JP5942601B2 - Electrophotographic photosensitive member, electrophotographic cartridge, and image forming apparatus - Google Patents

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 the multilayer electrophotographic photoreceptor, the charge transport layer may contain a polyarylate resin, a specific electron transport material as a charge transport material, and a hole transport material, thereby reducing the residual potential. In particular, the present invention relates to an electrophotographic photosensitive member, an image forming apparatus, and a cartridge that exhibit excellent performance such as electrical characteristics and wear resistance.

The electrophotographic technology is widely used as a copying machine, a printer, and a printing machine because a high-quality image can be obtained immediately.
For the electrophotographic photoreceptor (hereinafter referred to as “photoreceptor” as appropriate) which is the core of the electrophotographic technology, an organic photoconductive material having advantages such as non-polluting, easy film formation and easy production was used. Photoconductors are widely used.

  In recent years, due to the demand for higher image quality, the diameter of toner has been reduced, and in particular, the shape of a chemical toner is often close to a sphere, so that when the toner remaining on the photoreceptor is cleaned with a blade, the toner slips through. This is likely to occur, and as a result, there is a high possibility of image defects such as dirt. For this reason, measures are often taken to bring the cleaning blade into contact with the photosensitive member with a strong pressure to prevent the toner from slipping through, and the photosensitive member is likely to be worn. Therefore, as a means for improving the surface mechanical properties of the photoreceptor, polyester resin, especially polyarylate resin, which is wholly aromatic polyester resin, has a high elastic deformation rate. It has been put into practical use.

  Although there are various disturbance factors that affect the performance of the photoconductor, the chargeability, light attenuation behavior, and their effects can be reduced by exposure to external light during application / post-processing, replacement, or maintenance of the photoconductor. Regarding the so-called light fatigue characteristics that impair repeated stability, there are cases where measures are taken to shield the light as much as possible on the hardware side, but it is disadvantageous in terms of cost, and it is most desirable that the photoreceptor itself originally does not light fatigue. . On the other hand, most of the recent electrophotographic photoreceptors are organic photoreceptors, and it has been difficult to say that sufficient countermeasures have been taken with respect to the light fatigue characteristics. Therefore, the slight potential fluctuation as described above becomes apparent as an image defect. Risk is high.

Japanese Patent Laid-Open No. 7-271067 Japanese Patent Laid-Open No. 7-271069 US Pat. No. 6,080,518 JP-A-9-281728 Japanese Patent Laid-Open No. 10-020523

The polyarylate resin is useful as a means for improving the surface mechanical properties of the photoreceptor, but generally has a problem that the electrical characteristics are insufficient as compared with the polycarbonate resin.
In addition, it has been studied to contain a diphenoquinone compound in order to improve the electrical characteristics of the electrophotographic photoreceptor (Patent Documents 1 to 5), but when used with a polyarylate resin, Combinations with hole transport materials have not been studied.

As a result of intensive studies to solve the above-mentioned problems, the present invention provides an electrophotographic photosensitive member having a laminated photosensitive layer, in addition to a polyarylate resin, a specific electron transporting material and a hole transporting material in the charge transporting layer. The present inventors have found that an electrophotographic photosensitive member that can reduce residual potential and is less susceptible to light fatigue can be obtained by introducing.
The gist of the present invention is an electrophotographic photosensitive member having a multilayer photosensitive layer on a conductive support, wherein the charge transport layer of the multilayer photosensitive layer contains an electron transport material, a hole transport material, and a polyarylate resin. And
Electron transporting material density functional calculation B3LYP / 6-31G (d, p) energy level E_lumo the resulting LUMO of structural optimization calculation by the following formula
-3.30> E_lumo (eV)> -3.55
A diphenoquinone derivative satisfying
And the energy level E_homo of HOMO obtained as a result of structural optimization calculation by density functional calculation B3LYP / 6-31G (d, p) of the hole transport material is
E_homo> -4.67 (eV)
In the electrophotographic photosensitive member, the cartridge including the electrophotographic photosensitive member, and the image forming apparatus.

According to the present invention, the surface mechanical properties of the photoreceptor are improved, and the residual potential of the electrophotographic photoreceptor can be reduced by introducing a specific electron transport material and hole transport material. This is because the electron transport material of the present invention is useful for charge delivery at the charge generation layer / charge transport layer interface, or the photosensitive layer / substrate interface, and in the case of having an undercoat layer, at the undercoat layer / charge generation layer interface. It is thought to be because.
In addition, it is possible to obtain a photoconductor that is less susceptible to light fatigue by specifically cutting the wavelength of light that adversely affects the photoconductor because the electron transport material becomes a coloring component.

1 is a schematic diagram illustrating an example 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, embodiments for carrying out the present invention will be described in detail. In addition, this invention is not limited to the following embodiment, In the range which does not deviate from the summary, it can change arbitrarily and can implement.
<Polyarylate resin>
First, the polyarylate resin used as the binder resin contained in the charge transport layer of the laminated photosensitive layer will be described.
A preferable polyarylate resin is represented by the following general formula (1).

(In the formula (1), Ar ^{1 to} Ar ⁴ each independently represents an arylene group which may have a substituent, and X represents a single bond, an oxygen atom, a sulfur atom, or the following formula (2). Group or the following formula (3)
The group represented by these is shown. R ¹ and R ^{2 in} Formula (2) each independently represent a hydrogen atom, an alkyl group, or an aryl group, and R ¹ and R ² may be bonded to form a ring. R ³ in formula (3) is an alkylene group, an arylene group, or a group represented by the following formula (4), and R ⁴ and R ^{5 in} formula (4) are each independently an alkylene group. Ar ⁵ represents an arylene group. k represents an integer of 0 or more. Y is a single bond, an oxygen atom, a sulfur atom, or a group represented by the following formula (5). In the formula (5), R ⁶ and R ⁷ are each independently a hydrogen atom, an alkyl group, an alkoxy group. Represents a group or an aryl group, and R ⁶ and R ⁷ may combine to form a ring. )

In the above formula (1), the number of carbon atoms contained in the arylene group of Ar ^{1 to} Ar ⁴ is usually 6 or more, and the upper limit thereof is usually 20 or less, preferably 10 or less, more preferably 6. is there. If the number of carbon atoms is too large, the production cost increases and the electrical characteristics may also deteriorate.
Specific examples of the arylene group of Ar ^{1 to} Ar ⁴ include 1,2-phenylene group, 1,3-phenylene group, 1,4-phenylene group, naphthylene group, anthrylene group, phenanthrylene group, and the like. Of these, a 1,4-phenylene group is preferred from the viewpoint of electrical characteristics. An arylene group may be used individually by 1 type, and may be used 2 or more types by arbitrary ratios and combinations.

Specific examples of the substituents for Ar ^{1 to} Ar ⁴ include an alkyl group, an aryl group, a halogen group, and an alkoxy group. Among them, considering the mechanical properties as a binder resin for the photosensitive layer and the solubility in the coating solution for forming the photosensitive layer, the alkyl group is preferably a methyl group, an ethyl group, a propyl group, or an isopropyl group, and is preferably an aryl group. Is preferably a phenyl group or a naphthyl group, a halogen group is preferably a fluorine atom, a chlorine atom, a bromine atom or an iodine atom, and an alkoxy group is preferably a methoxy group, an ethoxy group, a propoxy group or a butoxy group.

In addition, when a substituent is an alkyl group, carbon number of the alkyl group is usually 1 or more, and usually 10 or less, preferably 8 or less, more preferably 2 or less.
More specifically, Ar ³ and Ar ⁴ each independently preferably has a substituent number of 0 or more and 2 or less, more preferably has a substituent from the viewpoint of adhesion, and among these, substitution from the viewpoint of wear resistance. It is particularly preferable that the number of groups is one. Moreover, as a substituent, an alkyl group is preferable and a methyl group is particularly preferable.

From the above viewpoint, at least one of Ar ³ and Ar ⁴ is preferably an arylene group having a substituent.
On the other hand, Ar ¹ and Ar ² each independently preferably have 0 or more and 2 or less substituents, and more preferably have no substituents from the viewpoint of wear resistance.
In the above formula (1), when k is 1 or more, X represents a single bond, an oxygen atom, a sulfur atom, a group represented by the above formula (2), or a group represented by the above formula (3). R ¹ and R ^{2 in} Formula (2) each independently represent a hydrogen atom, an alkyl group, or an aryl group, and R ¹ and R ² are bonded to form a ring such as a cycloalkylidene group. It may be. R ³ in formula (3) is an alkylene group, an arylene group, or a group represented by the above formula (4), and R ⁴ and R ^{5 in} formula (4) are each independently an alkylene group. Ar ⁵ represents an arylene group.

In Formula (1), preferable X includes an oxygen atom, a sulfur atom, a structure represented by Formula (2), or a divalent organic residue having a structure represented by Formula (3).
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 Formula (2) include a cyclopentylidene group, a cyclohexylidene group, and a cycloheptylidene group. Furthermore, examples of the alkylene group represented by R ³ in 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.

Among these, X is preferably an oxygen atom. At that time, k is preferably 1.
In the above formula (1), Y is a single bond, an oxygen atom, a sulfur atom, or a group represented by the above formula (5).
R ⁶ and R ^{7 in} 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, R ⁶ and R ⁷ in the formula (5) are preferably phenyl groups and naphthyl groups as aryl groups, As an alkoxy group, a methoxy group, an ethoxy group, and a butoxy group are 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 for producing the polyester resin, Y is a single bond, —O—, —S—, —CH ₂ —, —CH (CH ₃ ) —, —C (CH ₃ ) ₂ — and cyclohexylene are preferable, —CH ₂ —, —CH (CH ₃ ) —, —C (CH ₃ ) ₂ — and cyclohexylene are particularly preferable, and —CH ₂ is particularly preferable. _{2 -, - CH (CH 3} ) - is.

In the electrophotographic photoreceptor used in the present invention, the polyester resin (1) is preferably a polyester resin having a repeating structure represented by the following general formula (6) when k = 1. In the following general formula (6), Ar ^{6 to} Ar ⁹ 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 (6), Ar ^{6 to} Ar ⁹ correspond to the above Ar ^{1 to} Ar ⁴ , respectively, 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 (6), Ar ⁸ and Ar ⁹ are phenylene groups having a methyl group, and Ar ⁶ and Ar ⁷ are particularly preferably phenylene groups having no substituent. R ⁸ represents a hydrogen atom or an alkyl group. The alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and particularly preferably a methyl group.

  The viscosity average molecular weight of the polyester resin used in the present invention is arbitrary as long as the effect of the present invention is not significantly impaired, but is preferably 10,000 or more, more preferably 20,000 or more, and the upper limit is preferably It is desirable that it is 70,000 or less, more preferably 50,000 or less. If the value of the viscosity average molecular weight is too small, the mechanical strength of the polyester resin may be insufficient, and if it is too large, the viscosity of the coating solution for forming the photosensitive layer may be too high and the productivity may decrease. is there. In addition, a viscosity average molecular weight can be measured by the method as described in an Example using an Ubbelohde type capillary viscometer etc., for example.

<Electron transport material>
The present invention is characterized in that the charge transport layer contains an electron transport material as a charge transport material together with a hole transport material. The electron transport material contained is the LUMO energy level E_lumo obtained as a result of structural optimization calculation by density functional calculation B3LYP / 6-31G (d, p).
E_lumo (eV)> -3.55
It is characterized by satisfying. Preferably E_lumo (eV)> -3.52.
The upper limit is −3.30> E_lumo (eV), preferably −3.33> E_lumo (eV).

By containing an electron transport material in the range of E_lumo, the residual potential of the electrophotographic photosensitive member can be reduced, which is preferable.
The content of the electron transport material is usually 0.2 parts by mass or more, preferably 0.5 parts by mass or more, and 30 parts by mass or less, preferably 20 parts by mass with respect to 100 parts by mass of the binder resin in the charge transport layer. It is as follows. When the amount is less than this range, the effect of containing the electron transport material cannot be obtained, and when the amount is more than the above range, electrical characteristics such as an increase in residual potential are observed.

  Specific examples of the electron transport material used in the present invention include the following compounds.

Among these, diphenoquinone derivatives are preferably used.
<Hole transport material>
As the hole transport material, the HOMO energy level E_homo obtained as a result of the structural optimization calculation by density functional calculation B3LYP / 6-31G (d, p) of the hole transport material is
E_homo> -4.67 (eV)
It is characterized by satisfying. E_homo> −4.65 (eV) is preferable, and E_homo> −4.63 (eV) is most preferable. The higher the HOMO energy level, the lower the post-exposure potential and the better the electrophotographic photoreceptor. On the other hand, if E_homo is too high, problems such as reduced gas resistance and ghosting occur, so E_homo <-4.30 (eV) is preferable, E_homo <-4.50 (eV) is more preferable, E_homo <-4.56 ( eV) is most preferred.

In addition, the restricted Hartree-Fock method calculation in the stable structure obtained after the structure optimization calculation by density functional calculation B3LYP / 6-31G (d, p) of the hole transport material (basic function is 6-31G (d, p )), The calculated value αcal of the polarizability α is expressed by the following equation αcal> 70 (Å ³ )
Is preferable, αcal> 80 (Å ³ ) is more preferable, and αcal> 90 (最 も³ ) is most preferable. This is because a charge transport layer containing a hole transport material having a large αcal exhibits high charge mobility, and by using the charge transport layer, an electrophotographic photoreceptor excellent in chargeability and sensitivity can be obtained. On the other hand, if αcal is too large, the solubility of the hole transport material is lowered, and therefore αcal <200 (Å ³ ), preferably αcal <150 (Å ³ ), and αcal <130 (Å ³ ) Is more preferable, and αcal <110 ( ³ ) is most preferable.
As the hole transporting material contained in the photosensitive layer of the electrophotographic photoreceptor of the present invention, specifically, a hole transporting material represented by the following general formula (7) or (8) is preferably used.

In formula (7), R ^{9 to} R ¹⁵ each represents an independent hydrogen atom, alkyl group, aryl group, or alkoxy group. n represents an integer of 1 to 3, k ′, l, q and r each independently represents an integer of 1 to 5; m, o and p each independently represents an integer of 1 to 4 .
Specifically, as R ^{9 to} R ¹⁵ , the alkyl group includes a linear alkyl group such as a methyl group, an ethyl group, an n-propyl group, and an n-butyl group, and a branched alkyl group such as an isopropyl group and an ethylhexyl group. And a cyclic alkyl group such as a cyclohexyl group, the aryl group includes an optionally substituted phenyl group, naphthyl group, etc., and the alkoxy group includes a methoxy group, an ethoxy group, n- Examples include linear alkoxy groups such as propoxy group and n-butoxy group, branched alkyl groups such as isopropoxy group and ethylhexyloxy group, and cyclohexyloxy group.

Among these, as R ⁹ and R ¹⁰ , a hydrogen atom, a methyl group, an ethyl group, a methoxy group, and an ethoxy group are preferable from the viewpoint of versatility of raw materials for production and hole transport ability as a hole transport material. The bonding position of each substituent to the benzene ring can be usually any of the o-position, m-position and p-position with respect to the styryl group, but from the viewpoint of ease of production, the o-position or p-position. Any of the positions is preferred.

Among these, as R ^{11 to} R ¹³ , a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, and an alkoxy group having 1 to 8 carbon atoms are preferable from the versatility of production raw materials. An atom, an alkyl group having 1 to 6 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms are more preferable, and a hydrogen atom and an alkyl group having 1 to 2 carbon atoms are more preferable from the viewpoint of light attenuation characteristics as an electrophotographic photosensitive member. In view of hole transport ability as a hole transport material, a hydrogen atom is particularly preferable.

Among these, as R ¹⁴ and R ¹⁵ , a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, and an alkoxy group having 1 to 8 carbon atoms are preferable from the viewpoint of versatility of the production raw material, and from the viewpoint of handleability during production. , A hydrogen atom, an alkyl group having 1 to 6 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms are more preferable. From the viewpoint of light attenuation characteristics as an electrophotographic photosensitive member, an alkyl group having 1 to 4 carbon atoms and a carbon number An alkoxy group having 1 to 4 is more preferable, an alkyl group having 1 to 4 carbon atoms is particularly preferable from the viewpoint of resistance to ozone of the electrophotographic photosensitive member, and a methyl group or ethyl group is preferable from the viewpoint of hole transport ability as a hole transport material. The group is most preferred. Furthermore, when R ^{14 to} R ¹⁵ are a methyl group or an ethyl group, the bonding position of each substituent to the benzene ring can be any position of the o-position, m-position or p-position with respect to the styryl group. However, from the viewpoint of ease of production, either the o-position or the p-position is preferable. When the total of alkyl groups such as methyl group and ethyl group for one benzene ring is 2 or more, it is preferably substituted at either o-position or p-position, from the viewpoint of electrophotographic photoreceptor characteristics, More preferably, the total number of alkyl groups is 2, and it is more preferable that the two substituents are respectively substituted at the p-position and the o-position, or both are substituted at the o-position.

k ′, l, q, and r each independently represent an integer of 1 to 5, and m, o, and p each independently represents an integer of 1 to 4. When k ′, l, m, o, p, q, and r each represent an integer of 2 or more, a plurality of R ^{1 to} R ⁷ bonded to the benzene ring may be different from each other, and bonded to the benzene ring. The plurality of R ^{9 to} R ¹⁵ may also be different from each other.
n represents an integer of 1 to 3. When n increases, the solubility in the coating solvent tends to decrease, and thus it is preferably 1 or 2, and more preferably 2 from the viewpoint of the hole transport ability as a hole transport material.

  The arylene group portion to which the diphenylamino group is bonded represents a phenylene group when n = 1, a biphenylene group when n = 2, or a terphenylene group when n = 3. The position at which the two diphenylamino groups are bonded to the arylene group is not limited as long as the effect of the present invention is not significantly impaired. However, when n = 1, the two diphenylamino groups have two diphenylamino groups from the viewpoint of the chargeability of the electrophotographic photosensitive member. It is preferable that the m-position relationship is established at the bonding position of the phenylene group. In the case of n = 2, from the viewpoint of hole transport ability as a hole transport material, the position where the diphenylamino group is bonded to the biphenylene group is preferably bonded to the 4th and 4 ′ positions of the biphenylene group, and n = In the case of 3, the p-terphenylene group is preferable among the terphenylene groups because of the versatility of the raw materials for production, and the bonding position of the diphenylamine group to the p-terphenylene group is from the viewpoint of the hole transport ability as a hole transport material. Bonding at the 4th and 4 ″ positions is preferred.

In addition, the electrophotographic photoreceptor of the present invention may usually contain a compound represented by the formula (7) as a single component in the photosensitive layer, or a compound having a different structure represented by the formula (7). You may contain as a mixture of these. As a mixture, in the case where a plurality of so-called positional isomers, in which only the substitution positions of R ^{9 to} R ¹⁵ are different, are mixed in the structure represented by the formula (7), the electronic states are close to each other and the charge transport trap In addition to being difficult to become, it is preferable from the viewpoint of suppressing crystal formation in the coating solution or film. As the positional isomers, it is more preferable to use a mixture of R ⁹ and R ¹⁰ having different substitution positions from the viewpoint of ease of synthesis of the compound, and the substitution positions of R ⁹ and R ¹⁰ are the o positions. , P-position is most preferably used in combination.

In the formula ^(8), each of R 16 ^{to R 20} independently hydrogen atom, an alkyl group, an aryl group, an alkoxy group. s, t, and u represent integers of 1 to 5, and v and w represent integers of 1 to 4, respectively.
Specifically as R < ¹⁶ > -R < ²⁰ >, as an alkyl group, linear alkyl groups, such as a methyl group, an ethyl group, n-propyl group, n-butyl group, branched alkyl groups, such as an isopropyl group and an ethylhexyl group And a cyclic alkyl group such as a cyclohexyl group, the aryl group includes an optionally substituted phenyl group, naphthyl group, etc., and the alkoxy group includes a methoxy group, an ethoxy group, n- Examples include linear alkoxy groups such as propoxy group and n-butoxy group, branched alkyl groups such as isopropoxy group and ethylhexyloxy group, and cyclohexyloxy group.

Among these, as R ¹⁶ , a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, and an alkoxy group having 1 to 8 carbon atoms are preferable from the viewpoint of versatility of production raw materials, and a hydrogen atom from the viewpoint of handleability during manufacturing. , More preferably an alkyl group having 1 to 6 carbon atoms and an alkoxy group having 1 to 6 carbon atoms. From the aspect of light attenuation characteristics as an electrophotographic photosensitive member, an alkyl group having 1 to 4 carbon atoms and 1 to 4 carbon atoms are preferred. Are more preferable, from the viewpoint of resistance to ozone of the electrophotographic photoreceptor, an alkyl group having 1 to 4 carbon atoms is particularly preferable, and from a solubility aspect, a linear or branched alkyl group having 3 to 4 carbon atoms is preferable. Most preferred. Further, when R ¹⁶ is an alkyl group, the substituent can be bonded to the benzene ring at any position of the o-position, m-position or p-position with respect to the styryl group. In view of the above, the o-position and / or the p-position are preferable.

Among these, as R ¹⁷ and R ¹⁸ , a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, and an alkoxy group having 1 to 8 carbon atoms are preferable from the versatility of production raw materials. An atom, an alkyl group having 1 to 6 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms are more preferable, and a hydrogen atom and an alkyl group having 1 to 2 carbon atoms are more preferable from the viewpoint of light attenuation characteristics as an electrophotographic photosensitive member. In view of hole transport ability as a hole transport material, a hydrogen atom is particularly preferable.

Among these, R ¹⁹ and R ²⁰ are preferably a hydrogen atom, a methyl group, an ethyl group, a methoxy group, and an ethoxy group from the viewpoints of versatility of raw materials for production and hole transport capability as a hole transport material. The bonding position of each substituent to the benzene ring can be usually any of the o-position, m-position and p-position with respect to the styryl group, but from the viewpoint of ease of production, the o-position or p-position. Any of the positions is preferred.
Examples of the structure of the hole transport material suitable for the present invention are shown below. The following structures are illustrated to make the present invention more concrete, and are not limited to the following structures unless departing from the concept of the present invention.

  The amount of the hole transporting material contained in the present invention is arbitrary as long as the effects of the present invention are not significantly impaired. However, if the amount is too small, it is disadvantageous for charge transport and the electrical characteristics are deteriorated. Therefore, it is usually 20 parts by weight or more, preferably 30 parts by weight or more, and too much for 100 parts by weight of the binder resin in the photosensitive layer. And the glass point transfer point (Tg) is too low, and the wear resistance may be deteriorated, so that it is usually 200 parts by mass or less, preferably 150 parts by mass or less.

Next, the electrophotographic photoreceptor of the present invention will be described including other components.
[I. Electrophotographic photoreceptor]
The photoreceptor of the present invention is a multilayer photoreceptor in which a charge generation layer and a charge transport layer are usually provided on a conductive support (also referred to as “conductive substrate”).
[I-1. Conductive support]
There is no particular limitation on the conductive support, but for example, metal materials such as aluminum, aluminum alloy, stainless steel, copper, and nickel, and conductive powder 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. These may be used alone or in combination of two or more in any combination and ratio. As a form of the conductive support, a drum form, a sheet form, a belt form or the like is used. Further, a conductive material having an appropriate resistance value may be used on a conductive support made of a metal material in order to control conductivity and surface properties and to cover defects.

Moreover, when using metal materials, such as an aluminum alloy, as an electroconductive support body, you may use, after giving an anodic oxide film. When an anodized film is applied, it is desirable to perform a sealing treatment by a known method.
The surface of the support may be smooth, or may be roughened by using a special cutting method or performing a polishing treatment. Further, it may be roughened by mixing particles having an appropriate particle diameter with the material constituting the support. Also, for cost reduction,
It is also possible to use the drawing tube as it is without performing the cutting treatment.

[I-2. Undercoat layer]
An undercoat layer may be provided between the conductive support and the photosensitive layer in order to improve adhesion and blocking properties. As the undercoat layer, known examples disclosed in JP-A-2007-293319 can be used.
[I-3. Photosensitive layer]
As for the laminated type photosensitive layer, a charge generation layer and a charge transport layer are laminated in this order from the conductive support side, and a charge transport layer and a charge generation layer are laminated in this order from the conductive support side. Any one of them can be adopted, but a normal multilayer photosensitive layer that can exhibit the most balanced photoconductivity is preferable.

In the charge generation layer and the charge transport layer, a binder resin is used to ensure film strength.
In the case of a charge transport layer, it can be obtained by applying and drying a coating solution obtained by dissolving or dispersing a charge transport material and a binder resin in a solvent.
[I-3-1. Charge transport layer]
<Binder resin>
The binder resin of the charge transport layer of the present invention contains the polyarylate resin described above. The binder resin may be mixed with other resins as long as the effects of the present invention are not impaired. Examples of the other resins include butadiene resins, styrene resins, vinyl acetate resins, vinyl chloride resins, and acrylate esters. Polymers and copolymers of vinyl compounds such as resins, methacrylic ester resins, vinyl alcohol resins, ethyl vinyl ether, polyvinyl butyral resins, polyvinyl formal resins, partially modified polyvinyl acetals, polyamide resins, polyurethane resins, polycarbonate resins, cellulose ester resins , Phenoxy resin, silicon resin, silicon-alkyd resin, poly-N-vinylcarbazole resin, and the like. These binder resins can be used by crosslinking with an appropriate curing agent by heat, light or the like, and may be modified with a silicon reagent or the like. In that case, it is preferable that the ratio of polyarylate resin is 50 mass% or more.

[I-3-2. Charge generation layer]
The charge generation 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 generation material>
As an example of the charge generation material, a known material disclosed in Japanese Patent Application Laid-Open No. 2007-293319 can be used. Of these materials, metal-containing phthalocyanines containing a metal at the center of the phthalocyanine ring are preferable. Among metal-containing phthalocyanines, A-type (β-type), B-type (α-type), and D-type (Y-type) oxytitanium. More preferred are phthalocyanine, II-type chlorogallium phthalocyanine, V-type hydroxygallium phthalocyanine, G-type μ-oxo-gallium phthalocyanine dimer, etc. A-type (β-type), B-type (α-type), D-type (Y-type) More preferred is oxytitanium phthalocyanine.
In particular, it is preferable that oxytitanium phthalocyanine has a clear diffraction peak mainly at a Bragg angle (2θ ± 0.2 °) of 27.2 ° in a powder X-ray diffraction spectrum by CuKα characteristic X-ray.

In addition, the oxytitanium dirocyanine has a clear diffraction peak at a Bragg angle (2θ ± 0.2 °) of 9.0 ° to 9.7 ° in a powder X-ray diffraction spectrum by CuKα characteristic X-ray. ,preferable.
When an azo pigment is used as the charge generation material, various known bisazo pigments and trisazo pigments are preferably used.

  As the pigment used as the charge generation material, a preferable material may be determined depending on the exposure wavelength used. When the exposure wavelength is in the short wavelength region of about 380 nm to 500 nm, the above azo pigment is preferably used. On the other hand, when near-infrared light of about 630 to 780 nm is used, a phthalocyanine pigment having high sensitivity also in that region and a part of azo pigments are preferably used. On the other hand, even when environmental characteristics such as humidity dependency are required to be small, the Bragg angle (2θ ± 0.2 °) is set to 9.0 ° to 9.7 ° in the powder X-ray diffraction spectrum by CuKα characteristic X-ray. Since oxytitanium phthalocyanine having a clear diffraction peak is highly dependent on humidity, the above azo pigment is preferably used.

It is desirable that the particle size of the charge generating material used is sufficiently small. Specifically, it is usually 1 μm or less, preferably 0.5 μm or less.
Furthermore, if the amount of the charge generating material dispersed in the photosensitive layer is too small, sufficient sensitivity may not be obtained. If the amount is too large, the chargeability may decrease, the sensitivity may decrease, the smoothness may decrease due to aggregation, etc. There are harmful effects. Therefore, the amount of the charge generating material in the charge generating layer of the multilayer photosensitive layer is usually 20% by weight or more, preferably 40% by weight or more, and usually 90% by weight or less, preferably 70% by weight or less.

<Binder resin>
The binder resin used for the charge generation layer is not particularly limited. For example, a known material disclosed in Japanese Patent Application Laid-Open No. 2007-293319 can be used.
Specifically, the charge generation layer is prepared by dispersing a charge generation material in a solution obtained by dissolving the above-described binder resin in an organic solvent to prepare a coating solution, which is then formed on a conductive support (when an undercoat layer is provided). Is formed by coating (on the undercoat layer).
Next, other components of the photosensitive layer will be described.

[I-3-3. Other components]
Furthermore, the photosensitive layer may contain various additives. These additives are used to improve film formability, flexibility, mechanical strength, and the like. For example, plasticizers, short-wavelength light absorbers such as ultraviolet rays, antioxidants, and residual potential are suppressed. For example, residual potential inhibitors for improving dispersion stability, leveling agents for improving coating properties (for example, silicone oil, fluorine-based oil, etc.), surfactants and the like. In addition, 1 type may be used for an additive and it may use 2 or more types together by arbitrary combinations and a ratio.

[I-3-4. Film thickness]
In the photoreceptor of the present invention, the thickness of the photosensitive layer is not particularly limited as long as the effects of the present invention are not significantly impaired. In the case of a multilayer photoreceptor, the charge generation layer is preferably 0.1 μm or more and 1 μm. The charge transport layer is usually 5 μm or more, preferably 10 μm or more, and usually 40 μm or less, preferably 35 μm or less, more preferably 0.2 μm or more and 0.8 μm or less. The charge transport layer may be formed not only from a single layer but also from two or more different layers.

[I-4. Other layers]
A protective layer may be provided as the outermost surface layer on the photosensitive layer. Moreover, you may add an additive suitably to the said protective layer. Examples thereof include resin particles such as fluorine resin, silicone resin, and cross-linked polystyrene resin, and inorganic particles such as alumina particles and silica particles. Further, when the thickness of the protective layer is greater than 1 μm, the physical properties of the protective layer dominate the surface mechanical properties more than the influence of the lower layer. Therefore, the material used for the lower photosensitive layer is within the range specified in the present invention. Any known material may be used regardless of the above.

[I-5. Formation method of each layer]
There are no limitations on the method of forming each layer such as the undercoat layer, the photosensitive layer, and the protective layer. For example, a known method such as applying a coating solution obtained by dissolving or dispersing a material contained in a layer to be formed in a solvent directly onto a conductive support directly or via another layer is applied. it can. After coating, the photosensitive layer is formed by removing the solvent by drying.

  In this case, the coating method is not limited and may be arbitrary. For example, a dip coating method, a spray coating method, a nozzle coating method, a bar coating method, a roll coating method, a blade coating method, or the like can be used. Among these, the dip coating method is preferable because of its high productivity. Note that these coating methods may be performed by only one method, or may be performed by combining two or more methods.

[I-6. Photoconductor charging type]
The photoreceptor of the present invention is used for image forming applications by being used in an image forming apparatus described later. The laminated photoreceptor of the present invention is used with negative charging.
[I-7. Photoconductor exposure wavelength]
When forming an image, the photosensitive member of the present invention is exposed to writing light from an exposure unit to form an electrostatic latent image. The writing light used at this time is arbitrary as long as an electrostatic latent image can be formed, but monochromatic light having an exposure wavelength of usually 380 nm or more, particularly 400 nm or more and usually 850 nm or less is used. In particular, when monochromatic light of 480 nm or less is used, the photosensitive member can be exposed with light having a smaller spot size, and a high-quality image having high resolution and high gradation can be formed. When it is desired to obtain the light, exposure with monochromatic light of 480 nm or less is preferable.

[II. Image forming apparatus, process cartridge]
Next, an embodiment of an image forming apparatus using the electrophotographic photosensitive member of the present invention (an image forming apparatus of the present invention) will be described with reference to FIG. However, the embodiment is not limited to the following description, and can be arbitrarily modified without departing from the gist of the present invention.

As shown in FIG. 1, the image forming apparatus includes an electrophotographic photoreceptor 1, a charging device (charging means) 2, an exposure device (exposure means; image exposure means) 3, and a developing device (developing means) 4. Furthermore, a transfer device (transfer means) 5, a cleaning unit 6, and a fixing device (fixing means) 7 are provided as necessary.
The electrophotographic photoreceptor 1 is not particularly limited as long as it is the above-described electrophotographic photoreceptor of the present invention, but in FIG. 1, as an example, a drum in which the above-described photosensitive layer is formed on the surface of a cylindrical conductive support. The photoconductor is shown. A charging device 2, an exposure device 3, a developing device 4, a transfer device 5 and a cleaning unit 6 are arranged along the outer peripheral surface of the electrophotographic photosensitive member 1.

The charging device 2 charges the electrophotographic photosensitive member 1 and uniformly charges the surface of the electrophotographic photosensitive member 1 to a predetermined potential. In FIG. 1, a roller-type charging device (charging roller) is shown as an example of the charging device 2, but other corona charging devices such as corotron and scorotron, and contact-type charging devices such as charging brushes are often used.
The electrophotographic photosensitive member 1, the charging device 2, and the cleaning unit 6 are often used as cartridges (electrophotographic photosensitive member cartridge of the present invention, hereinafter referred to as “process cartridge” as appropriate) from the main body of the image forming apparatus. Designed to be removable and replaceable. For example, when the electrophotographic photosensitive member 1, the charging device 2, and the cleaning unit 6 are deteriorated, the process cartridge can be removed from the image forming apparatus main body, and another new process cartridge can be mounted on the image forming apparatus main body. It has become. Also, the toner described later is often stored in the toner cartridge and designed to be removable from the main body of the image forming apparatus. When the toner in the used toner cartridge runs out, this toner cartridge is removed. It can be removed from the main body of the image forming apparatus and another new toner cartridge can be mounted. Further, a process cartridge equipped with all of the electrophotographic photosensitive member 1, the charging device 2, the cleaning unit 6, and the toner may be used.

  The type of exposure apparatus 3 is not particularly limited as long as it can form an electrostatic latent image on the photosensitive surface of the electrophotographic photosensitive member 1 by performing exposure (image exposure) on the electrophotographic photosensitive member 1. Absent. Specific examples include halogen lamps, fluorescent lamps, lasers such as semiconductor lasers and He—Ne lasers, and LEDs (light emitting diodes). Further, exposure may be performed by a photoreceptor internal exposure method. The light used for the exposure is arbitrary, but is generally preferably monochromatic light. For example, monochromatic light with a wavelength (exposure wavelength) of 700 nm to 850 nm, monochromatic light with a wavelength of 600 nm to 700 nm slightly shorter, or with a wavelength of 300 nm to 500 nm. Exposure may be performed with short-wave monochromatic light or the like.

  The type of the developing device 4 is not particularly limited as long as it can develop the exposed electrostatic latent image on the electrophotographic photosensitive member 1 into a visible image. As a specific example, an arbitrary apparatus such as a dry development system such as cascade development, one-component conductive toner development, or two-component magnetic brush development, or a wet development system can be used. In FIG. 1, the developing device 4 includes a developing tank 41, an agitator 42, a supply roller 43, a developing roller 44, and a regulating member 45, and has a configuration in which toner T is stored inside the developing tank 41. . Further, a replenishing device (not shown) for replenishing the toner T may be attached to the developing device 4 as necessary. The replenishing device is configured to be able to replenish toner T from a container such as a bottle or a cartridge.

The supply roller 43 is formed from a conductive sponge or the like. The developing roller 44 is made of a metal roll such as iron, stainless steel, aluminum, or nickel, or a resin roll obtained by coating such a metal roll with a silicone resin, a urethane resin, a fluorine resin, or the like. The surface of the developing roller 44 may be smoothed or roughened as necessary.
The developing roller 44 is disposed between the electrophotographic photoreceptor 1 and the supply roller 43 and is in contact with the electrophotographic photoreceptor 1 and the supply roller 43, respectively. However, the developing roller 44 and the electrophotographic photosensitive member 1 may not be in contact with each other but may be close to each other. The supply roller 43 and the developing roller 44 are rotated by a rotation drive mechanism (not shown). The supply roller 43 carries the stored toner T and supplies it to the developing roller 44. The developing roller 44 carries the toner T supplied by the supply roller 43 and contacts the surface of the electrophotographic photosensitive member 1.

  The regulating member 45 is formed of a resin blade such as silicone resin or urethane resin, a metal blade such as stainless steel, aluminum, copper, brass, phosphor bronze, or a blade obtained by coating such metal blade with resin. The regulating member 45 normally abuts on the developing roller 44 and is pressed against the developing roller 44 side with a predetermined force by a spring or the like (a general blade linear pressure is 0.05 to 5 N / cm). If necessary, the regulating member 45 may be provided with a function of imparting charging to the toner T by frictional charging with the toner T.

The agitator 42 is provided as necessary, and is rotated by a rotation driving mechanism, and agitates the toner T and conveys the toner T to the supply roller 43 side. A plurality of agitators 42 may be provided with different blade shapes and sizes.
The type of the transfer device 5 is not particularly limited, and an apparatus using an arbitrary system such as an electrostatic transfer method such as corona transfer, roller transfer, or belt transfer, a pressure transfer method, or an adhesive transfer method can be used. . Here, it is assumed that the transfer device 5 includes a transfer charger, a transfer roller, a transfer belt, and the like disposed so as to face the electrophotographic photoreceptor 1. The transfer device 5 applies a predetermined voltage value (transfer voltage) having a polarity opposite to the charging potential of the toner T, and transfers a toner image formed on the electrophotographic photosensitive member 1 to a recording paper (paper, medium, transfer target). Transfer to P.

The cleaning unit 6 collects residual toner adhering to the photoreceptor 1 by scraping it off with a cleaning blade and storing it in a recovery container. The cleaning blade includes an elastic rubber member and a support member, and an edge member may be further provided on the photosensitive member contact portion of the elastic rubber member as necessary. Generally, polyurethane is used for these cleaning blade members. This is because polyurethane is an elastic body, has good wear resistance, has sufficient mechanical strength without adding a reinforcing agent, and is non-staining. However, it is known that the physical properties of polyurethane have temperature dependence. The temperature dependence appears particularly in the resilience and is a problem in cleaning. That is, when the impact resilience is lowered at a low temperature, a cleaning failure is caused. Therefore, it is desired to provide a highly functional cleaning blade that has sufficiently stable rebound resilience even when the environment changes. In particular, since the temperature inside the device is likely to rise with the recent downsizing of the device, such a reduction in the temperature dependence of the resilience is increasingly required. In order to obtain such a resilience polyurethane, the elastic rubber member or edge member is made of a polyester polyol obtained by reacting adipic acid and a diol component, or a polyurethane made from a caprolactone polyester polyol as a raw material. However, it is preferable from the viewpoint of improving the cleaning efficiency. The properties of polyurethane are: 100% permanent elongation is 3% or less, rebound resilience at 25 ° C is 20% or less, and the difference between the maximum and minimum rebound resilience between 10 ° C and 50 ° C is 30% or less. It is preferable that
Further, from the viewpoint of improving the cleaning property, it is preferable that the cleaning blade counter-contacts the photoconductor.

  The fixing device 7 includes an upper fixing member (fixing roller) 71 and a lower fixing member (fixing roller) 72, and a heating device 73 is provided inside the fixing member 71 or 72. FIG. 1 shows an example in which a heating device 73 is provided inside the upper fixing member 71. Each of the upper and lower fixing members 71 and 72 includes a fixing roll in which a metal base tube such as stainless steel or aluminum is coated with silicon rubber, a fixing roll in which Teflon (registered trademark) resin is coated, and a fixing sheet. A member can be used. Further, each of the fixing members 71 and 72 may be configured to supply a release agent such as silicone oil in order to improve releasability, or may be configured to forcibly apply pressure to each other by a spring or the like.

When the toner transferred onto the recording paper P passes between the upper fixing member 71 and the lower fixing member 72 heated to a predetermined temperature, the toner is heated to a molten state and cooled after passing through the recording paper. Toner is fixed on P.
The type of the fixing device is not particularly limited, and a fixing device of any type such as heat roller fixing, flash fixing, oven fixing, pressure fixing, etc. can be provided including those used here.

  In the electrophotographic apparatus configured as described above, a charging step for charging the photosensitive member, an exposure step for exposing the charged photosensitive member to form an electrostatic latent image, and developing the electrostatic latent image with toner. An image is recorded by performing a developing process and a transferring process for transferring the toner to the transfer target. That is, first, the surface (photosensitive surface) of the photoreceptor 1 is charged to a predetermined potential by the charging device 2 (charging process). At this time, charging may be performed by a DC voltage, or charging may be performed by superimposing an AC voltage on the DC voltage.

Subsequently, the photosensitive member is exposed to form an electrostatic latent image (exposure process). That is, the photosensitive surface of the charged photoreceptor 1 is exposed by the exposure device 3 according to the image to be recorded, and an electrostatic latent image is formed on the photosensitive surface.
Then, development of the electrostatic latent image formed on the photosensitive surface of the photoreceptor 1 is performed by the developing device 4 (developing process). The developing device 4 thins the toner T supplied by the supply roller 43 by a regulating member (developing blade) 45 and has a predetermined polarity (here, the same polarity as the charging potential of the photosensitive member 1) and positive polarity. ), And conveyed while being carried on the developing roller 44 to be brought into contact with the surface of the photoreceptor 1. When the charged toner T carried on the developing roller 44 comes into contact with the surface of the photoreceptor 1, a toner image corresponding to the electrostatic latent image is formed on the photosensitive surface of the photoreceptor 1.

The toner image is transferred to the recording paper P by the transfer device 5 (transfer process). Thereafter, the toner remaining on the photosensitive surface of the photoreceptor 1 without being transferred is removed by the cleaning unit 6.
After the transfer of the toner image onto the recording paper P, the final image is obtained by passing the fixing device 7 and thermally fixing the toner image onto the recording paper P.

  In addition to the above-described configuration, the image forming apparatus may have a configuration capable of performing, for example, a static elimination process. The neutralization step is a step of neutralizing the electrophotographic photosensitive member by exposing the electrophotographic photosensitive member, and a fluorescent lamp, an LED, or the like is used as the neutralizing device. In addition, the light used in the static elimination process is often light having an exposure energy that is at least three times that of the exposure light.

  The image forming apparatus may be further modified. For example, the image forming apparatus may be configured to perform a pre-exposure process, an auxiliary charging process, or the like, or may be configured to perform offset printing. A full-color tandem system configuration using toner may be used.

Hereinafter, the present invention will be described in more detail with reference to 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 departing from the gist thereof. Note that “parts” used in the present examples indicate “parts by mass” unless otherwise specified.
[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 (weight 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 weight 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.
As a charge generation material, 20 parts of titanium oxyphthalocyanine having a powder X-ray diffraction spectrum pattern with respect to CuKα characteristic X-ray shown in FIG. 2 and 280 parts of 1,2-dimethoxyethane are mixed and pulverized in a sand grind mill for 2 hours to form fine particles Dispersion processing was performed. Subsequently, 400 parts of a 2.5% 1,2-dimethoxyethane solution of polyvinyl butyral (trade name “Denkabutyral” # 6000C, manufactured by Denki Kagaku Kogyo Co., Ltd.) and 170 parts of 1,2-dimethoxyethane were mixed. To prepare a dispersion. This dispersion was applied onto the undercoat layer with a bar coater to form a charge generation layer so that the film thickness after drying was 0.4 μm.
Next, on this film, 40 parts of a hole transport material (1) having the following structure, 100 parts of a binder resin (1) having the following structure (viscosity average molecular weight: 37000), and an electron transport material having the following structure (1) 2 parts, 8 parts of an antioxidant having the following structure, and 0.05 part of silicone oil as a leveling agent dissolved in 640 parts of a tetrahydrofuran / toluene (8/2) mixed solvent (coating liquid I-1) And dried at 125 ° C. for 20 minutes, and a charge transport layer was provided so that the film thickness after drying was 18 μm to prepare a photoreceptor. This photoreceptor is referred to as a photoreceptor I-1.

[Comparative Example 1]
A photoreceptor I-0 was obtained in the same manner as in Example 1 except that the electron transport material (1) was not added.
[Example 2]
A photoconductor I-2 was obtained in the same manner as in Example 1 except that the electron transport material was changed to the electron transport material (2) having the following structure.

Example 3
A photoconductor I-3 was obtained in the same manner as in Example 1 except that the electron transport material was changed to the electron transport material (3) having the following structure.

[Comparative Example 2]
A photoconductor I-4 was obtained in the same manner as in Example 1 except that the electron transport material was changed to the electron transport material (4) having the following structure.

[Comparative Example 3]
A photoconductor I-5 was obtained in the same manner as in Example 1 except that the electron transport material was changed to the electron transport material (5) having the following structure.

[Comparative Example 4]
Except that the hole transport material (2) having the following structure was used as the hole transport material, the same operation as in Comparative Example 1 was performed to obtain Photosensitive II-0.

Example 4
Except for the addition of the electron transport material (1), the same operation as in Comparative Example 4 was performed to obtain Photosensitive II-1.
Example 5
A photoconductor II-2 was obtained in the same manner as in Example 4 except that the electron transport material (6) having the following structure was used as the electron transport material.

[Comparative Example 5]
A photoreceptor III-0 was obtained in the same manner as in Comparative Example 1 except that the hole transport material was changed to the hole transport material (3) having the following structure.

Example 6
Except for the use of the electron transport material (6), the same operation as in Comparative Example 5 was performed to obtain Photoreceptor III-
1 was obtained.
[Comparative Example 6]
A photoreceptor IV-0 was obtained in the same manner as in Comparative Example 1 except that the hole transport material was changed to the hole transport material (4) having the following structure.

Example 7
Except for using the electron transport material (6), the same operation as in Comparative Example 6 was performed to obtain a photoreceptor IV-1.
[Comparative Example 7]
Except that the binder resin (1) was changed to the binder resin (2) having the following structure in Comparative Example 1, the same operation as in Comparative Example 1 was performed to obtain a photoreceptor V-0.

Example 8
Except for adding the electron transport material (1) having the above structure, the same operation as in Comparative Example 7 was performed to obtain a photoreceptor V-1.

[Comparative Example 8]
Except that the binder resin (1) was changed to the binder resin (3) having the following structure in Comparative Example 1, the same operations as in Comparative Example 1 were performed to obtain a photoreceptor VI-0.

Example 9
A photoreceptor VI-1 was obtained in the same manner as in Comparative Example 8, except that the electron transport material (6) having the above structure was added.
[Comparative Example 9]
A photoreceptor VI-2 was obtained in the same manner as in Comparative Example 8, except that the electron transport material (5) having the above structure was added.

Example 10
In Example 5, except that the addition amount of the electron transport material (6) was 20 parts, the same operation as in Example 5 was performed to obtain a photoreceptor II-3.
Example 11
In Example 1, except that the addition amount of the electron transport material (1) was 0.5 part, the same operation as in Example 1 was carried out to obtain a photoreceptor I-6.

Example 12
In Example 6, except that the addition amount of the electron transport material (6) was 0.2 part, the same operation as in Example 6 was performed to obtain a photoreceptor III-2.
[Comparative Example 10]
A photoreceptor VII-0 was obtained in the same manner as in Comparative Example 8, except that the hole transport material (1) was changed to the hole transport material (4) having the above structure in Comparative Example 8.

[Comparative Example 11]
A photoreceptor VII-1 was obtained in the same manner as in Comparative Example 10 except that the electron transport material (5) having the above structure was added.
[Comparative Example 12]
In Comparative Example 1, except that the binder resin was changed to a binder resin (4) having the following structure, which was a polycarbonate resin, the same operation as in Comparative Example 1 was performed to obtain a photoreceptor VIII-0.

[Comparative Example 13]
A photoreceptor VIII-1 was obtained in the same manner as in Comparative Example 12, except that 2 parts of the electron transport material (1) was added.
[Comparative Example 14]
Photoreceptor IX- was prepared in the same manner as in Comparative Example 1 except that 40 parts of each of hole transport substances (5) and (6) having the following structure were used as the hole transport substance and that the binder resin was changed to (3) above. 0 was obtained.

[Comparative Example 15]
A photoconductor IX-1 was obtained in the same manner as in Comparative Example 14, except that 2 parts of the above (2) was used as the electron transport material.
The values of HOMO energy level E_homo and polarizability αcal of the hole transport materials (1) to (6) used in Examples and Comparative Examples are shown in Table 1 below.

  Moreover, the value of the LUMO energy level E_lumo of the electron transport materials (1) to (6) used in Examples and Comparative Examples is shown in Table 2 below.

<Electrical characteristics test>
Each photoconductor produced was affixed to an aluminum drum to establish electrical continuity between the aluminum drum and the aluminum vapor deposition layer of the photoconductor. It was mounted on the basis and application of photographic technology, edited by Electrophotographic Society, Corona, page 404-405), and electrical characteristics were evaluated by charging, exposure, potential measurement, and static elimination cycles.

In an environment of a temperature of 25 ° C. and a humidity of 50%, first, the photosensitive member was charged so that the initial surface potential was −700 V, and the halogen lamp light was changed to a monochromatic light of 780 nm by an interference filter and used as exposure light. Next, it exposed with the following exposure energy and measured the surface potential.
The surface potential when exposure light was irradiated at 0.2 μJ / cm ² was VL, and the time from exposure to potential measurement was 100 milliseconds. 660 nm LED light was used for the static elimination light.

  Table 3 shows the residual potential (ΔVR) from the comparative example not containing an electron transporting material, after the residual electric potential of each photoconductor manufactured in the examples and comparative examples after irradiation with static elimination light. When the residual potential is suppressed and lowered compared to the comparative example not containing due to the inclusion of the electron transport material, it is (-), and conversely, when the rise is worsened, (+) is compared with the comparative example. The difference was shown.

<Light fatigue test>
Subsequently, the photoreceptors I-0, 1 and II-0, 2 are irradiated with white fluorescent light (Neolmi Super FL20SS / W / 18 manufactured by Mitsubishi OSRAM), and the light intensity on the photoreceptor surface is 2000 lux. After adjustment, the sample was irradiated for 10 minutes, and then left in the dark for 10 minutes, and the same measurement was performed.
Table 3 shows the value of change in electrical characteristics (light fatigue) ΔVL of the initial surface potential VL before and after irradiation with the white fluorescent lamp. A negative numerical value indicates that the absolute value of each potential after light irradiation is smaller than the absolute value of the potential before light irradiation. It is preferable that the absolute value of the change ΔVL is small, indicating that the change in each potential is small even when light with high intensity is irradiated.

As can be seen from the above table, the residual potential is higher when the LUMO energy level E_lumo is −3.55 or less (Comparative Examples 2, 3, 9, and 11) than when it does not contain an electron transport material. It is not preferable because it deteriorates or does not improve. When the binder resin is a polycarbonate resin (Comparative Examples 12 and 13), it can be seen that the effect of containing the electron transport material is small when compared with the same hole transport material. Further, in the case where the value of E_homo of the hole transport material is −4.67 or less (Comparative Examples 14 and 15), the residual potential is not improved even if the electron transport material is contained.

  Furthermore, it can be seen that the inclusion of an electron transport material reduces the potential change (light fatigue) after irradiation with intense light.

1 Photoconductor
2 Charging device (charging roller)
3 Exposure equipment
4 Development device
5 Transfer device
6 Cleaning device
7 Fixing device
41 Developer tank
42 Agitator
43 Supply roller
44 Developing roller
45 Restriction 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 photosensitive member having a laminated photosensitive layer on a conductive support,
The charge transport layer of the laminated photosensitive layer contains an electron transport material, a hole transport material, and a polyarylate resin,
Electron transporting material density functional calculation B3LYP / 6-31G (d, p) energy level E_lumo the resulting LUMO of structural optimization calculation by the following formula
-3.30> E_lumo (eV)> -3.55
A diphenoquinone derivative satisfying
And the energy level E_homo of HOMO obtained as a result of structural optimization calculation by density functional calculation B3LYP / 6-31G (d, p) of the hole transport material is
E_homo> -4.67 (eV)
An electrophotographic photoreceptor characterized by satisfying   2. The electrophotographic photosensitive member according to claim 1, wherein the content of the electron transport material is 0.2 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the binder resin of the charge transport layer. Restricted Hartree-Fock calculation in stable structure obtained after structure optimization calculation by density functional calculation B3LYP / 6-31G (d, p) of the hole transport material (basic function is 6-31G (d, p) ), The calculated value αcal of the polarizability α is expressed as αcal> 70 (Å ³ )
The electrophotographic photoreceptor according to claim 1, wherein the electrophotographic photoreceptor is satisfied. The electrophotographic photoreceptor according to any one of claims 1 to 3 , wherein the polyarylate resin is represented by the following general formula (1).

(In the formula (1), Ar ^{1 to} Ar ⁴ each independently represents an arylene group which may have a substituent, and X represents a single bond, an oxygen atom, a sulfur atom, or the following formula (2). Or a group represented by the following formula (3): R ¹ and R ^{2 in} formula (2) each independently represent a hydrogen atom, an alkyl group, or an aryl group, and R ¹ and R ² May combine with each other to form a ring.
R ³ in the formula (4) is an alkylene group, an arylene group, or a group represented by the following formula (4), and R ⁴ and R ⁵ in the formula (4) each independently represent an alkylene group, Ar ⁵ represents an arylene group. k represents an integer of 0 or more. Y is a single bond, an oxygen atom, a sulfur atom, or a group represented by the following formula (5). In the formula (5), R ⁶ and R ⁷ are each independently a hydrogen atom, an alkyl group, It represents an alkoxy group or an aryl group, and R ⁶ and R ⁷ may be bonded to form a ring. )

Forming an electrophotographic photosensitive member according to any one of claims 1 to 4, charging means for charging the electrophotographic photoreceptor, an electrostatic latent image performs image exposure to the charged electrophotographic photosensitive member An electrophotographic cartridge comprising: an image exposure unit; a developing unit that develops the electrostatic latent image with toner; and a transfer unit that transfers the toner to a transfer target. An electrophotographic photosensitive member according to any one of claims 1 to 4, a charging means for charging the electrophotographic photoreceptor, exposing means for forming an electrostatic latent image by exposure to charged electrophotographic photosensitive member And a developing unit that develops the electrostatic latent image with toner, a transfer unit that transfers the toner to a transfer target, and a fixing unit that fixes the toner transferred to the transfer target. Image forming apparatus.

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