JP2008052014A - Electrophotographic photoreceptor, image forming apparatus, and process cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a positive charge type single layer photoreceptor having high sensitivity, excellent in charge stability and free of occurrence of abnormal images such as a residual image even after repeated use. <P>SOLUTION: The electrophotographic photoreceptor which is charged to positive polarity and used is obtained by disposing at least a photosensitive layer on a conductive support, wherein the photosensitive layer is a single layer containing at least a charge generating material, an electron transporting material expressed by general formula (1) and an organic sulfur-containing antioxidant. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a positively charged electrophotographic photosensitive member in which a combination of a specific charge transporting material and an organic sulfur-based antioxidant is contained in a single photosensitive layer and an abnormal image such as an afterimage does not occur even when it is repeatedly used, and The present invention relates to a positively chargeable image forming apparatus and a process cartridge.

  In recent years, there has been a remarkable development of information processing system machines using electrophotography. In particular, an optical printer that converts information into a digital signal and records information by light has a remarkable improvement in print quality and reliability. This digital recording technology is applied not only to printers but also to ordinary copying machines, and so-called digital copying machines have been developed. In addition, since a variety of information processing functions are added to a conventional copying machine equipped with this digital recording technology for analog copying, it is expected that its demand will increase further in the future. In addition, with the spread of personal computers and the improvement in performance, the progress of digital color printers for performing color output of images and documents is rapidly progressing.

  Electrophotographic photoreceptors used in these image forming apparatuses are roughly classified into organic photoreceptors and inorganic photoreceptors, but organic photoreceptors are easier to manufacture and less expensive than conventional inorganic photoreceptors, In recent years, it has been widely used because it has the advantages of various choices of photoconductor materials such as charge transport materials, charge generation materials, and binder resins, and a high degree of freedom in functional design.

The organic photoreceptor includes a single-layer photoreceptor in which a charge transport material (hole transport material, electron transport material) is dispersed in the same photosensitive layer together with a charge generation material, a charge generation layer containing the charge generation material, There is a laminated type photoreceptor in which a charge transport layer containing a charge transport material is laminated.
Most of the laminated photoreceptors are negatively charged, and the positively charged laminated photoreceptor has not been put into practical use. The reason is that an electron transport material having excellent electron transport ability, low toxicity, and high compatibility with the binder resin has not been put into practical use.

  However, in the negatively charged type, corona discharge used for charging is unstable compared to the positively charged type, and in order to generate ozone, nitrogen oxides, etc., these are adsorbed on the surface of the photoconductor, There is a problem that it is easy to cause chemical deterioration and further deteriorates the environment. From this point of view, the positively charged type photoconductor having a greater degree of freedom of use conditions is more advantageous as the photoconductor than the negatively charged type photoconductor.

  There is a single layer photoreceptor as such a positively charged photoreceptor. Single-layer photoreceptors mainly include both an electron transport material and a hole transport material as charge transport materials, and therefore have both positive and negative sensitivity. However, since the electron transporting material has a low electron transport capability, the positive charge is more sensitive, and most of the positive charge is used to take advantage of the positive charge as described above.

  Examples of single-layer photoconductors proposed so far include those described in Patent Documents 1 to 5, but these single-layer organic photoconductors have a higher residual potential than function-separated multilayer photoconductors. In addition, there is a problem peculiar to a single layer that a change in charging potential and post-exposure potential due to electrostatic repeated fatigue is large.

  In order to solve the problem of such a single layer type photoreceptor, development of a new electron transport material has been promoted in recent years. In particular, tetracarboxylic acid derivatives and naphthalenecarboxylic acid derivatives as disclosed in Patent Document 6 have excellent electron transporting ability, thus solving the problems of conventional single-layer photoreceptors and greatly improving electrostatic characteristics. It is possible to make it.

  The electron transport material represented by the general formula (1) used in the present invention is in the category of Patent Document 6, but has an excellent electron transport ability, and a single-layer photoreceptor using this electron transport material is An excellent single-layer photoconductor with high sensitivity and less sensitivity reduction due to repeated use. However, there is a problem that the charging property is low as in the conventional single-layer photoconductor. Further, the charging stability is low, and the charging potential is lowered by repeated use, and abnormal images such as background stains and fogging are likely to occur.

In addition, there is a problem that an afterimage (memory image) is easily generated in a single-layer photoconductor. In the case of the reversal development method, which is the mainstream of recent digital type image forming apparatuses, the photosensitive member is charged, the image portion is exposed, and the portion having a low surface potential of the photosensitive member is developed with toner having the same polarity as that of the photosensitive member. In the process, a bias having a polarity opposite to that of the photoconductor is applied to transfer the toner to a transfer medium. Thus, in the transfer process, a reverse polarity bias is applied in a state where the surface potential of the image portion is low, so that the surface potential of this portion is charged to a polarity opposite to the main charging polarity of the photoreceptor. In the case of a single-layer photoconductor, it has both positive and negative sensitivities by including an electron transport material and a hole transport material, so even if it is charged to the opposite polarity, it can be canceled to some extent by photostatic discharge, but it is completely canceled It cannot be done, and a potential difference remains. If the charging ability of the photoconductor is sufficient, the potential difference can be canceled and uniform charging can be performed in the next charging step, but if the charging capacity is low, the potential difference cannot be canceled even in the next charging and the next image is displayed. The history of the previous image remains. Since single-layer photoreceptors have low charge stability, afterimages are particularly likely to occur after repeated use.
When the electron transport material represented by the general formula (1) is used, the sensitivity characteristics of the single-layer type photoreceptor are dramatically improved. The present situation is that satisfactory results are not obtained, such as afterimages tend to occur due to use.

JP-A-8-328275 JP-A-7-64301 JP-A-9-281729 JP-A-6-130688 JP-A-9-151157 WO 2005/092901

  The present invention has been made in view of the above problems, and provides a positively charged single-layer photoconductor that has high sensitivity, is excellent in charging stability, and does not cause abnormal images such as afterimages even when used repeatedly. With the goal.

  As described above, the afterimage occurs because the image portion is charged to the opposite polarity (minus) to the main charging polarity (plus) of the photosensitive member in the transfer process, and the potential difference cannot be canceled in the next charging process. Therefore, in order to prevent the afterimage, it is necessary that the photosensitive member has a sufficient charging capability to cancel the potential difference generated in the transfer process. As a result of various investigations for improving the chargeability in the single-layer photoreceptor using the electron transport material represented by the general formula (1), the present inventors have made an oxidation that has been conventionally used for plastic materials and rubber materials. Among the inhibitors, the addition of a specific range of substances has improved the chargeability, and it has been found that no afterimage is generated even after repeated use.

That is, the said subject is solved by (1)-(7) of this invention shown below.
(1) “An electrophotographic photosensitive member used by being charged to a positive polarity, wherein the electrophotographic photosensitive member is provided with at least a photosensitive layer on a conductive support, and the photosensitive layer comprises at least a charge generating material and An electrophotographic photoreceptor comprising a single layer containing an electron transport material represented by formula (1) and an organic sulfur-based antioxidant;

（式中、Ｒ１、Ｒ２は、それぞれ独立に水素原子、置換又は無置換のアルキル基、置換又は無置換のシクロアルキル基、置換又は無置換のアラルキル基からなる群より選ばれる基を表わし、Ｒ３、Ｒ４、Ｒ５、Ｒ６、Ｒ７、Ｒ８、Ｒ９、Ｒ１０、Ｒ１１、Ｒ１２、Ｒ１３、Ｒ１４はそれぞれ独立に水素原子、ハロゲン原子、シアノ基、ニトロ基、アミノ基、水酸基、置換又は無置換のアルキル基、置換又は無置換のシクロアルキル基、置換又は無置換のアラルキル基からなる群より選ばれる基を表わし、ｎは繰り返し単位であり、０から１００までの整数を表わす。）」、
（２）「前記有機硫黄系酸化防止剤が下記一般式（２）で表わされる化合物であることを特徴とする前記第（１）項に記載の電子写真感光体；

Wherein R 1 and R 2 each independently represent a group selected from the group consisting of a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aralkyl group, and R 3 , R4, R5, R6, R7, R8, R9, R10, R11, R12, R13, R14 are each independently a hydrogen atom, halogen atom, cyano group, nitro group, amino group, hydroxyl group, substituted or unsubstituted alkyl group Represents a group selected from the group consisting of a substituted or unsubstituted cycloalkyl group and a substituted or unsubstituted aralkyl group, and n is a repeating unit and represents an integer of 0 to 100).
(2) “The electrophotographic photoreceptor according to item (1), wherein the organic sulfur-based antioxidant is a compound represented by the following general formula (2);

（式中ｎは８〜２５の整数である。）」、
（３）「前記電荷発生材料がフタロシアニンであることを特徴とする前記第（１）項又は第（２）項に記載の電子写真感光体」、
（４）「前記フタロシアニンがＣｕＫαの特性Ｘ線（波長１．５４２Å）に対するブラッグ角２θの回折ピーク（±０．２゜）として、少なくとも２７．２゜に最大回折ピークを有し、更に９．４゜、９．６゜、２４．０゜に主要なピークを有し、かつ最も低角側の回折ピークとして７．３゜にピークを有し、７．３゜のピークと９．４゜のピークの間にピークを有さないことを特徴とする前記第（３）項に記載の電子写真感光体」、
（５）「前記第（１）項乃至第（４）項のいずれかに記載の電子写真感光体が搭載されたことを特徴とする画像形成装置」、
（６）「現像方式が反転現像方式であることを特徴とする前記第（５）項に記載の画像形成装置」、
（７）「装置本体に対して着脱可能であり、少なくとも電子写真感光体を有する画像形成装置用プロセスカートリッジであって、該電子写真感光体が前記第（１）項乃至第（４）項の何れかに記載の電子写真感光体であることを特徴とするプロセスカートリッジ」。

(Where n is an integer from 8 to 25) ",
(3) "The electrophotographic photosensitive member according to item (1) or (2), wherein the charge generation material is phthalocyanine",
(4) “The phthalocyanine has a maximum diffraction peak at 27.2 ° as a diffraction peak (± 0.2 °) at a Bragg angle 2θ with respect to the characteristic X-ray (wavelength 1.542 mm) of CuKα. It has major peaks at 4 °, 9.6 ° and 24.0 °, and has a peak at 7.3 ° as the lowest diffraction peak, a peak at 7.3 ° and 9.4 °. The electrophotographic photosensitive member according to item (3), which has no peak between the peaks of
(5) "Image forming apparatus comprising the electrophotographic photosensitive member according to any one of (1) to (4)",
(6) “Image forming apparatus according to item (5), wherein the developing method is a reversal developing method”,
(7) “A process cartridge for an image forming apparatus that is detachable from the apparatus main body and has at least an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member is the item (1) to (4). A process cartridge characterized by being an electrophotographic photosensitive member according to any one of the above.

  According to the present invention, there is provided a positively charged single-layer photoreceptor that has high sensitivity and excellent charging stability and does not cause abnormal images such as afterimages even when used repeatedly. Also, by using this, an image forming apparatus capable of performing high-quality image formation over a long period of time is provided. In addition, a process cartridge with high convenience in handling is provided.

  In general, when an additive such as an antioxidant is added to the photosensitive layer, side effects such as deterioration in sensitivity and increase in residual potential occur even if the charging property is improved. However, in the single-layer photoconductor using the electron transport material of the general formula (1) of the present invention, when an organic sulfur-based antioxidant is added, there are almost no side effects such as sensitivity deterioration and residual potential increase, Can be improved. For this reason, it is possible to prevent abnormal images (background stain, fogging) and afterimages due to a decrease in chargeability even by repeated use.

  In addition, as a specific phenomenon when an organic sulfur-based antioxidant is used, the chargeability of positive charge is improved, and conversely, the chargeability of negative charge is greatly deteriorated (see the evaluation example described later). The reason for this is not clear, but the negative chargeability is greatly deteriorated, so that the photosensitive member is prevented from being negatively charged in the transfer process. As a result, the potential difference after transfer is reduced, and the afterimage is further reduced. It is thought that the situation will be difficult to occur.

  Since the electron transport material represented by the general formula (1) has a very excellent electron transport ability, the photoreceptor of the present invention has excellent sensitivity in both positive and negative polarities. Therefore, when the image forming apparatus has a light static elimination process, the potential difference generated by the transfer process can be sufficiently reduced, and an afterimage is hardly generated.

  Further, by using phthalocyanine as a charge generation material, it is possible to obtain a photoconductor having further improved sensitivity, low residual potential, and little deterioration in characteristics due to repeated use of the photoconductor. Among them, particularly a titanyl phthalocyanine as shown in the following structural formula (1) having titanium as a central metal can provide a particularly sensitive photoreceptor.

  Various crystal forms of titanyl phthalocyanine are known. Among them, titanyl phthalocyanine having a maximum diffraction peak at 27.2 ° with a Bragg angle 2θ exhibits particularly excellent sensitivity characteristics, and in particular, Japanese Patent Application Laid-Open No. 2001-19871. The maximum diffraction peak at 27.2 ° and the main peaks at 9.4 °, 9.6 °, 24.0 ° and the lowest diffraction peak By using titanyl phthalocyanine having a peak at 7.3 ° and having no peak between the 7.3 ° peak and the 9.4 ° peak, it is very sensitive and used repeatedly. In addition, it is possible to obtain a stable electrophotographic photosensitive member with little characteristic deterioration.

Hereinafter, the electrophotographic photosensitive member of the present invention will be described in detail with reference to the drawings.
FIG. 7 is a cross-sectional view schematically showing an example of an electrophotographic photosensitive member having the layer structure of the present invention, in which a photosensitive layer (22) is provided on a conductive support (21).
Examples of the conductive support (21) include those having a volume resistance of 10 ¹⁰ Ω · cm or less, such as metals such as aluminum, nickel, chromium, nichrome, copper, silver, gold, platinum, iron, tin oxide, An oxide such as indium oxide coated with film or cylindrical plastic or paper by vapor deposition or sputtering, or a plate of aluminum, aluminum alloy, nickel, stainless steel, etc., and drawing ironing method or impact ironing method It is possible to use pipes that have been surface-treated by cutting, superfinishing, polishing, etc. after being made into raw pipes by methods such as the Extruded Ironing method, Extruded Drawing method, and cutting method.

The photosensitive layer in the present invention comprises a single layer containing a charge generating material, the electron transport material of the general formula (1) and an organic sulfur-based antioxidant.
First, the charge generation material in the present invention will be described.
As the charge generation material used in the present invention, a known material can be used. For example, phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine, azulenium salt pigments, squaric acid methine pigments, azo pigments having carbazole skeleton, azo pigments having triphenylamine skeleton, azo pigments having diphenylamine skeleton, dibenzothiophene skeleton Azo pigments having fluorenone skeleton, azo pigments having oxadiazole skeleton, azo pigments having bis-stilbene skeleton, azo pigments having distyryl oxadiazole skeleton, azo pigments having distyrylcarbazole skeleton, perylene Pigments, anthraquinone or polycyclic quinone pigments, quinoneimine pigments, diphenylmethane and triphenylmethane pigments, benzoquinone and naphthoquinone pigments, cyanine and azomethine pigments, Jigoido based pigments, and bisbenzimidazole pigments. These charge generation materials can be used alone or as a mixture of two or more.

In the present invention, phthalocyanine pigments are particularly preferable from the viewpoint of various properties necessary for the present invention.
Among them, in particular, titanyl phthalocyanine having titanium as a central metal makes it possible to obtain a photosensitive layer with particularly high sensitivity, and the image forming apparatus can be speeded up. Further, among various crystal forms, titanyl phthalocyanine having a maximum diffraction peak at 27.2 ° with a Bragg angle 2θ exhibits particularly excellent sensitivity characteristics and is used favorably. In particular, it has a maximum diffraction peak at 27.2 ° described in JP-A-2001-19871, and further has main peaks at 9.4 °, 9.6 °, and 24.0 °, In addition, by using titanyl phthalocyanine having a peak at 7.3 ° as the diffraction peak on the lowest angle side and no peak between the 7.3 ° peak and the 9.4 ° peak, In addition, it is possible to obtain a stable electrophotographic photosensitive member that is highly sensitive and does not deteriorate in characteristics even when used repeatedly.

Next, the charge transport material will be described.
The electron transport material represented by the general formula (1) used in the present invention has the following structural skeleton.

（式中、Ｒ１、Ｒ２は、それぞれ独立に水素原子、置換又は無置換のアルキル基、置換又は無置換のシクロアルキル基、置換又は無置換のアラルキル基からなる群より選ばれる基を表わし、Ｒ３、Ｒ４、Ｒ５、Ｒ６、Ｒ７、Ｒ８、Ｒ９、Ｒ１０、Ｒ１１、Ｒ１２、Ｒ１３、Ｒ１４はそれぞれ独立に水素原子、ハロゲン原子、シアノ基、ニトロ基、アミノ基、水酸基、置換又は無置換のアルキル基、置換又は無置換のシクロアルキル基、置換又は無置換のアラルキル基からなる群より選ばれる基を表わし、ｎは繰り返し単位であり、０から１００までの整数を表わす。）

Wherein R 1 and R 2 each independently represent a group selected from the group consisting of a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aralkyl group, and R 3 , R4, R5, R6, R7, R8, R9, R10, R11, R12, R13, R14 are each independently a hydrogen atom, halogen atom, cyano group, nitro group, amino group, hydroxyl group, substituted or unsubstituted alkyl group Represents a group selected from the group consisting of a substituted or unsubstituted cycloalkyl group and a substituted or unsubstituted aralkyl group, and n is a repeating unit and represents an integer of 0 to 100.)

  The substituted or unsubstituted alkyl group is an alkyl group having 1 to 25 carbon atoms, preferably 1 to 10 carbon atoms, specifically a methyl group, an ethyl group, an n-propyl group, an n- Straight chain such as butyl group, n-pentyl group, n-hexyl group, n-peptyl group, n-octyl group, n-nonyl group, n-decyl group, i-propyl group, s-butyl group, t -Branched group such as butyl group, methylpropyl group, dimethylpropyl group, ethylpropyl group, diethylpropyl group, methylbutyl group, dimethylbutyl group, methylpentyl group, dimethylpentyl group, methylhexyl group, dimethylhexyl group, alkoxy Alkyl group, monoalkylaminoalkyl group, dialkylaminoalkyl group, halogen-substituted alkyl group, alkylcarbonylalkyl group, Kishiarukiru group, alkanoyloxy group, an aminoalkyl group, esterified optionally alkyl group substituted with a carboxyl group which have an alkyl group substituted by a cyano group are exemplified. The substitution position of these substituents is not particularly limited, and a group in which a part of carbon atoms of the substituted or unsubstituted alkyl group is substituted with a hetero atom (N, O, S, etc.) is also substituted. Included in the alkyl group.

  The substituted or unsubstituted cycloalkyl group includes a cycloalkyl ring having 3 to 25 carbon atoms, preferably 3 to 10 carbon atoms, specifically, a homocyclic ring from cyclopropane to cyclodecane, methylcyclo Those having an alkyl substituent such as pentane, dimethylcyclopentane, methylcyclohexane, dimethylcyclohexane, trimethylcyclohexane, tetramethylcyclohexane, ethylcyclohexane, diethylcyclohexane, t-butylcyclohexane, alkoxyalkyl groups, monoalkylaminoalkyl groups, dialkylamino Alkyl group, halogen-substituted alkyl group, alkoxycarbonylalkyl group, carboxyalkyl group, alkanoyloxyalkyl group, aminoalkyl group, halogen atom, amino group, esterified Which may be a carboxyl group, a cycloalkyl group substituted by a cyano group and the like. The substitution position of these substituents is not particularly limited, and a group in which a part of carbon atoms of the substituted or unsubstituted cycloalkyl group is substituted with a hetero atom (N, O, S, etc.) is also substituted. It is included in the cycloalkyl group.

Examples of the substituted or unsubstituted aralkyl group include groups in which an aromatic ring is substituted on the above-described substituted or unsubstituted alkyl group, and an aralkyl group having 6 to 14 carbon atoms is preferable. More specifically, benzyl group, perfluorophenylethyl group, 1-phenylethyl group, 2-phenylethyl group, terphenylethyl group, dimethylphenylethyl group, diethylphenylethyl group, t-butylphenylethyl group, 3- Examples thereof include a phenylpropyl group, a 4-phenylbutyl group, a 5-phenylpentyl group, a 6-phenylhexyl group, a benzhydryl group, and a trityl group.
Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

  The electron transport material represented by the general formula (1) is synthesized mainly by the following two synthesis methods.

Examples of the method for obtaining the starting material for producing the electron transport material represented by the general formula (1) include the following methods.
That is, naphthalenecarboxylic acid is synthesized from the following reaction formula according to a known synthesis method (for example, US Pat. No. 6,794,102, Industrial Organic Pigments 2nd edition, VCH, 485 (1997)).

式中、ＲｎはＲ３、Ｒ４、Ｒ７、Ｒ８を表わし、ＲｍはＲ５、Ｒ６、Ｒ９、Ｒ１０を表わす。

In the formula, Rn represents R3, R4, R7, R8, and Rm represents R5, R6, R9, R10.

  The electron transport material represented by the general formula (1) used in the present invention is a method of reacting the above naphthalenecarboxylic acid or its anhydride with amines to monoimidize, and using a buffer solution for naphthalenecarboxylic acid or its anhydride. It is obtained by a method of adjusting pH and reacting with diamines. Monoimidization is carried out without solvent or in the presence of a solvent. The solvent is not particularly limited, but it does not react with raw materials or products such as benzene, toluene, xylene, chloronaphthalene, acetic acid, pyridine, methylpyridine, dimethylformamide, dimethylacetamide, dimethylethyleneurea, dimethylsulfoxide, and the like. It is good to use what can be made to react at the temperature of -250 degreeC. For pH adjustment, a buffer solution prepared by mixing a basic aqueous solution such as lithium hydroxide or potassium hydroxide with an acid such as phosphoric acid is used. Carboxylic acid derivative dehydration reaction obtained by reacting carboxylic acid with amines or diamines is carried out without solvent or in the presence of a solvent. Although there is no restriction | limiting in particular as a solvent, It is good to use what reacts at the temperature of 50 to 250 degreeC, without reacting with raw materials and products, such as benzene, toluene, chloronaphthalene, bromonaphthalene, and acetic anhydride. Any reaction may be performed in the absence of a catalyst or in the presence of a catalyst, and is not particularly limited. For example, molecular sieves, benzenesulfonic acid, p-toluenesulfonic acid and the like can be used as a dehydrating agent.

The repeating unit n of the electron transport material represented by the general formula (1) is an integer of 0 to 100. The repeating unit n is determined from the weight average molecular weight (Mw). That is, the compound exists with a distribution in molecular weight. When n exceeds 100, the molecular weight of the compound increases and the solubility in various solvents decreases, so 100 or less is preferable. In particular, a dimer with n = 0 is preferable because of excellent solubility and photoreceptor characteristics.
On the other hand, for example, when n is 1, it is a trimer of naphthalene carboxylic acid, but excellent electron transfer characteristics can be obtained even for oligomers by appropriately selecting substituents for R1 and R2. In this way, a wide range of naphthalenecarboxylic acid derivatives from oligomers to polymers are synthesized depending on the number of repeating units n.
In the range where the molecular weight of the oligomer region is small, monodispersed compounds can be obtained by stepwise synthesis. In the case of a compound having a large molecular weight, a compound having a distribution in molecular weight is obtained.

  Below, the preferable example of the electron transport material represented by the said General formula (1) is given. However, the present invention is not limited to these compounds.

In addition, the electron transport material represented by the above structural formula (1-1) was manufactured by the following method.
<First step>
In a 200 ml four-necked flask, 5.0 g (18.6 mmol) of 1,4,5,8-naphthalenetetracarboxylic dianhydride and 50 ml of DMF were placed and heated to reflux. To this, a mixture of 2.14 g (18.6 mmol) of 2-aminoheptane and 25 ml of DMF was added dropwise with stirring. After completion of dropping, the mixture was heated to reflux for 6 hours. After completion of the reaction, the container was cooled and concentrated under reduced pressure. Toluene was added to the residue, and the residue was purified by silica gel column chromatography. Further, the recovered product was recrystallized from toluene / hexane to obtain 2.14 g of monoimide A (yield 31.5%).
<Second step>
Into a 100 ml four-necked flask, 2.0 g (5.47 mmol) of monoimide A, 0.137 g (2.73 mmol) of hydrazine monohydrate, 10 mg of p-toluenesulfonic acid, and 50 ml of toluene were heated and refluxed for 5 hours. It was. After completion of the reaction, the container was cooled and concentrated under reduced pressure. The residue was purified by silica gel column chromatography. Further, the recovered product was recrystallized from toluene / ethyl acetate to obtain 0.668 g (yield 33.7%) of the compound represented by the structural formula (1-1). In mass spectrometry (FD-MS), a peak of M / z = 726 was observed and identified as a target product. In the elemental analysis, calculated values were 69.41% carbon, 5.27% hydrogen, and 7.71% nitrogen, and the measured values were 69.52% carbon, 5.09% hydrogen, and 7.93% nitrogen.

In addition, the electron transport material represented by the above structural formula (1-2) was manufactured by the following method.
<First step>
In a 200 ml four-necked flask, 1,4,5,8-naphthalenetetracarboxylic dianhydride 10 g (37.3 mmol), hydrazine monohydrate 0.931 g (18.6 mmol), p-toluenesulfonic acid 20 mg, toluene 100 ml was added and heated to reflux for 5 hours. After completion of the reaction, the container was cooled and concentrated under reduced pressure. The residue was purified by silica gel column chromatography. The recovered product was recrystallized from toluene / ethyl acetate to obtain 2.84 g of dimer C (yield 28.7%).
<Second step>
In a 100 ml four-necked flask, 2.5 g (4.67 mmol) of dimer C and 30 ml of DMF were placed and heated to reflux. To this, a mixture of 2-aminopropane 0.278 g (4.67 mmol) and DMF 10 ml was added dropwise with stirring. After completion of dropping, the mixture was heated to reflux for 6 hours. After completion of the reaction, the reaction vessel was cooled and concentrated under reduced pressure. Toluene was added to the residue and the residue was purified by silica gel column chromatography to obtain 0.556 g of monoimide C (yield 38.5%).
<Third step>
In a 50 ml four-necked flask, 0.50 g (1.62 mmol) of monoimide C and 10 ml of DMF were placed and heated to reflux. To this, a mixture of 2-aminoheptane 0.186 g (1.62 mmol) and DMF 5 ml was added dropwise with stirring. After completion of dropping, the mixture was heated to reflux for 6 hours. After completion of the reaction, the reaction vessel was cooled and concentrated under reduced pressure. Toluene was added to the residue, and the residue was purified by silica gel column chromatography. Furthermore, the recovered product was recrystallized from toluene / hexane to obtain 0.243 g (yield 22.4%) of the compound represented by the structural formula (1-2). In mass spectrometry (FD-MS), the peak was identified as M / z = 670, and the product was identified as the target product. In the elemental analysis, the calculated values were 68.05% carbon, 4.51% hydrogen, and 8.35% nitrogen, and the measured values were 68.29% carbon, 4.72% hydrogen, and 8.33% nitrogen.

In addition, the electron transport material represented by the above structural formula (1-3) was manufactured by the following method.
<First step>
In a 200 ml four-necked flask, 5.0 g (18.6 mmol) of 1,4,5,8-naphthalenetetracarboxylic dianhydride and 50 ml of DMF were placed and heated to reflux. To this, a mixture of 1.10 g (18.6 mmol) of 2-aminopropane and 25 ml of DMF was added dropwise with stirring. After completion of dropping, the mixture was heated to reflux for 6 hours. After completion of the reaction, the reaction vessel was cooled and concentrated under reduced pressure. Toluene was added to the residue, and the residue was purified by silica gel column chromatography. Furthermore, the recovered product was recrystallized from toluene / hexane to obtain 2.08 g of monoimide B (yield 36.1%).
<Second step>
In a 100 ml four-necked flask, 2.0 g (6.47 mmol) of monoimide B, 0.162 g (3.23 mmol) of hydrazine monohydrate, 10 mg of p-toluenesulfonic acid, and 50 ml of toluene are heated and refluxed for 5 hours. It was. After completion of the reaction, the container was cooled and concentrated under reduced pressure. The residue was purified by silica gel column chromatography. Further, the recovered product was recrystallized from toluene / ethyl acetate to obtain 0.810 g (yield 37.4%) of the compound represented by the structural formula (1-3). In mass spectrometry (FD-MS), the peak of M / z = 614 was observed and identified as the target product. In the elemental analysis, the calculated values were 66.45% carbon, 3.61% hydrogen, and 9.12% nitrogen, and the measured values were 66.28% carbon, 3.45% hydrogen, and 9.33% nitrogen.

In addition, the electron transport material represented by the above structural formula (1-4) was manufactured by the following method.
<First step>
In a 200 ml four-necked flask, 5.0 g (9.39 mmol) of the above-mentioned dimer C and 50 ml of DMF were placed and heated to reflux. To this, a mixture of 2-aminoheptane 1.08 g (9.39 mmol) DMF 25 ml was added dropwise with stirring. After completion of dropping, the mixture was heated to reflux for 6 hours. After completion of the reaction, the reaction vessel was cooled and concentrated under reduced pressure. Toluene was added to the residue, and the residue was purified by silica gel column chromatography to obtain 1.66 g (yield 28.1%) of monoimide D.
<Second step>
A 100 ml four-necked flask was charged with 1.5 g (2.38 mmol) of monoimide D and 50 ml of DMF and heated to reflux. To this, a mixture of 2-aminooctane 0.308 g (2.38 mmol) and DMF 10 ml was added dropwise with stirring. After completion of dropping, the mixture was heated to reflux for 6 hours. After completion of the reaction, the reaction vessel was cooled and concentrated under reduced pressure. Toluene was added to the residue, and the residue was purified by silica gel column chromatography. Furthermore, the recovered product was recrystallized from toluene / hexane to obtain 0.328 g (yield 18.6%) of an electron transport material represented by the structural formula (1-4). In mass spectrometry (FD-MS), the peak of M / z = 740 was observed and identified as the target product. In the elemental analysis, the calculated values were 69.72% carbon, 5.44% hydrogen, and 7.56% nitrogen, and the measured values were 69.55% carbon, 5.26% hydrogen, and 7.33% nitrogen.

The electron transport material represented by the above structural formula (1-5) was produced by the following method.
<First step>
In a 200 ml four-necked flask, 5.0 g (9.39 mmol) of the above-mentioned dimer C and 50 ml of DMF were placed and heated to reflux. To this, a mixture of 2-aminoheptane 1.08 g (9.39 mmol) DMF 25 ml was added dropwise with stirring. After completion of dropping, the mixture was heated to reflux for 6 hours. After completion of the reaction, the reaction vessel was cooled and concentrated under reduced pressure. Toluene was added to the residue, and the residue was purified by silica gel column chromatography to obtain 1.66 g (yield 28.1%) of monoimide D.
<Second step>
A 100 ml four-necked flask was charged with 1.5 g (2.38 mmol) of monoimide D and 50 ml of DMF and heated to reflux. To this, a mixture of 0.408 g (2.38 mmol) of 6-aminoundecane and 10 ml of DMF was added dropwise with stirring. After completion of dropping, the mixture was heated to reflux for 6 hours. After completion of the reaction, the reaction vessel was cooled and concentrated under reduced pressure. Toluene was added to the residue, and the residue was purified by silica gel column chromatography. Furthermore, the recovered product was recrystallized from toluene / hexane to obtain 0.276 g (yield 14.8%) of the electron transport material represented by the structural formula (1-5) described above. In mass spectrometry (FD-MS), the peak of M / z = 782 was observed and identified as the target product. In the elemental analysis, the measured values were 70.77% carbon, 6.11% hydrogen, and 7.02% nitrogen while the calculated values were 70.57% carbon, 5.92% hydrogen, and 7.16% nitrogen.

In addition, the electron transport material represented by the above structural formula (1-13) was manufactured by the following method.
<First step>
In a 200 ml four-necked flask, 5.0 g (18.6 mmol) of 1,4,5,8-naphthalenetetracarboxylic dianhydride and 50 ml of DMF were placed and heated to reflux. To this, a mixture of 1.62 g (18.6 mmol) of 2-aminopentane and 25 ml of DMF was added dropwise with stirring. After completion of dropping, the mixture was heated to reflux for 6 hours. After completion of the reaction, the container was cooled and concentrated under reduced pressure. Toluene was added to the residue, and the residue was purified by silica gel column chromatography. Further, the recovered product was recrystallized from toluene / hexane to obtain 3.49 g of monoimide E (yield 45.8%).
<Second step>
In a 100 ml four-necked flask, 3.0 g (7.33 mmol) of the monoimide E, 0.983 g (3.66 mmol) of 1,4,5,8-naphthalenetetracarboxylic dianhydride, 0. 368 g (7.33 mmol), p-toluenesulfonic acid 10 mg, and toluene 50 ml were added and heated to reflux for 5 hours. After completion of the reaction, the container was cooled and concentrated under reduced pressure. The residue was purified twice by silica gel column chromatography. Further, the recovered product was recrystallized from toluene / ethyl acetate to obtain 0.939 g (yield 13.7%) of an electron transport material represented by the structural formula (1-13). In mass spectrometry (FD-MS), the peak of M / z = 934 was observed and identified as the target product. In the elemental analysis, the calculated values were 66.92% carbon, 3.67% hydrogen, and 8.99% nitrogen, and the measured values were 66.92% carbon, 3.74% hydrogen, and 9.05% nitrogen.

Next, the organic sulfur-based antioxidant will be described.
The organic sulfur-based antioxidant used in the present invention is not particularly limited as long as it is an antioxidant containing a sulfur atom, and various conventionally known ones can be used. When the compound represented by 2) is used, it is preferable because a residual potential increase and sensitivity deterioration hardly occur. This is considered to be caused by the fact that the compound represented by the general formula (2) has an ester group and is appropriately compatible in the photosensitive layer. Further, in the compound represented by the general formula (2), when n is smaller than 8, the compound is easily sublimated, and when it is larger than 25, the compatibility in the photosensitive layer is deteriorated and precipitates.
Specific examples of the organic sulfur-based antioxidant are shown in Tables 2 and 3, but the present invention is not limited to these.

In the present invention, it is essential to include the electron transport material of the general formula (1) as a charge transport material, but in addition to this, a known charge transport material, that is, an electron transport material and a hole transport material are used in combination. You can also.
Examples of the electron transport material include chloroanil, bromoanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2,4 , 5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2-b] thiophen-4-one, 1,3,7-tri Examples thereof include electron accepting substances such as nitrodibenzothiophene-5,5-dioxide.
These electron transport materials may be used alone or as a mixture of two or more.

As the hole transport material, an electron donating substance is preferably used.
Examples thereof include oxazole derivatives, oxadiazole derivatives, imidazole derivatives, triphenylamine derivatives, 9- (p-diethylaminostyrylanthracene), 1,1-bis- (4-dibenzylaminophenyl) propane, styrylanthracene, Examples include styrylpyrazolines, phenylhydrazones, α-phenylstilbene derivatives, thiazole derivatives, triazole derivatives, phenazine derivatives, acridine derivatives, benzofuran derivatives, benzimidazole derivatives, and thiophene derivatives.
These hole transport materials may be used alone or as a mixture of two or more.

Known polymer compounds can be used as the polymer compound that can be used as the binder component of the photosensitive layer. For example, polystyrene, styrene / acrylonitrile copolymer, styrene / butadiene copolymer, styrene / maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride / vinyl acetate copolymer, polyvinyl acetate, polyvinylidene chloride, Thermoplastic such as polyarylate resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, acrylic resin, silicone resin, fluorine resin, epoxy resin, melamine resin, urethane resin, phenol resin, alkyd resin Although thermosetting resin is mentioned, it is not limited to these.
Among these polymer compounds, polycarbonate resin is particularly preferable from the viewpoint of film quality.

  As a method for forming the photosensitive layer, a casting method from a solution dispersion system is preferable. In order to provide a photosensitive layer by the casting method, a coating solution prepared by dispersing or dissolving a charge generating material, a charge transporting material, a binder resin, and, if necessary, other components in an appropriate solvent is adjusted to an appropriate concentration. Adjust and apply.

In order to uniformly disperse the charge generation material in the photosensitive layer (in the coating solution), the charge generation material is previously ball milled with a binder resin, if necessary, using a solvent such as tetrahydrofuran, cyclohexanone, dioxane, dichloroethane, butanone, It is preferable to prepare a dispersion liquid dispersed by an attritor, a sand mill or the like.
Application can be performed by dip coating, spray coating, bead coating, or the like.

  Examples of the dispersion solvent that can be used in preparing the photosensitive layer coating solution provided as described above include ketones such as methyl ethyl ketone, acetone, methyl isobutyl ketone, and cyclohexanone, and ethers such as dioxane, tetrahydrofuran, and ethyl cellosolve. And aromatics such as toluene and xylene, halogens such as chlorobenzene and dichloromethane, and esters such as ethyl acetate and butyl acetate. These solvents can be used alone or in combination.

In the photosensitive layer, the charge generating material is 0.1 to 30% by weight, preferably 0.5 to 10% by weight, based on the entire photosensitive layer. The electron transport material is suitably 5 to 300 parts by weight, preferably 10 to 150 parts by weight, based on 100 parts by weight of the binder resin component. However, the electron transport material represented by the general formula (1) is preferably 50 to 100% by weight with respect to the entire electron transport material. The hole transport material is suitably 5 to 300 parts by weight, preferably 20 to 150 parts by weight with respect to 100 parts by weight of the binder resin component. The total amount of the electron transport material and the hole transport material is 20 to 300 parts by weight, preferably 30 to 200 parts by weight, based on 100 parts by weight of the binder resin component.
The organic sulfur-based antioxidant is suitably 0.05% to 5% by weight, preferably 0.1% to 1% by weight, based on the entire photosensitive layer.

Further, if necessary, other antioxidants, plasticizers, lubricants, low molecular compounds such as ultraviolet absorbers and leveling agents can be added to the photosensitive layer. These compounds can be used alone or as a mixture of two or more. The amount of the low molecular compound used is 0.1 to 50 parts by weight, preferably 0.1 to 20 parts by weight, based on 100 parts by weight of the binder resin, and the amount of the leveling agent used is 100 parts by weight of the binder resin. About 0.001 to 5 parts by weight is appropriate.
The film thickness of the photosensitive layer is suitably about 5 to 40 μm, preferably about 15 to 35 μm.

  As shown in FIG. 8, the electrophotographic photosensitive member used in the present invention may be provided with an undercoat layer (23) between the conductive support (21) and the photosensitive layer (22). The undercoat layer is provided for the purpose of improving adhesion, improving coatability of the upper layer, reducing residual potential, and preventing charge injection from the conductive support.

In general, the undercoat layer is mainly composed of a resin. However, considering that the photosensitive layer is applied on the resin using a solvent, the resin is a resin having high resistance to general organic solvents. Examples of such resins include water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate, alcohol-soluble resins such as copolymer nylon and methoxymethylated nylon, polyurethane, melamine resin, alkyd-melamine resin, and epoxy. Examples thereof include a curable resin that forms a three-dimensional network structure such as a resin.
In addition, a fine powder such as a metal oxide such as titanium oxide, silica, alumina, zirconium oxide, tin oxide, or indium oxide, or a metal sulfide or metal nitride may be added to the undercoat layer. These undercoat layers can be formed using an appropriate solvent and coating method, as in the case of the above-described photosensitive layer.
Further, as the undercoat layer, a metal oxide layer formed by using, for example, a sol-gel method using a silane coupling agent, a titanium coupling agent, a chromium coupling agent, or the like is also useful. In addition to this, alumina is provided by anodic oxidation, organic materials such as polyparaxylylene (parylene), and inorganic materials such as silicon oxide, tin oxide, titanium oxide, ITO, ceria are provided by the vacuum thin film manufacturing method. It can be used well as an undercoat layer.
The thickness of the undercoat layer is suitably from 0.1 to 10 μm, more preferably from 1 to 5 μm.

Next, the image forming apparatus of the present invention will be described.
FIG. 1 is a schematic view for explaining an image forming apparatus of the present invention, and modifications as described later also belong to the category of the present invention.
In FIG. 1, a photoreceptor (11) is a photoreceptor that satisfies the requirements of the present invention. Although the photoconductor (11) has a drum shape, it may have a sheet shape or an endless belt shape.
As the charging means (12), known means such as a corotron, a scorotron, a solid state charger (solid state charger), and a charging roller are used. The charging means (12) is preferably used in contact with or in close proximity to the photoreceptor from the viewpoint of reducing power consumption. In particular, in order to prevent contamination of the charging means (12), a charging mechanism disposed in the vicinity of the photoreceptor having an appropriate gap between the photoreceptor and the surface of the charging means is desirable.
As the transfer means (16), the above charger can be generally used, but a combination of a transfer charger and a separation charger is effective.
The light source used for the exposure means (13), the charge removal means (1A), etc. includes fluorescent lamps, tungsten lamps, halogen lamps, mercury lamps, sodium lamps, light emitting diodes (LEDs), semiconductor lasers (LDs), electroluminescence ( EL) in general. Various types of filters such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter can be used to irradiate only light in a desired wavelength range.
The toner (15) developed on the photoreceptor by the developing means (14) is transferred to the image receiving medium (18), but not all is transferred, and toner remaining on the photoreceptor is also generated. Such toner is removed from the photoreceptor by the cleaning means (17). As the cleaning means, a rubber cleaning blade, a brush such as a fur brush, a mag fur brush, or the like can be used.

FIG. 2 shows another example of an electrophotographic process according to the present invention. In FIG. 2, the photoconductor (11) satisfies the requirements of the present invention and has an endless belt shape.
Driven by drive means (1C), charged by charging means (12), image exposure by exposure means (13), development (not shown), transfer by transfer means (16), cleaning by pre-cleaning exposure means (1B). Pre-exposure, cleaning by the cleaning means (17), and static elimination by the static elimination means (1A) are repeated. In FIG. 2, light irradiation for pre-cleaning exposure is performed from the support side of the photoreceptor (in this case, the support is translucent).

  The above electrophotographic process exemplifies an embodiment of the present invention, and other embodiments are of course possible. For example, in FIG. 2, the pre-cleaning exposure is performed from the support side, but this may be performed from the photosensitive layer side, or image exposure and neutralization light irradiation may be performed from the support side. On the other hand, the light irradiation process is illustrated as image exposure, pre-cleaning exposure, and static elimination exposure. In addition, a pre-transfer exposure, a pre-exposure of image exposure, and other known light irradiation processes are provided to light the photosensitive member. Irradiation can also be performed.

  Further, the image forming means as described above may be fixedly incorporated in a copying machine, a facsimile, or a printer, but may be incorporated in these apparatuses in the form of a process cartridge. A process cartridge is a single device (part) that contains a photosensitive member and includes any one or more of charging means, exposure means, developing means, transfer means, cleaning means, and discharging means. It is. There are many shapes and the like of the process cartridge, but a general example is shown in FIG. Also in this case, the photoreceptor (11) is a photoreceptor that satisfies the requirements of the present invention. Although the photoconductor (11) has a drum shape, it may have a sheet shape or an endless belt shape.

FIG. 4 shows an example of a full-color image forming apparatus according to the present invention. In this electrophotographic apparatus, charging means (charging device) (12), exposure means (13), black (Bk), cyan (C), magenta (M), and yellow (Y) are disposed around the photoreceptor (11). Developing means (14Bk, 14C, 14M, 14Y) for each color toner, an intermediate transfer belt (1F) as an intermediate transfer member, and a cleaning means (17) are arranged in this order. Here, the subscripts Bk, C, M, and Y shown in the figure correspond to the color of the toner, and are added or omitted as appropriate.
The photoreceptor (11) is an electrophotographic photoreceptor that satisfies the requirements of the present invention. Each color developing means (14Bk, 14C, 14M, 14Y) can be controlled independently, and only the color developing means for image formation is driven. The toner image formed on the photoreceptor (11) is transferred onto the intermediate transfer belt (1F) by the first transfer means (1D) disposed inside the intermediate transfer belt (1F). The first transfer means (1D) is arranged so as to be able to come into contact with and separate from the photoreceptor (11), and the intermediate transfer belt (1F) is brought into contact with the photoreceptor (11) only during the transfer operation. The respective color images are sequentially formed, and the toner images superimposed on the intermediate transfer belt (1F) are collectively transferred to the image receiving medium (18) by the second transfer means (1E) and then fixed by the fixing means (19). The image is formed by fixing. The second transfer means (1E) is also arranged so as to be able to contact and separate from the intermediate transfer belt (1F), and abuts on the intermediate transfer belt (1F) only during the transfer operation.
In the transfer drum type electrophotographic apparatus, since the toner images of the respective colors are sequentially transferred onto the transfer material electrostatically attracted to the transfer drum, there is a limitation on the transfer material that cannot be printed on cardboard, as shown in FIG. Such an intermediate transfer type image forming apparatus is characterized in that the toner images of the respective colors are superimposed on the intermediate transfer body (1F), and therefore, there is no restriction on the transfer material. Such an intermediate transfer method is not limited to the apparatus shown in FIG. 4, and can be applied to the image forming apparatus shown in FIGS. 1, 2, 3 and 5 described later (a specific example is shown in FIG. 6). .

  FIG. 5 shows another example of a full-color image forming apparatus according to the present invention. This image forming apparatus is of a type using four colors of yellow (Y), magenta (M), cyan (C), and black (Bk) as toner, and an image forming unit is provided for each color. In addition, photoconductors (11Y, 11M, 11C, 11Bk) for each color are provided. The photoreceptor used in this electrophotographic apparatus is a photoreceptor that satisfies the requirements of the present invention. Around each photoconductor (11Y, 11M, 11C, 11Bk), charging means (12Y, 12M, 12C, 12Bk), exposure means (13Y, 13M, 13C, 13Bk), developing means (14Y, 14M, 14C, 14Bk), cleaning means (17Y, 17M, 17C, 17Bk) and the like are provided. Further, a transfer transfer belt (1G) as a transfer material carrier that comes in contact with and separates from each transfer position of each photoconductor (11Y, 11M, 11C, 11Bk) arranged on a straight line is hung by a driving means (1C). Has been passed. Transfer means (16Y, 16M, 16C, 16Bk) are disposed at transfer positions facing the respective photoconductors (11Y, 11M, 11C, 11Bk) with the conveyance transfer belt (1G) interposed therebetween.

  The image forming means as described above may be fixedly incorporated in a copying apparatus, a facsimile, or a printer, but may be incorporated in these apparatuses in the form of a process cartridge. A process cartridge is a single device (part) that contains a photoconductor and further includes a charging unit, an exposure unit, a developing unit, a transfer unit, a cleaning unit, a neutralizing unit, and the like.

Hereinafter, the present invention will be described by way of examples. Note that this does not limit the scope of the present invention. All parts are parts by weight.
(Photosensitive member production example 1)
Metal-free phthalocyanine was dispersed under the following composition and conditions to prepare a pigment dispersion.
Metal-free phthalocyanine pigment (Dainippon Ink Industries, Ltd .: Fastogen Blue8120B): 3 parts Cyclohexanone: 97 parts These were put in a glass pot with a diameter of 9 cm, and PSZ balls with a diameter of 0.5 mm were used.
Dispersion was carried out at a rotational speed of 100 rpm for 5 hours to obtain a pigment dispersion.
A photoreceptor coating solution having the following composition was prepared using the pigment dispersion.
Pigment dispersion: 60 parts Exemplified Compound No. 1-1 electron transport material: 20 parts Hole transport material (HTM1) having the following structure: 30 parts

例示化合物Ｎｏ．２−１の有機硫黄系酸化防止剤：１部
Ｚ型ポリカーボネート樹脂（帝人化成社製：パンライトＴＳ−２０５０）：５０部
シリコーンオイル（信越化学工業社製：ＫＦ５０）：０．０１部
テトラヒドロフラン：３５０部
こうして得られた感光層用塗工液を直径３０ｍｍ、長さ３４０ｍｍアルミニウムドラム上に、浸漬塗工法により塗布、１２０℃で２０分間乾燥し、２５μｍの感光層を形成し、感光体を作製した（感光体１とする）。

Exemplified Compound No. 2-1 organic sulfur-based antioxidant: 1 part Z-type polycarbonate resin (manufactured by Teijin Chemicals: Panlite TS-2050): 50 parts Silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: KF50): 0.01 parts Tetrahydrofuran: 350 parts The coating solution for photosensitive layer thus obtained was applied on an aluminum drum having a diameter of 30 mm and a length of 340 mm by a dip coating method, dried at 120 ° C. for 20 minutes to form a photosensitive layer of 25 μm, and a photoreceptor was produced. (Referred to as photoreceptor 1).

(Photosensitive member preparation example 2)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 1 except that titanyl phthalocyanine prepared according to the following synthesis example was used instead of the metal-free phthalocyanine pigment (Fastogen Blue8120B) used in Photoconductor Preparation Example 1. (Photoreceptor 2).

(Titanyl phthalocyanine used in Photoconductor Preparation Example 2)
A pigment was prepared according to Japanese Patent Application Laid-Open No. 2001-19871. That is, 29.2 g of 1,3-diiminoisoindoline and 200 ml of sulfolane are mixed, and 20.4 g of titanium tetrabutoxide is added dropwise under a nitrogen stream. After completion of the dropwise addition, the temperature was gradually raised to 180 ° C., and the reaction was carried out by stirring for 5 hours while maintaining the reaction temperature between 170 ° C. and 180 ° C. After completion of the reaction, the mixture was allowed to cool and then the precipitate was filtered, washed with chloroform until the powder turned blue, then washed several times with methanol, further washed several times with hot water at 80 ° C. and dried, Crude titanyl phthalocyanine was obtained. Dissolve the crude titanyl phthalocyanine in 20 times the amount of concentrated sulfuric acid, add dropwise to 100 times the amount of ice water with stirring, filter the precipitated crystals, and then repeat washing with water until the washing solution becomes neutral (ion-exchanged water after washing). PH value was 6.8), and a titanyl phthalocyanine pigment wet cake (water paste) was obtained. 40 g of the obtained wet cake (water paste) was put into 200 g of tetrahydrofuran, stirred for 4 hours, filtered and dried to obtain titanyl phthalocyanine powder.
The solid content concentration of the wet cake was 15 wt%. The weight ratio of the crystal conversion solvent to the wet cake is 33 times.
The obtained titanyl phthalocyanine powder was subjected to X-ray diffraction spectrum measurement under the following conditions. As a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to the characteristic X-ray of Cu-Kα (wavelength 1.542 mm), at least It has a maximum diffraction peak at 27.2 °, and further main peaks at 9.4 °, 9.6 °, and 24.0 °, and a peak at 7.3 ° as the lowest diffraction peak. And titanyl phthalocyanine powder having no peak between the peak at 7.3 ° and the peak at 9.4 °.
An X-ray diffraction spectrum is shown in FIG.

(X-ray diffraction spectrum measurement conditions)
X-ray tube: Cu
Voltage: 50kV
Current: 30mA
Scanning speed: 2 ° / min Scanning range: 3 ° to 40 °
Time constant: 2 seconds

(Photosensitive member production examples 3 to 13)
Photoconductors were prepared in the same manner as in Photoconductor Preparation Example 2 except that the electron transport materials and organic sulfur-based antioxidants used in Photoconductor Preparation Example 2 were changed to those shown in Table 4 (Photoconductors 3 to 13 and To do).

(Photoreceptor Preparation Example 14)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 2 except that the hole transport material used in Photoconductor Preparation Example 2 was changed to a hole transport material (HTM2) having the following structure.

(Photoreceptor Preparation Example 15)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 2 except that the hole transport material used in Photoconductor Preparation Example 2 was changed to a hole transport material (HTM3) having the following structure.

(Photoreceptor Production Example 16)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 2 except that no organic sulfur-based antioxidant was added in Photoconductor Preparation Example 2 (referred to as Photoconductor 16).

(Photoreceptor Preparation Example 17)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 2 except that the organic sulfur-based antioxidant used in Photoconductor Preparation Example 2 was changed to an antioxidant (AO1) having the following structure (referred to as Photoconductor 17). .

(Photoreceptor Preparation Example 18)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 2 except that the organic sulfur-based antioxidant used in Photoconductor Preparation Example 2 was changed to an antioxidant (AO2) having the following structure (referred to as Photoconductor 18). .

(Photoreceptor Preparation Example 19)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 2 except that the organic sulfur-based antioxidant used in Photoconductor Preparation Example 2 was changed to an antioxidant (AO3) having the following structure (referred to as Photoconductor 19). .

(Photoreceptor Preparation Example 20)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 2 except that the electron transport material used in Photoconductor Preparation Example 2 was changed to an electron transport material (ETM1) having the following structure (referred to as Photoconductor 20).

(Photoconductor Preparation Example 21)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 2 except that the electron transport material used in Photoconductor Preparation Example 2 was changed to an electron transport material (ETM2) having the following structure (referred to as Photoconductor 21).

(Examples 1-15, Comparative Examples 1-6)
After the produced photoreceptors 1 to 21 are mounted, they are mounted on an image forming apparatus (Ricoh's imgio Neo 270 remodeling machine, a power pack that has been remodeled so as to be positively charged), and a writing rate 5% chart ( On the entire surface of A4, a printing durability test was performed to print a total of 50,000 sheets using characters equivalent to 5% as an image area).
The toner and developer used were exchanged for toner and developer having polarity reversed from those dedicated to imgio Neo 270.
Also, the charging means of the image forming apparatus uses an external power source, and the bias voltage applied to the charging roller is set so that the charging potential of each photoconductor becomes +600 V at the start of the test. The test was conducted. The developing bias was + 450V. The test environment is 23 ° C. and 55% RH.
Afterimage evaluation and exposure area potential evaluation were performed before and after the printing durability test.

[Afterimage evaluation]
An evaluation image having a solid black portion and a halftone portion as shown in FIG. 10 was output and the afterimage was evaluated. Evaluation performed rank evaluation. The evaluation rank is as follows.
<Afterimage rank>
◎: Afterimage does not occur ○: Faintly visible △: Afterimage occurs ×: Very bad

[Bright part potential]
The surface potential of the photosensitive member when the photosensitive member is charged to +600 V, subjected to image exposure (entire exposure), and moved to the developing portion position.
The surface potential of the photosensitive member was measured by mounting a surface potential meter on the developing part.
The results are shown in Table 4.

(Photoreceptor evaluation example)
Further, for the photoreceptors 2 to 6 and the photoreceptors 16 to 21, the chargeability of the photoreceptors was evaluated before and after the printing durability test.
Evaluation is made using Ricoh's imgio Neo 270 remodeling machine (a surface potential meter is installed in the development section, and an external power source is used as the charging means, and the charging polarity can be freely changed). The negative chargeability was evaluated.

<Evaluation methods>
[Positive charge evaluation]
The charging conditions were set so that the charging potential of the initial photosensitive member 16 was +500 V, and the charging potentials of the other photosensitive members were measured with the charging conditions maintained. Evaluation after the printing durability test was performed under the same charging conditions.
[Negative charging evaluation]
Charging conditions were set so that the charging potential of the initial photosensitive member 16 was −500 V, and the charging potentials of the other photosensitive members were measured with the charging conditions maintained. Evaluation after the printing durability test was performed under the same charging conditions.
The results are shown in Table 5.

As is clear from the above embodiments, the photoreceptor satisfying the requirements of the present invention does not generate afterimages even after repeated use, and further, there is little fluctuation in the bright part potential. Therefore, the image forming apparatus of the present invention can output a high-quality image that does not generate an abnormal image such as an afterimage over a long period of time.
Moreover, it can be seen from the results of the photoreceptor evaluation examples that a photoreceptor satisfying the requirements of the present invention can maintain a high positive charge even after repeated use. On the other hand, the photoconductor 19 using AO 3 as the antioxidant can maintain the positive charge, but the afterimage is generated from the result of Comparative Example 4. In the case of the photoconductor of the present invention, the negative chargeability is greatly reduced. For this reason, it is considered that the photoconductor is prevented from being negatively charged in the transfer step and no afterimage is generated.

1 is a schematic cross-sectional view illustrating an example of an image forming apparatus according to the present invention. It is a schematic cross section which shows another example of the image forming apparatus which concerns on this invention. It is a schematic cross section showing an example of a process cartridge according to the present invention. It is a schematic cross section which shows another example of the image forming apparatus which concerns on this invention. FIG. 6 is a schematic cross-sectional view showing still another example of the image forming apparatus according to the present invention. FIG. 6 is a schematic cross-sectional view showing still another example of the image forming apparatus according to the present invention. It is sectional drawing which shows the example of the layer structure of the electrophotographic photoreceptor which concerns on this invention. It is sectional drawing which shows the example of another layer structure of the electrophotographic photoreceptor which concerns on this invention. It is a X-ray-diffraction spectrum figure of the titanyl phthalocyanine synthesize | combined in the Example. It is a figure which shows the image for evaluation used in the Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Electrophotographic photoreceptor 12 ... Charging means 13 ... Exposure means 14 ... Developing means 15 ... Toner 16 ... Transfer means 17 ... Cleaning means 18 ... Image receiving medium 19 ... Fixing means 1A ... Charging means 1B ... Pre-cleaning exposure means 1C ... Drive means 1D ... First transfer means 1E ... Second transfer means 1F ... Intermediate transfer member 1G ... Conveyance transfer belt 21 ... Conductive support 22 ... Photosensitive layer 23 ... Undercoat layer

Claims (7)

An electrophotographic photosensitive member used by being charged to a positive polarity, wherein the electrophotographic photosensitive member is provided with at least a photosensitive layer on a conductive support, and the photosensitive layer comprises at least a charge generating material and the following general formula (1) An electrophotographic photosensitive member comprising a single layer containing an electron transport material represented by the formula (1) and an organic sulfur-based antioxidant.

Wherein R 1 and R 2 each independently represent a group selected from the group consisting of a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aralkyl group, and R 3 , R4, R5, R6, R7, R8, R9, R10, R11, R12, R13, R14 are each independently a hydrogen atom, halogen atom, cyano group, nitro group, amino group, hydroxyl group, substituted or unsubstituted alkyl group Represents a group selected from the group consisting of a substituted or unsubstituted cycloalkyl group and a substituted or unsubstituted aralkyl group, and n is a repeating unit and represents an integer of 0 to 100.) 2. The electrophotographic photoreceptor according to claim 1, wherein the organic sulfur-based antioxidant is a compound represented by the following general formula (2).

(In the formula, n is an integer of 8 to 25.) The electrophotographic photosensitive member according to claim 1, wherein the charge generation material is phthalocyanine. The phthalocyanine has a maximum diffraction peak at 27.2 ° as a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to the characteristic X-ray (wavelength 1.542 mm) of CuKα, and further 9.4 °, 9 It has major peaks at .6 ° and 24.0 ° and has a peak at 7.3 ° as the lowest angled diffraction peak, between the 7.3 ° peak and the 9.4 ° peak. The electrophotographic photosensitive member according to claim 3, which has no peak. An image forming apparatus comprising the electrophotographic photosensitive member according to claim 1. 6. The image forming apparatus according to claim 5, wherein the developing system is a reversal developing system. A process cartridge for an image forming apparatus, which is detachable from an apparatus main body and has at least an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to any one of claims 1 to 4. A process cartridge characterized by that.

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