JP4719085B2 - Electrophotographic photosensitive member, image forming apparatus, process cartridge - Google Patents

Description

  The present invention relates to an electrophotographic photosensitive member, an image forming apparatus, and a process cartridge used for copying, printers, facsimiles and the like.

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 image forming apparatuses are roughly classified into organic photoreceptors and inorganic photoreceptors, but organic photoreceptors are easier to manufacture than conventional inorganic photoreceptors, are inexpensive, and charge transport. In recent years, it has been widely used because it has the advantage that there are various options for photoconductor materials such as materials, charge generation materials, and binder resins, and the degree of freedom in functional design is high.

The organic photoreceptor includes a single-layer photoreceptor in which a charge transport material (a hole transport material, an 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, and a charge. There is a laminate type photoreceptor in which a charge transport layer containing a 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. On the other hand, single-layer type photoreceptors generally have positive and negative sensitivities, but most of them are used with positive charge because of the low electron transport ability of electron transport materials.

  As a few examples of electron transport materials having an electron transport ability, Patent Document 1 (Japanese Patent Laid-Open No. 1-206349) proposes a compound having a diphenoquinone structure as a charge transport agent for an electrophotographic photoreceptor. Further, Patent Document 2 (Japanese Patent Laid-Open No. 4-295835) proposes a monolayer dispersion type positively charged organic photoreceptor containing a diphenoquinone derivative. However, these single layer type organic photoconductors have a higher residual potential than the functionally separated type multi-layer photoconductors, and have the problems inherent to a single layer that the charging potential due to electrostatic repeated fatigue and the change in potential after exposure are large. Have.

  In order to solve the problem of such a single layer type photoreceptor, in recent years, development of a new electron transport material has been promoted, and a disclosure example thereof is also recognized. Tetracarboxylic acid derivatives and naphthalenecarboxylic acid derivatives as disclosed in Patent Document 3 (International Publication No. WO2005 / 092901) have an excellent electron transporting ability, and thus solve the problems of conventional single layer type photoreceptors. It is possible to greatly improve the electrostatic characteristics.

  In the case where the support of the single layer type photoreceptor using the naphthalenecarboxylic acid derivative represented by the above <General Formula 1> and <General Formula 2> is a flexible sheet such as an aluminum-deposited PET sheet or a nickel belt, It has been found that a large warp generally referred to as curl occurs during layer deposition. Therefore, when the photosensitive layer is formed using the naphthalenecarboxylic acid derivative, the volumetric shrinkage of the photosensitive layer is relatively large. Therefore, when the photosensitive layer is formed on a rigid support, the photosensitive layer in which internal stress is accumulated. The problem of becoming became clear. In the photosensitive layer in which the internal stress is accumulated, cracks due to standing at high temperature and adhesion of oil, and physical cracks due to external force from a constant contact member such as a charging roller and a cleaning blade are likely to occur, leading to a decrease in image quality. In addition, when minute cracks frequently occur, the amount of wear due to repeated image formation increases, and the life of the photoreceptor may be shortened. In addition, since the internal stress is high, the adhesive strength between the support and the photosensitive layer is weakened, and a fatal problem of peeling of the photosensitive layer occurs.

  In general, a small amount of an additive (plasticizer, etc.) may be contained for relaxing internal stress in the photosensitive layer, but the single-layer type photoreceptor has a structure in which the charge generation function and the transport function are expressed in one layer. In many cases, the electrostatic properties of the photoreceptor are often lowered by the interaction between the functional materials, and no suitable additive has been found to relieve the stress in the photosensitive layer. In addition, in order to improve the adhesive strength between the single-layer type photosensitive layer and the support, examples including a polyester resin (Patent Document 4: Japanese Patent No. 3262998, Patent Document 5: Japanese Patent Laid-Open No. 10-268540) are also included. As can be seen, in the case of a photosensitive layer having a relatively large volume shrinkage, it is difficult to obtain sufficient adhesive strength for image formation over a long period of time.

  As described above, when the naphthalene carboxylic acid derivatives of the above <General Formula 1> and <General Formula 2> having excellent electron transport ability are used, the electrical characteristics of the single layer type photoreceptor are dramatically improved. In the present situation, there is a problem of generation of cracks due to volume shrinkage of the material, and satisfactory results with respect to mechanical durability are not obtained.

JP-A-1-206349 JP-A-4-295853 International Publication Number WO2005 / 092901 International Publication Specification Japanese Patent No. 3262998 Japanese Patent Laid-Open No. 10-268540

The present invention has been made in view of the current situation, and for a conventional single-layer type electrophotographic photosensitive member, by using a specific electron transport material, the stability of photosensitivity and electrostatic characteristics is improved, and photosensitivity is achieved. It is an object to improve the mechanical durability (crack resistance, adhesive strength, etc.) of the layer and achieve the following objects.
The present invention is an image forming apparatus using a single-layer type electrophotographic photosensitive member, which can form a higher-speed image and can output a high-quality image even in repeated image formation over a long period of time. An object is to provide a body, an image forming apparatus, and a process cartridge.

As described above, the naphthalenecarboxylic acid derivatives of the above-mentioned <general formula 1> and <general formula 2> used in the present invention have an excellent electron transporting ability, thereby solving the problems of conventional single-layer type photoreceptors. Although it is possible to greatly improve the electrical characteristics, it becomes a sensitive layer having a high internal stress, and thus there remains a problem in the mechanical durability (crack resistance, adhesive strength, etc.) of the photosensitive layer.
As a result of intensive studies to solve the above-mentioned problems, the inventors have found that in an image forming apparatus using a single-layer type electrophotographic photoreceptor containing a naphthalenecarboxylic acid derivative having an excellent electron transport ability, By using a glycol derivative, it has been found that the internal stress of the photosensitive layer can be alleviated without sacrificing the electrostatic characteristics of the photoreceptor, and as a result, a high-quality image can be output even during repeated image formation over a long period of time. The inventors have found that an electrophotographic photosensitive member, an image forming apparatus, and a process cartridge with high reliability can be provided, and have reached the present invention.

It is a fact found by experiments that can reduce the internal stress of the photosensitive layer by adding a mono- or diester derivative or monoether derivative of polyalkylene glycol. The mechanism is not known in detail, but the reason is as follows. It is estimated that In the photosensitive layer using the naphthalenecarboxylic acid derivatives of the above <General Formula 1> and <General Formula 2>, the large internal stress is considered to be due to the relatively high crystallinity of the electron transport material. By adding a mono- or diester derivative or monoether derivative of alkylene glycol, which is generally known as a surfactant, to the photosensitive layer, the naphthalenecarboxylic acid derivatives that occur during the formation of the photosensitive layer (or other low molecular weight compounds) It is thought that the cohesive effect of the components and binder resin) is reduced and the internal stress is relaxed, but the detailed mechanism is not clear.

  Specifically, in an electrophotographic photoreceptor having at least a photosensitive layer on a conductive support, the photosensitive layer is at least a charge generating material and an electron transport material represented by the following <General Formula 1> or <General Formula 2> The photosensitive layer is high by containing 2 to 15 wt% of the polyalkylene ethylene glycol derivative represented by the following <General Formula 4> to <General Formula 6> with respect to the charge transport material. Mechanical durability due to internal stress can be reduced.

｛但し、上記一般式中、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し、Ｒ３、Ｒ４、Ｒ５、Ｒ６、Ｒ７、Ｒ８、Ｒ９、Ｒ１０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す。｝

{However, in the above general formula, R1 and R2 are each independently a group selected from the group consisting of a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, and a substituted or unsubstituted aralkyl group. R 3, R 4, R 5, R 6, R 7, R 8, R 9, R 10 are each independently a hydrogen atom, halogen atom, cyano group, nitro group, amino group, hydroxyl group, substituted or unsubstituted alkyl group, substituted or unsubstituted A group selected from the group consisting of a substituted cycloalkyl group and a substituted or unsubstituted aralkyl group. }

｛但し、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し、ｎは繰り返し単位であり、１から１００までの整数を表す。｝

{However, in the formula, 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, and a substituted or unsubstituted aralkyl group. , R3, 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 The group selected from the group which consists of an alkyl group, a substituted or unsubstituted cycloalkyl group, and a substituted or unsubstituted aralkyl group is represented, n is a repeating unit and represents the integer of 1-100. }

Examples of polyalkylene ethylene glycol derivatives that relieve internal stress and do not adversely affect electrostatic properties include the following.
A mono- or diester of polyalkylene glycol represented by the following <General Formula 4> and <General Formula 5>.

〔ここで、ｍ＝２〜４、ｎ＝１〜３０（平均付加モル数）、Ｒ１，Ｒ２は炭素数１〜３０のアルキル基またはアルケニル基、好ましくは１０〜２０のアルキル基またはアルケニル基を示す〕

[Where m = 2 to 4, n = 1 to 30 (average number of added moles), R1 and R2 each represents an alkyl group or alkenyl group having 1 to 30 carbon atoms, preferably an alkyl group or alkenyl group having 10 to 20 carbon atoms. Show

  Examples thereof include polyethylene glycol monostearate, polyethylene glycol monooleate, polyethylene glycol distearate, polyethylene glycol dilaurate, and polyethylene glycol dioleate.

  The polyalkylene glycol monoether is a polyalkylene glycol monoether represented by the following <general formula 6>.

（式中ｍは２〜４、Ｒは炭素数１〜３０のアルキル基、好ましくは炭素数１０〜２０のアルキル基、置換もしくは無置換のアリール基、好ましくは炭素数１〜２０のアルキル基で置換されたフェニル基を、ｎは平均付加モル数を示し、１以上、好ましくは１〜１００の実数を表わす。）

(In the formula, m is 2 to 4, R is an alkyl group having 1 to 30 carbon atoms, preferably an alkyl group having 10 to 20 carbon atoms, a substituted or unsubstituted aryl group, preferably an alkyl group having 1 to 20 carbon atoms. (In the substituted phenyl group, n represents an average added mole number and represents a real number of 1 or more, preferably 1 to 100.)

  For example, polyoxyethylene nonyl phenyl ether, polyoxyethylene lauryl ether, polyoxyethylene octyl phenyl ether and the like can be mentioned.

  The above polyalkylene glycol derivatives can be used alone or in combination of several kinds. In order to relieve the internal stress of the photosensitive layer, it is preferable to add 2 to 20 wt% of the above polyalkylene glycol derivative with respect to the electron transport material. If it is 1 wt% or less, the internal stress relaxation effect is difficult to obtain, and if it is 15 wt% or more, the internal stress increases the relaxation effect, but the adhesive strength between the photosensitive layer and the support decreases. The addition amount is more preferably 2 to 15 wt%.

  Furthermore, the adhesive strength can be improved by adding 2 to 15 wt% of a polyester resin in the electrophotographic photosensitive member as described above in a more preferable form with respect to the binder resin. The polyalkylene glycol derivative can reduce the internal stress of the photosensitive layer as the amount added is increased, but conversely, due to its surface active effect, it tends to lower the adhesive strength between the photosensitive layer and the support. Therefore, in a region where the addition amount of the polyalkylene glycol derivative is relatively large, the internal stress can be relaxed while maintaining the adhesive strength by the combined use with the polyester resin.

The polyester-based resin used as a more preferable embodiment in the present invention is preferably a polyester derived from a dibasic acid mainly composed of an aromatic dicarboxylic acid and a diol, from the viewpoint of solubility in a solvent and compatibility with a polycarbonate. Is preferably a copolyester.
Examples of the aromatic dicarboxylic acid component include terephthalic acid, isophthalic acid, phthalic acid, P-β-oxyethoxybenzoic acid, naphthalene-2,6-dicarboxylic acid, diphenoxyethane-4,4′-dicarboxylic acid, and the like. Examples of other dicarboxylic acids include hexahydroterephthalic acid, adipic acid, sebacic acid, succinic acid, dimer acid, maleic acid, fumaric acid, and xylene dicarboxylic acid.
On the other hand, the diol component includes ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexylene glycol, diethylene glycol, triethylene glycol, cyclohexanedimethanol, bisphenol A or bisphenol F ethylene oxide. Examples include glycol components such as adducts.
The aromatic dicarboxylic acid component desirably accounts for 40 mol% or more, particularly 60 mol% or more of the dibasic acid component from the viewpoint of the mechanical properties, moisture resistance, durability and electrical properties of the photosensitive layer. The acid component of this polyester contains a combination of terephthalic acid and isophthalic acid, while satisfying the above properties, the purpose of improving the solubility and the like, and lowering the glass transition point, the adhesion of the photosensitive layer to the substrate It is suitable for the purpose of improving. Of course, an aliphatic dibasic acid component other than the aromatic dicarboxylic acid may be contained within the range satisfying the above requirements, and these aliphatic dibasic acid components are useful for improving the solubility of the polyester.
The glycol component may be ethylene glycol alone or a combination of ethylene glycol and other glycols such as neopentyl glycol, in which case the amount ratio is within a molar ratio of 1:10 to 10: 1. May be.

The polyester used in the present invention has a glass transition point (Tg) of 90 ° C. or lower, particularly 75 ° C. or lower, which is useful for improving the peel resistance. The number average molecular weight is in the range of 10,000 to 30,000, and the acid value is preferably 2 or less from the viewpoint of mechanical properties and durability of the photosensitive layer.
The polyester may be a homopolyester or a copolyester alone or a blend of two or more of these.
The addition amount of the polyester resin is preferably 2 to 20 wt% with respect to the binder resin. If 1 wt%, the adhesive strength is insufficient, and if it is 20 wt% or more, the layer is included in the photosensitive layer due to a compatibility problem with the main binder resin. Since it becomes easy to raise | generate separation, the more preferable addition amount of the polyester-type resin is 2-15 wt%.

Furthermore, the sensitivity is improved by using a specific material for the charge generation material. In the present invention, a known material can be used as the charge generating material, but among them, a material having a phthalocyanine structure is preferable in combination with the charge transporting material used in the present invention.
Among them, in particular, by using titanyl phthalocyanine as shown in the following structural formula (7) having titanium as a central metal, it is possible to obtain a particularly highly sensitive photoconductor and further increase the speed as an image forming apparatus. Is possible.

［式中、Ｘ1、Ｘ2、Ｘ3、Ｘ4は、それぞれ独立に異なっていてもよいハロゲン原子を表しｍ、ｎ、ｌ及びｋは、各々独立に０〜４の整数を表す。］

[Wherein, X1, X2, X3 and X4 each independently represent a halogen atom which may be different, m, n, l and k each independently represent an integer of 0 to 4; ]

References relating to the synthesis method and electrophotographic properties of titanyl phthalocyanine include, for example, JP-A-57-148745, JP-A-59-36254, JP-A-59-44054, and JP-A-59-31965. JP, 61-239248, JP, 62-67094, A, etc. are mentioned. In addition, various crystal systems are known for titanyl phthalocyanine. JP-A 59-49544, JP-A 59-166959, JP-A 61-239248, JP-A 62-67094. JP-A-63-366, JP-A-63-116158, JP-A-64-17066, JP-A-2001-19871, etc. each describe a titanyl phthalocyanine having a different crystal form. .
Of these 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 having no peak between the 7.3 ° peak and the 9.4 ° peak, Without losing sensitivity, it is possible to obtain a stable electrophotographic photosensitive member that does not cause a decrease in chargeability even when used repeatedly.

  Furthermore, since the photoconductor of the present invention has improved sensitivity characteristics in the negative polarity as compared with a conventional positively charged photoconductor, it can be used in a negative charging process. Single layer type photoreceptors are less expensive than multilayer type photoreceptors because of their layer structure and ease of manufacture, so a reversal development system using multilayer type photoreceptors in a negative charging process that has been widely used in the past. By combining the single layer type photoreceptor of the present invention with the image forming apparatus, the cost of the image forming apparatus can be reduced.

  That is, according to the present invention, the above-mentioned problem is (1) “in an electrophotographic photosensitive member having a photosensitive layer on at least a conductive support, wherein the photosensitive layer is at least a charge generating material, a charge transport layer material, and a binder resin. The charge transport layer material comprises an electron transport material represented by the following <general formula 1> or <general formula 2>, and the polyalkylene glycol mono- or diester derivative or monoether derivative is An electrophotographic photoreceptor containing 2 to 15 wt% of the charge transport material;

｛但し、上記一般式中、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し、Ｒ３、Ｒ４、Ｒ５、Ｒ６、Ｒ７、Ｒ８、Ｒ９、Ｒ１０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す。｝

{However, in the above general formula, R1 and R2 are each independently a group selected from the group consisting of a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, and a substituted or unsubstituted aralkyl group. R 3, R 4, R 5, R 6, R 7, R 8, R 9, R 10 are each independently a hydrogen atom, halogen atom, cyano group, nitro group, amino group, hydroxyl group, substituted or unsubstituted alkyl group, substituted or unsubstituted A group selected from the group consisting of a substituted cycloalkyl group and a substituted or unsubstituted aralkyl group. }

｛但し、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し、ｎは繰り返し単位であり、１から１００までの整数を表す。｝」、
（２）「前記電子写真感光体が、ポリエステル系樹脂をバインダー樹脂に対し２〜１５ｗｔ％含有す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」、
（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）項または第（２）項に記載の電子写真感光体」、
（４）「前記フタロシアニンがチタニルフタロシアニンである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）「前記チタニルフタロシアニンがＣｕ−Ｋα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（４）項に記載の電子写真感光体」、
（６）「前記電荷輸送材料が、前記電子輸送材料に加えて、さらに下記＜一般式３＞で表される電子輸送材料を含有することを特徴とする前記第（１）項乃至第（５）項の何れかに記載の電子写真感光体；

{However, in the formula, 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, and a substituted or unsubstituted aralkyl group. , R3, 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 The group selected from the group which consists of an alkyl group, a substituted or unsubstituted cycloalkyl group, and a substituted or unsubstituted aralkyl group is represented, n is a repeating unit and represents the integer of 1-100. } ",
(2) "The electrophotographic photosensitive member according to (1) above, wherein the electrophotographic photosensitive member contains 2 to 15 wt% of a polyester resin with respect to the binder resin",
(3) "The electrophotographic photosensitive member according to (1) or (2) above, wherein the charge generation material is phthalocyanine",
(4) "The electrophotographic photosensitive member according to (3) above, wherein the phthalocyanine is titanyl phthalocyanine",
(5) “The titanyl phthalocyanine has a maximum diffraction peak at 27.2 ° as a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to Cu—Kα rays (wavelength 1.542 mm). 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 (4), which has no peak between the peaks of
(6) “The charge transporting material further includes an electron transporting material represented by the following <general formula 3> in addition to the electron transporting material,” (1) to (5) ) The electrophotographic photosensitive member according to any one of items

｛式中、Ｒ１５、Ｒ１６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し、Ｒ１７、Ｒ１８、Ｒ１９、Ｒ２０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す。｝」により達成される。
また、上記課題は本発明の（７）「少なくとも電子写真感光体と、該電子写真感光体を帯電する帯電手段と、帯電後に像露光を行って静電潜像を形成する像露光手段と、該静電潜像を現像する現像手段と、現像像を転写する手段とを有する画像形成装置において、該電子写真感光体が前記第（１）項乃至第（６）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画像形成装置」、
（８）「正帯電で帯電プロセスを行うことを特徴とする前記第（７）項に記載の画像形成装置」、
（９）「負帯電で帯電プロセスを行うことを特徴とする前記第（７）項に記載の画像形成装置」、
（１０）「転写手段の形状が、ローラ状又はベルト状であることを特徴とする前記第（７）項乃至第（９）項の何れかに記載の画像形成装置」、
（１１）「前記画像形成装置が複数の電子写真感光体を具備してなり、それぞれの電子写真感光体上に現像された単色のトナー画像を順次重ね合わせてカラー画像を形成することを特徴とする前記第（７）項乃至第（１０）項の何れかに記載の画像形成装置」、
（１２）「前記画像形成装置が電子写真感光体上に現像されたトナー画像を中間転写体上に一次転写したのち、該中間転写体上のトナー画像を記録材上に二次転写する中間転写手段を有する画像形成装置であって、複数色のトナー画像を中間転写体上に順次重ね合わせてカラー画像を形成し、該カラー画像を記録材上に一括で二次転写することを特徴とする前記第（７）項乃至第（１１）項の何れかに記載の画像形成装置」により達成される。
また、上記課題は本発明の（１３）「少なくとも電子写真感光体を具備してなる画像形成装置用プロセスカートリッジであって、前記第（７）項乃至第（１２）項の何れかに記載の画像形成装置に用いられる画像形成装置用プロセスカートリッジ」により達成される。

{Wherein R15 and R16 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 R17 , R18, R19 and R20 are each independently a hydrogen atom, halogen atom, cyano group, nitro group, amino group, hydroxyl group, substituted or unsubstituted alkyl group, substituted or unsubstituted cycloalkyl group, substituted or unsubstituted aralkyl. Represents a group selected from the group consisting of groups. } ".
Further, the above-mentioned problem is (7) “at least an electrophotographic photosensitive member, a charging unit that charges the electrophotographic photosensitive member, an image exposing unit that forms an electrostatic latent image by performing image exposure after charging, The image forming apparatus having a developing unit that develops the electrostatic latent image and a unit that transfers the developed image, wherein the electrophotographic photosensitive member is any one of the items (1) to (6). An image forming apparatus characterized by being an electrophotographic photosensitive member ",
(8) “Image forming apparatus according to item (7), wherein the charging process is performed by positive charging”,
(9) “The image forming apparatus according to (7), wherein the charging process is performed with negative charging”,
(10) “The image forming apparatus according to any one of (7) to (9), wherein the shape of the transfer unit is a roller shape or a belt shape”;
(11) “The image forming apparatus includes a plurality of electrophotographic photoreceptors, and a single color toner image developed on each electrophotographic photoreceptor is sequentially superimposed to form a color image. The image forming apparatus according to any one of (7) to (10),
(12) “Intermediate transfer in which the image forming apparatus primarily transfers a toner image developed on an electrophotographic photosensitive member onto an intermediate transfer member, and then secondarily transfers the toner image on the intermediate transfer member onto a recording material. An image forming apparatus having means for forming a color image by sequentially superimposing toner images of a plurality of colors on an intermediate transfer member, and performing secondary transfer of the color image collectively onto a recording material This is achieved by the image forming apparatus according to any one of (7) to (11).
The above-described problem is (13) “a process cartridge for an image forming apparatus comprising at least an electrophotographic photosensitive member,” according to any one of (7) to (12). This is achieved by the “process cartridge for image forming apparatus” used in the image forming apparatus.

  As will be apparent from the following detailed and specific description, the construction shown in the claims of the present invention improves the photosensitivity and the stability of electrostatic characteristics of the single-layer type photoreceptor, and improves the mechanical durability. A photoreceptor excellent in (crack resistance, adhesive strength, etc.) can be obtained. In the image forming apparatus using this single-layer type electrophotographic photosensitive member, a highly reliable electrophotographic photosensitive member capable of forming a high-quality image even when repeated image formation over a long period of time is possible. This provides an extremely excellent effect that a forming apparatus and a process cartridge can be provided.

  The electrophotographic apparatus used in the present invention will be described below with reference to the drawings. In any of the drawings, the photoconductor is an electrophotographic photoconductor that satisfies the requirements of the present invention.

FIG. 1 is a schematic view for explaining an example of an image forming element of an electrophotographic apparatus according to the present invention, and modifications as described later also belong to the category of the present invention.
In FIG. 1, a photoconductor (11) is an electrophotographic photoconductor 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.
As the transfer means (16), the above charger can be generally used, but a roller or sheet-like transfer means is effective.
(13) represents an exposure means, and a semiconductor laser (LD), a light emitting diode (LED), or the like can be used. In some cases, various 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. .
(1A) is a static elimination means and is used according to necessity. Examples of the light source include fluorescent materials, tungsten lamps, halogen lamps, mercury lamps, sodium lamps, light emitting diodes (LEDs), semiconductor lasers (LDs), electroluminescence (ELs) and the like.
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.
When the electrophotographic photosensitive member is positively (negatively) charged and image exposure is performed, a positive (negative) electrostatic latent image is formed on the surface of the photosensitive member. If this is developed with a positive (negative) toner, a negative image can be obtained. A known method is applied to the developing unit, and a known method is also used for the charge eliminating unit.
Since the present invention is characterized by comprising a plurality of image forming elements as shown in FIG. 1, a plurality of these image forming elements are used in a horizontal or oblique arrangement.

FIG. 2 shows an example for explaining another example of the image forming element of the electrophotographic apparatus according to the present invention. In FIG. 2, a photoconductor (11) is an electrophotographic photoconductor that 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).

Also in the exposure means (13) of FIG. 2, a semiconductor laser (LD), a light emitting diode (LED), or the like can be used as a light source. In some cases, various 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. .
Since the present invention is characterized by comprising a plurality of image forming elements as shown in FIG. 2, a plurality of these image forming elements may be used horizontally or diagonally.
The image forming elements described above exemplify the embodiments 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, in the light irradiation process, image exposure, pre-cleaning exposure, and static elimination exposure are illustrated. In addition, pre-exposure exposure, 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 a charging unit, an exposure unit, a developing unit, a transfer unit, a cleaning unit, and a charge eliminating unit. There are many shapes and the like of the process cartridge, but a general example is shown in FIG.
These process cartridges are detachable and easy to maintain.
Since the present invention is characterized by comprising a plurality of image forming elements in the form of process cartridges as shown in FIG. 3, a plurality of these image forming elements are used horizontally or obliquely.

4 and 5 show an example of the entire full-color electrophotographic apparatus according to the present invention. This electrophotographic apparatus is a type that uses 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 (11) used in this electrophotographic apparatus is an electrophotographic photoreceptor that satisfies the requirements of the present invention. Around each of the photoconductors (11Y), (11M), (11C), and (11Bk) is similarly a charging unit (12), an exposure unit (13), a developing unit (14), a cleaning unit (17), and the like. It is arranged.
The exposure means (13) ((13Y), (13M), (13C), (13Bk), (13Y), (13M), (13C), (13Bk) in FIG. 5 is also the same) is a light source as described above. As described above, in the present invention, a semiconductor laser (LD), a light emitting diode (LED), or the like can be used as a light source in the present invention. In some cases, various 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. .
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), and (11Bk) arranged on a straight line is a driving unit. (1C). A transfer means (16) is disposed at a transfer position facing each of the photoconductors (1Y), (1M), (1C), and (1Bk) with the conveyance transfer belt (1G) interposed therebetween.
Also in the electrophotographic apparatus as shown in FIGS. 4 and 5, it is possible to use the detachable process cartridge as described above as an image forming element for each color.

Next, the electrophotographic photosensitive member used in the present invention will be described in detail.
The photosensitive layer of the electrophotographic photosensitive member in the present invention may be a single layer type photosensitive layer containing a charge generating substance and a charge transporting substance in a single layer.
FIG. 6 is a cross-sectional view schematically showing an example of the electrophotographic photosensitive member used in the electrophotographic apparatus of the present invention. At least a charge generating material and a charge transporting material (< A photosensitive layer (22) containing a binder resin and an electron transport material represented by the general formula 1> or <general formula 2> is provided.

  Although not shown, an undercoat layer can be provided between the conductive support (21) and the photosensitive layer (22), or a surface protective layer can be provided on the photosensitive layer (22).

(Conductive support)
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, A film or cylindrical plastic or paper coated with an oxide such as indium oxide by vapor deposition or sputtering, or a plate made of aluminum, aluminum alloy, nickel, stainless steel, and the like, and a drawing ironing method, impact It is possible to use a tube that has been surface-treated by cutting, superfinishing, polishing, or the like after being formed into a bare pipe by a method such as the Ironing method, the Extruded Ironing method, the Extracted Drawing method, or the cutting method.

(Underlayer)
In the electrophotographic photoreceptor used in the present invention, an undercoat layer may be provided between the photosensitive layer and the conductive support. The undercoat layer is provided for the purpose of improving adhesiveness, preventing moire, 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 photosensitive layer described above.

  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.

(Single layer type photosensitive layer)
As a material that can be used for the charge transport material even in the case of a single layer configuration, it is essential to use the electron transport material represented by the above-mentioned <General Formula 1> or <General Formula 2>. A known electron transport material (acceptor) and hole transport material (donor) can be used in combination.
The compounding ratio of each constituent material is as follows.
The charge generation material is suitably 0.01 to 50 parts by weight, preferably 0.1 to 30 parts by weight with respect to 100 parts by weight of the binder resin.
The electron transport material is suitably 1 to 100 parts by weight, preferably 5 to 80 parts by weight with respect to 100 parts by weight of the binder resin.
The hole transport material is suitably 5 to 200 parts by weight, preferably 20 to 150 parts by weight, based on 100 parts by weight of the binder resin.
The ratio of the electron transporting material to the hole transporting material is 1: 9 to 9: 1, preferably 2: 8 to 8: 2.
In order to satisfy the high sensitivity of the photoreceptor, it is preferable that the amount of the charge transport material (electron transport material + hole transport material) is 70 parts by weight or more with respect to 100 parts by weight of the binder resin component. .

Examples of the solvent that can be used in preparing the photosensitive layer coating solution include ketones such as methyl ethyl ketone, acetone, methyl isobutyl ketone, and cyclohexanone, 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.
Further, if necessary, low-molecular compounds such as antioxidants, plasticizers, lubricants and 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 polymer compound such as a binder resin. About 0.001 to 5 parts by weight is appropriate for 100 parts by weight. As such leveling agents, silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, polymers or oligomers having a perfluoroalkyl group in the side chain, and the like can be used.
As the coating method, a dipping method, a spray coating method, a ring coating method, a roll coater method, a gravure coating method, a nozzle coating method, a screen printing method, or the like is employed.
The film thickness of the photosensitive layer is suitably about 10 to 45 μm, preferably about 15 to 36 μm, and when resolution is required, 25 μm or less is appropriate.

(Charge generation material for single-layer photosensitive layer)
As the charge generating material that can be used for the photosensitive layer having a single layer structure, 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 a carbazole skeleton, azo pigments having a triphenylamine skeleton, azo pigments having a diphenylamine skeleton, dibenzo An azo pigment having a thiophene skeleton, an azo pigment having a fluorenone skeleton, an azo pigment having an oxadiazol skeleton, an azo pigment having a bisstilbene skeleton, an azo pigment having a distyryl oxadiazol skeleton, and a distyrylcarbazole skeleton Azo pigments, 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 singly or as a mixture of two or more. As described above, phthalocyanine pigments are particularly preferable from the viewpoint of various properties required for the present invention.

By using titanyl phthalocyanine having titanium as a central metal among phthalocyanine-based pigments, a photosensitive layer having particularly high sensitivity can be obtained, and the speed of the electrophotographic apparatus can be further increased. 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 having no peak between the 7.3 ° peak and the 9.4 ° peak, Without losing sensitivity, it is possible to obtain a stable electrophotographic photosensitive member that does not cause a decrease in chargeability even when used repeatedly.
These pigments are preferably dispersed in advance by a ball mill, attritor, sand mill or the like using a solvent such as tetrahydrofuran, cyclohexanone, dioxane, dichloroethane or butanone. Moreover, you may disperse | distribute with binder resin as needed at the time of dispersion | distribution.

(Electron transport material of single-layer type photosensitive layer)
The electron transport material represented by <General Formula 1> or <General Formula 2> used in the present invention has a structural skeleton shown below.

｛但し、上記一般式中、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し、Ｒ３、Ｒ４、Ｒ５、Ｒ６、Ｒ７、Ｒ８、Ｒ９、Ｒ１０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す。｝

{However, in the above general formula, R1 and R2 are each independently a group selected from the group consisting of a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, and a substituted or unsubstituted aralkyl group. R 3, R 4, R 5, R 6, R 7, R 8, R 9, R 10 are each independently a hydrogen atom, halogen atom, cyano group, nitro group, amino group, hydroxyl group, substituted or unsubstituted alkyl group, substituted or unsubstituted A group selected from the group consisting of a substituted cycloalkyl group and a substituted or unsubstituted aralkyl group. }

｛但し、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し、ｎは繰り返し単位であり、１から１００までの整数を表す。｝

{However, in the formula, 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, and a substituted or unsubstituted aralkyl group. , R3, 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 The group selected from the group which consists of an alkyl group, a substituted or unsubstituted cycloalkyl group, and a substituted or unsubstituted aralkyl group is represented, n is a repeating unit and represents the integer of 1-100. }

｛式中、Ｒ１５、Ｒ１６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し、Ｒ１７、Ｒ１８、Ｒ１９、Ｒ２０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す。｝

{Wherein R15 and R16 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 R17 , R18, R19 and R20 are each independently a hydrogen atom, halogen atom, cyano group, nitro group, amino group, hydroxyl group, substituted or unsubstituted alkyl group, substituted or unsubstituted cycloalkyl group, substituted or unsubstituted aralkyl. Represents a group selected from the group consisting of groups. }

  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.

  Specifically, an electron transport material represented by the following general formula (1) is preferably an electron transport material represented by the following structural formulas (8) to (14) in that the obtained image has high quality. . In the formula, Me represents a methyl group.

Examples of the method for producing the electron transport material represented by <General Formula 1> include the following methods.
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を表し、ＲｍはＲ５、Ｒ６、Ｒ９、Ｒ１０を表す。」

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

  The electron transport material represented by <general formula 1> used in the present invention is a method of reacting the above naphthalene carboxylic acid or its anhydride with amines to monoimidize, or using naphthalene carboxylic acid or its anhydride with a buffer. 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 in the absence of a 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 carried out without 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 electron transport material represented by the structural formula (10) can be produced 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 with a toluene / hexane mixed solvent to obtain 2.08 g (yield 36.1%) of monoimide B.
(Second step)
In a 100 ml four-necked flask, add 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, and heat to reflux 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 with a toluene / ethyl acetate mixed solvent to obtain 0.810 g (yield 37.4%) of an electron transport material represented by the structural formula (10). In mass spectrometry (FD-MS), the peak of M / z = 614 was observed, and it was identified as the target product. In the elemental analysis, the calculated values are 66.45% carbon, 3.61% hydrogen, and 9.12% nitrogen, whereas the measured values are 66.28% carbon, 3.45% hydrogen, and 9.33 nitrogen. %there were.

The electron transport material represented by the structural formula (12) can be produced 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. Furthermore, the recovered product was recrystallized with a mixed solvent of toluene / ethyl acetate to obtain 2.84 g of dimer C (yield 28.7%).
(Second step)
In a 200 ml four-necked flask, 5.0 g (9.39 mmol) of 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) and 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 purified by silica gel column chromatography to obtain 1.66 g (yield 28.1%) of monoimide D.
(Third process)
In a 100 ml four-necked flask, 1.5 g (2.38 mmol) of monoimide D and 50 ml of DMF were placed 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 with a toluene / hexane mixed solvent to obtain 0.276 g (yield 14.8%) of an electron transport material represented by the structural formula (12). In mass spectrometry (FD-MS), the peak of M / z = 782 was observed and identified as the target product. In the elemental analysis, the calculated values are 70.57% carbon, 5.92% hydrogen, and 7.16% nitrogen, whereas the measured values are 70.77% carbon, 6.11% hydrogen, and 7.02 nitrogen. %there were.

  The electron transport material represented by <General Formula 2> is mainly synthesized by the following two synthesis methods.

〈一般式２〉で表される電荷輸送材料の繰り返し単位ｎは１から１００の整数である。
繰り返し単位ｎは、重量平均分子量（Ｍｗ）から求められる。すなわち化合物は分子量に分布をもった状態で存在する。ｎが１００を超えると化合物の分子量が大きくなり、各種溶媒に対する溶解性が落ちるため、１００以下が好ましい。
一方、例えばｎが１の場合はナフタレンカルボン酸の三量体であるが、Ｒ１、Ｒ２の置換基を適切に選択することにより、オリゴマーでも優れた電子移動特性が得られる。このように繰り返し単位ｎの数により、オリゴマーからポリマーまで幅広い範囲のナフタレンカルボン酸誘導体が合成される。
オリゴマー領域の分子量が小さい範囲では、段階的に合成することで、単分散の化合物を得ることができる。分子量が大きい化合物の場合は、分子量に分布を持った化合物が得られる。
〈一般式２〉で表される電子輸送材料としては具体的に以下の構造式（１５）〜構造式（１７）のものが例示できる。

The repeating unit n of the charge transport material represented by <General Formula 2> is an integer of 1 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.
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.
Specific examples of the electron transport material represented by <General Formula 2> include the following structural formulas (15) to (17).

  In addition to these electron transport materials, the addition of the electron transport material represented by the above-mentioned <general formula 3> can further alleviate shrinkage during film formation without reducing the charge transport capability. It becomes. Moreover, since the film becomes dense by the addition, there is an advantage that it is less susceptible to the influence of acid gas, that is, there is an effect that gas resistance is improved. In addition, since the film becomes dense, the wear resistance is also improved.

Specific examples of the electron transport material represented by <General Formula 3> include the following structural formulas (18) and (19).
[Structural Formula 18]

（但し、式中、両端の末端基はＭｅ（メチル基）を表す。
[構造式１９]

(However, in the formula, the terminal groups at both ends represent Me (methyl group).
[Structural Formula 19]

（但し、式中、両端の末端基はＭｅ（メチル基）を表す。）

(However, in the formula, the terminal groups at both ends represent Me (methyl group).)

  The addition amount of these electron transport materials is not particularly limited, but is preferably about 1% to 50%, and more preferably 5% to 30% with respect to the total amount of the electron transport material. This is because when the addition amount is less than 1%, the film quality improvement is slight and no clear effect is observed, and when the addition amount is 50% or more, the charge transport ability tends to be slightly lowered.

  Although it is essential to use the electron transport material represented by the above-mentioned <General Formula 1> or <General Formula 2>, as other electron transport materials, for example, chloranil, 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-trinitrodibenzothiophene-5,5-dioxide, the following structural formulas (20), (21 ) Or an electron accepting substance such as a derivative thereof may be used in combination.

(Hole transport material for single-layer photosensitive layer)
As the hole transport material, an electron donating material 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, thiophene derivatives, and enamine derivatives.
These hole transport materials may be used alone or as a mixture of two or more.

(Binder resin for single-layer photosensitive layer)
Examples of the polymer compound that can be used as the binder component include polystyrene, styrene / acrylonitrile copolymer, styrene / butadiene copolymer, styrene / maleic anhydride copolymer, polyester, polyvinyl chloride, and vinyl chloride / acetic acid. Vinyl copolymer, polyvinyl acetate, polyvinylidene chloride, polyarylate resin, polycarbonate,
Examples include 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, and other thermoplastic or thermosetting resins. In particular, polycarbonate resin is preferable, but is not limited thereto.
These polymer compounds can be used singly or as a mixture of two or more kinds, or as a copolymer comprising two or more kinds of raw material monomers, and further copolymerized with a charge transport material.
For the purpose of ensuring the stability of the single-layer type photosensitive layer against environmental fluctuations, when using an electrically inactive polymer compound, for example, polyester, polycarbonate, acrylic resin, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyethylene Polypropylene, fluororesin, polyacrylonitrile, acrylonitrile / styrene / butadiene copolymer, styrene / acrylonitrile copolymer, ethylene / vinyl acetate copolymer and the like are effective.
Here, the electrically inactive polymer compound refers to a polymer compound that does not include a chemical structure exhibiting photoconductivity such as a triarylamine structure.
When these resins are used in combination with a binder resin as an additive, the addition amount is preferably 50 wt% or less because of restrictions on light attenuation sensitivity.

(Additive)
To the extent that the object of the present invention is not impaired, the anti-oxidant, the plastic layer is applied to each layer such as a single-layer photosensitive layer, an undercoat layer, and a protective layer for the purpose of improving environmental resistance, reducing sensitivity, and preventing an increase in residual potential. Examples thereof include adding an agent, a lubricant, and an ultraviolet absorber.

As the antioxidant that can be added to each layer, the following are preferable for the above purpose.
(A) Phenolic compounds 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, n-octadecyl-3- (4 '-Hydroxy-3', 5'-di-t-butylphenol), 2,2'-methylene-bis- (4-methyl-6-t-butylphenol), 2,2'-methylene-bis- (4- Ethyl-6-tert-butylphenol), 4,4′-thiobis- (3-methyl-6-tert-butylphenol), 4,4′-butylidenebis- (3-methyl-6-tert-butylphenol), 1,1 , 3-Tris- (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4 -Hydroxybenzyl) benzene, te Lakis- [methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate] methane, bis [3,3′-bis (4′-hydroxy-3′-t-butyl) Phenyl) butyric acid] glycol ester, tocopherols.
(B) Paraphenylenediamines N-phenyl-N′-isopropyl-p-phenylenediamine, N, N′-di-sec-butyl-p-phenylenediamine, N-phenyl-N-sec-butyl-p-phenylene Diamine, N, N′-di-isopropyl-p-phenylenediamine, N, N′-dimethyl-N, N′-di-t-butyl-p-phenylenediamine.
(C) Hydroquinones 2,5-di-t-octylhydroquinone, 2,6-didodecylhydroquinone, 2-dodecylhydroquinone, 2-dodecyl-5-chlorohydroquinone, 2-t-octyl-5-methylhydroquinone, 2 -(2-Octadecenyl) -5-methylhydroquinone.
(D) Organic sulfur compounds dilauryl-3,3′-thiodipropionate, distearyl-3,3′-thiodipropionate, ditetradecyl-3,3′-thiodipropionate.
(E) Organic phosphorus compounds Triphenylphosphine, tri (nonylphenyl) phosphine, tri (dinonylphenyl) phosphine, tricresylphosphine, tri (2,4-dibutylphenoxy) phosphine.

As the plasticizer that can be added to each layer, the following are preferred for the above purpose.
(A) Phosphate ester plasticizer Triphenyl phosphate, tricresyl phosphate, trioctyl phosphate, octyl diphenyl phosphate, trichloroethyl phosphate, cresyl diphenyl phosphate, tributyl phosphate, tri-2-ethylhexyl phosphate, Triphenyl phosphate.
(B) Phthalate ester plasticizers Dimethyl phthalate, diethyl phthalate, diisobutyl phthalate, dibutyl phthalate, diheptyl phthalate, di-2-ethylhexyl phthalate, diisooctyl phthalate, di-n-octyl phthalate, phthalate Dinonyl acid, diisononyl phthalate, diisodecyl phthalate, diundecyl phthalate, ditridecyl phthalate, dicyclohexyl phthalate, butyl benzyl phthalate, butyl lauryl phthalate, methyl oleyl phthalate, octyl decyl phthalate, dibutyl fumarate, dioctyl fumarate .
(C) Aromatic carboxylic acid ester plasticizers Trioctyl trimellitic acid, tri-n-octyl trimellitic acid, octyl oxybenzoate.
(D) Aliphatic dibasic ester plasticizer dibutyl adipate, di-n-hexyl adipate, di-2-ethylhexyl adipate, di-n-octyl adipate, adipic acid n-octyl-n-decyl , Diisodecyl adipate, dicapryl adipate, di-2-ethylhexyl azelate, dimethyl sebacate, diethyl sebacate, dibutyl sebacate, di-n-octyl sebacate, di-2-ethylhexyl sebacate, di-2 sebacate -Ethoxyethyl, dioctyl succinate, diisodecyl succinate, dioctyl tetrahydrophthalate, di-n-octyl tetrahydrophthalate.
(E) Fatty acid ester derivatives butyl oleate, glycerol monooleate, methyl acetylricinoleate, pentaerythritol ester, dipentaerythritol hexaester, triacetin, tributyrin.
(F) Oxyacid ester plasticizer Methyl acetyl ricinoleate, butyl acetyl ricinoleate, butyl phthalyl butyl glycolate, tributyl acetyl citrate.
(G) Epoxy plasticizer Epoxidized soybean oil, epoxidized linseed oil, butyl epoxy stearate, decyl epoxy stearate, octyl epoxy stearate, benzyl epoxy stearate, dioctyl epoxy hexahydrophthalate, didecyl epoxy hexahydrophthalate.
(H) Dihydric alcohol ester plasticizer diethylene glycol dibenzoate, triethylene glycol di-2-ethylbutyrate.
(I) Chlorinated plasticizer Chlorinated paraffin, chlorinated diphenyl, chlorinated fatty acid methyl, methoxychlorinated fatty acid methyl.
(J) Polyester plasticizer Polypropylene adipate, polypropylene sebacate, polyester, acetylated polyester.
(K) Sulfonic acid derivatives p-toluenesulfonamide, o-toluenesulfonamide, p-toluenesulfoneethylamide, o-toluenesulfoneethylamide, toluenesulfone-N-ethylamide, p-toluenesulfone-N-cyclohexylamide.
(L) Citric acid derivatives Triethyl citrate, triethyl acetyl citrate, tributyl citrate, tributyl acetyl citrate, tri-2-ethylhexyl acetyl citrate, acetyl citrate-n-octyldecyl.
(M) Others Terphenyl, partially hydrogenated terphenyl, camphor, 2-nitrodiphenyl, dinonylnaphthalene, methyl abietic acid.

As the lubricant that can be added to each layer, the following are preferable for the above purpose.
(A) Hydrocarbon compound Liquid paraffin, paraffin wax, microwax, low-polymerized polyethylene.
(B) Fatty acid compounds Lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid.
(C) Fatty acid amide compounds Stearylamide, palmitylamide, oleinamide, methylenebisstearamide, ethylenebisstearamide.
(D) Ester compound Fatty acid lower alcohol ester, fatty acid polyhydric alcohol ester, fatty acid polyglycol ester.
(E) Alcohol compounds Cetyl alcohol, stearyl alcohol, ethylene glycol, polyethylene glycol, polyglycerol.
(F) Metal soap Lead stearate, cadmium stearate, barium stearate, calcium stearate, zinc stearate, magnesium stearate.
(G) Natural wax Carnauba wax, candelilla wax, beeswax, whale wax, ibotarou, montan wax.
(H) Others Silicone compounds and fluorine compounds.

As the ultraviolet absorber that can be added to each layer, the following are preferable for the above purpose.
(A) Benzophenone series 2-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 2,2 ′, 4-trihydroxybenzophenone, 2,2 ′, 4,4′-tetrahydroxybenzophenone, 2,2′-dihydroxy-4- Methoxybenzophenone.
(B) Salsylate series Phenyl salsylate, 2,4-di-t-butylphenyl-3,5-di-t-butyl-4-hydroxybenzoate.
(C) Benzotriazole type (2′-hydroxyphenyl) benzotriazole, (2′-hydroxy5′-methylphenyl) benzotriazole, (2′-hydroxy3′-tertiarybutyl 5′-methylphenyl) 5-chloro Benzotriazole.
(D) Cyanoacrylate-based ethyl-2-cyano-3,3-diphenyl acrylate, methyl 2-carbomethoxy 3 (paramethoxy) acrylate.
(E) Quencher (metal complex)
Nickel (2,2′thiobis (4-t-octyl) phenolate) normal butylamine, nickel dibutyldithiocarbamate, cobalt dicyclohexyldithiophosphate.
(F) HALS (hindered amine)
Bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, 1- [2- [3- (3 5-di-t-butyl-4-hydroxyphenyl) propionyloxy] ethyl] -4- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] -2,2,6 6-tetramethylpyridine, 8-benzyl-7,7,9,9-tetramethyl-3-octyl-1,3,8-triazaspiro [4,5] undecane-2,4-dione, 4-benzoyloxy- 2,2,6,6-tetramethylpiperidine.

  Hereinafter, the present invention will be described by way of examples. However, this does not limit the scope of the present invention. All parts are parts by weight.

[Synthesis Example of Electron Transport Material 1 (= Electron Transport Material of Structural Formula (8))]
(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)
In 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 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 0.668 g (yield 33.7%) of the electron transport material represented by the structural formula (8). (Referred to as electron transport material 1)

質量分析（ＦＤ−ＭＳ）において、Ｍ／ｚ＝７２６のピークが観測されたことにより目的物であると同定した。元素分析は計算値、炭素６９．４１％、水素５．２７％、窒素７．７１％に対し、実測値で炭素６９．５２％、水素５．０９％、窒素７．９３％あった。

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.

[Synthesis Example of Electron Transport Material 2 (= Electron Transport Material of Structural Formula (9))]
(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)
A 100 ml four-necked flask was charged with 2.5 g (4.67 mmol) of both-bodies C and 30 ml of DMF 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 process)
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. Further, the recovered product was recrystallized from toluene / hexane to obtain 0.243 g (yield 22.4%) of an electron transport material represented by the structural formula (9). (Referred to as electron transport material 2)

質量分析（ＦＤ−ＭＳ）において、Ｍ／ｚ＝６７０のピークが観測されたことにより目的物であると同定した。元素分析は計算値、炭素６８．０５％、水素４．５１％、窒素８．３５％に対し、実測値で炭素６８．２９％、水素４．７２％、窒素８．３３％あった。

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.

[Synthesis Example of Electron Transport Material 3 (= Electron Transport Material of Structural Formula (11))]
(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 (11). (Referred to as electron transport material 3)

質量分析（ＦＤ−ＭＳ）において、Ｍ／ｚ＝７４０のピークが観測されたことにより目的物であると同定した。元素分析は計算値、炭素６９．７２％、水素５．４４％、窒素７．５６％に対し、実測値で炭素６９．５５％、水素５．２６％、窒素７．３３％あった。

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.

[Synthesis Example of Electron Transport Material 4 (= Electron Transport Material of Structural Formula (15))]
[Structural formula (15)]

（第一工程）
２００ｍｌ４つ口フラスコに、１，４，５，８−ナフタレンテトラカルボン酸二無水物５．０ｇ（１８．６ｍｍｏｌ）、ＤＭＦ５０ｍｌを入れ、加熱還流させた。これに、２−アミノペンタン１．６２ｇ（１８．６ｍｍｏｌ）とＤＭＦ２５ｍｌの混合物を攪拌しながら滴下した。滴下終了後、６時間加熱還流させた。反応終了後、容器を冷却し、減圧濃縮した。残渣にトルエンを加え、シリカゲルカラムクロマトグラフィーにて精製した。更に回収品をトルエン／ヘキサンにより再結晶し、モノイミド体E ３．４９ｇ（収率４５．８％）を得た。
（第二工程）
１００ｍｌ４つ口フラスコに、モノイミド体E ３．０ｇ（７．３３ｍｍｏｌ）と、１，４，５，８−ナフタレンテトラカルボン酸二無水物０．９８３ｇ（３．６６ｍｍｏｌ）、ヒドラジン一水和物０．３６８ｇ（７．３３ｍｍｏｌ）、ｐ−トルエンスルホン酸１０ｍｇ、トルエン５０ｍｌを入れ、５時間加熱還流させた。反応終了後、容器を冷却し、減圧濃縮した。残渣をシリカゲルカラムクロマトグラフィーにて２回精製した。更に回収品をトルエン／酢酸エチルにより再結晶し、構造式（１５）で表される電子輸送材料４を０．９３９ｇ（収率１３．７％）得た。質量分析（ＦＤ−ＭＳ）において、Ｍ／ｚ＝９３４のピークが観測されたことにより目的物であると同定した。元素分析は計算値、炭素６６．８１％、水素３．６７％、窒素８．９９％に対し、実測値で炭素６６．９２％、水素３．７４％、窒素９．０５％であった。（電子輸送剤材料４とする。）

(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 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 the electron transport material 4 represented by the structural formula (15). 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 66.81% carbon, 3.67% hydrogen, and 8.99% nitrogen, and the measured values were 66.92% carbon, 3.74% hydrogen, and 9.05% nitrogen. (Referred to as electron transfer material 4)

(Pigment synthesis example 1)
A pigment was produced according to the method described in the production example of JP-A-2-8256 (Japanese Patent Publication No. 7-91486). That is, 9.8 g of phthalodinitrile and 75 ml of 1-chloronaphthalene are stirred and mixed, and 2.2 ml of titanium tetrachloride is added dropwise under a nitrogen stream. After completion of the dropping, the temperature was gradually raised to 200 ° C., and the reaction was carried out by stirring for 3 hours while maintaining the reaction temperature between 200 ° C. and 220 ° C. After completion of the reaction, the mixture was allowed to cool to 130 ° C. and filtered while hot, then washed with 1-chloronaphthalene until the powder turned blue, then washed several times with methanol, and further with hot water at 80 ° C. After washing twice, it was dried to obtain a pigment. (Referred to as pigment 1)
The obtained titanyl phthalocyanine powder was subjected to X-ray diffraction spectrum measurement under the following conditions and confirmed to be the same as the spectrum described in the publication.

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

(Pigment synthesis 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. (Water paste) was obtained. 2 g of the obtained wet cake (water paste) was put into 20 g of tetrahydrofuran, stirred for 4 hours, filtered and dried to obtain titanyl phthalocyanine powder (referred to as pigment 2).

  The obtained titanyl phthalocyanine powder was subjected to X-ray diffraction spectrum measurement under the conditions of Pigment Synthesis Example 1, and a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to Cu—Kα rays (wavelength 1.542 mm) described in the publication. ) Having a maximum diffraction peak at least 27.2 °, and further having main peaks at 9.4 °, 9.6 °, and 24.0 °, and the diffraction peak at the lowest angle side as 7. It was confirmed that the titanyl phthalocyanine had a peak at 3 ° and no peak between the peak at 7.3 ° and the peak at 9.4 °.

(Preparation of photoconductor of Comparative Example 1)
Metal-free phthalocyanine was dispersed under the following composition and conditions to prepare a pigment dispersion.

Metal-free phthalocyanine pigment 3 parts (Dainippon Ink and Chemicals Co., Ltd .: Fastogen Blue 8120B)
97 parts of cyclohexanone Using a PSZ ball having a diameter of 0.5 mm in a glass pot having a diameter of 9 cm, dispersion was performed at a rotation speed of 100 rpm for 5 hours.

  A photoconductor coating solution having the following composition was prepared using the dispersion.

80 parts of the dispersion liquid 60 parts of the hole transport material of the following structural formula (22)

電子輸送材料１ ４０部
Ｚ型ポリカーボネート樹脂（帝人化成製：パンライトＴＳ−２０５０） １００部
シリコーンオイル（信越化学工業社製：ＫＦ５０） ０．０２部
テトラヒドロフラン ７００部
こうして得られた感光層用塗工液をφ３０ｍｍ、長さ３４０ｍｍアルミニウムドラム上に、浸漬塗工法にて塗布、１２０℃で２０分間乾燥し、２５μｍの感光層を形成し、感光体ドラムを作製した。

Electron transport material 1 40 parts Z-type polycarbonate resin (Teijin Chemicals: Panlite TS-2050) 100 parts Silicone oil (Shin-Etsu Chemical Co., Ltd .: KF50) 0.02 parts Tetrahydrofuran 700 parts Coating of photosensitive layer thus obtained The solution was applied on an aluminum drum having a diameter of 30 mm and a length of 340 mm by a dip coating method and dried at 120 ° C. for 20 minutes to form a photosensitive layer of 25 μm, thereby preparing a photosensitive drum.

(Production of photoconductors of Comparative Examples 2 to 6)
As shown in Table 1, a photoconductor drum was produced in the same manner as the photoconductor of Comparative Example 1 except that the charge generation material type and the electron transport material type were changed, and the photoconductors of Comparative Examples 2 to 6 were obtained. .

(Preparation of photoconductor of Comparative Example 7)
A photosensitive drum was prepared in the same manner as in Comparative Example 1 except that the electron transport material 1 in the photoconductor of Comparative Example 1 was changed to the one represented by the following structural formula (electron transport material 5). No. 7 photoconductor was obtained.

（式中ｎは１〜１００まで数値を表し、これらのものの混合体である。式中、両端の末端基はＭｅ（メチル基）を表す。）

(In the formula, n represents a numerical value from 1 to 100 and is a mixture of these. In the formula, the end groups at both ends represent Me (methyl group).)

(Preparation of photoconductor of Comparative Example 8)
In the photoreceptor of Comparative Example 1, the photoreceptor is the same as shown in Table 1 except that the addition amount of the hole transport material is changed to 60 parts by weight and the addition amount of the electron transport material 1 is changed to 40 parts by weight. A drum was produced to obtain a photoreceptor of Comparative Example 8.

(Preparation of photoconductor of Comparative Example 9)
In the photoconductor of Comparative Example 8, a photoconductor drum was prepared in the same manner except that 50 parts by weight of the electron transport material 1 and 10 parts by weight of the material represented by the following structural formula (18) were added. A photoreceptor of Comparative Example 9 was obtained.

（式中、両端の末端基はＭｅ（メチル基）を表す。）

(In the formula, the terminal groups at both ends represent Me (methyl group).)

(Preparation of photoconductor of Comparative Example 10)
A photoconductor drum was prepared in the same manner as in the photoconductor of Comparative Example 1 except that a predetermined amount of an alkylene glycol derivative was added as shown in Table 1, and a photoconductor of Comparative Example 10 was obtained.
However, the photoconductor of Comparative Example 10 was not evaluated because the amount of the alkylene glycol derivative added was too large, causing the photosensitive layer to undergo layer separation and poor film formability.

(Production of photoconductors of Examples 1 to 9)
In the photoreceptors of Comparative Examples 1 to 9, all of the example numbers are the same except that a predetermined amount of an alkylene glycol derivative species was added as shown in Table 1 and a predetermined amount of a polyester resin (Byron 200: manufactured by Toyobo) was added. Photoconductor drums were produced in the same manner as the corresponding photoconductors of Comparative Examples, and photoconductors of Examples 1 to 9 were obtained.
The alkylene glycol derivatives in Table 1 are MO400: polyethylene glycol monooleate manufactured by Sanyo Chemical MS400: polyethylene glycol monostearate manufactured by Sanyo Chemical DS300: polyethylene glycol distearate manufactured by Sanyo Chemical DO1000: polyethylene glycol dioleate manufactured by Sanyo Chemical.
Examples 1 to 8 are reference examples.

(Evaluation of stability of actual machine dark potential and post-exposure potential by repeated image formation of photoconductor)
1. Use positive charging Replace the power pack of Ricoh's imgio Neo 270 (write laser wavelength is 780 nm, with neutralization LED), remodel it to roller charging (positive polarity) and roller transfer (negative polarity), positive charging toner and development The image forming apparatus 1 changed to an agent was loaded with the photoreceptors of Comparative Examples 1 to 7 and Examples 1 to 9, and a printing durability test was performed to print a total of 10,000 sheets on the A4 side using a 5% writing rate chart. The charging potential of the photoconductor at the start of the test was set to be +600 V, and the test was performed under these charging conditions until the end of the test. The developing bias was + 450V. The test environment is 23 ° C. and 55% RH. The dark potential before and after the printing test and the post-exposure potential were measured, and the amount of change was evaluated. Table 2 shows the absolute value of the initial VD (dark potential), the initial VL (the absolute value of the post-exposure potential), the amount of decrease in the absolute value of VD after the output of 10,000 images, and the amount of increase in the absolute value of VL.
2. Using negative charging Image forming apparatus using Ricoh's imgio Neo 270 (write laser wavelength is 780 nm, with neutralization LED), roller charging (negative polarity), roller transfer (negative positive polarity), changed to negative charging toner and developer 2 was mounted with the photoconductors of Comparative Examples 8-9 and Examples 8-9, and a printing durability test was performed to print 10,000 sheets in total on the A4 side using a 5% writing rate chart. The charging potential of the photoconductor at the start of the test was set to be −600 V, and the test was performed under these charging conditions until the end of the test. The developing bias was −450V. The test environment is 23 ° C. and 55% RH. The dark potential before and after the printing test and the post-exposure potential were measured, and the amount of change was evaluated. Table 2 shows the absolute value of the initial VD (dark potential), the initial VL (the absolute value of the post-exposure potential), the amount of decrease in the absolute value of VD after the output of 10,000 images, and the amount of increase in the absolute value of VL.

(Evaluation of crack resistance of photoconductor)
1. Chemical crack resistance A small amount of oleic acid is applied thinly on the prepared photoreceptor and left at 40 ° C. for 5 days, then mounted on the image forming apparatus 1, and a halftone gray image and white paper are output to generate cracks in the image. The occurrence was visually evaluated. The results are shown in Table 2. Evaluation was performed according to the following criteria.
◎: No problem ○: Slightly small cracks occurred △: Slight cracks occurred ×: Cracks recognized at a glance Mechanical crack resistance An elastic rubber roller is pressed against the produced photoreceptor at 10 N / m, and is rotated about 100,000 revolutions with the photoreceptor in an environment at a temperature of 5 ° C., and then returned to room temperature and applied to the image forming apparatus 1 described above. A halftone gray image and a blank paper were output, and the occurrence of cracks was visually evaluated on the image. The results are shown in Table 2. Evaluation was performed based on the same criteria as described above.

(Evaluation of adhesion of photoconductor)
Each photoconductor was cut with a cutter in the same manner as the base eye test, and 100 base squares of 1 mm square were made, and an adhesive tape was applied on the grid according to the JIS Z 0237-1980 adhesive tape / adhesive sheet test method. Thereafter, the film was peeled by 90 ° with respect to the tangential line in the drum circumferential direction and evaluated. According to JIS K 5400-1979, Nichiban cello tape (registered trademark) CT-24 was used. The results are shown in Table 2. The adhesiveness indicates the number of 100 grids (1 mm square) that were not turned over.

  As shown in Table 2, in the photoreceptor using the single layer type electrophotographic photoreceptor containing the specific naphthalenecarboxylic acid derivative having excellent electron transport ability, by using a polyalkylene glycol derivative in the photosensitive layer, It can be seen that the internal stress of the photosensitive layer can be relaxed and the crack resistance can be improved without sacrificing the electrostatic characteristics of the photoreceptor. In addition to the addition of the specific alkylene glycol derivative, it is possible to further increase the adhesive strength by using a polyester resin addition in combination. As a result, it is possible to provide a highly reliable electrophotographic photosensitive member, image forming apparatus, and process cartridge capable of outputting a high-quality image even when image formation is repeated over a long period of time.

Although the embodiments and examples of the present invention have been specifically described above, the present invention is not limited to these embodiments and examples, and these embodiments and examples of the present invention are not limited thereto. Can be changed or modified without departing from the spirit and scope of the present invention.

1 is a schematic cross-sectional view illustrating an example of an electrophotographic apparatus according to the present invention. It is a schematic cross section which shows another example of the electrophotographic apparatus which concerns on this invention. It is a schematic cross section which shows another example of the electrophotographic apparatus which concerns on this invention. It is a schematic cross section which shows another example of the electrophotographic apparatus which concerns on this invention. It is a schematic cross section which shows another example of the electrophotographic apparatus which concerns on this invention. It is sectional drawing which shows the layer structure of the electrophotographic photoreceptor which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Electrophotographic photoreceptor 12 ... Charging means 13 ... Exposure means 14 ... Development means 15 ... Toner 16 ... Transfer means 17 ... Cleaning means 18 ... Image receiving medium 19 ... Fixing means 1A ... Static elimination means 1B ... Pre-cleaning exposure means 1C ... Driving means 1D ... First transfer means 1E ... Second transfer means 1F ... Intermediate transfer body DESCRIPTION OF SYMBOLS 1G ... Image receiving medium carrier 21 ... Conductive support 22 ... Photosensitive layer 36 Photoconductor 37 Charger charger 38 Cleaning brush 39 Image exposure part 40 Developing roller

Claims (12)

In an electrophotographic photoreceptor having at least a photosensitive layer on a conductive support, the photosensitive layer is composed of at least a charge generation material, a charge transport layer material, and a binder resin, and the charge transport layer material is represented by the following <General Formula 1>. Or an electron transport material represented by <general formula 2> and an electron transport material represented by the following <general formula 3>, wherein a mono- or diester derivative or monoether derivative of polyalkylene glycol is used as the charge transport material. 2 to 15 wt% of an electrophotographic photoreceptor,

{However, in the above general formula, R1 and R2 are each independently a group selected from the group consisting of a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, and a substituted or unsubstituted aralkyl group. R 3, R 4, R 5, R 6, R 7, R 8, R 9, R 10 are each independently a hydrogen atom, halogen atom, cyano group, nitro group, amino group, hydroxyl group, substituted or unsubstituted alkyl group, substituted or unsubstituted A group selected from the group consisting of a substituted cycloalkyl group and a substituted or unsubstituted aralkyl group. }

{However, in the formula, 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, and a substituted or unsubstituted aralkyl group. , R3, 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 The group selected from the group which consists of an alkyl group, a substituted or unsubstituted cycloalkyl group, and a substituted or unsubstituted aralkyl group is represented, n is a repeating unit and represents the integer of 1-100. }

{Wherein R15 and R16 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 R17 , R18, R19 and R20 are each independently a hydrogen atom, halogen atom, cyano group, nitro group, amino group, hydroxyl group, substituted or unsubstituted alkyl group, substituted or unsubstituted cycloalkyl group, substituted or unsubstituted aralkyl. Represents a group selected from the group consisting of groups. }   2. The electrophotographic photosensitive member according to claim 1, wherein the electrophotographic photosensitive member contains 2 to 15 wt% of a polyester-based resin with respect to the binder resin.   The electrophotographic photosensitive member according to claim 1, wherein the charge generation material is phthalocyanine.   4. The electrophotographic photoreceptor according to claim 3, wherein the phthalocyanine is titanyl phthalocyanine.   The titanyl phthalocyanine has a maximum diffraction peak at 27.2 ° as a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to Cu-Kα rays (wavelength 1.542 mm), 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 4, which has no peak. At least an electrophotographic photosensitive member, a charging unit that charges the electrophotographic photosensitive member, an image exposure unit that performs image exposure after charging to form an electrostatic latent image, and a developing unit that develops the electrostatic latent image; 6. An image forming apparatus having a means for transferring a developed image, wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to any one of claims 1 to 5 . The image forming apparatus according to claim 6 , wherein the charging process is performed with positive charging. The image forming apparatus according to claim 6 , wherein the charging process is performed with negative charging. The shape of the transfer means, the image forming apparatus according to any one of claims 6 to 8, characterized in that a roller-shaped or belt-shaped. Claim 6, wherein the image forming apparatus is comprises a plurality of electrophotographic photosensitive member, successively superimposed toner images of a single color that developed on each of the electrophotographic photosensitive member onto and forming a color image The image forming apparatus according to any one of Items 9 to 9 . An image having intermediate transfer means for primary transfer of the toner image developed on the electrophotographic photosensitive member onto the intermediate transfer member by the image forming apparatus and then secondary transfer of the toner image on the intermediate transfer member onto the recording material. 7. The forming apparatus according to claim 6 , wherein a color image is formed by sequentially superimposing a plurality of color toner images on an intermediate transfer member, and the color image is secondarily transferred collectively onto a recording material. The image forming apparatus according to claim 10 . An image forming apparatus for the process cartridge comprising comprising at least an electrophotographic photosensitive member, an image forming apparatus for a process cartridge used in an image forming apparatus according to any one of claims 6 to 11.

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