may be applied to a conductive support of a metal material in order to control conductivity, surface properties, etc., or to cover defects.

When a metal material such as an aluminum alloy is used as the conductive support, it is preferable to use an anodized film as a blocking layer in order to prevent image black spots and fogging due to leakage from the substrate. When an anodized film is applied, it is desirable to perform a sealing treatment by a known method.
The support surface may be smooth, or may be roughened by using a special cutting method or polishing. Further, it may be roughened by mixing particles having an appropriate particle diameter with the material constituting the support.

<Underlayer>
An undercoat layer is preferably provided as a blocking layer between the conductive support and the photosensitive layer described below for the purpose of improving adhesiveness and blocking properties. As the undercoat layer, a resin, a resin in which particles such as a metal oxide are dispersed, or the like is used. These may be used alone or in combination with particles of several resins, metal oxides and the like.

Examples of metal oxide particles used for the undercoat layer include metal oxide particles containing one metal element such as titanium oxide, aluminum oxide, silicon oxide, zirconium oxide, zinc oxide, iron oxide, calcium titanate, titanium Examples thereof include metal oxide particles containing a plurality of metal elements such as strontium acid and barium titanate. One kind of these particles may be used alone, or a plurality of kinds of particles may be mixed and used. Among these metal oxide particles, titanium oxide and aluminum oxide are preferable, and titanium oxide is particularly preferable. The surface of the titanium oxide particles may be treated with an inorganic substance such as tin oxide, aluminum oxide, antimony oxide, zirconium oxide, or silicon oxide, or an organic substance such as stearic acid, polyol, or silicon. As the crystal form of the titanium oxide particles, any of rutile, anatase, brookite, and amorphous can be used. Moreover, the thing of a several crystal state may be contained.
In addition, various particle sizes of the metal oxide particles can be used. Among these, from the viewpoint of characteristics and liquid stability, the average primary particle size is usually 1 nm or more, preferably 10 nm or more, and usually 100 nm or less. Preferably it is 50 nm or less.

  The undercoat layer is preferably formed in a form in which metal oxide particles are dispersed in a binder resin. As binder resin used for the undercoat layer, epoxy resin, polyethylene resin, polypropylene resin, acrylic resin, methacrylic resin, polyamide resin, vinyl chloride resin, vinyl chloride resin, vinyl acetate resin, phenol resin, polycarbonate resin, polyurethane resin, Known binder resins such as polyimide resin, vinylidene chloride resin, polyvinyl acetal resin, vinyl chloride-vinyl acetate copolymer, polyvinyl alcohol resin, polyurethane resin, polyacrylic acid resin and the like can be mentioned. These may be used alone or in combination of two or more in any combination and ratio. Moreover, you may use with the hardening | curing form with the hardening | curing agent. Among these, alcohol-soluble copolymerized polyamides, modified polyamides, and the like are preferable because they exhibit good dispersibility and coatability.

Although the use ratio of the inorganic particles to the resin can be arbitrarily selected, it is usually preferably used in the range of 10% by mass or more and 500% by mass or less from the viewpoint of the stability of the dispersion and coating properties.
The thickness of the undercoat layer is arbitrary as long as the effects of the present invention are not significantly impaired, but the viewpoint of improving the electrical characteristics, strong exposure characteristics, image characteristics, repeat characteristics, and coating properties during production of the electrophotographic photosensitive member. Therefore, it is usually 0.01 μm or more, preferably 0.1 μm or more, more preferably 0.25 μm or more, further preferably 0.5 μm or more, and particularly preferably 0.75 μm or more. Moreover, it is 30 micrometers or less normally, Preferably it is 20 micrometers or less. A known antioxidant or the like may be mixed in the undercoat layer. The undercoat layer may contain pigment particles, resin particles and the like for the purpose of preventing image defects.

<Photosensitive layer>
When the photosensitive layer has a blocking layer such as the above-described undercoat layer on the conductive support, it is formed thereon. As a type of the photosensitive layer, a layered structure composed of two or more layers including a charge generation layer in which a charge generation material is dispersed in a binder resin and a charge transport layer in which a charge transport material is dispersed in a binder resin. A function-separated type (hereinafter referred to as “laminated photosensitive layer” as appropriate) is employed.

In addition, as the laminated photosensitive layer, a charge-generating layer and a charge transport layer are laminated in this order from the conductive support side, and conversely, a charge transport layer and a charge generation layer are formed from the conductive support side. There are reverse laminated photosensitive layers provided in order, and any of them can be adopted, but a forward laminated photosensitive layer that can exhibit the most balanced photoconductivity is preferable.
In the present invention, the metal complex or metal salt of the aromatic carboxylic acid represented by the formula (I) and the polyarylate resin are contained in the charge transport layer.

<Charge generation layer>
The charge generation layer of the laminated photosensitive layer (function-separated type photosensitive layer) contains a charge generation material and usually contains a binder resin and other components used as necessary. Such a charge generation layer is prepared by, for example, preparing a coating solution by dissolving or dispersing fine particles of a charge generation material and a binder resin in a solvent or a dispersion medium. It can be obtained by coating and drying on the top (on the undercoat layer when an undercoat layer is provided) and on the charge transport layer in the case of a reverse laminated type photosensitive layer.

[Charge generating material]
The charge generating material may be used alone or in a mixed state with several dyes and pigments.
Examples of the charge generation material include inorganic photoconductive materials such as selenium and its alloys, cadmium sulfide, and organic photoconductive materials such as organic pigments. Organic photoconductive materials are preferred, and organic photoconductive materials are particularly preferable. Pigments are preferred. Examples of organic pigments include phthalocyanine pigments, azo pigments, dithioketopyrrolopyrrole pigments, squalene (squarylium) pigments, quinacridone pigments, indigo pigments, perylene pigments, polycyclic quinone pigments, anthanthrone pigments, and benzimidazole pigments. . Among these, phthalocyanine pigments or azo pigments are particularly preferable as dyes used in the mixed state from the viewpoint of photosensitivity. When organic pigments are used as the charge generating substance, usually, fine particles of these organic pigments are used in the form of a dispersion layer bound with various binder resins.

When a phthalocyanine pigment is used as the charge generation material, specifically, metal-free phthalocyanine and metal-containing phthalocyanine are used. Specific examples of metal-containing phthalocyanines include metals such as copper, indium, gallium, tin, titanium, zinc, vanadium, silicon, germanium, or their oxides, halides, hydroxides, alkoxides, and the like. Various crystal forms of phthalocyanines are used. In particular, oxytitanium phthalocyanines such as A type (also known as β type), B type (also known as α type), and D type (also known as Y type), which are highly sensitive crystal types, chloro such as vanadyl phthalocyanine, chloroindium phthalocyanine, and type II Preference is given to gallium phthalocyanine, hydroxygallium phthalocyanine such as V type, μ-oxo-gallium phthalocyanine dimer such as G type and I type, and μ-oxo-aluminum phthalocyanine dimer such as type II.

Among these phthalocyanines, D-type (Y-type) oxytitanium having a clear diffraction peak mainly at a Bragg angle (2θ ± 0.2 °) of 27.2 ° in the powder X-ray diffraction spectrum by CuKα characteristic X-ray Phthalocyanine is preferred.
The aforementioned crystal forms are mainly produced by crystal conversion from amorphous or low crystalline oxytitanium phthalocyanine. These crystal types are metastable crystal types, exhibit various crystal types and particle shapes depending on the manufacturing method, and have characteristics as an electrophotographic photosensitive member such as charge generation ability, charging property, and dark decay. It is known to depend on

As a method for producing the aforementioned D-type (Y-type) oxytitanium phthalocyanine, it is preferable that the phthalocyanine crystal precursor is obtained by contacting an organic solvent after chemical treatment.
In the present invention, the chemical treatment is not a method of obtaining amorphous oxytitanium phthalocyanine or low-crystalline oxytitanium phthalocyanine using only physical force (for example, mechanical grinding), but is a chemistry such as dissolution and reaction. This is a treatment method for adjusting amorphous or low crystalline oxytitanium phthalocyanine using a mechanical phenomenon. On the other hand, when an azo pigment is used as a charge generation material, various known azo pigments can be used as long as they have sensitivity to a light source for light input. Trisazo pigments are preferably used.

When a metal-free phthalocyanine compound or a metal-containing phthalocyanine compound is used as the charge generation material, a highly sensitive photoreceptor can be obtained with respect to a laser beam having a relatively long wavelength, for example, a laser beam having a wavelength around 780 nm. Further, when an azo pigment such as monoazo, diazo, or trisazo is used, white light, laser light having a wavelength around 660 nm, or laser light having a relatively short wavelength (for example, a wavelength in the range of 380 nm to 500 nm). It is possible to obtain a photoreceptor having sufficient sensitivity to the laser beam).
Therefore, it is preferable to use a combination of an azo pigment and a phthalocyanine compound because it is possible to have spectral sensitivity characteristics in different spectral regions of the visible region and the near red region.

[Binder resin]
Examples of the binder resin used for the charge generation layer in the function-separated photoreceptor include polyvinyl butyral resin, polyvinyl formal resin, partially acetalized polyvinyl butyral resin in which a part of butyral is modified with formal, acetal, etc. Polyvinyl acetal resin, polyarylate resin, polycarbonate resin, polyester resin, modified ether polyester resin, phenoxy resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyvinyl acetate resin, polystyrene resin, acrylic resin, methacrylic resin, polyacrylamide Resin, polyamide resin, polyvinyl pyridine resin, cellulose resin, polyurethane resin, epoxy resin, silicone resin, polyvinyl alcohol resin, polyvinyl pyrrolidone resin, casein, chloride Vinyl chloride-vinyl acetate, such as nyl-vinyl acetate copolymer, hydroxy-modified vinyl chloride-vinyl acetate copolymer, carboxyl-modified vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer Copolymer, styrene-butadiene copolymer, vinylidene chloride-acrylonitrile copolymer, styrene-alkyd resin, silicon-alkyd resin, phenol-formaldehyde resin and other insulating resins, poly-N-vinylcarbazole, polyvinylanthracene, It can be selected from organic photoconductive polymers such as polyvinyl perylene, but is not limited to these polymers. These binder resins may be used alone or in combination of two or more.

[Formation method]
Specifically, the charge generation layer in the function-separated type photoconductor is prepared by dispersing a charge generation material by dispersing the above-mentioned binder resin in an organic solvent and then applying the coating solution on the conductive support (with an undercoat layer). If provided, it is formed by coating (on the undercoat layer).
Solvents used for the preparation of coating solutions and dispersion media for dissolving the binder resin include, for example, saturated aliphatic solvents such as pentane, hexane, octane and nonane, aromatic solvents such as toluene, xylene and anisole, chlorobenzene, Halogenated aromatic solvents such as dichlorobenzene and chloronaphthalene, amide solvents such as dimethylformamide and N-methyl-2-pyrrolidone, alcohol solvents such as methanol, ethanol, isopropanol, n-butanol and benzyl alcohol, glycerin, Aliphatic polyhydric alcohols such as polyethylene glycol, chain solvents such as acetone, cyclohexanone, methyl ethyl ketone, and cyclic ketone solvents, ester solvents such as methyl formate, ethyl acetate, n-butyl acetate, methylene chloride, chloroform, 1, 2-Dichro Halogenated hydrocarbon solvents such as ethane, linear ether solvents such as diethyl ether, dimethoxyethane, tetrahydrofuran, 1,4-dioxane, methylcellosolve, ethylcellosolve, acetonitrile, dimethylsulfoxide, sulfolane, hexa Examples include aprotic polar solvents such as methyl phosphate triamide, and those that do not dissolve the undercoat layer described above are preferably used. These can be used alone or in combination of two or more.

In the charge generation layer of the function-separated type photoreceptor, the compounding ratio (mass) of the binder resin and the charge generation material is 10 to 1000 parts by weight, preferably 30 to 500 parts by weight with respect to 100 parts by weight of the binder resin. The film thickness is usually 0.1 μm to 10 μm, preferably 0.15 μm to 0.6 μm. If the ratio of the charge generation material is too high, the stability of the coating solution may be reduced due to aggregation of the charge generation material. On the other hand, if the ratio of the charge generating substance is too low, the sensitivity as a photoreceptor may be reduced.
As a method for dispersing the charge generation material, a known dispersion method such as a ball mill dispersion method, an attritor dispersion method, or a sand mill dispersion method can be used. In this case, it is effective to refine the particles to a particle size of 0.5 μm or less, preferably 0.3 μm or less, more preferably 0.15 μm or less.

<Charge transport layer>
[Binder resin]
For the charge transport layer, a binder resin is used to ensure film strength. The charge transport layer can be obtained by applying and drying a coating solution obtained by dissolving or dispersing a charge transport material and various binder resins in a solvent.
As the binder resin, the polyarylate resin described above is used, but other resins can be blended and used. Examples of resins that can be used in combination include polymers and copolymers of vinyl compounds such as butadiene resins, styrene resins, vinyl acetate resins, vinyl chloride resins, acrylic ester resins, methacrylic ester resins, vinyl alcohol resins, and ethyl vinyl ethers. , Polyvinyl butyral resin, polyvinyl formal resin, partially modified polyvinyl acetal, polycarbonate resin, polyester resin, polyamide resin, polyurethane resin, cellulose ester resin, phenoxy resin, silicone resin, silicon-alkyd resin, poly-N-vinylcarbazole resin, etc. Polycarbonate resin is particularly preferable. These resins may be modified with a silicon reagent or the like. These can also be used by crosslinking with an appropriate curing agent by heat, light or the like.

[Charge transport material]
The charge transport material is not particularly limited, and any material can be used. Examples of known charge transport materials include aromatic nitro compounds such as 2,4,7-trinitrofluorenone, cyano compounds such as tetracyanoquinodimethane, electron withdrawing materials such as quinone compounds such as diphenoquinone, and carbazole derivatives. , Indole derivatives, imidazole derivatives, oxazole derivatives, pyrazole derivatives, thiadiazole derivatives, heterocyclic compounds such as benzofuran derivatives, aniline derivatives, hydrazone derivatives, aromatic amine derivatives, stilbene derivatives, butadiene derivatives, enamine derivatives, and a plurality of these compounds Examples thereof include an electron donating substance such as a polymer in which a species is bonded, or a polymer having a group composed of these compounds in the main chain or side chain. Among these, carbazole derivatives, aromatic amine derivatives, stilbene derivatives, butadiene derivatives, enamine derivatives, and those in which a plurality of these compounds are bonded are preferable.

Any one of these charge transport materials may be used alone, or two or more thereof may be used in any combination.
Preferred specific examples of the charge transport material are shown below. In the following compounds, R represents the same or different substituents. Specifically, a hydrogen atom, an alkyl group, an alkoxy group, a phenyl group, an arylalkyl and the like are preferable. Particularly preferred is a methyl group, an ethyl group or a benzyl group. N is an integer of 0 or more and 2 or less.
The following exemplary compounds are specific examples of charge transport materials that can be used, and are not limited thereto.

  The ratio of the binder resin to the charge transport material is usually 10 parts by mass or more with respect to 100 parts by mass of the binder resin, and preferably 30 parts by mass or more from the viewpoint of reducing the residual potential. From a viewpoint, 35 mass parts or more is more preferable. On the other hand, from the viewpoint of thermal stability of the photosensitive layer, it is usually 150 parts by mass or less, preferably 120 parts by mass or less from the viewpoint of compatibility between the charge transport material and the binder resin, and from the viewpoint of printing durability. 100 mass parts or less are more preferable, and 80 mass parts or less are especially preferable from a viewpoint of scratch resistance.

The thickness of the charge transport layer is not particularly limited, but is usually 5 μm or more, preferably 10 μm or more, on the other hand, usually 50 μm or less, preferably 45 μm or less, from the viewpoint of long life, image stability, and high resolution. The range is preferably 40 μm or less.
It should be noted that each layer constituting the laminated type has a well-known antioxidant, plasticizer, UV absorption for the purpose of improving film forming properties, flexibility, coating properties, stain resistance, gas resistance, light resistance, etc. An agent, an electron-withdrawing compound, a leveling agent, a visible light shielding agent, and the like may be included.

Examples of the antioxidant include hindered phenol compounds and hindered amine compounds. Examples of the leveling agent include silicone oil and fluorine oil.
<Other functional layers>
In the multilayer photoreceptor, a protective layer may be provided on the outermost layer for the purpose of preventing the photosensitive layer from being worn and preventing or reducing the deterioration of the photosensitive layer due to a discharge substance generated from a charger or the like. The protective layer is formed by containing a conductive material in an appropriate binder resin, or charge transporting ability such as a triphenylamine skeleton as described in JP-A-9-190004 and JP-A-10-252377. The copolymer using the compound which has can be used.

Examples of the conductive material used for the protective layer include aromatic amino compounds such as TPD (N, N′-diphenyl-N, N′-bis- (m-tolyl) benzidine), antimony oxide, indium oxide, tin oxide, and oxide. Metal oxides such as titanium, tin oxide-antimony oxide, aluminum oxide, and zinc oxide can be used, but are not limited thereto.
As the binder resin used for the protective layer, known resins such as polyamide resin, polyurethane resin, polyester resin, epoxy resin, polyketone resin, polycarbonate resin, polyvinyl ketone resin, polystyrene resin, polyacrylamide resin, and siloxane resin can be used. Further, a copolymer of the above resin with a skeleton having a charge transporting ability such as a triphenylamine skeleton as described in JP-A-9-190004 can also be used.
Further, for the purpose of reducing the frictional resistance and wear on the surface of the photoconductor, and increasing the transfer efficiency of the toner from the photoconductor to the transfer belt and paper, etc., the surface layer is made of a fluororesin, silicone resin, polyethylene resin, or the like. You may contain the particle | grains which consist of these resin, and the particle | grains of an inorganic compound. Alternatively, a layer containing these resins and particles may be newly formed as a surface layer.

<Method for forming each layer>
Each layer constituting the above-described photoreceptor is formed by dip coating, spray coating, nozzle coating, bar coating, roll coating, blade coating on a conductive support obtained by dissolving or dispersing a substance to be contained in a solvent. It is formed by repeating a coating / drying step sequentially for each layer by a known method such as coating.

  There are no particular restrictions on the solvent or dispersion medium used for the preparation of the coating liquid, and there are portions that overlap with the charge generation layer coating liquid. Specific examples include alcohols such as methanol, ethanol, propanol, and 2-methoxyethanol. , Ethers such as tetrahydrofuran, 1,4-dioxane and dimethoxyethane, esters such as methyl formate and ethyl acetate, ketones such as acetone, methyl ethyl ketone, cyclohexanone and 4-methoxy-4-methyl-2-pentanone, benzene, Aromatic hydrocarbons such as toluene, xylene, dichloromethane, chloroform, 1,2-dichloroethane, 1,1,2-trichloroethane, 1,1,1-trichloroethane, tetrachloroethane, 1,2-dichloropropane, trichloroethylene, etc. Chlorinated hydrocarbons, n-buty Examples include nitrogen-containing compounds such as amine, isopropanolamine, diethylamine, triethanolamine, ethylenediamine, and triethylenediamine, and aprotic polar solvents such as acetonitrile, N-methylpyrrolidone, N, N-dimethylformamide, and dimethylsulfoxide. . Moreover, these may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and kinds.

The amount of the solvent or the dispersion medium used is not particularly limited, but considering the purpose of each layer and the properties of the selected solvent / dispersion medium, it is appropriately determined so that the physical properties such as the solid content concentration and viscosity of the coating liquid are within a desired range. It is preferable to adjust.
For example, in the case of the charge transport layer, the solid content concentration of the coating solution is usually 5% by mass or more, preferably 10% by mass or more, and usually 40% by mass or less, preferably 35% by mass or less.
In the case of the charge generation layer, the solid content concentration of the coating solution is usually 0.1% by mass or more, preferably 1% by mass or more, and usually 15% by mass or less, preferably 10% by mass or less. To do.

Each layer constituting these photoconductors is formed by applying the coating solution obtained by the above-described method on a support using a known coating method, repeating the coating and drying steps for each layer, and sequentially coating the layers. The Examples of the coating method include a dip coating method, a spray coating method, a spinner coating method, a bead coating method, a wire bar coating method, a blade coating method, a roller coating method, an air knife coating method, and a curtain coating method. Other known coating methods can also be used. Among them, the dip coating method is particularly preferable.
The coating solution is preferably dried by touching at room temperature, followed by heating or drying in a temperature range of usually 30 ° C. or more and 200 ° C. or less for 1 minute to 2 hours, while still or blowing. Further, the heating temperature may be constant, or heating may be performed while changing the temperature during drying.

<Cartridge, image forming apparatus>
Next, a drum cartridge and an image forming apparatus using the electrophotographic photosensitive member of the present invention will be described with reference to FIG.
In FIG. 1, reference numeral 1 denotes a drum-shaped photoconductor which is driven to rotate at a predetermined peripheral speed in the direction of an arrow about an axis. The photosensitive member 1 is uniformly charged at a predetermined positive or negative potential on the surface thereof by the charging unit 2 during the rotation process, and then exposure for forming a latent image is performed by the image exposure unit in the exposure unit 3. The formed electrostatic latent image is then developed with toner by the developing unit 4, and the toner developed image is sequentially transferred onto a transfer body (paper or the like) fed from the paper feeding unit by the corona transfer unit 5. The image-transferred transfer body is then sent to the fixing means 7 where the image is fixed and printed out of the apparatus. The surface of the photoreceptor 1 after the image transfer is cleaned by the cleaning unit 6 to remove the transfer residual toner, and is neutralized by the neutralization unit for the next image formation.

  In using the electrophotographic photosensitive member of the present invention, as a charger, in addition to a corona charger such as corotron and scorotron, a direct charging means for charging a charged member by contacting a directly charged member to which a voltage is applied. May be used. Examples of the direct charging means include a contact charger such as a charging roller and a charging brush. As the direct charging means, any one that involves air discharge or injection charging that does not involve air discharge is possible. In addition, as a voltage applied at the time of charging, in the case of only a direct current voltage, an alternating current can be superimposed on a direct current.

For the exposure, a halogen lamp, a fluorescent lamp, a laser (semiconductor, He—Ne), LED, a photoreceptor internal exposure system, or the like is used. As the digital electrophotographic system, it is preferable to use a laser, LED, optical shutter array, or the like. . As the wavelength, in addition to 780 nm monochromatic light, it is possible to use monochromatic light in the 600 to 700 nm region and slightly shorter wavelength.
In the development process, a dry development method such as cascade development, one-component insulating toner development, one-component conductive toner development, two-component magnetic brush development, or the like is used. As the toner, in addition to the pulverized toner, chemical toners such as suspension granulation, suspension polymerization, and emulsion polymerization aggregation can be used. In particular, in the case of chemical toners, those having a small particle diameter of about 4 to 8 μm are used, and those having a shape close to a sphere, and those outside the potato-like sphere can also be used. The polymerized toner is excellent in charging uniformity and transferability, and is preferably used for high image quality.

For the transfer process, electrostatic transfer methods such as corona transfer, roller transfer, and belt transfer, pressure transfer methods, and adhesive transfer methods are used. For fixing, heat roller fixing, flash fixing, oven fixing, pressure fixing, IH fixing, belt fixing, IHF fixing, etc. are used. These fixing methods may be used alone or in combination with a plurality of fixing methods. May be.
For cleaning, brush cleaner, magnetic brush cleaner, electrostatic brush cleaner, magnetic roller cleaner, blade cleaner, etc. are used.
In many cases, the static elimination step is omitted, but when used, a fluorescent lamp, LED, or the like is used, and an exposure energy that is three times or more of the exposure light is often used as the intensity.
In addition to these processes, a pre-exposure process and an auxiliary charging process may be included.

  In the present invention, a plurality of components such as the drum-shaped photosensitive member 1, the charging unit 2, the developing unit 4 and the cleaning unit 6 are integrally combined as a drum cartridge, and the drum cartridge is copied. It may be configured to be detachable from the main body of an electrophotographic apparatus such as a machine or a laser beam printer. For example, at least one of the charging unit 2, the developing unit 4, and the cleaning unit 6 can be integrally supported together with the drum-shaped photoreceptor 1 to form a cartridge.

  Hereinafter, the present invention will be described in more detail with reference to production examples, examples and comparative examples. In addition, the following examples are shown in order to explain the present invention in detail, and the present invention is not limited to the following examples unless it is contrary to the gist thereof.

<Photosensitive sheet preparation method>
[Example 1]
Aluminum oxide particles having an average primary particle diameter of 13 nm (Aluminum Oxide C, manufactured by Nippon Aerosil Co., Ltd.) were dispersed in a mixed solvent of methanol / 1-propanol with ultrasonic waves to obtain a dispersion slurry of aluminum oxide. The dispersion slurry, a mixed solvent of methanol / 1-propanol (mass ratio 7/3), and ε-caprolactam [compound represented by the following formula (A)] / bis (4-amino-3-methylcyclohexyl) methane [Compound represented by the following formula (B)] / hexamethylenediamine [compound represented by the following formula (C)] / decamethylene dicarboxylic acid [compound represented by the following formula (D)] / octadecamethylene dicarboxylic acid [following Copolymer polyamide pellets having a composition molar ratio of the compound represented by formula (E) of 60% / 15% / 5% / 15% / 5% are stirred and mixed while heating to obtain polyamide pellets. After dissolution, ultrasonic dispersion treatment is performed to obtain a solid content concentration of 8.0% containing aluminum oxide / copolymerized polyamide at a mass ratio of 1/1. It was a gas layer for dispersion.

The coating solution for forming the undercoat layer thus obtained was applied on a polyethylene terephthalate sheet (thickness 75 μm) vapor-deposited on the surface with a wire bar so that the film thickness after drying was 1.2 μm, and dried. Thus, an undercoat layer was provided.
Next, Bragg angle (2θ ± 0.2) in X-ray diffraction by CuKα ray obtained by making it amorphous by mechanical treatment by the same method as Comparative Synthesis Example 1 of JP-A-2007-148387 and contacting with solvent. ) Shows a strong diffraction peak at 27.3 °, 10 parts by mass of oxytitanium phthalocyanine having the powder X-ray diffraction spectrum shown in FIG. 2 is added to 150 parts by mass of 1,2-dimethoxyethane, and pulverized and dispersed with a sand grind mill. Treatment was performed to prepare a pigment dispersion. 160 parts by mass of the pigment dispersion thus obtained was added to 100 parts by mass of a 5% 1,2-dimethoxyethane solution of polyvinyl butyral (trade name # 6000C, manufactured by Denki Kagaku Kogyo Co., Ltd.), and an appropriate amount of 1,2 -Dimethoxyethane was added to finally prepare a coating solution for forming a charge generation layer having a solid content concentration of 4.0% by mass.
This charge generation layer forming coating solution was applied on the above-described undercoat layer with a wire bar so that the film thickness after drying was 0.4 μm, and then dried to form a charge generation layer.

Next, 40 parts by mass of CTM (1) represented by the following structural formula as a charge transport material, and 3,5-ditertiarybutylsalicylic acid aluminum salt (trade name: Bontron, manufactured by Orient Chemical Industries) as a metal salt of an aromatic carboxylic acid 0.5 parts by mass of E-108), 4 parts by mass of an antioxidant (1) represented by the following formula as an antioxidant, and a polyarylate resin (PAR-A, viscosity average molecular weight 41,000 having the following repeating structure) ) 100 parts by mass, and 0.05 parts by mass of silicone oil as a leveling agent are mixed with 640 parts by mass of a mixed solvent of tetrahydrofuran and toluene (tetrahydrofuran 80% by mass, toluene 20% by mass) to form a charge transport layer forming coating solution. Was prepared.

This charge transport layer forming coating solution is applied onto the above-described charge generation layer using an applicator so that the film thickness after drying is 25 μm, and dried at 125 ° C. for 20 minutes to form a charge transport layer. A sample was prepared.
[Example 2]
Example 1 except that 0.5 parts by mass of zinc salt of 3,5-ditertiarybutylsalicylic acid (trade name: Bontron E-84, manufactured by Orient Chemical Industries) was added instead of aluminum salt of 3,5-ditertiarybutylsalicylic acid The same operation was performed to obtain a sample.

[Comparative Example 1]
A sample was obtained in the same manner as in Example 1 except that 3,5-ditertiarybutylsalicylic acid aluminum salt was not added.
Example 3
A sample was obtained in the same manner as in Example 1 except that 40 parts by mass of CTM (2) having the following structure was used instead of CTM (1) as the charge transport material.

Example 4
Example 3 except that 0.5 parts by mass of 3,5-ditertiarybutylsalicylic acid zinc salt (trade name: Bontron E-84, manufactured by Orient Chemical Industries) was added instead of 3,5-ditertiarybutylsalicylic acid aluminum salt The same operation was performed to obtain a sample.
[Comparative Example 2]
A sample was obtained in the same manner as in Example 3 except that 3,5-ditertiarybutylsalicylic acid aluminum salt was not added.

Example 5
Except for using 80 parts by mass of CTM (3) having the following structure instead of CTM (1) as a charge transport material and adding 0.1 part by mass of 3,5-ditertiarybutylsalicylic acid aluminum salt, The same operation as in Example 1 was performed to obtain a sample.

[Comparative Example 3]
A sample was obtained in the same manner as in Example 5 except that 3,5-ditertiarybutylsalicylic acid aluminum salt was not added.
Example 6
A sample was obtained in the same manner as in Example 5 except that CTM (4) having the following structure was used instead of CTM (3) as the charge transport material.

[Comparative Example 4]
A sample was obtained in the same manner as in Example 6 except that 3,5-ditertiarybutylsalicylic acid aluminum salt was not added.
Example 7
A sample was obtained in the same manner as in Example 5 except that CTM (5) having the following structure was used instead of CTM (3) as the charge transport material.

[Comparative Example 5]
A sample was obtained in the same manner as in Example 7 except that 3,5-ditertiarybutylsalicylic acid aluminum salt was not added.
Example 8
A sample was obtained in the same manner as in Example 5 except that CTM (6) having the following structure was used instead of CTM (3) as the charge transport material.

[Comparative Example 6]
A sample was obtained in the same manner as in Example 8, except that 3,5-ditertiarybutylsalicylic acid aluminum salt was not added.
Example 9
A sample was obtained in the same manner as in Example 5 except that CTM (7) having the following structure was used instead of CTM (3) as the charge transport material.

[Comparative Example 7]
A sample was obtained in the same manner as in Example 9 except that 3,5-ditertiarybutylsalicylic acid aluminum salt was not added.
Example 10
A sample was obtained in the same manner as in Example 5 except that CTM (8) having the following structure was used instead of CTM (3) as the charge transport material.

[Comparative Example 8]
A sample was obtained in the same manner as in Example 10 except that 3,5-ditertiarybutylsalicylic acid aluminum salt was not added.
Example 11
Instead of oxytitanium phthalocyanine used in Example 1 as the charge generation material, x-type metal-free phthalocyanine is used, and CTM (9) having the following structure is used as the charge transport material instead of CTM (1). -A sample was obtained in the same manner as in Example 1 except that the amount of aluminum ditertiarybutylsalicylate (trade name: Bontron E-108, manufactured by Orient Chemical Industries) was 0.1 parts by mass.

[Comparative Example 9]
A sample was obtained in the same manner as in Example 11 except that 3,5-ditertiarybutylsalicylic acid aluminum salt was not added.
Example 12
A sample was obtained in the same manner as in Example 11 except that V-type hydroxygallium phthalocyanine was used instead of x-type metal-free phthalocyanine as the charge generation material.

[Comparative Example 10]
A sample was obtained in the same manner as in Example 12 except that 3,5-ditertiarybutylsalicylic acid aluminum salt was not added.
[Reference Example 1]
A sample was obtained in the same manner as in Example 12 except that polycarbonate resin (PCR-B) having the following repeating structure was used as the binder resin for the charge transport layer instead of PAR-A.

[Reference Example 2]
A sample was obtained in the same manner as in Reference Example 1 except that 3,5-ditertiarybutylsalicylic acid aluminum salt was not added.
Example 13
As a charge generation material, it is obtained by making it amorphous by chemical treatment in the same manner as in Synthesis Example 4 and then contacting with a solvent, and Bragg angle (2θ ± 0.2) in X-ray diffraction using CuKα rays. Showed a strong diffraction peak at 27.3 °, and a sample was obtained in the same manner as in Example 11 except that oxytitanium phthalocyanine having a powder X-ray diffraction spectrum shown in FIG. 3 was used.
[Comparative Example 13]
A sample was obtained in the same manner as in Example 14 except that 3,5-ditertiarybutylsalicylic acid aluminum salt was not added.

<Evaluation of electrical characteristics of photoconductor>
Using an electrophotographic characteristic evaluation apparatus (basic and applied electrophotographic technology, edited by the Electrophotographic Society, Corona, pages 404-405) prepared according to the Electrophotographic Society measurement standard, the photoconductor is made into an aluminum drum. Attached to a cylindrical shape, the aluminum drum and the aluminum base of the photoconductor are connected, and then the drum is rotated at a constant rotational speed. went.

At that time, the initial surface potential was −700 V, exposure was 780 nm, and charge removal was monochromatic light of 660 nm. The surface potential (VL) when 780 nm light was irradiated at 1.0 μJ / cm ² was measured. In the VL measurement, the time required for the exposure-potential measurement was 100 ms. The measurement environment was a temperature of 25 ° C. and a relative humidity of 50%. The smaller the absolute value of the VL value, the better the electrical characteristics. The results of electrical characteristics are shown in Table-1.

From the above “Table 1”, it can be seen that the absolute value of VL is reduced by containing a carboxylic acid metal salt regardless of the type of the charge transport material. Further, it can be seen that this effect is more remarkable when the binder resin is a polyarylate resin than when the binder resin is a polycarbonate resin.
<Example 14>
In Example 1, the mass of the binder resin (polyvinyl butyral) in the coating solution for forming the charge generation layer was doubled, and the coating solution for forming the charge transport layer was used as the charge transport material, and 50 parts by mass of CTM (1). , 0.2 parts by mass of aluminum salt of 3,5-ditertiarybutylsalicylic acid (trade name: Bontron E-108, manufactured by Orient Chemical Industries) as a metal salt of aromatic carboxylic acid, and 8 parts by mass of antioxidant (1) , Polyarylate resin (PAR-A, viscosity average molecular weight 41,
000) was 100 parts by mass, and a sample was obtained in the same manner as in Example 1 except that 0.05 part by mass of silicone oil was used as the leveling agent.

<Comparative example 14>
A sample was obtained in the same manner as in Example 14 except that 3,5-ditertiarybutylsalicylic acid aluminum salt was not added.
<Example 15>
A sample was obtained in the same manner as in Example 14 except that polyarylate resin (PAR-B) having the following repeating structure was used as the binder resin for the charge transport layer instead of PAR-A.

<Comparative Example 15>
A sample was obtained in the same manner as in Example 15 except that 3,5-ditertiarybutylsalicylic acid aluminum salt was not added.
<Example 16>
A sample was obtained in the same manner as in Example 14 except that polyarylate resin (PAR-C) having the following repeating structure was used as the binder resin for the charge transport layer instead of PAR-A.

<Comparative Example 16>
A sample was obtained in the same manner as in Example 16 except that 3,5-ditertiarybutylsalicylic acid aluminum salt was not added.
<Reference Example 3>
A sample was obtained in the same manner as in Example 14 except that the polycarbonate resin (PCR-B) used in Reference Example 1 was used instead of PAR-A as the binder resin for the charge transport layer.

<Reference Example 4>
A sample was obtained in the same manner as in Reference Example 3 except that 3,5-ditertiarybutyl salicylic acid aluminum salt was not added.
<Evaluation of electrical characteristics of photoconductor>
Using the same apparatus as in Examples 1 to 13, the surface potential (VL) of the sample was measured.
Further, the irradiation energy (half exposure energy: μJ / cm ² ) when the surface potential was half of the initial surface potential (−350 V) was measured as sensitivity (E _2/1 ). The results are shown in Table-2.

<Evaluation of adhesiveness>
Samples for adhesion tests were obtained in the same manner except that the photosensitive layers in Examples 14 to 16, Comparative Examples 14 to 16, and Reference Examples 1 and 2 were provided on an aluminum plate instead of an aluminum-deposited polyethylene terephthalate sheet. It was. On these adhesion test photoreceptors, cuts were made at intervals of 2 mm using an NT cutter to produce 5 × 5 25 squares. Cellotape (registered trademark) (manufactured by Nichiban Co., Ltd.) was applied from above, and the adhesion of the photosensitive layer was tested by pulling it up to 90 ° with respect to the adhesion surface. The number of strips of the peeled photosensitive layer was recorded at two locations per sample. The smaller the number of squares of the peeled photosensitive layer, the better the adhesiveness. The results are shown in Table-2.

From the above "Table-2", it can be seen that the absolute value of VL is reduced by containing a metal carboxylate. Furthermore, it can be seen that this effect is more pronounced when the binder resin is a polyarylate resin than when the binder resin is a polycarbonate resin.
In addition, it can be seen that the adhesiveness of the photosensitive layer to the substrate is improved particularly in PAR-A and PAP-C by containing a carboxylic acid metal salt. On the other hand, when the binder resin is a polycarbonate resin, the effect due to the inclusion of the carboxylic acid metal salt is not seen because the adhesiveness is originally good.

1 Photoconductor (Electrophotographic photoconductor)
2 Charging device (charging roller; charging unit)
3 Exposure equipment (exposure section)
4 Development device (development unit)
5 Transfer device 6 Cleaning device (cleaning part)
7 Fixing Device 41 Developing Tank 42 Agitator 43 Supply Roller 44 Developing Roller 45 Regulating Member 71 Upper Fixing Member (Pressure Roller)
72 Lower fixing member (fixing roller)
73 Heating device T Toner P Recording paper (paper, medium)

Claims (6)

In an electrophotographic photoreceptor having at least a charge generation layer and a charge transport layer as a photosensitive layer on a conductive support,
An electrophotographic photoreceptor, wherein the charge transport layer contains a metal complex or metal salt of an aromatic carboxylic acid represented by the following general formula (I), and a polyarylate resin.
ArCOOH (I)
(In the formula (I), Ar represents an aryl group having 30 or less carbon atoms which may have a substituent.) The electrophotographic photosensitive member according to claim 1, wherein the aromatic carboxylic acid represented by the general formula (I) has a structure represented by the following general formula (II) or (III).

(In the formulas (II) and (III), the substituents R ^{11 to} R ¹³ each independently represent a halogen atom, an alkyl group, an alkoxy group, an amino group, a nitrile group, a nitro group, a carboxyl group, or an aryl group. Ring A represents an aromatic ring having 5 to 10 carbon atoms, a represents an integer of 0 to 2, and b and c represent integers of 0 to 4. However, R ^{11 to} R ¹³ are bonded to each other to form a ring. You may do it.) The electrophotographic photosensitive member according to claim 1, wherein the polyarylate resin is a polyarylate resin having a repeating structure represented by the following general formula [1].

(In the general formula [1], Ar ^{1 to} Ar ⁴ may be the same or different and each independently represents an arylene group which may have a substituent. X represents a single bond, an oxygen atom, sulfur. 2 represents a divalent organic residue having an atom, a structure represented by Formula [2], or a structure represented by Formula [3], wherein R ¹ and R ^{2 in} Formula [2] are each independently A hydrogen atom, an alkyl group, an aryl group, or a cycloalkylidene group formed by combining R ¹ and R ^2, and R ³ in the formula [3] represents an alkylene group, an arylene group, or a formula a group represented by [4], an alkylene group and ^{R 4} and ^{R 5} are each independently of the formula [4], .k Ar ⁵ is representative of the arylene group is an integer of 0-5. Y has a single bond, a sulfur atom, an oxygen atom, or a structure represented by the formula [5]. That represents a divalent organic residue. Equation [5] R ⁶ and R ⁷ in each independently represent a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or R ⁶ and R ⁷ and is formed by combining Represents a cycloalkylidene group.)

  4. The undercoat layer according to claim 1, further comprising a subbing layer in which metal oxide particles are dispersed in a resin as a blocking layer between the conductive support and the photosensitive layer. 5. Electrophotographic photoreceptor.   The electrophotographic photosensitive member according to any one of claims 1 to 4, a charging unit that charges the electrophotographic photosensitive member, an exposure unit that exposes the charged electrophotographic photosensitive member to form an electrostatic latent image, An electrophotographic photosensitive member cartridge comprising: a developing unit that develops an electrostatic latent image formed on the electrophotographic photosensitive member; and a cleaning unit that cleans the electrophotographic photosensitive member.   The electrophotographic photosensitive member according to any one of claims 1 to 4, a charging unit that charges the electrophotographic photosensitive member, an exposure unit that exposes the charged electrophotographic photosensitive member to form an electrostatic latent image, And an image forming apparatus comprising: a developing unit that develops the electrostatic latent image formed on the electrophotographic photosensitive member.

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