JP5309465B2 - Electrophotographic photosensitive member and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a single-layer type electrophotographic photoreceptor on which coating liquid for forming a photosensitive layer is superior in stability and which has excellent electric characteristics, and an image forming apparatus equipped with the photoreceptor. <P>SOLUTION: The electrophotographic photoreceptor having a single-layer type photosensitive layer on a conductive base is characterized in that the photosensitive layer contains at least two or more kinds of triaryl-amine based diamine compounds having different chemical structures. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to an electrophotographic photosensitive member and an image forming apparatus used for a copying machine, a printer, and the like. More specifically, the present invention relates to a single-layer electrophotographic photoreceptor excellent in the stability of a coating solution for forming a photosensitive layer and having good electrical characteristics, and an image forming apparatus including the photoreceptor.

  Electrophotographic technology is widely used in the fields of copiers and various printers because of its immediacy and high quality images. An electrophotographic photosensitive material (hereinafter also simply referred to as “photosensitive member”), which is the core of electrophotographic technology, is an organic photoconductive substance having advantages such as non-pollution, easy film formation, and easy manufacture. A photoconductor using is used.

  In organic electrophotographic photoreceptors, so-called function-separated type photoreceptors that share the functions of charge generation and movement with separate compounds have a large room for material selection, and the characteristics of the photoreceptor can be easily controlled. Since then, it has become the mainstream of development. From the viewpoint of the layer structure, a single layer type electrophotographic photosensitive member (hereinafter referred to as a single layer type photosensitive member) having a charge generation material and a charge transport material in the same layer, a charge generation material and a charge transport material are provided. A laminated electrophotographic photoreceptor (hereinafter referred to as a laminated photoreceptor) that is separated and laminated in separate layers (charge generation layer and charge transport layer) is known.

  Of these, the laminated type photoreceptors are of this type because most of the current photoreceptors are of this type because the functions are easily optimized for each layer and the characteristics can be easily controlled from the viewpoint of the photoreceptor design. Most of such laminated photoreceptors have at least a charge generation layer and a charge transport layer in this order on a substrate. In the charge transport layer, there are very few suitable electron transport materials, whereas many hole transport materials having a good characteristic are known. For this reason, in a laminated photoreceptor using such a hole transport material, a negative charging method is adopted for charging. In such a negative charging method, when the photosensitive member is charged by negative corona discharge, the generated ozone may adversely affect the environment and the photosensitive member characteristics.

  On the other hand, since the single-layer type photoreceptor can be used for either a negative charging system or a positive charging system, if the positive charging system is used, the generation of ozone, which is a problem with the above-mentioned multilayer photoreceptor, is reduced. Can be suppressed. For this reason, some of the electrical characteristics are inferior to the negatively charged multi-layer photoreceptor, but some have been put into practical use. In addition to the effect on the generation of ozone, the single-layer type photosensitive member has advantages such as fewer coating steps and hardly causing interference fringes with semiconductor laser light. In addition to the advantages described above, the single-layer type photoreceptor absorbs most of the incident light near the surface of the photosensitive layer and generates charges, so that the diffusion of incident light in the photosensitive layer is almost negligible. Furthermore, there is an advantage that the distance of charge movement until the surface charge after charging is neutralized is shorter than that of the multilayer type photoreceptor. For this reason, image blur due to light diffusion and charge diffusion is difficult to occur, and not only high resolution can be expected, but also the degree of charge diffusion and incident light diffusion changes greatly even when the film thickness of the photosensitive layer is increased. In addition, the resolution does not decrease much (for example, see Patent Documents 1 to 5).

On the other hand, a single-layer type photoreceptor has a feature that the sensitivity and residual potential as a photoreceptor greatly change depending on the compatibility of materials because substances having various functions are collectively contained in the layer as compared with a multilayer photoreceptor. Therefore, a particularly suitable charge transport material has been demanded. Among them, when an azo compound or a perylene derivative is used as a charge generation material, it is known that a charge transport material of triarylamine diamine exhibits a low residual potential (see, for example, Patent Documents 6 and 7). ).
JP-A-61-77054 JP-A 61-188543 JP-A-2-228670 Japanese Examined Patent Publication No. 7-97223 Japanese Examined Patent Publication No. 7-97225 Japanese Patent Publication No. 5-20742 JP 2005-43814 A

  However, even when these triarylamine-based diamine charge transport materials are used, there are cases where the electrical characteristics are insufficient.

  Further, when these triarylamine-based diamine charge transport materials showing a low residual potential as a single-layer type photoreceptor are contained in the coating solution for forming a photosensitive layer, there is always a problem of precipitation. In other words, there is no problem if the photosensitive member is prepared (applied) immediately after preparing the coating solution, but if the coating solution is to be applied after being stored for several days or more, it is a charge transport material for triarylamine diamine in the coating solution. As a result, it was difficult to withstand actual use.

  The present invention has been made to solve such problems. That is, an object of the present invention is to provide a single-layer electrophotographic photoreceptor excellent in the stability of a coating solution for forming a photosensitive layer and having good electrical characteristics, and an image forming apparatus provided with the photoreceptor. There is to do.

  As a result of intensive studies, the present inventors have made a single-layer photosensitive layer containing a plurality of specific triarylamine-based diamine charge transport materials, whereby the photosensitive layer-forming coating solution becomes stable, and the photoreceptor is It has been found that it exhibits good electrical characteristics, and the present invention has been completed. That is, the first gist of the present invention is an electrophotographic photosensitive member having a single-layer type photosensitive layer on a conductive support, wherein the photosensitive layer is a compound represented by the following general formula (1), and the following general formula ( 2) The electrophotographic photosensitive member is characterized by containing the compound represented by 2).

(In General Formulas (1) and (2), Ar ¹ and Ar ³ each independently represents a naphthyl group optionally having an unsubstituted alkyl group having 3 or less carbon atoms as a substituent, Ar ² , Ar ⁴ each independently represent a phenyl group which may have a non-substituted alkyl group having 3 or less carbon atoms as a substituent, the a r ⁷ to Ar ¹⁰ Waso respectively independently, carbon as a substituent Represents a phenyl group or a naphthyl group which may have an unsubstituted alkyl group of formula 3 or less , and Ar ⁵ , Ar ⁶ , Ar ¹¹ and Ar ¹² each independently have a methyl group as a substituent. to Table phenylene group which may. However, the compound represented by the compound represented by formula (1) and general formula (2) are different.)

  The second gist of the present invention resides in the above-described electrophotographic photoreceptor, wherein the single-layer type photosensitive layer contains oxytitanium phthalocyanine.

  The third aspect of the present invention is to form an electrostatic latent image by exposing the electrophotographic photosensitive member of the present invention, a charging member for charging the electrophotographic photosensitive member, and the charged electrophotographic photosensitive member. An image forming apparatus comprising: an exposure apparatus for developing the image forming apparatus; and a developing apparatus for developing the electrostatic latent image formed on the electrophotographic photosensitive member.

  According to the present invention, it is possible to obtain a single layer type electrophotographic photosensitive member having a stable coating solution for forming a single layer type photosensitive layer and having excellent electrical characteristics.

  Hereinafter, the best mode for carrying out the present invention will be described in detail. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary.

[Electrophotographic photoreceptor]
The electrophotographic photoreceptor of the present invention has a single-layer type photosensitive layer (hereinafter also simply referred to as “photosensitive layer”) on a conductive support, and the photosensitive layer is represented by the following general formula (1). And a triarylamine diamine compound represented by the following general formula (2). This monolayer type photosensitive layer is obtained by dispersing a charge generation material in a layer containing a charge transport material and a binder resin, and is represented by the triarylamine diamine compound represented by the general formulas (1) and (2) Is contained as a charge transport material in the photosensitive layer.

In General Formulas (1) and (2), Ar ^{1 to} Ar ⁴ and Ar ^{7 to} Ar ¹⁰ each independently represent an aryl group which may have a substituent, and Ar ⁵ , Ar ⁶ , Ar ¹¹ and Ar ¹² represents an arylene group which may each independently have a substituent, and at least one of Ar ^{1 to} Ar ⁴ represents a condensed ring. However, the compound represented by the general formula (1) and the compound represented by the general formula (2) are different.

  First, the triarylamine-based diamine compound contained in the photosensitive layer will be described, and then the layer structure of the electrophotographic photoreceptor will be described.

[Triarylamine diamine compound]
The triarylamine-based diamine compound represented by the above general formula (1) and the triarylamine-based diamine compound represented by the above general formula (2), which are included in at least a single-layer type photosensitive layer, have different chemical structures. In the present invention, at least two kinds of triarylamine-based diamine compounds having different chemical structures are included.

In the compound represented by the general formula (1), Ar ^{1 to} Ar ⁴ each independently represents an aryl group which may have a substituent, and Ar ⁵ and Ar ⁶ each independently have a substituent. An arylene group which may be substituted, and at least one of the aryl groups of Ar ^{1 to} Ar ⁴ is a condensed ring.

In General Formula (1), Ar ^{1 to} Ar ⁴ each independently represents an aryl group which may have a substituent. Examples of the aryl group include a phenyl group, a naphthyl group, and an anthryl group. In the compound represented by the general formula (1), at least one of the aryl groups of Ar ^{1 to} Ar ⁴ is a condensed ring. The condensed ring may be any ring, but it is a ring having the largest number of non-accumulated double bonds, preferably an aromatic ring, and particularly preferably an optionally substituted naphthyl It is a ring composed only of a hydrocarbon such as a group and an anthryl group. The number of rings included in each condensed ring is not limited, but the number of rings is preferably 5 or less, more preferably 3 or less, and particularly preferably 2. The number of the condensed ring itself in the compound represented by the general formula (1) may be two or three as long as it is one or more, and all four may be condensed rings. Particularly preferred is a case where condensed rings are bonded to the left and right nitrogen atoms constituting the general formula (1) (when Ar ¹ and Ar ³ are condensed rings). Among the aryl groups of Ar ^{1 to} Ar ^4, the aryl group other than the condensed ring is a phenyl group that may have a substituent.

The type of the substituent that each of the aryl groups of Ar ^{1 to} Ar ⁴ may independently have is not particularly limited unless it is contrary to the gist of the present invention. Examples thereof include a methyl group, an ethyl group, and a propyl group. Alkyl groups such as isopropyl group, pentyl group, isopentyl group, neopentyl group, 1-methylbutyl group, 1-methylheptyl group, dodecyl group, hexadecyl group and octadecyl group; phenyl group; aralkyl groups such as benzyl group and phenethyl group; An alkoxy group; a hydroxy group; a nitro group; a halogen atom, and the like. These exemplified substituents may be further substituted with these exemplified substituents.

An aryl group of Ar ¹ to Ar ⁴ is not limited to the number of carbon atoms of the substituent which may have independently, usually 8 or less, preferably 6 or less, more preferably 3 or less. If the number of carbon atoms of the substituent is too large, it is not preferable because the residual potential tends to be high. When the above exemplified substituents are further substituted with the above exemplified substituents, it is desirable that the total number of carbon atoms including the substituents satisfy the above range.

Especially, as a substituent which the aryl group of Ar < ¹ > -Ar < ⁴ > may have, an unsubstituted or substituted hydrocarbon group is preferable and an unsubstituted alkyl group is more preferable. Among the unsubstituted alkyl, specifically, a methyl group is particularly preferable.

In addition, the aryl group of Ar < ¹ > -Ar < ⁴ > may have two or more said exemplary substituents each independently. However, the number of substituents that each of the aryl groups Ar ^{1 to} Ar ⁴ has is usually 2 or less, preferably 1 or less. Further, the total number of substituents contained in the aryl groups of Ar ^{1 to} Ar ⁴ is usually 6 or less, preferably 4 or less.

In General Formula (1), Ar ⁵ and Ar ⁶ each independently represent an arylene group which may have a substituent. Examples of the arylene group include a phenylene group, a naphthylene group, and an anthranylene group, but a phenylene group and a naphthylene group are more preferable, and a phenylene group is particularly preferable.

The type of the substituent that each of the arylene groups of Ar ⁵ and Ar ⁶ may independently have is not particularly limited unless it is contrary to the gist of the present invention. Examples thereof include a methyl group, an ethyl group, and a propyl group. Alkyl groups such as isopropyl group, pentyl group, isopentyl group, neopentyl group, 1-methylbutyl group, 1-methylheptyl group, dodecyl group, hexadecyl group and octadecyl group; aryl groups such as phenyl group, naphthyl group and anthryl group; Examples include aralkyl groups such as benzyl group and phenethyl group. These exemplified substituents may be further substituted with these exemplified substituents.

The number of carbon atoms of the substituent that each of the arylene groups of Ar ⁵ and Ar ⁶ may independently have is not limited, but is usually 8 or less, preferably 5 or less, and more preferably 3 or less. If the number of carbon atoms of the substituent is too large, it is not preferable because the residual potential tends to be high. When the above-mentioned exemplified substituents are further substituted with the above-mentioned exemplified substituents, it is preferable that the total number of carbon atoms including the substituents satisfy the above range.

Especially, as a substituent which the arylene group of Ar < ⁵ >, Ar < ⁶ > may have, an unsubstituted alkyl group is preferable. Among the unsubstituted alkyl groups, a methyl group is specifically preferable.

The number of substituents that each of the arylene groups of Ar ⁵ and Ar ⁶ has is not particularly limited, but is usually preferably 1 or 0, and particularly preferably 0.

  Next, specific examples of the structure of the compound represented by the general formula (1) are illustrated. The following Exemplified Compounds 1 to 24 are exemplified for the purpose of explaining the present invention in detail, and are not limited to the following structures unless they are contrary to the gist of the present invention. In the following exemplary compounds, a line protruding linearly from an aryl group, arylene group or oxygen atom represents a methyl group, and a line protruding linearly represents an ethyl group.

  Next, the compound represented by the general formula (2) will be described. The triarylamine diamine compound represented by the general formula (2) has a chemical structure different from that of the triarylamine diamine compound represented by the general formula (1). Different chemical structures can be used by arbitrarily selecting, for example, from the above exemplary compounds.

Similarly to the case of the general formula (1), in the compound represented by the general formula (2), Ar ^{7 to} Ar ¹⁰ each independently represents an aryl group which may have a substituent, and Ar ¹¹ And Ar ¹² each independently represents an arylene group which may have a substituent.

As in the case of the general formula (1), in the general formula (2), Ar ^{7 to} Ar ¹⁰ each independently represents an aryl group which may have a substituent. Examples of the aryl group include a phenyl group, a naphthyl group, and an anthryl group. Although all of the aryl groups of Ar ^{7 to} Ar ¹⁰ include cases where they are not condensed rings, at least one is preferably a condensed ring, and particularly preferably two or more are condensed rings. The condensed ring may be any ring, but it is a ring having the largest number of non-accumulated double bonds, preferably an aromatic ring, and particularly preferably an optionally substituted naphthyl It is a ring composed only of a hydrocarbon such as a group and an anthryl group. The number of rings included in each condensed ring is not limited, but the number of rings is preferably 5 or less, more preferably 3 or less, and particularly preferably 2. Among the aryl groups of Ar ^{7 to} Ar ^10, the aryl group other than the condensed ring is a phenyl group which may have a substituent.

The types of substituents that the aryl groups of Ar ^{7 to} Ar ¹⁰ may independently have are not particularly limited as in the case of the general formula (1) as long as they are not contrary to the gist of the present invention. As methyl groups, ethyl groups, propyl groups, isopropyl groups, pentyl groups, isopentyl groups, neopentyl groups, 1-methylbutyl groups, 1-methylheptyl groups, dodecyl groups, hexadecyl groups, octadecyl groups and other alkyl groups; phenyl groups Aralkyl groups such as benzyl group and phenethyl group; alkoxy groups; hydroxy groups; nitro groups; halogen atoms, and the like. These exemplified substituents may be further substituted with these exemplified substituents.

Although there is no restriction | limiting in carbon number of the substituent which the aryl group of Ar < ⁷ > -Ar < ¹⁰ > may have independently, Usually, it is 8 or less, Preferably it is 6 or less, More preferably, it is 3 or less. If the number of carbon atoms of the substituent is too large, it is not preferable because the residual potential tends to be high. When the above exemplified substituents are further substituted with the above exemplified substituents, it is desirable that the total number of carbon atoms including the substituents satisfy the above range.

Especially, as a substituent which the aryl group of Ar < ⁷ > -Ar < ¹⁰ > may have, an unsubstituted or substituted hydrocarbon group is preferable and an unsubstituted alkyl group is more preferable. Among the unsubstituted alkyl, specifically, a methyl group is particularly preferable.

In addition, the aryl group of Ar < ⁷ > -Ar < ¹⁰ > may have two or more above-mentioned exemplary substituents each independently. However, the number of substituents that each of the aryl groups of Ar ^{7 to} Ar ¹⁰ has is usually 2 or less, preferably 1 or less. In addition, the total number of substituents contained in the aryl groups of Ar ^{7 to} Ar ¹⁰ is usually 6 or less, preferably 4 or less.

In General Formula (2), Ar ¹¹ and Ar ¹² each independently represent an arylene group which may have a substituent. Examples of the arylene group include a phenylene group, a naphthylene group, and an anthranylene group, but a phenylene group and a naphthylene group are more preferable, and a phenylene group is particularly preferable.

The type of the substituent that each of the arylene groups of Ar ¹¹ and Ar ¹² may independently have is not particularly limited as long as it does not contradict the gist of the present invention. Examples thereof include a methyl group, an ethyl group, and a propyl group. Alkyl groups such as isopropyl group, pentyl group, isopentyl group, neopentyl group, 1-methylbutyl group, 1-methylheptyl group, dodecyl group, hexadecyl group and octadecyl group; aryl groups such as phenyl group, naphthyl group and anthryl group; Examples include aralkyl groups such as benzyl group and phenethyl group. These exemplified substituents may be further substituted with these exemplified substituents.

The number of carbon atoms of the substituent that each of the arylene groups of Ar ¹⁰ and Ar ¹² may independently have is not limited, but is usually 8 or less, preferably 5 or less, and more preferably 3 or less. If the number of carbon atoms of the substituent is too large, it is not preferable because the residual potential tends to be high. When the above-mentioned exemplified substituents are further substituted with the above-mentioned exemplified substituents, it is preferable that the total number of carbon atoms including the substituents satisfy the above range.

Especially, as a substituent which the arylene group of Ar < ¹¹ >, Ar < ¹² > may have, an unsubstituted alkyl group is preferable. Among the unsubstituted alkyl groups, a methyl group is specifically preferable.

The number of substituents that each of the arylene groups of Ar ¹¹ and Ar ¹² has is not particularly limited, but is usually preferably 1 or 0, and particularly preferably 0.

  Next, specific examples of the structure of the compound represented by the general formula (2) are illustrated. As long as the triarylamine diamine compound represented by the general formula (2) has a chemical structure different from that of the triarylamine diamine compound represented by the general formula (1), the above exemplary compounds 1 to 24 are used. In addition, the following exemplary compounds a to o can be used. The following exemplary compounds a to o are exemplified for explaining the present invention in detail, and are not limited to the following structures unless contrary to the gist of the present invention. In the following exemplary compounds, the line protruding linearly from the phenyl group or phenylene group represents a methyl group, and the line protruding linearly represents an ethyl group.

As described above, as the charge transport material, there are a triarylamine-based diamine compound represented by the general formula (1) and a triarylamine-based diamine compound represented by the general formula (2) having a different chemical structure. Used together. At this time, the mixing ratio of the triarylamine diamine compound represented by the general formula (1) and the triarylamine diamine compound represented by the general formula (2) is not particularly limited, but the general formula (1): When expressed by the general formula (2), the range of 3: 1 to 1: 3 is preferable, and the range of 2: 1 to 1: 2 is more preferable .

[Conductive support]
As the conductive support, for example, a metal material such as aluminum, aluminum alloy, stainless steel, copper, nickel, or a resin material imparted with conductivity by adding conductive powder such as metal, carbon, tin oxide, Mainly used are resin, glass, paper, or the like obtained by depositing or coating a conductive material such as aluminum, nickel, ITO (indium-tin oxide) on its surface. 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 coated on a conductive support made of a metal material for controlling conductivity, surface property, etc., or for covering defects.

  When a metal material such as an aluminum alloy is used as the conductive support, it may be used after anodizing, chemical conversion coating or the like. When anodizing is performed, it is desirable to perform sealing by a known method.

  The surface of the conductive 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 conductive support.

[Underlayer]
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, a resin alone or a resin in which particles such as metal oxide or a dispersant such as an organic pigment are dispersed in the resin is used. 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. In this way, only one type of particle may be used, or a plurality of types 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 silicone. As the crystal form of the titanium oxide particles, any of rutile, anatase, brookite, and amorphous can be used. A thing of a several crystalline state may be contained.

  In addition, various particle diameters of the metal oxide particles can be used. Among these, from the viewpoint of characteristics and liquid stability, the average primary particle diameter is preferably 10 nm to 100 nm, particularly preferably 10 nm to 50 nm. It is as follows.

  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, phenoxy, epoxy, polyvinylpyrrolidone, polyvinyl alcohol, casein, polyacrylic acid, celluloses, gelatin, starch, polyurethane, polyimide, polyamide, etc. are used alone or in a cured form together with a curing agent. Among them, alcohol-soluble copolymer polyamides, modified polyamides, and the like are preferable because they exhibit good dispersibility and coatability.

  In particular, in the single-layer type photoreceptor of the present invention, the charge generation layer constituting the multilayer photoreceptor can be substituted for the undercoat layer. In this case, a phthalocyanine pigment or an azo pigment dispersed and applied in a binder resin is preferably used. In this case, electrical characteristics may be particularly excellent, which is preferable. As the binder resin, polyvinyl acetal resins are preferably used, and polyvinyl butyral resin is particularly preferably used.

  The addition ratio of the dispersing agent such as particles and pigment to the binder resin can be arbitrarily selected, but it is preferably used in the range of 10% by weight or more and 500% by weight or less in view of the stability of the dispersion and the coating property.

  The thickness of the undercoat layer can be arbitrarily selected, but is preferably 0.1 μm to 25 μm from the viewpoint of photoreceptor characteristics and coatability. Moreover, you may add a well-known antioxidant etc. to an undercoat layer.

[Photosensitive layer]
In the single-layer type photosensitive layer of the present invention, the charge transport material is dissolved or dispersed in the binder resin and the charge generation material is dispersed to form the same layer. Specifically, for example, a coating liquid is prepared by dissolving or dispersing a charge transport material, a charge generation material, and the like and a binder resin in a solvent, and this is formed on a conductive support (if an undercoat layer is provided, an undercoat is provided). It can be obtained by coating on a layer and drying.

  Examples of the binder resin used in the photosensitive layer include vinyl polymers such as polymethyl methacrylate, polystyrene, and polyvinyl chloride, and copolymers thereof, polycarbonate, polyarylate, polyester, polyester carbonate, polysulfone, polyimide, phenoxy, and epoxy. , Silicone resins and the like, and these partially crosslinked cured products can also be used. Of the binder resins, polycarbonate resins and polyarylate resins are particularly preferable. These resins may be used alone or in combination.

  In the present invention, the photosensitive layer includes a triarylamine-based diamine compound represented by the general formula (1) described above as a charge transport material and a triaryl represented by the general formula (2) having a chemical structure different from the compound. Both reelamine diamine compounds are used. As the charge transport material, at least these two types of triarylamine-based diamine compounds are used, but three or more types of triarylamine-based diamine compounds having different chemical structures may be used in combination.

  Furthermore, a conventionally known electron transport material may be used in combination as the charge transport material. The electron transport material used in combination is not particularly limited as long as it is a conventionally known material. For example, aromatic nitro compounds such as 2,4,7-trinitrofluorenone, and cyano compounds such as tetracyanoquinodimethane And electron withdrawing substances such as quinone compounds such as diphenoquinone, and conventionally known cyclic ketone compounds and perylene pigments (perylene derivatives). Examples of the electron transport material include compounds having the structures of the following formulas (I) to (XI).

  Preferable electron transport materials include perylene derivatives represented by the following general formulas P-1 to P-3.

In the general formulas P-1 to P-3, R ¹ , R ² and R ⁵ are each independently hydrogen, an alkyl group which may have a substituent, or an aryl which may have a substituent. Represents a group. In the alkyl group which may have a substituent, an alkyl group having 6 or less carbon atoms such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a tert-butyl group, a pentyl group, and a hexyl group is preferable. Alkyl groups having 3 or less carbon atoms such as methyl group, ethyl group, propyl group and isopropyl group are particularly preferable. Examples of the substituent that the alkyl group may have include an alkyl group or an aryl group, and an alkyl group having 3 or less carbon atoms or an aryl group having 2 or less rings is preferable. In the aryl group which may have a substituent, an aryl group having 3 or less rings such as a phenyl group, a naphthyl group and an anthryl group is preferable, and a phenyl group is particularly preferable. Examples of the substituent that the aryl group may have include an alkyl group and an aryl group, preferably an alkyl group having 3 or less carbon atoms or an aryl group having 2 or less rings.

In the general formulas P-1 to P-3, R ³ , R ⁴ and R ⁶ are preferably divalent aromatic hydrocarbons, and particularly preferably phenylene groups.

Among the general formulas P- ^{1 to} P-3, a perylene derivative represented by the following general formula P-4, in which R ¹ and R ² are aryl groups which may have a substituent, may be preferably exemplified. it can. In the following formulae, R ^{7 to} R ¹⁰ each independently represent a lower alkyl group. Examples of the lower alkyl group include alkyl groups having 1 to 6 carbon atoms such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, tert-butyl group, pentyl group, and hexyl group.

  Specific examples of the perylene derivative represented by the general formula P-4 include N, N′-bis (3,5-dimethylphenyl) perylene-3,4,9,10-tetracarboxydiimide, N, N′— Bis (3-methyl-5-ethylphenyl) perylene-3,4,9,10-tetracarboxydiimide, N, N′-bis (3,5-diethylphenyl) perylene-3,4,9,10-tetra Carboxydiimide, N, N′-bis (3,5-dipropylphenyl) perylene-3,4,9,10-tetracarboxydiimide, N, N′-bis (3,5-diisopropylphenyl) perylene-3, 4,9,10-tetracarboxydiimide, N, N′-bis (3-methyl-5-isopropylphenyl) perylene-3,4,9,10-tetracarboxydiimide, N, N′- Su (3-ethyl-5-isopropylphenyl) perylene-3,4,9,10-tetracarboxydiimide, N, N′-bis (3,5-dibutylphenyl) perylene-3,4,9,10-tetra Carboxydiimide, N, N′-bis (3-methyl-5-di-tert-butylphenyl) perylene-3,4,9,10-tetracarboxydiimide, N, N′-bis (3,5-dipentylphenyl) ) Perylene-3,4,9,10-tetracarboxydiimide, N, N′-bis (3,5-dihexylphenyl) perylene-3,4,9,10-tetracarboxydiimide, and the like. May be used alone or in admixture of two or more.

  When the perylene derivative is contained as an electron transport material, the content ratio of the perylene derivative is not particularly limited, but for example, with respect to 100 parts by weight of the binder resin in the photosensitive layer, preferably 1 part by weight or more and 20 parts by weight or less, Particularly preferred is 2 to 10 parts by weight.

  Moreover, in this invention, you may use together other hole transport materials other than the said triarylamine type diamine compound which is a hole transport material. The hole transport material used in combination is not particularly limited as long as it is a conventionally known material. For example, heterocyclic rings such as carbazole derivatives, indole derivatives, imidazole derivatives, oxazole derivatives, pyrazole derivatives, thiadiazole derivatives, benzofuran derivatives, etc. Compound, aniline derivative, hydrazone derivative, aromatic amine derivative, stilbene derivative, butadiene derivative, enamine derivative and a compound in which a plurality of these compounds are bonded, or a group having a group consisting of these compounds in the main chain or side chain And electron donating substances such as coalescence. Among these, carbazole derivatives, aromatic amine derivatives, stilbene derivatives, butadiene derivatives, enamine derivatives, and those in which a plurality of these compounds are bonded, or heavy chains having groups composed of these compounds in the main chain or side chain. And electron donating substances such as coalescence. 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. In addition, there is no restriction | limiting in particular also in the number of these hole transport materials used together.

  When the previously known hole transport material is used in combination, the ratio of both is not particularly limited, but the weight ratio of the triarylamine diamine compound to the total amount of the triarylamine diamine compound and other hole transport materials used in combination However, it is preferable to use together so that it may become 50 weight% or more, It is further more preferable to use together so that it may become 80 weight% or more, and it is especially preferable not to use together.

  The blending ratio of the binder resin constituting the photosensitive layer and the charge transporting material (electron transporting material and / or hole transporting material) is arbitrary, but usually the charge transporting material is 20 weights per 100 parts by weight of the binder resin. Mix at a ratio of at least parts. Among them, from the viewpoint of reducing the residual potential, it is preferable to blend the charge transport material in a proportion of 30 parts by weight or more with respect to 100 parts by weight of the binder resin, and from the viewpoint of stability and charge mobility when repeatedly used. More preferably, the charge transport material is blended in a proportion of 40 parts by weight or more. On the other hand, from the viewpoint of the thermal stability of the photosensitive layer, it is preferable to blend the charge transport material at a ratio of 150 parts by weight or less with respect to 100 parts by weight of the binder resin, and the compatibility between the charge transport material and the binder resin. From the viewpoint, it is preferable to blend the charge transport material in a proportion of 120 parts by weight or less, and from the viewpoint of printing durability, it is more preferable to blend the charge transport material in a proportion of 100 parts by weight or less, and further scratch resistance. From the viewpoint of properties, it is particularly preferable to blend the charge transport material in a proportion of 80 parts by weight or less. In the present invention, at least two triarylamine-based diamine compounds are used in combination as a charge transport material. When a plurality of charge transport materials are used, the total of these charge transport materials is within the above range. .

  Examples of the charge generation material include selenium and its alloys, cadmium sulfide, other inorganic photoconductive materials, phthalocyanine pigments, azo pigments, quinacridone pigments, indigo pigments, perylene pigments, polycyclic quinone pigments, anthanthrone pigments, benzimidazoles. Various photoconductive materials such as organic pigments such as pigments can be used, and organic pigments, phthalocyanine pigments, azo pigments, and perylene pigments are particularly preferable, and phthalocyanine pigments are particularly preferable.

  When using a phthalocyanine compound as the charge generation material, specifically, a metal such as metal-free phthalocyanine, copper, indium, gallium, tin, titanium, zinc, vanadium, silicon, germanium, or an oxide or halide thereof. Phthalocyanines are used. Examples of the ligand to a metal atom having 3 or more valences include a hydroxyl group and an alkoxy group in addition to the oxygen atom and chlorine atom shown above. Particularly preferred are X-type, τ-type metal-free phthalocyanine, oxytitanium phthalocyanine such as A-type and B-type, oxyvanadium phthalocyanine, chloroindium phthalocyanine, chlorogallium phthalocyanine, and hydroxygallium phthalocyanine. Of the crystal types of oxytitanium phthalocyanine mentioned here, A type and B type are described in W.W. It has been shown by Heller et al. As phase I and phase II, respectively (Zeit. Kristallogr. 159 (1982) 173), and type A is known as a stable type. In the present invention, in the powder X-ray diffraction using CuKα rays, it is preferable to use a crystal type characterized by a clear peak at a diffraction angle 2θ ± 0.2 ° of 27.2 °. As the phthalocyanine compound, only a single compound may be used, or several mixed states may be used. As the mixed state in the phthalocyanine compound or the crystalline state here, the respective constituent elements may be mixed and used later, or a mixed state is generated in the production and processing steps of the phthalocyanine compound such as synthesis, pigmentation, and crystallization. It can be stuffed. As such treatment, acid paste treatment, grinding treatment, solvent treatment and the like are known.

  In this case, the particle size of the charge generating material needs to be sufficiently small, and is preferably 1 μm or less, more preferably 0.5 μm or less. If the amount of the charge generating material dispersed in the photosensitive layer is too small, sufficient sensitivity cannot be obtained, and if it is too large, there are adverse effects such as a decrease in chargeability and a decrease in sensitivity, for example, relative to the total weight of the photosensitive layer. It is preferably used in the range of 0.5 to 50% by weight, more preferably in the range of 1 to 20% by weight, and particularly preferably in the range of 1 to 5% by weight.

  The photosensitive layer is formed in such a form that these charge transport material and charge generation material are bound to a binder resin. The photosensitive layer is preferably composed of a single layer, but may be a laminate of a plurality of layers having different constituent components or composition ratios. Even in the latter case, it is called a single-layer type photoreceptor because of the function of the material in the layer.

  The film thickness of the photosensitive layer is usually 5 to 50 μm, more preferably 10 to 45 μm. Also in this case, known plasticizers for improving film formability, flexibility, mechanical strength, additives for suppressing residual potential, dispersion aids for improving dispersion stability, coatability Leveling agents and surfactants such as silicone oil, fluorine oil and other additives may be added to improve the viscosity.

  A protective layer may be provided on the photosensitive layer for the purpose of preventing wear of the photosensitive layer or preventing or reducing deterioration of the photosensitive layer due to discharge products generated from a charger or the like.

  Further, for the purpose of reducing frictional resistance and wear on the surface of the photoreceptor, the surface layer may contain a fluorine-based resin, a silicone resin, or the like. Moreover, the particle | grains which consist of these resin, and the particle | grains of an inorganic compound may be included.

[Method for preparing electrophotographic photoreceptor]
The method for preparing the electrophotographic photosensitive member to which the exemplary embodiment is applied is not particularly limited. Usually, the layer constituting the photosensitive member is a dip coating method or a spray known as a method for forming a photosensitive layer of the electrophotographic photosensitive member. It is formed by coating on a support by a coating method, a nozzle coating method, a bar coating method, a roll coating method, a blade coating method or the like. Among these, the dip coating method is preferable because of its high productivity.

  As a method for forming the layer, a known method such as sequential application of a coating solution obtained by dissolving or dispersing a substance contained in the layer in a solvent can be applied. In the present invention, the coating liquid can be stabilized by containing at least two types of triarylamine diamine compounds having different chemical structures in the coating liquid.

[Image forming apparatus]
Next, an embodiment of an image forming apparatus using the electrophotographic photosensitive member 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 photosensitive member 1, a charging device 2, an exposure device 3, and a developing device 4, and further, a transfer device 5, a cleaning device 6, and a fixing device as necessary. A device 7 is provided.

  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 device 6 are disposed along the outer peripheral surface of the electrophotographic photosensitive member 1.

  The charging device 2 charges the electrophotographic photoreceptor 1 positively, and uniformly charges the surface of the electrophotographic photoreceptor 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 a corona charging device such as a corotron or a scorotron, a contact type charging device such as a charging brush, etc. are often used.

  In many cases, the electrophotographic photosensitive member 1 and the charging device 2 are designed to be removable from the main body of the image forming apparatus as a cartridge including both of them (hereinafter referred to as a photosensitive cartridge as appropriate). For example, when the electrophotographic photoreceptor 1 or the charging device 2 deteriorates, the photoreceptor cartridge can be removed from the image forming apparatus main body, and another new photosensitive cartridge can be mounted on the image forming apparatus main body. ing. 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 cartridge equipped with all of the electrophotographic photosensitive member 1, the charging device 2, and the toner may be used.

  The type of the exposure apparatus 3 is not particularly limited as long as it can expose the electrophotographic photoreceptor 1 to form an electrostatic latent image on the photosensitive surface of the electrophotographic photoreceptor 1. Specific examples include halogen lamps, fluorescent lamps, lasers such as semiconductor lasers and He—Ne lasers, LEDs, and the like. Further, exposure may be performed by a photoreceptor internal exposure method. The light used for the exposure is arbitrary. For example, the exposure may be performed using monochromatic light with a wavelength of 780 nm, monochromatic light with a wavelength slightly shorter than 600 nm to 700 nm, or monochromatic light with a wavelength shorter than 380 nm to 500 nm. .

  The type of the developing device 4 is not particularly limited, and any device such as a dry development method such as cascade development, one-component conductive toner development, two-component magnetic brush development, or a wet development method 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. This 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. 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 by a resin blade such as a silicone resin or a urethane resin, a metal blade such as stainless steel, aluminum, copper, brass, phosphor bronze, or a blade obtained by coating such a metal blade with a resin. The regulating member 45 contacts the developing roller 44 and is pressed against the developing roller 44 side with a predetermined force by a spring or the like (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 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 toner T is arbitrary, and in addition to the powdery toner, a polymerized toner using a suspension polymerization method, an emulsion polymerization method, or the like can be used. In particular, when a polymerized toner is used, a toner having a small particle diameter of about 4 to 8 μm is preferable, and the toner particles are used in various shapes ranging from a nearly spherical shape to a shape outside the spherical shape on the potato. be able to. The polymerized toner is excellent in charging uniformity and transferability and is suitably used for high image quality.

  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 that are disposed 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 the toner image formed on the electrophotographic photosensitive member 1 to a recording paper (paper, medium) P. Is.

  There is no restriction | limiting in particular about the cleaning apparatus 6, Arbitrary cleaning apparatuses, such as a brush cleaner, a magnetic brush cleaner, an electrostatic brush cleaner, a magnetic roller cleaner, a blade cleaner, can be used. The cleaning device 6 is for scraping off residual toner adhering to the photoreceptor 1 with a cleaning member and collecting the residual toner.

  The fixing device 7 includes an upper fixing member (pressure 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, a fixing sheet, or the like. 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 an arbitrary method such as heat roller fixing, flash fixing, oven fixing, pressure fixing, or the like can be provided.

  In the electrophotographic apparatus configured as described above, an image is recorded as follows. That is, first, the surface (photosensitive surface) of the photoreceptor 1 is charged to a predetermined positive potential (for example, +600 V) by the charging device 2. 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 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. The developing device 4 develops the electrostatic latent image formed on the photosensitive surface of the photoreceptor 1.

  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. This toner image is transferred onto the recording paper P by the transfer device 5. Thereafter, the toner remaining on the photosensitive surface of the photoreceptor 1 without being transferred is removed by the cleaning device 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 embodiment will be described more specifically based on examples. In addition, the following examples are shown in order to describe the present invention in detail, and the present invention is not limited to the examples shown below unless it is contrary to the gist thereof. Moreover, the description of “parts” in the following examples, comparative examples and reference examples indicates “parts by weight” unless otherwise specified.

<Manufacture of photosensitive drum>
Example 1
High-speed fluidized mixing of rutile type titanium oxide having an average primary particle diameter of 40 nm (“TTO55N” manufactured by Ishihara Sangyo Co., Ltd.) and 3% by weight of methyldimethoxysilane (“TSL8117” manufactured by Toshiba Silicone Co., Ltd.) A surface milled titanium oxide obtained by mixing in a kneading machine ("SMG300" manufactured by Kawata Co., Ltd.) and mixing at a high speed at a rotational peripheral speed of 34.5 m / second is ball milled in a mixed solvent of methanol / 1-propanol. To obtain a dispersion slurry of hydrophobized titanium oxide. The dispersion slurry, a mixed solvent of methanol / 1-propanol / toluene, and ε-caprolactam [compound represented by the following formula (A)] / bis (4-amino-3-methylcyclohexyl) methane [the following formula ( Compound represented by B)] / hexamethylenediamine [compound represented by the following formula (C)] / decamethylene dicarboxylic acid [compound represented by the following formula (D)] / octadecamethylene dicarboxylic acid [following formula The compound represented by (E)] has a composition molar ratio of 60% / 15% / 5% / 15% / 5% and is agitated and mixed with pellets of copolymerized polyamide to dissolve the polyamide pellets. Then, ultrasonic dispersion treatment is performed, so that the weight ratio of methanol / 1-propanol / toluene is 7/1/2, and the hydrophobically treated titanium oxide / copolymerized polymer. Containing de in a weight ratio 3/1 was undercoat layer dispersion having a solid concentration of 18.0% by weight.

  The undercoat layer forming coating solution thus obtained is dried on a cylinder made of an aluminum alloy having an outer diameter of 30 mm, a length of 244 mm, and a wall thickness of 0.75 mm so that the film thickness after drying becomes 1.2 μm. An undercoat layer was provided by dip coating and drying.

  Next, in X-ray diffraction by CuKα ray, a Bragg angle (2θ ± 0.2) showed a strong diffraction peak at 27.3 °, and 5 parts by weight of oxytitanium phthalocyanine having a powder X-ray diffraction spectrum shown in FIG. Dispersed together with 70 parts by weight by a sand grind mill. Similarly, 8 parts by weight of a perylene derivative, which is an electron transport material represented by the following structure, was dispersed by a sand grind mill together with 112 parts by weight of toluene. On the other hand, a hole transport material represented by the following structure, that is, 30 parts by weight of each of charge transport material (1-1) and charge transport material (1-2), which are triarylamine diamine compounds having different chemical structures, total 60 Part by weight and 100 parts by weight of a polycarbonate resin having the following structure as a repeating unit are dissolved in 420 parts by weight of toluene, 0.05 parts by weight of silicone oil is added as a leveling agent, and the above two dispersions are added thereto. It mixed so that it might become uniform with a homogenizer. The coating solution thus prepared was dip-coated on the above-described undercoat layer so that the film thickness after drying was 25 μm to form a photosensitive layer, thereby obtaining a single-layer type photoreceptor A1.

  Further, this photosensitive layer forming coating solution was stored at room temperature for 1 month, and Photoreceptor A2 was produced in the same manner as Photoreceptor A1 was produced. At this time, no deposit or the like of the charge transport material was observed in the coating solution, and the coating solution was in a good state.

(Example 2)
Except that (1-1) was 20 parts by weight and (1-2) was 40 parts by weight as the hole transport material (charge transport material), the same as Example 1 Photoconductor B1 was obtained.

  Further, this photosensitive layer forming coating solution was stored at room temperature for 1 month, and Photoreceptor B2 was produced in the same manner as Photoreceptor B1 was produced. At this time, no deposit or the like of the charge transport material was observed in the coating solution, and the coating solution was in a good state.

(Example 3)
In X-ray diffraction by CuKα ray, a Bragg angle (2θ ± 0.2) shows a strong diffraction peak at 27.3 °, and 10 parts by weight of oxytitanium phthalocyanine having a powder X-ray diffraction spectrum shown in FIG. In addition to 150 parts by weight of dimethoxyethane, pulverization and dispersion treatment was performed with a sand grind mill to prepare a pigment dispersion. 160 parts by weight of the pigment dispersion thus obtained was mixed with 100 parts by weight 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-dimethoxy. In addition to ethane, a dispersion having a solid content concentration of 4.0% was finally produced.

  This dispersion is dip-coated on a cylinder made of an aluminum alloy having an outer diameter of 30 mm, a length of 244 mm, and a wall thickness of 0.75 mm so that the film thickness after drying is 0.4 μm, and then dried and subtracted. A layer was formed. On this, the same photosensitive layer as in Example 1 was dip-coated by 25 μm to obtain a photoreceptor C1.

  Further, as used in Example 1, the photosensitive layer forming coating solution was stored at room temperature for 1 month, and Photoreceptor C2 was produced in the same manner as Photoreceptor C1 was produced. At this time, no deposit or the like of the charge transport material was observed in the coating solution, and the coating solution was in a good state.

(Comparative Example 1)
A photoconductor D1 was obtained in exactly the same manner as in Example 1, except that 60 parts by weight of the compound (1-1) was used alone as a hole transport material (charge transport material).

  Further, this photosensitive layer forming coating solution was stored at room temperature for 1 month, and a photoconductor D2 was produced in the same manner as the photoconductor D1 was produced. At this time, precipitation of the charge transport material was observed in the coating solution, and small spots were observed on the photoreceptor.

(Comparative Example 2)
A photoconductor E1 was obtained in the same manner as in Example 1, except that 60 parts by weight of the compound (1-2) alone was used as the hole transport material (charge transport material).

  Further, this photosensitive layer-forming coating solution was stored at room temperature for 1 month, and Photoreceptor E2 was produced in the same manner as Photoreceptor E1 was produced. At this time, precipitation of the charge transport material was observed in the coating solution, and small spots were observed on the photoreceptor.

(Comparative Example 3)
Example 1 except that a total of 60 parts by weight of the compound (2-1) 30 parts by weight and (2-2) 30 parts by weight represented by the following structure was used as the hole transport substance (charge transport material). The photoconductor F1 was obtained in exactly the same manner.

  Further, this photosensitive layer forming coating solution was stored at room temperature for 1 month, and a photoconductor F2 was produced in the same manner as the photoconductor F1 was produced. At this time, precipitation of the charge transport material was observed in the coating solution, and small spots were observed on the photoreceptor.

(Comparative Example 4)
A photoconductor G1 was obtained in the same manner as in Example 1 except that 60 parts by weight of the compound (2-2) was used alone as a hole transport material (charge transport material).

  Further, this photosensitive layer forming coating solution was stored at room temperature for 1 month, and a photoconductor G2 was produced in the same manner as the photoconductor G1 was produced. At this time, precipitation of the charge transport material was observed in the coating solution, and small spots were observed on the photoreceptor.

(Comparative Example 5)
A photoconductor H1 was obtained in the same manner as in Example 1 except that 60 parts by weight of the following hydrazone compound (3) was used as the hole transport material (charge transport material).

  Further, this photosensitive layer forming coating solution was stored at room temperature for 1 month, and Photoreceptor H2 was produced in the same manner as Photoreceptor H1 was produced. At this time, no deposit or the like of the charge transport material was observed in the coating solution, and the coating solution was in a good state.

Example 4
In the same manner as in Example 1, except that 20 parts by weight of the compound (2-2) and 40 parts by weight of the compound (1-2) were used as the hole transport material (charge transport material). Body I1 was obtained.

  Further, this photosensitive layer forming coating solution was stored at room temperature for 1 month, and Photoreceptor I2 was produced in the same manner as Photoreceptor I1 was produced. At this time, no deposit or the like of the charge transport material was observed in the coating solution, and the coating solution was in a good state.

  The manufactured photoreceptor drums A1 to I1 and A2 to I2 were subjected to the following electrical property test and image evaluation test. The results are summarized in Table 1.

<Electrical characteristics test>
Using the electrophotographic characteristic evaluation apparatus manufactured in accordance with the electrophotographic society measurement standard (Electrophotographic Society, edited by “Basic and Application of Continued Electrophotographic Technology”, Corona, 1996, pages 404 to 405) The body drum was rotated at a constant rotational speed of 60 rpm, and an electrical property evaluation test was performed by a cycle of charging, exposure, potential measurement, and static elimination. At that time, the surface potential after exposure (when the initial surface potential of the photosensitive member is charged to +900 V and the light of the halogen lamp is changed to 780 nm monochromatic light with an interference filter and exposed at 1.0 μJ / cm ² ( Hereinafter, it may be referred to as VL). In the VL measurement, the time required from the exposure to the potential measurement was 100 ms. The measurement environment was a temperature of 25 ° C. and a relative humidity of 50%.

<Image evaluation test>
The photosensitive drum is mounted on a drum cartridge (DR510) of a commercially available laser printer HL-5140 (Brother) used for positive charging, and a halftone image is output, and an image using a standard drum (DR510 genuine) is used. And the presence or absence of black spots were confirmed. The image density is indicated by “deep”, “good”, “thin”, “extremely thin”, and “black spot” is indicated only when a black spot occurs. There was no photoreceptor with a “dark” image.

  From the above results, the single-layer electrophotographic photosensitive member shows a sufficiently low light potential only by using a triarylamine diamine compound having a different chemical structure unique to the present invention as a charge transport material, It was found that the coating liquid for layer formation did not cause the precipitation of the charge transport material, and the electrical characteristics became stable over time.

  In particular, as in Comparative Example 3, the conventionally used triphenylamine compound is not sufficient in the effect of preventing precipitation due to multiple use, and only when a triarylamine diamine compound having a different chemical structure unique to the present invention is used. It was revealed that the effect of preventing precipitation due to multiple use was great.

  In addition, as in Example 3, it was also revealed that a low bright part potential can be achieved by using a phthalocyanine compound for the undercoat layer.

1 is a conceptual diagram illustrating an embodiment of an image forming apparatus using an electrophotographic photosensitive member of the present invention. 1 is an X-ray diffraction pattern of oxytitanium phthalocyanine used in Examples.

Explanation of symbols

1 Photoconductor 2 Charging device (charging roller)
DESCRIPTION OF SYMBOLS 3 Exposure apparatus 4 Developing apparatus 5 Transfer apparatus 6 Cleaning apparatus 7 Fixing apparatus 41 Developing tank 42 Agitator 43 Supply roller 44 Developing roller 45 Control member 71 Upper fixing member (pressure roller)
72 Lower fixing member (fixing roller)
73 Heating device T Toner P Recording paper

Claims (7)

In an electrophotographic photosensitive member having a single-layer type photosensitive layer on a conductive support, the photosensitive layer contains a compound represented by the following general formula (1) and a compound represented by the following general formula (2). An electrophotographic photosensitive member characterized by the above.

(In General Formulas (1) and (2), Ar ¹ and Ar ³ each independently represents a naphthyl group optionally having an unsubstituted alkyl group having 3 or less carbon atoms as a substituent, Ar ² , Ar ⁴ each independently represent a phenyl group which may have a non-substituted alkyl group having 3 or less carbon atoms as a substituent, the a r ⁷ to Ar ¹⁰ Waso respectively independently, carbon as a substituent Represents a phenyl group or a naphthyl group which may have an unsubstituted alkyl group of formula 3 or less , and Ar ⁵ , Ar ⁶ , Ar ¹¹ and Ar ¹² each independently have a methyl group as a substituent. to Table phenylene group which may. However, the compound represented by the compound represented by formula (1) and general formula (2) are different.)   2. The electrophotographic photosensitive member according to claim 1, wherein the single-layer type photosensitive layer contains oxytitanium phthalocyanine.   3. The electron according to claim 2, wherein the oxytitanium phthalocyanine exhibits a clear peak at a Bragg angle 2θ ± 0.2 ° of 27.2 ° in powder X-ray diffraction using CuKα characteristic X-rays. Photoconductor.   The electrophotographic photosensitive member according to claim 1, wherein the single-layer type photosensitive layer contains a perylene derivative.   5. The single layer type photoreceptor having an undercoat layer between the conductive support and the single layer type photosensitive layer, wherein the undercoat layer contains a phthalocyanine compound. 2. The electrophotographic photosensitive member according to item 1.   An electrophotographic photosensitive member according to any one of claims 1 to 5, a charging member for charging the electrophotographic photosensitive member, and an exposure device for exposing the charged electrophotographic photosensitive member to form an electrostatic latent image; And a developing device for developing the electrostatic latent image formed on the electrophotographic photosensitive member. 7. The image forming apparatus according to claim 6, further comprising a charging member that positively charges the electrophotographic photosensitive member.

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