JP2007108658A - Image forming apparatus and process cartridge for image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which has excellent electrostatic durability and provides high image quality and a longer operating life without causing scratches on a photoreceptor and image defects even when it is used for a long period of time. <P>SOLUTION: The image forming apparatus includes a photoreceptor, a charging device configured to uniformly charge the surface of the photoreceptor, an image exposing device configured to perform image exposure of the uniformly charged photoreceptor to form an electrostatic latent image, a developing device configured to develop the electrostatic latent image, a device to transfer the developed image, and a cleaning device configured to remove the transfer residual toner on the photoreceptor. The image forming apparatus is characterized in that the photoreceptor has a photosensitive layer containing at least a charge generating substance and a charge transport substance on a conductive substrate, the photosensitive layer contains a charge transport substance expressed by general formula (1), the cleaning device has a brush with a loop-shaped tip, which rotates while being brought into contact with the photoreceptor, and the loop-shaped tip side of the brush is directed to the upstream side of the rotation direction of the brush from the root part. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus that performs an image forming operation using an electrophotographic process, and a process cartridge for the image forming apparatus.

In general, the “electrophotographic process” means that a photoconductive photosensitive member is first charged in a dark place by, for example, corona discharge, then exposed to an image, and an electrostatic latent image is obtained by selectively dissipating the charge only at the exposed portion. One of the image forming methods in which this latent image portion is developed with visualization fine particles (toner) composed of a colorant such as a dye or pigment and a binder such as a polymer substance and visualized to form an image. One.
In recent years, an image forming apparatus using an electrophotographic process such as an electrophotographic copying machine or an electrophotographic printer is required to have high image quality and high durability.
In many cases, the life of an image forming apparatus using such an electrophotographic process is determined by the photoreceptor.
Since the photoreceptor is repeatedly charged and exposed as described above over a long period of time, the chargeability gradually decreases, and the potential of the exposed area increases, so that a sufficient static electricity is formed to form an electrostatic latent image. Electric contrast cannot be obtained.
In order to solve this, it is necessary to improve the charge transport material which is the main material for forming the photosensitive layer. Initially, even if the characteristics are good, if electrostatic fatigue is applied in the repeated electrophotographic process, sufficient characteristics cannot be obtained with conventional charge transport materials.

Another factor that determines the durability of the photoreceptor is wear of the photoreceptor over time. This is because, in the electrophotographic process, the photoconductor gradually deteriorates and wears by being repeatedly subjected to mechanical and chemical actions in repeated processes of charging, exposure, development, transfer, and cleaning.
As the wear progresses, the charging ability is reduced, which causes abnormal images. Accordingly, in order to achieve high durability in an image forming apparatus using an electrophotographic process, it is very important to use a photoconductor excellent in wear resistance.
Techniques such as providing a protective layer to improve the wear resistance of the photoreceptor have been proposed in Patent Document 1, Patent Document 2, Patent Document 3, Patent Document 4, Patent Document 5, and the like.
However, although these improve the wear resistance, the bright portion potential increases due to repeated use over a long period of time, and image deterioration such as a decrease in image density occurs. In addition, although such a protective layer has high mechanical strength and improved wear resistance, if foreign matter adheres to the surface of the photoreceptor for some reason, scratches are likely to occur and image defects resulting from the scratches are generated. There are aspects that are difficult to use in the process.

In recent years, the use of toner having a small particle diameter is increasing in order to improve image quality.
This is because the use of such a small particle size toner dramatically improves the image quality. However, while having such advantages, the small particle size toner has a small particle size, so that it is difficult to clean the photoconductor, and the toner that has not been cleaned on the photoconductor is liable to stick.
As the image forming apparatus is highly durable, there are cases where foreign matter adheres to the photoreceptor due to accumulation of paper dust generated from the paper used, aggregates such as toner additives, and other foreign matters.
When such a phenomenon occurs, the output image is abnormal, leading to so-called image defects. When such an image defect occurs, the lifetime of the image forming apparatus is determined at the stage where the defect has occurred in the image, no matter how highly durable the photoreceptor is.
Therefore, in order to prevent such a situation, a technique for strengthening the cleaning conditions of the photoconductor by placing emphasis on the removal of foreign matters such as transfer residual toner and paper dust on the photoconductor can be considered. However, if the cleaning conditions are inevitably increased, abnormal wear may occur on the photoconductor, or the surface roughness of the photoconductor may increase, resulting in an early cleaning failure and image defects.
For example, in order to increase the toner removal capability with a conventionally used cut pile brush, a brush that is stronger and has a larger yarn thickness must be employed. However, when using a thick pile of cut pile brushes as used in the past, the edge of the fracture surface makes point contact with the photoreceptor, scratching the surface, causing abnormal wear, and consequently image defects. It will occur.

If the cleaning conditions are unnecessarily strong, scratches caused by repeated rubbing increase, and various image defects resulting from the scratches, such as streak-like defects due to residual toner that passes through the scratches in the cleaning portion, There is a problem in that toner particles enter and adhere to the scratched portion, resulting in minute spotted defects.
Such image defects tend to occur more frequently when using small-diameter toners, which are increasingly used for the purpose of improving image quality in recent years, especially spherical toners such as polymerized toners. It has been very difficult to achieve both a good image and high durability for maintaining it for a long period of time.
In order to obtain an image forming apparatus with high image quality and high durability in this way, the main material of the photoconductor, which is the key to image formation, is changed to improve electrostatic durability and increase durability. A cleaning device that makes full use of durability and does not cause scratches on the surface of the photoreceptor is essential. However, since such a requirement could not be satisfied so far, an image forming apparatus having high image quality and high durability has not been obtained.

JP-A-1-205171 Japanese Patent Laid-Open No. 7-333881 Japanese Patent Laid-Open No. 8-15887 JP-A-8-123053 Japanese Patent Laid-Open No. 8-146664

  The object of the present invention is to solve the above-mentioned problems, and is excellent in electrostatic durability, and does not cause photoconductor scratches even when used for a long period of time. The object is to provide a long-life image forming apparatus.

（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。）
本発明の第２は、感光体と、この感光体の表面を一様に帯電する帯電装置と、一様帯電後に像露光をおこない静電潜像を形成する像露光装置と、前記静電潜像を現像する現像装置と、現像像を転写する装置と、前記感光体の転写残トナーをクリーニングするクリーニング装置を備える画像形成装置において、前記感光体が導電性基体上に少なくとも電荷発生物質と電荷輸送物質を含有する感光層が構成され、且つ前記感光層中に下記一般式（２）で表される電荷輸送物質を含み、且つ前記クリーニング装置が、先端をループ状に形成した前記感光体に接触しながら回転するブラシを有し、前記ブラシのループ先端側が根元部よりブラシ回転方向上流側に向けられていることを特徴とする画像形成装置に関する。

（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。）
本発明の第３は、前記電荷輸送物質に加えて、さらに下記一般式（３）で表される電荷輸送物質を含有することを特徴とする請求項１または２記載の画像形成装置に関する。

（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。）
本発明の第４は、前記電荷発生物質がチタニルフタロシアニンであることを特徴とする請求項１〜３のいずれかに記載の画像形成装置に関する。
本発明の第５は、前記ブラシの回転方向が感光体の回転方向に対して接触面で同方向であることを特徴とする請求項１〜４のいずれかに記載の画像形成装置に関する。
本発明の第６は、前記ブラシの感光体回転方向下流側に感光体に接する弾性体ゴムブレードを有することを特徴とする請求項１〜５のいずれかに記載の画像形成装置に関する。
本発明の第７は、前記弾性体ゴムブレードの感光体への当接方向が感光体の回転方向に対しカウンター方向であることを特徴とする請求項６記載の画像形成装置に関する。
本発明の第８は、前記弾性体ゴムブレードの感光体への当接圧が１０〜３０ｇ／ｃｍであることを特徴とする請求項６又は７記載の画像形成装置に関する。
本発明の第９は、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、該電子写真感光体が請求項１〜４のいずれかに記載のものであることを特徴とする画像形成装置用プロセスカートリッジに関する。 The image forming apparatus of the present invention has achieved the above-mentioned problems by setting the photoconductor constituent material and the optimum cleaning conditions for the photoconductor. That is, the object of the present invention has been achieved by adopting one of the following configurations.
A first aspect of the present invention is a photosensitive member, a charging device that uniformly charges the surface of the photosensitive member, an image exposure device that performs image exposure after uniform charging to form an electrostatic latent image, and the electrostatic latent image. An image forming apparatus comprising: a developing device that develops an image; a device that transfers a developed image; and a cleaning device that cleans residual transfer toner on the photoconductor. The photoconductor has at least a charge generating substance and a charge on a conductive substrate. A photosensitive layer containing a transport material is formed, and the charge transport material represented by the following general formula (1) is included in the photosensitive layer, and the cleaning device is formed on the photoreceptor having a tip formed in a loop shape. The present invention relates to an image forming apparatus having a brush that rotates while being in contact with each other, wherein a tip end side of the loop of the brush is directed upstream of a root portion in a brush rotation direction.

Wherein R 1 and R 2 each independently represent a group selected from the group consisting of a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aralkyl group, and R 3 , R4, R5, R6, R7, R8, R9, R10 are each independently a hydrogen atom, a halogen atom, a cyano group, a nitro group, an amino group, a hydroxyl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group. Represents a group selected from the group consisting of a group, a substituted or unsubstituted aralkyl group.)
A second aspect of the present invention is a photoreceptor, a charging device that uniformly charges the surface of the photoreceptor, an image exposure device that performs image exposure after uniform charging to form an electrostatic latent image, and the electrostatic latent image. An image forming apparatus comprising: a developing device that develops an image; a device that transfers a developed image; and a cleaning device that cleans residual transfer toner on the photoconductor. The photoconductor has at least a charge generating substance and a charge on a conductive substrate. A photosensitive layer containing a transport material is formed, and the charge transport material represented by the following general formula (2) is included in the photosensitive layer, and the cleaning device has a loop formed on the photosensitive member. The present invention relates to an image forming apparatus having a brush that rotates while being in contact with each other, wherein a tip end side of the loop of the brush is directed upstream of a root portion in a brush rotation direction.

Wherein R 1 and R 2 each independently represent a group selected from the group consisting of a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aralkyl group, and R 3 , R4, R5, R6, R7, R8, R9, R10, R11, R12, R13, R14 are each independently a hydrogen atom, halogen atom, cyano group, nitro group, amino group, hydroxyl group, substituted or unsubstituted alkyl group Represents a group selected from the group consisting of a substituted or unsubstituted cycloalkyl group and a substituted or unsubstituted aralkyl group, and n is a repeating unit and represents an integer of 1 to 100.)
A third aspect of the present invention relates to the image forming apparatus according to claim 1 or 2, further comprising a charge transport material represented by the following general formula (3) in addition to the charge transport material.

(Wherein R15 and R16 each independently represents 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.)
A fourth aspect of the present invention relates to the image forming apparatus according to any one of claims 1 to 3, wherein the charge generating substance is titanyl phthalocyanine.
The fifth aspect of the present invention relates to the image forming apparatus according to any one of claims 1 to 4, wherein the rotation direction of the brush is the same as the contact surface with respect to the rotation direction of the photosensitive member.
A sixth aspect of the present invention relates to the image forming apparatus according to any one of claims 1 to 5, further comprising an elastic rubber blade in contact with the photoconductor on the downstream side of the brush in the photoconductor rotation direction.
7. The image forming apparatus according to claim 6, wherein a contact direction of the elastic rubber blade to the photosensitive member is a counter direction with respect to a rotating direction of the photosensitive member.
An eighth aspect of the present invention relates to the image forming apparatus according to claim 6 or 7, wherein a contact pressure of the elastic rubber blade to the photosensitive member is 10 to 30 g / cm.
According to a ninth aspect of the present invention, there is provided a process cartridge for an image forming apparatus comprising at least an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member is one according to any one of claims 1 to 4. This relates to a process cartridge for an image forming apparatus.

As a result of intensive studies in view of the above-mentioned problems of the prior art, the present invention uses a material represented by the above general formula as a charge transport material and combines with the cleaning conditions shown below to produce a high-quality image free from image defects. It became possible to obtain over a long period of time.
As the mechanism of the cleaning device combined with the photoconductor, the cleaning device has a brush that comes into contact with the photoconductor having the tip formed in a loop shape, so that the shape of the brush tip in contact with the photoconductor becomes a so-called line contact state. Even if a brush material with thick bristles and a strong back is used, foreign matters such as transfer residual toner and paper dust can be effectively removed without damaging the surface of the photoreceptor.
In addition, since the brush tip of the brush is directed to the upstream side of the brush rotation direction with respect to the rotation direction, even if the brush is a strong brush, the contact with the photoconductor is soft, and rotational torque is reduced. It is possible to reduce driving power.
Further, in addition to these charge transport materials, the charge transport material represented by the above general formula (3) is further added to alleviate shrinkage during film formation without reducing the charge transport capability, and aluminum deposited PET When a flexible sheet such as a sheet or a nickel belt is used as a support, it is possible to reduce warpage generally referred to as curl. 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 improved and the compatibility with the brush of the present invention is very good.
In addition, the use of a brush formed in a loop shape improves the ability to remove foreign matter, so that even if the rotation direction of the brush is the same as that of the contact surface with respect to the rotation direction of the photosensitive member, it has sufficient cleaning properties and scratches on the photosensitive member. Even if a foreign object with high hardness such as a mark is mixed into the brush, the chance of contact between the foreign object and the photoconductor is reduced, so that the possibility of scratches on the photoconductor can be reduced, and the waist is strong. Even in the case of a brush, the contact with the photosensitive member is soft, and the rotational torque can be reduced and the driving power can be saved.

Further, by providing an elastic rubber blade in contact with the photoconductor downstream of the brush in the rotation direction of the photoconductor, more effective cleaning can be performed, and the contact direction is a counter direction with respect to the rotation direction of the photoconductor. Therefore, more suitable cleaning is possible. In addition, by setting the contact pressure of the elastic rubber blade to the photoconductor to 10 to 30 g / cm, it is possible to perform sufficient cleaning while suppressing abnormal wear of the photoconductor in the image forming apparatus.
This is due to the fact that the contact pressure in this range is the most excellent transfer residual toner removal capability and a value that does not cause scratches when adhering to foreign matter, as a result of numerous studies.
If the contact pressure becomes too weak, the transfer residual toner may not be completely removed and the process proceeds to the next image forming process, which may cause abnormal images. This is because there is a case where wear of the photoreceptor is promoted.
The charge generating material of the photoreceptor is preferably a titanyl phthalocyanine structure in combination with the charge transport material used in the present invention.

Next, the photoreceptor used in the image forming apparatus of the present invention will be described below.
In the photoreceptor used in the image forming apparatus of the present invention, as a conductive support, a conductor or an insulator subjected to a conductive treatment, for example, a metal such as Al, Fe, Cu, Au, or an alloy thereof, polyester, polycarbonate, A material in which a thin film of a metal such as Al, Ag, or Au or a conductive material such as In ₂ O ₃ or SnO ₂ is formed on an insulating substrate such as polyimide or glass, paper that has been subjected to conductive treatment, or the like can be used. The shape of the conductive support is not particularly limited, and either a drum shape or a belt shape can be used.

Next, the photosensitive layer of the photoreceptor used in the image forming apparatus of the present invention will be described.
The photosensitive layer in the present invention includes a single layer type and a multilayer type, and both can be used, but here, for convenience of explanation, a multilayer type in which the photosensitive layer is first separated into a charge generation layer and a charge transport layer. Is described.
First, the charge generation layer will be described.
The charge generation layer is a layer mainly composed of a charge generation material, and a binder resin may be used as necessary. A known material can be used as the charge generating substance.
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, dibenzothiophene skeleton Azo pigments having fluorenone skeleton, azo pigments having oxadiazole skeleton, azo pigments having bis-stilbene skeleton, azo pigments having distyryl oxadiazole skeleton, azo pigments having distyrylcarbazole skeleton, perylene Pigments, anthraquinone or polycyclic quinone pigments, quinoneimine pigments, diphenylmethane and triphenylmethane pigments, benzoquinone and naphthoquinone pigments, cyanine and azomethine pigments, Jigoido based pigments, and bisbenzimidazole pigments. These charge generation materials can be used alone or as a mixture of two or more.

チタニルフタロシアニンの合成法や電子写真特性に関する文献としては、例えば特開昭５７−１４８７４５号公報、特開昭５９−３６２５４号公報、特開昭５９−４４０５４号公報、特開昭５９−３１９６５号公報、特開昭６１−２３９２４８号公報、特開昭６２−６７０９４号公報などが挙げられる。また、チタニルフタロシアニンには種々の結晶系が知られており、特開昭５９−４９５４４号公報、特開昭５９−４１６１６９、特開昭５９−１６６９５９号公報、特開昭６１−２３９２４８号公報、特開昭６２−６７０９４号公報、特開昭６３−３６６号公報、特開昭６３−１１６１５８号公報、特開昭６３−１９６０６７号公報、特開昭６４−１７０６６号公報、特開２００１−１９８７１号公報等に各々結晶形の異なるチタニルフタロシアニンが記載されている。
これらの結晶形のうち、ブラッグ角２θの２７．２°に最大回折ピークを有するチタニルフタロシアニンが特に優れた感度特性を示し、良好に使用される。特に、特開２００１−１９８７１号公報に記載されている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、該７．３゜のピークと９．４゜のピークの間にピークを有さないチタニルフタロシアニンを用いることで、高感度を失うことなく、繰り返し使用しても帯電性の低下を生じない安定した電子写真感光体を得ることができる。
加えて平均粒子サイズが０．６０μｍ以下であるチタニルフタロシアニン結晶であることによって、高感度を失うことなく繰り返し使用によっても帯電性の低下を生じない安定な電子写真感光体を得ることができ、さらに地肌汚れ特性が著しく改善できる。
これは平均粒子サイズが０．６０μｍより大きくなると接触面積が低下し電荷発生効率が低下するためである。 Among them, in particular, by using titanyl phthalocyanine as shown in the following structural formula (A) having titanium as a central metal, a photosensitive layer having particularly high sensitivity can be obtained, and the image forming apparatus can be further reduced in size and speed. It is possible to measure.

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, such as JP-A-59-49544, JP-A-59-416169, JP-A-59-166959, JP-A-61-239248, JP-A-62-67094, JP-A-63-366, JP-A-63-116158, JP-A-63-196067, JP-A-64-17066, JP-A-2001-19871 Patent Documents and the like describe titanyl phthalocyanines having different crystal forms.
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 °, and By using titanyl phthalocyanine having a peak at 7.3 ° as the diffraction peak at the lowest angle and having no peak between the 7.3 ° peak and the 9.4 ° peak, high sensitivity can be obtained. Without losing it, a stable electrophotographic photosensitive member that does not cause a decrease in chargeability even when used repeatedly can be obtained.
In addition, by using the titanyl phthalocyanine crystal having an average particle size of 0.60 μm or less, it is possible to obtain a stable electrophotographic photosensitive member that does not cause deterioration in chargeability even after repeated use without losing high sensitivity. The background dirt property can be remarkably improved.
This is because when the average particle size is larger than 0.60 μm, the contact area is lowered and the charge generation efficiency is lowered.

The binder resin used as necessary for the charge generation layer includes polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, and poly-N-vinylcarbazole. Polyacrylamide is used. These binder resins can be used alone or as a mixture of two or more. Furthermore, you may add the electric charge transport material mentioned later as needed.
Examples of the method for forming the charge generation layer include a casting method from a solution dispersion system. In order to provide the charge generation layer by the casting method, the above-described charge generation material is optionally mixed with a binder resin using a solvent such as tetrahydrofuran, cyclohexanone, dioxane, dichloroethane, or butanone by a ball mill, an attritor, a sand mill, or the like. It can be formed by dispersing and coating the dispersion after diluting it appropriately. The coating can be performed using a dip coating method, a spray coating method, a bead coating method, or the like.
The thickness of the charge generation layer provided as described above is suitably about 0.01 to 5 μm, preferably 0.05 to 2 μm.

Next, the charge transport layer will be described.
The charge transport layer is formed by dissolving, coating and forming a film using a solvent such as tetrahydrofuran, cyclohexanone, dioxane, dichloroethane, butanone together with a charge transport material and a binder resin. As the coating method, dip coating, spray coating, bead coating, or the like can be used.
Binders that can be used as the charge transport layer include polycarbonate (bisphenol A type, bisphenol Z type, bisphenol C type, or copolymers thereof) with good film properties, polyarylate, polysulfone, polyester, methacrylic resin, polystyrene, acetic acid. Vinyl, epoxy resin, phenoxy resin, etc. are used. These binders can be used alone or as a mixture of two or more.
The charge transport material used in the present invention is represented by the above general formula (1) or general formula (2).
By incorporating the compound represented by the general formula (1) or the general formula (2) into the photosensitive layer, the electrostatic stability over a long period of time, which is impossible with the conventional image forming apparatus, that is, the charging potential and It is possible to realize an image forming apparatus that can improve the electrical durability that keeps the difference in exposure part potential, so-called electrostatic contrast stable, and can stably obtain high-quality images even in long-term repeated use. It becomes.
Further, the compound represented by the general formula (1) or the general formula (2) has very high stability against active gas such as ozone or nitrogen oxide gas, and such active gas is generated from the charger. This is very advantageous for use in an image forming apparatus.
This is considered to be resistant to the gas as described above because of its strong N-basic molecular structure.
That is, it is possible to obtain an image forming apparatus that is very excellent in terms of chemical durability in addition to the mechanical durability and electrical durability described above. Therefore, when designing various electrophotographic image forming apparatuses, it is possible to prevent an increase in size and cost, and it is possible to provide a user with a machine that is inexpensive and easy to install.

In the formula of the compound represented by the general formula (1), general formula (2) or general formula (3) used here, R1, R2, R15 and R16 are each independently a hydrogen atom, substituted or unsubstituted. Represents a group selected from the group consisting of an alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aralkyl group, and R3, R4, R5, R6, R7, R8, R9, R10, R11, R12, R13. , R14, R17, R18, R19, R20 are each independently a hydrogen atom, a halogen atom, a cyano group, a nitro group, an amino group, a hydroxyl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, substituted or Represents a group selected from the group consisting of unsubstituted aralkyl 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.

More specifically, charge transport materials represented by the following formulas (4) to (8) can be given.
In the formula, Me represents a methyl group.

〔式中、Ｒｎは一般式（１）におけるＲ３、Ｒ４、Ｒ５、Ｒ６を表し、Ｒｍは一般
式（１）におけるＲ７、Ｒ８、Ｒ９、Ｒ１０を表す。〕 Specific examples of the method for synthesizing and producing the charge transport material represented by the 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), etc.).

[Wherein, Rn represents R3, R4, R5, R6 in the general formula (1), and Rm represents R7, R8, R9, R10 in the general formula (1). ]

The charge transporting substance represented by the general formula (1) used in the present invention is a method of reacting the above naphthalenecarboxylic acid or its anhydride with amines to monoimidize, and using a buffer solution for naphthalenecarboxylic acid or its anhydride. It is obtained by a method of adjusting pH and reacting with diamines. Monoimidization is carried out without solvent or in the presence of a solvent. The solvent is not particularly limited, but it does not react with raw materials or products such as benzene, toluene, xylene, chloronaphthalene, acetic acid, pyridine, methylpyridine, dimethylformamide, dimethylacetamide, dimethylethyleneurea, dimethylsulfoxide, and the like. What is made to react at the temperature of -250 degreeC is good to use.
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 charge transport material represented by the above formula (4) was 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 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. Furthermore, the recovered product was recrystallized with toluene / hexane to obtain 2.14 g of monoimide A (yield 31.5%).
Second Step A 100 ml four-necked flask was charged with 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, and heated for 5 hours. Refluxed. After completion of the reaction, the container was cooled and concentrated under reduced pressure. The residue was purified by silica gel column chromatography. Further, the recovered product was recrystallized from toluene / ethyl acetate to obtain 0.668 g (yield 33.7%) of the compound represented by the formula (4).
In mass spectrometry (FD-MS), a peak of M / z = 726 was observed and identified as a target product. In the elemental analysis, the calculated values were 69.52% carbon, 5.27% hydrogen, and 7.71% nitrogen, and the measured values were 69.52% carbon, 5.09% hydrogen, and 7.93% nitrogen.

The charge transport material represented by the above formula (5) was produced by the following method.
First Step In a 200 ml four-necked flask, 10 g (37.3 mmol) of 1,4,5,8-naphthalenetetracarboxylic dianhydride and 0.931 g (18.6 mmol) of hydrazine monohydrate, p-toluenesulfonic acid 20 mg and 100 ml of toluene 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 by silica gel column chromatography. Further, the recovered product was recrystallized from toluene / ethyl acetate to obtain 2.84 g of dimer C (yield 28.7%).
Second Step In a 100 ml four-necked flask, 2.5 g (4.67 mmol) of dimer C and 30 ml of DMF were placed and heated to reflux. To this, a mixture of 2-aminopropane 0.278 g (4.67 mmol) and DMF 10 ml was added dropwise with stirring. After completion of dropping, the mixture was heated to reflux for 6 hours. After completion of the reaction, the reaction vessel was cooled and concentrated under reduced pressure. Toluene was added to the residue and purified by silica gel column chromatography to obtain 0.556 g of monoimide C (yield 38.5%).
Third Step A 50 ml four-necked flask was charged with 0.50 g (1.62 mmol) of monoimide C and 10 ml of DMF and heated to reflux. To this, a mixture of 2-aminoheptane 0.186 g (1.62 mmol) and DMF 5 ml was added dropwise with stirring. After completion of dropping, the mixture was heated to reflux for 6 hours. After completion of the reaction, the reaction vessel was cooled and concentrated under reduced pressure. Toluene was added to the residue, and the residue was purified by silica gel column chromatography. Furthermore, the recovered product was recrystallized from toluene / hexane to obtain 0.243 g (yield 22.4%) of the compound represented by the above formula (5).
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.

The charge transport material represented by the above formula (6) was 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 from toluene / hexane to obtain 2.08 g of monoimide B (yield 36.1%).
Second Step A 100 ml four-necked flask was charged with 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 heated for 5 hours. Refluxed. After completion of the reaction, the container was cooled and concentrated under reduced pressure. The residue was purified by silica gel column chromatography. Further, the recovered product was recrystallized from toluene / ethyl acetate to obtain 0.810 g (yield 37.4%) of the charge transport material represented by the formula (6).
In mass spectrometry (FD-MS), the peak of M / z = 614 was observed and identified as the target product. In the elemental analysis, the calculated values were 66.45% carbon, 3.61% hydrogen, and 9.12% nitrogen, and the measured values were 66.28% carbon, 3.45% hydrogen, and 9.33% nitrogen.

The charge transport material represented by the above formula (7) was produced by the following method.
First Step In a 200 ml four-necked flask, 5.0 g (9.39 mmol) of the above-mentioned dimer C and 50 ml of DMF were added 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 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 the charge transport material represented by the formula (7).
In mass spectrometry (FD-MS), the peak of M / z = 740 was observed and identified as the target product. In the elemental analysis, the calculated values were 69.72% carbon, 5.44% hydrogen, and 7.56% nitrogen, and the measured values were 69.55% carbon, 5.26% hydrogen, and 7.33% nitrogen.

The charge transport material represented by the above formula (8) was produced by the following method.
First Step In a 200 ml four-necked flask, 5.0 g (9.39 mmol) of the above-mentioned dimer C and 50 ml of DMF were added 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 the residue was purified by silica gel column chromatography to obtain 1.66 g (yield 28.1%) of monoimide D.
Second Step A 100 ml four-necked flask was charged with 1.5 g (2.38 mmol) of monoimide D and 50 ml of DMF and heated to reflux. To this, a mixture of 0.408 g (2.38 mmol) of 6-aminoundecane and 10 ml of DMF was added dropwise with stirring. After completion of dropping, the mixture was heated to reflux for 6 hours. After completion of the reaction, the reaction vessel was cooled and concentrated under reduced pressure. Toluene was added to the residue, and the residue was purified by silica gel column chromatography. Further, the recovered product was recrystallized with toluene / hexane to obtain 0.276 g (yield 14.8%) of the charge transport material represented by the above formula (8).
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 were 70.77% carbon, 6.11% hydrogen, and 7.02% nitrogen while the calculated values were 70.57% carbon, 5.92% hydrogen, and 7.16% nitrogen.

The content of the compound represented by the general formula (1) or the general formula (2) is preferably 10 wt% to 70 wt%, more preferably 30 wt% to 60 wt%, based on the total solid content of the entire photosensitive layer.
If the amount added is too large, problems such as a decrease in wear resistance, a decrease in charging potential, and an increase in dark decay may appear. If the amount added is too small, sufficient electrostatic contrast may not be obtained, There may be a problem that the image suppression effect is not sufficiently exhibited.
The thickness of the charge transport layer provided as described above is suitably 5 to 100 μm, and preferably 10 to 30 μm.

Next, another charge transport material used in the present invention is represented by the general formula (2).
By incorporating the compound represented by the general formula (2) into the photosensitive layer, long-term electrostatic stability that is impossible with conventional image forming apparatuses, that is, the difference between the charged potential and the exposed portion potential, As a result, it is possible to realize an image forming apparatus that improves the electrical durability that keeps the so-called electrostatic contrast stable, and can stably obtain a high-quality image even in repeated use over a long period of time.
Further, the compound represented by the general formula (2) is very stable with respect to an active gas such as ozone or nitrogen oxide gas, and is used for an image forming apparatus in which such an active gas is generated from a charger. Has become very advantageous.
This is considered to be resistant to the gas as described above because of its strong N-basic molecular structure.
That is, it is possible to obtain an image forming apparatus that is very excellent in terms of chemical durability in addition to the mechanical durability and electrical durability described above. Therefore, when designing various electrophotographic image forming apparatuses, it is possible to prevent an increase in size and cost, and it is possible to provide a user with a machine that is inexpensive and easy to install.

In the compound represented by the general formula (2) used herein, R1 and R2 are each independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted group. R3, R4, R5, R6, R7, R8, R9, R10, R11, R12, R13, and R14 are each independently a hydrogen atom, a halogen atom, a cyano group, or a nitro group. Represents a group selected from the group consisting of a group, an amino group, a hydroxyl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aralkyl group, and n is a repeating unit. Represents an integer up to 100.
More specifically, charge transport materials represented by the following formulas (9) to (11) can be given.
[However, in both formulas, the terminal groups at both ends represent Me (methyl group). ]

Specifically, the charge transport material represented by the general formula (2) is synthesized mainly by the following two synthesis methods.

The repeating unit n of the charge transport material represented by the 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.

The charge transport material represented by the above formula (9) was 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 1.62 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, hydrazine monohydrate 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 compound represented by the formula (9).
In mass spectrometry [FD-MS], the peak of M / z = 934 was observed and identified as the target product. In the elemental analysis, the calculated values were 66.92% carbon, 3.67% hydrogen, and 8.99% nitrogen, and the measured values were 66.92% carbon, 3.74% hydrogen, and 9.05% nitrogen.

〔ただし、式中、両端の末端基はＭｅ（メチル基）を表す。〕

〔ただし、式中、両端の末端基はＭｅ（メチル基）を表す。〕
これらの電荷輸送物質の添加量としては特に限定されるものではないが、好ましくは電荷輸送物質全体量に対して１％から５０％程度であり、より好ましくは５％〜３０％である。添加量が１％未満であると膜質改善が軽微で明確な効果が見られず、５０％以上となると電荷輸送能がやや低下する傾向がみられる場合があるからである。 Specific examples of the charge transport material represented by the general formula (3) that can be added to these charge transport materials include the following compounds.

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

[However, in the formula, the terminal groups at both ends represent Me (methyl group). ]
The amount of these charge transport materials to be added is not particularly limited, but is preferably about 1% to 50%, more preferably 5% to 30% with respect to the total amount of the charge 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.

Next, a single layer type photosensitive layer will be described.
When a single photosensitive layer is provided by a casting method or the like, the charge generation material described above, the charge transport material represented by the general formula (1) or the general formula (2), or a material such as a binder resin is used. A single-layer structure may be used. In the case of a single layer configuration, since the charge transport material represented by the general formula (1) is basically an electron transport material, it is preferable to use a hole transport material in combination for transporting holes. As the hole transporting substance, any known substance can be used, but in particular, an oxazole derivative and an oxadiazole derivative (described in JP-A Nos. 52-139065 and 52-139066) imidazole derivatives (special No. 34-10366), a triphenylamine derivative (described in US Pat. No. 3,180,730), a benzidine derivative (described in Japanese Patent Publication No. 58-32372), an α-phenylstilbene derivative (Japanese Patent Laid-Open No. 57-73075). Hydrazone derivatives (described in JP-A-55-154955, JP-A-55-15694, JP-A-55-52063, JP-A-56-81850, etc.), triphenyl Methane derivatives (described in Japanese Examined Patent Publication No. 51-10983), anthracene derivatives (Japanese Patent Laid-Open No. Sho 5) -94829), styryl derivatives (described in JP-A-56-29245, JP-A-58-198043), carbazole derivatives (described in JP-A-58-58552), pyrene derivatives ( JP-A-2-190863) is preferable. The thickness of the single photosensitive layer is suitably about 5 to 100 μm, and preferably about 10 to 30 μm.

In the present invention, in addition to the charge transport material represented by the general formula (3), a plasticizer or a leveling agent may be further added to the photosensitive layer. As the plasticizer, those used as plasticizers for general resins such as dibutyl phthalate and dioctyl phthalate can be used as they are, and the amount used is about 0 to 30 parts by weight with respect to 100 parts by weight of the binder resin. Is appropriate.
As the leveling agent, silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, and polymers or oligomers having a perfluoroalkyl group in the side chain are used, and the amount used is 0 with respect to 100 parts by weight of the binder resin. About 1 part by weight is appropriate.

In the present invention, an antioxidant may be added for the purpose of preventing the decrease in sensitivity and the increase in residual potential, in order to improve environmental resistance. The antioxidant may be added to any layer containing an organic substance, but good results are obtained when it is added to a layer containing a charge transport material.
The following are mentioned as antioxidant which can be used for this invention.
Monophenol compounds 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, stearyl-β- (3,5-di- t-butyl-4-hydroxyphenyl) propionate and the like.
Bisphenol compounds 2,2'-methylene-bis- (4-methyl-6-tert-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) and the like.
Polymer phenolic compound 1,1,3-tris- (2-methyl-4-hydroxy-5-t-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3 , 5-di-t-butyl-4-hydroxybenzyl) benzene, tetrakis- [methylene-3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane, bis [ 3,3′-bis (4′-hydroxy-3′-t-butylphenyl) butyric acid] glycol ester, tocophenols and the like.
Paraphenylenediamines N-phenyl-N'-isopropyl-p-phenylenediamine, N, N'-di-sec-butyl-p-phenylenediamine, N-phenyl-N-sec-butyl-p-phenylenediamine, N , N'-di-isopropyl-p-phenylenediamine, N, N'-dimethyl-N, N'-di-t-butyl-p-phenylenediamine, and the like.
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 and the like.
Organic sulfur compounds dilauryl-3,3'-thiodipropionate, distearyl-3,3'-thiodipropionate, ditetradecyl-3,3'-thiodipropionate, and the like.
Organic phosphorus compounds Triphenylphosphine, tri (nonylphenyl) phosphine, tri (dinonylphenyl) phosphine, tricresylphosphine, tri (2,4-dibutylphenoxy) phosphine and the like.
These compounds are known as antioxidants such as rubbers, plastics, oils and fats, and commercially available products can be easily obtained. The addition amount of the antioxidant in the present invention is 0.1 to 100 parts by weight, preferably 2 to 30 parts by weight with respect to 100 parts by weight of the charge transport material.

  In the image forming apparatus of the present invention, an intermediate layer can be appropriately provided between the conductive support and the photosensitive layer. Although it is an intermediate layer that can be used, an intermediate layer is generally used that has a resin as a main component, but considering that these resins are coated with a photosensitive layer using a solvent, It is desirable that the resin is highly resistant to dissolution in 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 resin, melamine resin, and epoxy resin. And a curable resin that forms a three-dimensional network structure. In addition, metal oxides exemplified by titanium oxide, silica, alumina, zirconium oxide, tin oxide, indium oxide, etc., or fine powders such as metal sulfides and metal nitrides are added as fillers in the intermediate layer to further stabilize The charged property can be maintained. These intermediate layers can be formed using an appropriate solvent and a coating method, and the film thickness is 0.1 to 20, preferably 0.5 to 10 μm.

Next, an image forming process of the image forming apparatus of the present invention will be described.
FIG. 1 is a schematic diagram for explaining an electrophotographic process, and modifications as described below also belong to the category of the present invention.
In FIG. 1, the photoconductor 1 has a drum shape, but may be a sheet or an endless belt.
For the charging charger 3, the pre-transfer charger 7, the transfer charger 10, the separation charger 11, and the pre-cleaning charger 13, known means such as a corotron, a scorotron, a solid state charger, and a charging roller are used. It is done.
As the transfer means, the above charger can be generally used. However, as shown in the figure, a combination of a transfer charger and a separation charger is effective.
Various light sources such as a semiconductor laser can be used as the light source of the image exposure unit 5.
In addition to the steps shown in FIG. 1, it is possible to provide the photosensitive member with light irradiation in a transfer step, a static elimination step, a cleaning step, a pre-exposure step, etc. It is not limited.
The developing unit 6 is a two-component developing unit having a developer composed of toner and carrier. The toner and carrier to be used are not particularly limited, but for the purpose of improving the image quality, a small particle size type is used. In general, the small particle size toner means an average particle size of about 3 to 9 μm, and the small particle size carrier means a carrier of about 30 to 60 μm.
The toner developed on the photosensitive member 1 by this developing unit is transferred to the transfer paper 9, but not all is transferred, and toner remaining on the photosensitive member 1 is also generated.
In order to remove such transfer residual toner, a cleaning brush and a cleaning blade in contact with the photosensitive member are used as a cleaning device. However, in some cases, a charge eliminating step by a pre-cleaning charger as shown in FIG.

Here, the cleaning device used in the present invention will be described.
The cleaning device used in the present invention has a brush that comes into contact with the photoreceptor having a tip formed in a loop shape as shown in FIG. 2, and the loop tip side of the brush is directed upstream of the brush rotation direction from the root portion. It is characterized by. FIG. 2 is an enlarged view showing the shape of the brush tip, FIG. 3 is a cross-sectional view of the rotating brush, and the arrow in the figure indicates the direction of rotation.
The material of the brush is not particularly limited, and general materials can be used. Examples of the brush material include nylon, polyester, rayon, polycarbonate, methacrylic resin, acrylic resin, etc. These resins can be used alone or in combination of two or more. Can be used as a mixture. The brush fiber may be subjected to a conductive treatment.
As a conductive treatment, a method of coating a metal on a normal fiber surface by a method such as plating, vacuum deposition, or sputtering, or a method of forming an organic layer in which a conductive fine particle dispersion polymer such as carbon or metal is dispersed on the fiber surface. Examples thereof include a method of blending conductive fine particle-dispersed polymers or multi-core composite spinning.
As the thickness of the brush fiber, one having 5 to 30 (denier / filament) is generally used. As the brush density, the loop density of the brush formed in a loop shape is particularly preferably 50 to 100 loops per 1 cm ² from the viewpoint of cleaning properties and durability.
A suitable brush loop length is 2 to 10 mm. As an example of the cleaning brush, as shown in FIG. 4, a loop pile brush made by weaving a loop-shaped brush around a base fabric is wound around a metal core and bonded thereto.
In addition, as for the material of the elastic rubber blade provided so as to be in contact with the photoconductor on the downstream side of the brush in the rotation direction of the photoconductor, generally used elastic materials such as silicone rubber and urethane rubber can be used. Although the blade thickness is not particularly limited, it is preferably about 1 mm to 7 mm, but the contact pressure with the photoreceptor is particularly preferably in the range of 10 to 30 g / m for the reason described above. The contact direction of the elastic rubber blade to the photoconductor is more preferably a counter direction with respect to the rotation direction of the photoconductor.

When a positive (negative) charge is applied to the electrophotographic photosensitive member 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 toner of negative (positive) polarity (detection fine particles), a positive image can be obtained, and if developed with toner of positive (negative) polarity, 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.
The above illustrated electrophotographic process exemplifies one example of an embodiment of the present invention, and of course, other embodiments are possible.

  According to the present invention, a highly durable image forming apparatus excellent in image quality and a process cartridge for an image forming apparatus can be obtained.

EXAMPLES Next, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited to these Examples.
In addition, all the parts used in an Example represent a weight part.

次いで、φ１００ｍｍ、長さ３６０ｍｍのアルミニウムドラム上に、前記感光層塗工液を用いて浸漬塗工をおこない成膜して、１２０℃で１５分乾燥した。
なお感光層は２４．５μｍの厚さとなるような昇降速度条件で作製し実施例１用の感光体を作製した。 Examples 1-4
First, electrophotographic photoreceptors used in Examples 1 to 4 were obtained in the following manner.
<Photoconductor for Example 1>
The following components were mixed in an aluminum drum having a diameter of 100 mm and a length of 360 mm as a conductive support, ball milling was performed, coating by an immersion method, and heating and drying to form a 3.5 μm intermediate layer.
The photoreceptor used in Example 1 was produced as follows.
First, as a charge generation material, 30 parts by weight of a titanyl phthalocyanine pigment represented by the following pigment synthesis example 1 and 970 parts by weight of cyclohexanone were dispersed in a ball mill device for 2 hours to obtain a charge generation material dispersion.
Separately from this, 340 parts by weight of tetrahydrofuran, 49 parts by weight of polycarbonate resin (Z polycarbonate, viscosity average molecular weight: 40,000, manufactured by Teijin Chemicals Ltd.), 20 parts by weight of the charge transport material of the formula (4) synthesized by the method described above Part, 29.5 parts by weight of the charge transport material represented by the following structural formula (B), and 0.1 part by weight of silicone oil (KF50-100CS manufactured by Shin-Etsu Chemical Co., Ltd.) are dissolved therein. 66.6 parts by weight of the dispersion was added and stirred to obtain a photosensitive layer coating solution.

Next, dip coating was performed on the aluminum drum having a diameter of 100 mm and a length of 360 mm using the photosensitive layer coating solution, followed by drying at 120 ° C. for 15 minutes.
The photosensitive layer was prepared under the ascending / descending speed condition so as to have a thickness of 24.5 μm, and a photoreceptor for Example 1 was prepared.

(Pigment synthesis example 1)
A pigment was prepared according to Japanese Patent Application Laid-Open No. 2001-19871. That is, 29.2 g of 1,3-diiminoisoindoline and 200 ml of sulfolane are mixed, and 20.4 g of titanium tetrabutoxide is added dropwise under a nitrogen stream. After completion of the dropwise addition, the temperature was gradually raised to 180 ° C., and the reaction was carried out by stirring for 5 hours while maintaining the reaction temperature between 170 ° C. and 180 ° C. After completion of the reaction, the mixture was allowed to cool, and then the precipitate was filtered, washed with chloroform until the powder turned blue, then washed several times with methanol, further washed several times with hot water at 80 ° C., and dried. Crude titanyl phthalocyanine was obtained. Dissolve the crude titanyl phthalocyanine in 20 times the amount of concentrated sulfuric acid, add dropwise to 100 times the amount of ice water with stirring, filter the precipitated crystals, and then repeat washing with water until the washing solution becomes neutral (ion-exchanged water after washing). PH value was 6.8), and a titanyl phthalocyanine pigment wet cake (water paste) was obtained. 40 g of the obtained wet cake (water paste) was put into 200 g of tetrahydrofuran, stirred for 4 hours, filtered and dried to obtain titanyl phthalocyanine powder. This is designated as Pigment 1.
The solid content concentration of the wet cake was 15 wt%. The weight ratio of the crystal conversion solvent to the wet cake is 33 times. In addition, the halide is not used for the raw material of the synthesis example 1.
The obtained titanyl phthalocyanine powder was subjected to X-ray diffraction spectrum measurement under the following conditions. As a result, the Bragg angle 2θ with respect to the characteristic X-ray of Cu—Kα (wavelength: 1.542 mm) was 27.2 ± 0.2 ° with the maximum peak. Has a peak at the lowest angle of 7.3 ± 0.2 °, no peak between 7.3 ° peak and 9.4 ° peak, and no peak at 26.3 ° It was titanyl phthalocyanine powder.
(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 The average particle size in the charge generation layer coating solution using this titanyl phthalocyanine was measured by CAPA-700 manufactured by Horiba, Ltd. and found to be 0.31 μm.

<Photoconductor for Example 2>
The same procedure as in the photoconductor for Example 1 was carried out except that the charge transport material of formula (4) in the photoconductor for Example 1 was replaced with the charge transport material represented by formula (5) synthesized by the method described above. A photoreceptor for Example 2 was prepared.

<Photoreceptor for Example 3>
The same procedure as in the photoconductor for Example 1 was carried out except that the charge transport material of formula (4) in the photoconductor for Example 1 was replaced with the charge transport material represented by formula (6) synthesized by the method described above. A photoreceptor for Example 3 was prepared.

<Photoreceptor for Example 4>
The same procedure as in the photoconductor for Example 1 was carried out except that the charge transport material of formula (4) in the photoconductor for Example 1 was replaced with the charge transport material represented by formula (7) synthesized by the method described above. A photoreceptor for Example 4 was prepared.

ただし、式中、両端の末端基はＭｅ（メチル基）を表す。 Example 5
In the photoreceptor for Example 1, the charge transport material of Formula (4) was replaced with the charge transport material represented by Formula (9) described above, and for Example 5 in the same manner as the photoreceptor for Example 1. A photoconductor was prepared.

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

ただし、式中、両端の末端基はＭｅ（メチル基）を表す。 Example 6
In the photoreceptor for Example 1, in the same manner as in the photoreceptor for Example 1, except that the charge transport material represented by the formula (4) is replaced with the charge transport material represented by the above formula (10). A photoconductor was prepared.

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

ただし、式中、ｎは１〜１００までの数値を表し、これらのものの混合体である。両端の末端基はＭｅ（メチル基）を表す。 Example 7
In the photoreceptor for Example 1, the charge transport material of Formula (4) was replaced with the charge transport material represented by Formula (11) described above, and for Example 6 in the same manner as the photoreceptor for Example 1. A photoconductor was prepared.

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

ただし、式中、両端の末端基はＭｅ（メチル基）を表す。 Example 8
In Example 1, except that 15 parts of the charge transport material represented by the formula (4) was added and 5 parts of the charge transport material represented by the following formula (12) was newly added, all the same as in Example 1, An electrophotographic photosensitive member for Example 8 was produced.

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

An image forming apparatus in which the electrophotographic photosensitive members for Examples 1 to 8 thus produced were modified based on the digital multifunction peripheral Imagio MF7070 (manufactured by Ricoh Co., Ltd.) and the drum linear velocity, cleaning unit, and power pack were modified. The evaluation was performed.
As shown in FIG. 1, the tip of the cleaning unit has a loop shape at the tip, and the overall shape of the brush is a loop pile brush made by weaving a loop-shaped brush as shown in FIG. Was formed by winding and adhering to a metal core.
As shown in FIG. 2, the cross-section was set so that the tip end side of the loop was directed upstream of the root portion in the brush rotation direction. The loop density woven into the base fabric was 70 per cm ² .
The rotation direction of the cleaning brush is the same at the contact position with the photosensitive member, the photosensitive member linear velocity is set to 180 mm / sec, and the fur brush linear velocity is set to 200 mm / sec (1.11 times the photosensitive member). did. The contact method of the cleaning blade to the photosensitive member was a counter direction with respect to the rotation direction of the photosensitive member, and the contact pressure of the cleaning blade to the photosensitive member was set to 20 g / cm.
Using such an image forming apparatus, a paper passing copy test was performed, and the following items were evaluated after 10,000 sheets and 200,000 sheets.
<Image quality>
The output image is evaluated as “good”, “slightly reduced”, “bad” by comprehensively evaluating solid defects, local defects such as black spots, white spots, black stripes, white stripes, and abnormal images such as background stains. Classified into three stages.
<In-machine potential (exposure part potential)>
The exposed portion potential when the charged potential was −800 V was evaluated.
<Photoconductor cleaning failure>
The presence or absence of transfer residual toner on the surface of the photoreceptor after the paper passing test was evaluated.
The case where the cleaning was sufficiently performed and no transfer residual toner was seen was marked with ◯, and the case where the cleaning failure occurred and the transfer residual toner was seen was marked with X.
<Photoconductor surface scratch>
Observation of scratches on the surface of the photoconductor after the paper passing test is observed with a laser microscope (VK-8500, manufactured by Keyence Corporation). “○” indicates that there are no noticeable scratches. “△” indicates a case that does not appear in the image, and “X” indicates a case where there is a large and deep scratch that appears in the image.

The evaluation results are shown in Table 1 below.

Example 9
In Example 1, the rotation direction of the brush of the cleaning unit is the reverse direction at the contact position with the photosensitive member, and the brush linear velocity is 180 mm / sec (relative linear velocity is 360 mm / sec) with respect to the photosensitive member linear velocity of 180 mm / sec. Except for the above, the same evaluation as in Example 1 was performed to obtain Example 9.

Example 10
In Example 1, the same evaluation as in Example 1 was performed except that the contact pressure of the cleaning blade of the cleaning unit to the photosensitive member was 10 g / cm.

Example 11
In Example 1, the same evaluation as in Example 1 was performed except that the contact pressure of the cleaning blade of the cleaning unit to the photosensitive member was 15 g / cm.

Example 12
In Example 1, the same evaluation as in Example 1 was performed except that the contact pressure of the cleaning blade of the cleaning unit to the photosensitive member was 30 g / cm.

Example 13
In Example 1, the same evaluation as in Example 1 was performed except that the contact pressure of the cleaning blade of the cleaning unit to the photosensitive member was 40 g / cm.

Example 14
In Example 1, the same evaluation as in Example 1 was performed except that the contact method of the cleaning blade of the cleaning unit to the photoconductor was changed from the counter direction to the photoconductor rotation direction (trail direction) with respect to the photoconductor rotation direction. Example 14 was carried out.
The evaluation results similar to those in Table 1 are shown in Table 2.

＜比較例２用感光体＞
実施例１用感光体において式（４）の電荷輸送物質を下記構造式（Ｇ）で表される電荷輸送物質に代えた以外は実施例１用感光体と同様にして比較例１用の感光体を作製した。

＜比較例３用感光体＞
実施例１用感光体において式（４）の電荷輸送物質を下記構造式（Ｈ）で表される電荷輸送物質に代えた以外は実施例１用感光体と同様にして比較例１用の感光体を作製した。

このようにして作製した比較例１〜３用の電子写真感光体を用いて実施例１と全く同様の評価をおこない比較例１〜３とした。 Comparative Examples 1-3
First, electrophotographic photoreceptors used in Comparative Examples 1 to 3 were obtained in the following manner.
<Photoconductor for Comparative Example 1>
The photoconductor for Comparative Example 1 was prepared in the same manner as the photoconductor for Example 1, except that the charge transport material represented by formula (4) in the photoconductor for Example 1 was replaced with the charge transport material represented by the following structural formula (F). The body was made.

<Photoconductor for Comparative Example 2>
The photoconductor for Comparative Example 1 was prepared in the same manner as the photoconductor for Example 1, except that the charge transport material represented by formula (4) in the photoconductor for Example 1 was replaced with the charge transport material represented by the following structural formula (G). The body was made.

<Photoconductor for Comparative Example 3>
The photoconductor for Comparative Example 1 was prepared in the same manner as the photoconductor for Example 1 except that the charge transport material represented by formula (4) in the photoconductor for Example 1 was replaced with the charge transport material represented by the following structural formula (H). The body was made.

Using the electrophotographic photoreceptors for Comparative Examples 1 to 3 thus produced, the same evaluation as in Example 1 was performed to obtain Comparative Examples 1 to 3.

These evaluation results are shown in Table 3 below.

Comparative Example 4
The same evaluation as in Example 1 was performed except that no brush was installed in the cleaning unit in Example 1.

Comparative Example 5
Evaluation was performed in exactly the same manner as in Example 1, except that the brush loop tip side of the cleaning unit in Example 1 was prepared so as to face the downstream side of the brush rotation direction from the root part.

Comparative Example 6
The same evaluation as in Example 1 was performed except that the brush tip of the cleaning unit in Example 1 did not have a loop shape and had a straight hair brush tip having a uniform length from the brush base. .

Comparative Example 7
The same evaluation as in Example 1 was performed except that the brush tip of the cleaning unit in Example 1 did not have a loop shape and had a straight hair brush tip having an unspecified length from the brush base. It was.

以上の結果より本発明の条件を満たした画像形成装置の場合においてはいずれも高画質で且つ高耐久な結果となるが、本発明の要件を満たしていない比較例の場合は繰返し使用時において画像品質が不良となり十分な耐久性が得られないことがわかる。 These evaluation results are shown in Table 4 below.

From the above results, in the case of an image forming apparatus satisfying the conditions of the present invention, both results are high in image quality and highly durable. However, in the case of a comparative example that does not satisfy the requirements of the present invention, the image is repeatedly used. It turns out that the quality is poor and sufficient durability cannot be obtained.

Schematic for demonstrating an electrophotographic process. The enlarged view which shows the shape of a brush hair tip. Rotating brush cross section The figure which shows an example of a cleaning brush.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Static elimination lamp 3 Charger charger 4 Eraser 5 Image exposure part 6 Developing unit 7 Charger before transfer 8 Registration roller 9 Transfer paper 10 Transfer charger 11 Separation charger 12 Separation claw 13 Charger before cleaning 14 Cleaning brush 15 Cleaning blade

Claims (9)

A photoconductor, a charging device that uniformly charges the surface of the photoconductor, an image exposure device that forms an electrostatic latent image by performing image exposure after uniform charging, and a developing device that develops the electrostatic latent image An image forming apparatus comprising a device for transferring a developed image and a cleaning device for cleaning the transfer residual toner of the photosensitive member, wherein the photosensitive member contains at least a charge generating material and a charge transporting material on a conductive substrate. And the photosensitive layer contains a charge transport material represented by the following general formula (1), and the cleaning device rotates a brush rotating in contact with the photoconductor having a tip formed in a loop shape. An image forming apparatus, wherein a tip end side of a loop of the brush is directed upstream of a root portion in a brush rotation direction.

Wherein R 1 and R 2 each independently represent a group selected from the group consisting of a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aralkyl group, and R 3 , R4, R5, R6, R7, R8, R9, R10 are each independently a hydrogen atom, a halogen atom, a cyano group, a nitro group, an amino group, a hydroxyl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group. Represents a group selected from the group consisting of a group, a substituted or unsubstituted aralkyl group.) A photoconductor, a charging device that uniformly charges the surface of the photoconductor, an image exposure device that forms an electrostatic latent image by performing image exposure after uniform charging, and a developing device that develops the electrostatic latent image An image forming apparatus comprising a device for transferring a developed image and a cleaning device for cleaning the transfer residual toner of the photosensitive member, wherein the photosensitive member contains at least a charge generating material and a charge transporting material on a conductive substrate. And the photosensitive layer contains a charge transport material represented by the following general formula (2), and the cleaning device rotates a brush rotating in contact with the photoconductor having a tip formed in a loop shape. An image forming apparatus, wherein a tip end side of a loop of the brush is directed upstream of a root portion in a brush rotation direction.

(In the formula, R1 and R2 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 And represents a group selected from the group consisting of an alkyl group, a substituted or unsubstituted cycloalkyl group, and a substituted or unsubstituted aralkyl group, and n is a repeating unit and represents an integer of 1 to 100.) 3. The image forming apparatus according to claim 1, further comprising a charge transport material represented by the following general formula (3) in addition to the charge transport material.

(Wherein R15 and R16 each independently represents 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 image forming apparatus according to claim 1, wherein the charge generation material is titanyl phthalocyanine.   The image forming apparatus according to claim 1, wherein the rotation direction of the brush is the same as the contact surface with respect to the rotation direction of the photosensitive member.   6. The image forming apparatus according to claim 1, further comprising an elastic rubber blade in contact with the photosensitive member on the downstream side of the brush in the rotational direction of the photosensitive member.   7. The image forming apparatus according to claim 6, wherein a contact direction of the elastic rubber blade with the photosensitive member is a counter direction with respect to a rotating direction of the photosensitive member.   8. The image forming apparatus according to claim 6, wherein a contact pressure of the elastic rubber blade to the photosensitive member is 10 to 30 g / cm. A process cartridge for an image forming apparatus, comprising at least an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member is one according to any one of claims 1 to 4. cartridge.

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