JP5095982B2 - Image forming apparatus, process cartridge, and image forming method - Google Patents

Description

  The present invention relates to an image forming apparatus such as a copying machine, a facsimile machine, and a printer, a process cartridge used therefor, and an image forming method using them.

  In an image forming apparatus having an image carrier such as a photoconductor in an image forming apparatus such as a copying machine, a facsimile machine, or a printer, the image carrier is charged, exposed, and exposed in accordance with the rotation of the image carrier. Image formation is performed by performing a development process, a transfer process, and the like. The discharge product generated in the charging step and remaining on the surface of the image carrier, and the residual toner or toner component remaining on the surface of the image carrier after the transfer step are removed through a cleaning process.

  In the cleaning process, as a generally used cleaning method, a method using a cleaning blade such as a rubber blade which is inexpensive, has a simple mechanism, and has excellent cleaning properties is known.

  However, since the cleaning blade is pressed against the image carrier to remove the residue on the surface of the image carrier, stress due to friction between the image carrier surface and the cleaning blade is large, and the cleaning blade is worn. When the image carrier is an organic photoreceptor, the surface layer of the photoreceptor is worn, shortening the life of the cleaning blade and the organic photoreceptor.

  In recent years, in order to meet the demand for higher image quality, the toner used for image formation has become a small particle size. However, in an image forming apparatus using a small particle size toner, residual toner is The ratio of passing through the cleaning blade increases, especially when the dimensional accuracy and assembly accuracy of the cleaning blade are not sufficient, or when the cleaning blade partially oscillates, the toner slips violently, and the cleaning performance Was not sufficient, and the formation hindered the improvement of image quality.

  Therefore, in order to extend the life of the organic photoreceptor and maintain high image quality over a long period of time, it is necessary to reduce the deterioration of members such as the photoreceptor and the cleaning blade due to friction and improve the cleaning performance.

  Therefore, in recent image forming apparatuses, a technique for improving the cleaning property by supplying a lubricant to the image carrier and forming a film of the lubricant is employed.

  When such a technique is used, if the amount of lubricant applied is too small, it will not be able to exert a sufficient effect on the wear of the image carrier, scratches, and deterioration of the cleaning blade, while excessive lubricant is applied. When applied, excess lubricant accumulates on the image carrier, causing problems such as blurring in the formed image, excess lubricant mixed in the developer, and the performance of the developer decreases. Therefore, it is necessary to adjust and control the amount of lubricant applied.

  Therefore, in an image forming apparatus using a lubricant, it has been attempted to control the amount of lubricant supplied to the image carrier.

  For example, [Patent Document 1] proposes an image forming apparatus in which the amount of lubricant supplied is controlled in accordance with the driving distance of a photoconductor as an image carrier. This image forming apparatus is a contact charging tandem machine, and at least the lubricant is applied to the photoconductor until the driving distance of the photoconductor reaches 525 m corresponding to approximately 1250 sheets of A3 size paper. It is supposed that 0.4 g or more is applied.

  However, such an image forming apparatus is excellent in performing a specific image formation, but when performing a wide variety of image formation, there are many problems particularly in an initial stage where the use of a photoreceptor is started.

[Patent Document 1] only controls the amount of lubricant supplied to the photoreceptor, and does not disclose how much of the supplied lubricant should be present on the photoreceptor.
However, it is not the amount supplied but the amount actually applied to the surface of the photoconductor that is effective for protecting the photoconductor and preventing deterioration due to the formation of a lubricant film. There was a problem that the amount of lubricant applied to the surface was unknown.

On the other hand, recently, in the charging process, so-called AC charging using a charging member such as a charging roller for charging an AC voltage superimposed on a DC voltage is used.
This AC charging has excellent performance such as high uniformity of the charging potential of the image carrier, little generation of oxidizing gas such as ozone and NOx, and further miniaturization of the apparatus.

  However, since the positive and negative discharges of several hundred to several thousand times per second are repeated between the charging member and the image carrier depending on the frequency, the image carrier is subjected to this large number of discharges and the surface layer is deteriorated. Accelerated.

  However, if a lubricant is applied to the image carrier, the AC charging energy is first absorbed by the lubricant, making it difficult to reach the image carrier and protecting the image carrier. That is, the application of the lubricant is effective not only in reducing deterioration of members such as an image carrier and a cleaning blade due to friction but also in suppressing deterioration of the image carrier due to charging.

  However, when this AC charging is performed using a system called a proximity charging system in which a charging member is arranged close to the image carrier, the lubricant film formed on the image carrier receives AC charging. Disappear. This disappearance rate is very fast and is much faster than in the case of a system using corona discharge.

  That is, when the lubricant is applied while forming an image while applying AC charging, the lubricant is supplied to the surface of the image carrier to protect the image carrier by forming a film depending on the supply amount of the lubricant. In contrast, the phenomenon in which the surface of the image bearing member deteriorates due to AC charging is likely to occur faster.

  However, if the supply amount of the lubricant is increased in order to avoid the deterioration of the image carrier due to charging, as in the case of applying the lubricant as a countermeasure against wear as described above, the change in the properties of the blur and the developer. If the supply amount of the lubricant is suppressed and a sufficient amount of the lubricant is not uniformly applied to the surface of the image carrier, the deterioration progresses due to AC charging. There was a problem.

  Thus, the application of the lubricant is effective for both the deterioration of the member due to wear and the deterioration of the image carrier due to charging, but depending on the amount of application, the effectiveness and the image quality may be reduced. It is extremely important to adjust and control the viscosity in order to secure the effect of the lubricant.

  In such a situation, in order to prevent chemical deterioration of the surface of the charged object due to the discharge that occurs between the charging roller and the image bearing member by applying AC charging by the proximity charging method, [Patent Document 2] In addition, zinc stearate is used as the lubricant, and the amount of zinc stearate applied to the surface of the image carrier is defined by the ratio of zinc element to all elements on the surface of the image carrier detected by XPS analysis.

  According to the XPS analysis method, only elements on the extreme surface of the sample are detected. It is very effective to protect the surface of the image carrier from AC charging by determining how much of the surface of the organophotoreceptor is covered with zinc stearate by this method, that is, by determining the coverage. It is.

  The XPS analysis method detects all elements other than hydrogen on the surface of the sample. Therefore, when the surface of the organophotoreceptor is analyzed using the XPS analysis method, the element ratio of the organophotoreceptor increases as the zinc stearate coverage increases. It approaches the element ratio of zinc stearate.

When the zinc stearate coverage becomes 100%, the element ratio theoretically matches the element ratio of zinc stearate, and the detected amount of zinc is saturated.
That is, when zinc stearate (M ₃₆ H ₇₀ O ₄ Zn) covers the entire surface of the photoreceptor, the XPS is calculated from the ratio of elements other than hydrogen in the molecule of zinc stearate (M ₃₆ H ₇₀ O ₄ Zn). The theoretical ratio of zinc element to all elements detected by the analytical method is 2.44%.

  Even if the amount of zinc stearate on the surface of the photoreceptor is further increased from such a state, all the elements detected by the XPS analysis method are detected when the coverage is 100% or more because only the extreme surface is detected. The upper limit of the ratio of zinc element to the upper limit is 2.44%.

  Therefore, in order to define a sufficient amount of lubricant for protecting the surface of the image carrier from the energy received by AC charging, a technique that saturates the measured value as in XPS analysis is not sufficient. Besides, it is necessary to define the absolute amount of lubricant.

  In [Patent Document 2], the evaluation of the deterioration of the surface of the image carrier due to AC charging while applying the lubricant is sufficiently performed, but the lubricant is used to protect the image carrier from AC charging. Since it has not been evaluated for the influence on the image and the cleaning property when the coating is applied, it is difficult to say that it is a realistic system.

  That is, the image forming apparatus disclosed in the embodiment of [Patent Document 2] is provided with a mechanism for extending the lubricant with a cleaning blade or the like after applying the lubricant and before passing through the AC charging process. Therefore, the applied lubricant exists as powder or lump, and unevenness occurs between the place where the lubricant is placed on the surface of the image carrier and the place where it is not placed.

  The supplied lubricant is supplied to the charging step in the form of powder or lump. At this time, the portion on which the lubricant is placed is not scraped on the surface of the image carrier, but the portion on which the lubricant is not placed. Then, protection by the lubricant is not performed, and the surface layer is scraped.

  Here, the inventors have investigated in detail the presence of zinc stearate in the initial and time-lapse states when an alternating voltage is applied by the proximity charging method, and found the following. .

  That is, when the application of the lubricant on the surface of the image carrier is uneven when starting to use the image carrier, AC charging is applied to the place where the lubricant is placed once the lubricant is formed, and The film disappears, but when the lubricant is supplied again, the film is re-formed. On the other hand, AC charging is applied to the part where the lubricant is not placed due to uneven application, and the part where the surface of the image carrier has deteriorated is retained even if the lubricant is applied on the deteriorated image carrier surface. I found it difficult to do.

  Therefore, the part that was initially charged with AC charge without forming a film progressed over time in a state where the lubricant was not retained, and the part where the lubricant film was initially formed was supplied with lubricant. If there is, the film is formed again and deterioration is difficult to proceed, and if there is uneven application of the lubricant at the initial stage, local deterioration will proceed.

  However, in [Patent Document 2], although the amount of zinc immediately after the application of zinc stearate is evaluated, the amount of zinc after AC charging is not evaluated, as in the image forming apparatus of [Patent Document 2]. It has been found that when there is unevenness in the application of the lubricant or when the retention of the lubricant is not ensured over time, the image carrier is deteriorated and a high-quality image cannot be retained.

  That is, when the image forming apparatus disclosed in the embodiment of [Patent Document 2] is used and an image is formed under actual use conditions, abnormalities such as streaks appear in the image due to uneven wear of the image carrier. I found out.

On the other hand, in order to meet the need to define the absolute amount of lubricant as described above, [Patent Document 3] uses a means for combining an XRF analysis method in addition to an XPS analysis method.
When XRF analysis is used, analysis is possible to a depth of several millimeters for organic substances, so even when the lubricant is thick on the surface of the image carrier, the amount of lubricant should be quantified. Is possible.

  Therefore, by combining the XRF analysis method, in addition to the image carrier surface coverage of the lubricant by the XPS analysis method, the lubricant applied on the surface of the image carrier when the coverage reaches 100%. Can also be quantified.

That is, in order to define the state in which the lubricant is completely covered on the surface of the image carrier by eliminating the portion where the lubricant is not applied, the coverage of the lubricant is defined by XPS analysis, In order to define a protective film having a sufficient thickness to protect the image, the absolute amount of the lubricant is regulated by the XRF analysis method. This is very effective for maintaining image formation.
[Patent Document 3] also defines a deviation in the coverage of the lubricant, which is important for preventing uneven wear of the image carrier as described above.

  The effects obtained by defining the amount of lubricant applied include reduction of friction between the image carrier and the cleaning blade, improvement of cleaning properties, and protection of the image carrier from discharge energy received by charging. .

  However, when the corona charging method as in [Patent Document 3] is used, the discharge energy received by charging is relatively small. Therefore, the effect of defining the coating amount of the lubricant is mainly due to the image carrier and the cleaning brake. The friction with the door is reduced.

  Here, paying attention to the charging method, in the corona charging method as used in [Patent Document 3], the charging device is sufficiently separated from the image carrier, and the energy received by the image carrier due to charging is small. Even when image formation is performed while charging the image bearing member, the lubricant sufficiently covers the image bearing surface over a long period of time, and it is easy to reduce friction due to friction between the image bearing member and the cleaning blade. To be realized.

  However, when an AC voltage is applied by contact or proximity charging using a charging roller or the like, the energy received by the image carrier by the discharge is very large, so that the lubrication applied to the image carrying surface as described above. The disappearance rate of the agent is significantly faster than that of the corona charging method.

  Therefore, even if the system established by the corona charging method described in [Patent Document 3] is applied to a system that applies an AC voltage directly or by a proximity charging method, there is a high possibility that sufficient protection of the image carrier cannot be secured. . That is, an AC voltage is applied by direct or proximity charging to charge the image carrier, and when a lubricant is applied while forming an image, the lubricant film immediately disappears due to AC charging, and the image carrier It is thought that the surface will deteriorate.

  Specifically, in [Patent Document 3], in order to protect the image carrier from deterioration, the lubricant coverage obtained by the XPS analysis method is set to 5% to 100%. In the case where AC charging is applied, if the coverage is as small as 5%, a 95% portion of the surface of the image carrier not coated with the lubricant is deteriorated.

  As described above, the deteriorated portion is difficult to be re-formed even if the lubricant is supplied again, and image formation is performed without the formation of the film catching up, and the deterioration of the surface of the image carrier proceeds. End up. Therefore, the above-mentioned range is not appropriate for the coverage of the image carrier with the lubricant, and should be the upper limit of the above range.

  In [Patent Document 3], the coverage of the lubricant obtained by the XRF analysis method is set to 100% to 130%. The coverage of 100% in the XRF analysis method means that the entire image carrier is covered with a layer of a lubricant film when the coverage is 100% when the extreme surface is analyzed by XPS. The 130% coverage in the analytical method means that the XPS coverage is 100%. For example, 70% of the image carrier surface is covered with one layer of lubricant, and the other 30% is a two-layer lubricant. Means covered.

  It is known that a film of a lubricant such as zinc stearate is formed in a layer shape, and thus the film increases in thickness by a multiple of a specific thickness. That is, as the amount of lubricant applied increases, the film thickness does not increase continuously, but increases for example in multiples of about 5 nm. When the lubricant is unevenly distributed, for example, the film thickness increases while taking a step structure of about 5 nm, and a step-like change in film thickness of about 5 nm is observed. Therefore, as described above, the coverage in the XRF analysis method may exceed 100%.

  However, even when a 1.3 layer lubricant is applied to the surface of the image bearing member, when AC charging is applied directly or by proximity charging, the lubricant disappears immediately due to the energy generated by the discharge, and the image bearing The body surface will deteriorate. Therefore, in the case where AC charging is applied by direct or proximity charging, the amount of such lubricant applied is not sufficient.

JP 2000-75752 A JP 2005-17469 A JP 2004-198662 A

  As described above, in view of these deterioration due to friction between the image carrier and the cleaning blade and deterioration of the image carrier due to charging, various techniques for applying a lubricant to the image carrier have been proposed. Adjustment and control of the coating amount of the agent is not sufficient, and particularly in a configuration in which AC charging is performed by a contact method or a proximity method, such adjustment and control is insufficient.

Under such circumstances, as described above, the inventors have found the following as a result of detailed analysis of deterioration of the image carrier and the like.
In other words, if there is uneven application of the lubricant to the image carrier, the image carrier is protected from charging in a portion where the lubricant is sufficiently applied, but in the absence of the lubricant, local discharge is caused by charging discharge. If the surface of the image carrier deteriorates and the surface of the image carrier once deteriorates, the lubricant is difficult to hold even if the lubricant is supplied again while forming an image. Has been found to progress.

  In particular, when an image carrier is uniformly charged by superimposing an alternating current voltage on a direct current voltage using a charging roller or the like by a direct charging method, the lubricant applied to protect the image carrier is discharged by discharge. It was found that the disappearance rate was very fast, the lubricant film supplied to the surface of the image carrier could not catch up, and the surface of the image carrier deteriorated before the film was formed again. .

  Therefore, the inventors have repeatedly studied how to prevent local deterioration of the image carrier surface due to uneven application of the lubricant and maintain a constant amount of lubricant film over time. The present invention has been made based on these findings.

  That is, when applying a lubricant to the surface of the image carrier while forming an image, there is a charging process and toner input, so a sufficient amount of lubricant to withstand AC charging is uniformly applied to the entire surface of the image carrier. Although it is very difficult to apply, it is relatively easy to uniformly apply a sufficient amount of lubricant in a system without a charging step, a transfer step, and a development step.

  Also, once the part of the image carrier where the lubricant is not placed is charged and deteriorates, it is difficult to hold the lubricant on the surface of the image carrier even if a new lubricant is supplied after that. However, even if the lubricant deteriorates and disappears due to charging, if the new lubricant is supplied, the surface of the image carrier is easily covered.

  Therefore, if an image carrier with a sufficient uniform amount of lubricant applied is used in the stage before using the image carrier, the lubricant is supplied while performing image formation and image formation after that. However, the surface of the image carrier can be kept in a uniform and sufficient amount of lubricant with a smaller amount of lubricant supplied than before.

  The present invention prevents the phenomenon in which the lubricant applied to the surface of the image carrier is lost by the discharge in the charging step, and the image carrier surface is deteriorated by the discharge. Due to uneven application of lubricant on the surface of the image carrier, it is possible to prevent the portion where the lubricant is thinly coated on the surface of the image carrier or the portion where the lubricant is not present from being locally deteriorated due to charging. An image forming apparatus and process that is excellent in the protection effect of the support, suppresses the wear of the image support due to friction between the image support and the cleaning blade, has good cleaning performance of the image support, and can realize high image quality over a long period of time. It is an object to provide a cartridge and an image forming method.

In order to achieve the above object, an invention according to claim 1 has an image carrier, and the image carrier before use is obtained by applying a lubricant outside the apparatus, and the lubricant is zinc stearate. The amount of the zinc stearate applied to the image carrier before use is 3.1 × 10 ⁻⁹ to 4.8 × 10 ^{− in an} amount per unit area on the image carrier. ^The image forming apparatus has ⁹ mol / cm ² and the zinc stearate coverage by XPS analysis is 91% or more .

According to a second aspect of the invention, in the image forming apparatus according to claim 1, further comprising a charging means for charging said image bearing member, a charging method of the image bearing member by said charging means is a contact type or proximity type The charging means performs AC charging in which an AC voltage is superimposed on a DC voltage.

According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect , the lubricant is supplied to the image carrier in the form of a powder having a particle size of 50 μm or less. The surface layer contains 0.05 to 0.5 μm filler.

According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the surface layer of the image carrier is formed of a thermosetting substance.

According to a fifth aspect of the present invention, in the image forming apparatus according to the fourth aspect , the thermosetting substance is a trifunctional or more radical polymerizable monomer having no charge transporting structure and a monofunctional having a charge transporting structure. And the surface layer is formed by curing the thermosetting substance.

According to a sixth aspect of the present invention, in the image forming apparatus according to the fourth or fifth aspect , the film thickness of the surface layer is 1 to 10 μm.

According to a seventh aspect of the invention, in the image forming apparatus according to any one of the first to sixth aspects, the maximum resolution is 1000 dpi or more.

An eighth aspect of the invention is a process cartridge that is used in the image forming apparatus according to any one of the first to seventh aspects and includes at least the image carrier.

According to a ninth aspect of the invention, there is provided an image forming method for forming an image using the image forming apparatus according to any one of the first to seventh aspects or the process cartridge according to the eighth aspect .

The present invention includes an image carrier, wherein the image carrier before use is coated with a lubricant outside the apparatus, and the lubricant is zinc stearate. The amount of zinc stearate applied is 3.1 × 10 ⁻⁹ to 4.8 × 10 ⁻⁹ mol / cm ² per unit area on the image carrier, and XPS analysis In the image forming apparatus in which the coverage of the zinc stearate by 91% or more is used, it is possible to quickly start the first image formation using an image carrier pre-coated with a lubricant, It is easy to form a thin film on the image carrier and absorbs energy by charging while reducing the frictional force between the image carrier and other members, and is excellent in protecting the image carrier. Image carrier and other members Can suppress the deterioration of the There is no absorption of incident light, an inexpensive substance is used as a lubricant, there is no uneven application of the lubricant on the surface of the image carrier, and the amount of applied lubricant is necessary and sufficient. It is possible to prevent deterioration of the image carrier and other members from progressing due to electrification and friction with other members, and to prevent image blurring and lubrication. It is possible to prevent the agent from adhering to other members easily or mixing excessive lubricant into the developer, and it is easy to clean and can perform image formation with higher image quality over time. An image forming apparatus that can be used can be provided.

A charging unit for charging the image carrier, and the charging method of the image carrier by the charging unit is a contact method or a proximity method, and the charging unit is an AC charging in which an AC voltage is superimposed on a DC voltage. if performing the, small, less generation of oxidizing gas such as NO _X and ozone stable provided with a charging unit that can be uniformly charged, it is possible to perform image forming high-quality images A forming apparatus can be provided.

The lubricant is supplied to the image carrier in the form of a powder having a particle size of 50 μm or less, and the image carrier contains 0.05 to 0.5 μm filler in the surface layer. For example, irregularities are formed on the surface of the image carrier. For example, when the lubricant is stretched by a blade, particles of 50 μm or less of the lubricant are trapped in the grooves formed on the surface of the image carrier by the filler. Is easily held on the image carrier, and the blade does not adhere due to the irregularities on the surface of the image carrier, so that a gap is easily formed between the blade and the surface of the image carrier, and the lubricant is present in a more appropriate amount and uniformly. Therefore, it is possible to provide an image forming apparatus that can perform the function of the lubricant more satisfactorily and can form a high-quality image.

  If the surface layer of the image carrier is formed of a thermosetting substance, it can be a surface layer with extremely high mechanical strength, and it is deteriorated due to wear or charging due to friction with the cleaning blade. It is possible to provide an image forming apparatus that is equipped with a highly durable image carrier that is suppressed and stably holds the lubricant on its surface, and that can perform high-quality image formation over time.

  The thermosetting substance includes a trifunctional or higher functional radical polymerizable monomer having no charge transporting structure and a monofunctional radical polymerizable compound having a charge transporting structure, and the surface layer includes the thermosetting substance. If the material is formed by curing, the surface layer can be made inexpensive and have high mechanical strength, and it can be prevented from being worn and charged due to friction with the cleaning blade. It is possible to provide an image forming apparatus equipped with a highly durable image carrier that can be held on the surface and capable of performing high-quality image formation over time.

  If the film thickness of the surface layer is 1 to 10 μm, the film thickness of the surface layer is too thin and easily disappears due to friction with other members. In addition, the surface layer thickness is too large and the sensitivity of the image carrier, the post-exposure potential increase, and the residual potential increase do not occur, thereby suppressing the cost of forming the surface layer. An image forming apparatus capable of forming a high-quality image with time can be provided.

  If the maximum resolution is 1000 dpi or higher, high-resolution image formation is possible, and the high resolution provides an image forming apparatus that is excellent in high-quality and high-quality image formation over time. be able to.

The present invention is used in the image forming apparatus according to any one of claims 1 to 7 and is in a process cartridge including at least the image carrier, and therefore contributes to image formation with high image quality over time. In addition, it is possible to provide a process cartridge excellent in exchangeability such as an image carrier.

The present invention resides in an image forming apparatus according to any one of claims 1 to 7 or an image forming method for forming an image using the process cartridge according to claim 8 , so that the image quality is improved over time. An image forming method capable of forming an image can be provided.

  FIG. 1 shows an outline of an image forming apparatus to which the present invention is applied. The image forming apparatus 100 is a color laser printer, but may be other types of image forming apparatuses such as other types of printers, facsimile machines, copiers, and multifunction machines of copiers and printers. The image forming apparatus 100 performs an image forming process based on an image signal corresponding to image information received from the outside. The image forming apparatus 100 can form an image using plain paper generally used for copying, OHP sheets, thick paper such as cards and postcards, and envelopes as sheet-like recording media. .

  The image forming apparatus 100 includes photosensitive drums 20Y and 20M which are latent image carriers as image carriers that can form images as images corresponding to colors separated into yellow, magenta, cyan, and black, respectively. , 20C, 20BK are arranged in parallel, in other words, a tandem system is adopted.

  The photosensitive drums 20Y, 20M, 20C, and 20BK that are the surface moving members are rotatably supported by a frame (not shown) of the main body 99 of the image forming apparatus 100, and in this order from the upstream side in the A1 direction that is the moving direction of the transfer belt 11. Are lined up. Y, M, C, and BK added after the numerals of the respective symbols indicate members for yellow, magenta, cyan, and black.

  Each of the photosensitive drums 20Y, 20M, 20C, and 20BK is an image forming unit for forming yellow (Y), magenta (M), cyan (C), and black (BK) images. It is provided in 60C and 60BK.

  The photosensitive drums 20Y, 20M, 20C, and 20BK are positioned on the outer peripheral surface side of the transfer belt 11 as an intermediate transfer member, that is, an endless belt disposed almost at the center in the main body 99, that is, on the image forming surface side. ing.

  The transfer belt 11 is movable in the direction of the arrow A1 while facing the photosensitive drums 20Y, 20M, 20C, and 20BK. Visible images, that is, toner images formed on the respective photosensitive drums 20Y, 20M, 20C, and 20BK are respectively superimposed and transferred onto the transfer belt 11 that moves in the direction of the arrow A1, and then collectively onto the transfer sheet S that is a recording medium. It is designed to be transcribed.

  The lower portion of the transfer belt 11 faces the photosensitive drums 20Y, 20M, 20C, and 20BK, and the opposed portions transfer the toner images on the photosensitive drums 20Y, 20M, 20C, and 20BK. A transfer portion 98 for transferring to the transfer belt 11 is formed.

  In the superimposing transfer to the transfer belt 11, the toner images formed on the photosensitive drums 20Y, 20M, 20C, and 20BK are transferred to the same position on the transfer belt 11 while the transfer belt 11 moves in the A1 direction. As described above, voltage application by the primary transfer rollers 12Y, 12M, 12C, and 12BK disposed at positions facing the photosensitive drums 20Y, 20M, 20C, and 20BK across the transfer belt 11 causes the A1 direction upstream. The timing is shifted toward the downstream side.

  The transfer belt 11 is an elastic belt whose entire layer is formed using an elastic member such as a rubber agent. The transfer belt 11 may be a single-layer elastic belt, may be an elastic belt using a part of the elastic belt, or a conventionally used fluorine-based resin, polycarbonate resin, or polyimide resin. Or an inelastic belt may be used.

  Each of the transfer belts 11 has a detent guide (not shown) as a detent member at each edge thereof. The offset guide is provided to prevent the transfer belt 11 from being biased in any direction perpendicular to the paper surface in FIG. 1 when the transfer belt 11 rotates in the A1 direction. The stopper guide is made of urethane rubber, but can be made of various rubber materials such as silicon rubber.

  The image forming apparatus 100 is disposed in the main body 99 so as to oppose the four image forming units 60Y, 60M, 60C, and 60BK and the respective photosensitive drums 20Y, 20M, 20C, and 20BK. A transfer belt unit 10 as an intermediate transfer unit provided; a secondary transfer roller 5 as a secondary transfer bias roller as a transfer member which is disposed opposite to the transfer belt 11 and is driven by the transfer belt 11; And an optical scanning device 8 that is an optical writing unit as a latent image forming unit disposed facing the lower side of the image forming units 60Y, 60M, 60C, and 60BK.

  The image forming apparatus 100 also has a sheet as a sheet feeding cassette in which a large number of transfer sheets S transported between the photosensitive drums 20Y, 20M, 20C, and 20BK and the transfer belt 11 can be stacked in the main body 99. Each photosensitive drum 20Y is fed at a predetermined timing in accordance with the toner image forming timing of the feeding device 61 and the recording sheet S conveyed from the sheet feeding device 61 by the image forming units 60Y, 60M, 60C, and 60BK. , 20M, 20C, 20BK and the transfer belt 11 and the registration roller pair 4 fed toward the transfer portion 98, and a sensor (not shown) for detecting that the leading edge of the transfer paper S has reached the registration roller pair 4. is doing.

  The image forming apparatus 100 also includes a fixing device 6 as a roller fixing type fixing unit for fixing the toner image on the transfer sheet S to which the toner image is transferred, and a fixed transfer sheet S in the main body 99. A discharge roller 7 as a pair of discharge rollers for discharging to the outside of the main body 99, and toner bottles 9Y and 9M disposed above the transfer belt unit 10 and filled with toner of each color of yellow, cyan, magenta, and black. , 9C, 9BK, and a discharge tray 17 on the upper side of the main body 99 on which the transfer sheets S discharged from the main body 99 by the discharge roller 7 are stacked.

  The image forming apparatus 100 also includes a driving device (not shown) that rotationally drives the photosensitive drums 20Y, 20M, 20C, and 20BK, and a power source as a bias applying unit (not shown) that applies a secondary transfer bias to the secondary transfer roller 5. Bias control means, drum detection means (not shown) for detecting attachment / detachment of the photosensitive drums 20Y, 20M, 20C, 20BK, and unit detection means (not shown) for detecting attachment / detachment of the image forming units 60Y, 60M, 60C, 60BK, respectively. And a control means (not shown) including a CPU (not shown) and a memory for controlling the overall operation of the image forming apparatus 100 based on detection results by various detection means.

  In addition to the transfer belt 11, the transfer belt unit 10 includes primary transfer rollers 12Y, 12M, 12C, and 12BK as primary transfer bias rollers, and a drive roller 72 that is a drive member around which the transfer belt 11 is wound. A cleaning counter roller 74 as a tension roller, a tension roller 75 that stretches the transfer belt 11 together with the driving roller 72 and the cleaning counter roller 74, and a surface of the transfer belt 11 that is disposed facing the transfer belt 11 to clean the transfer belt 11. And a cleaning device 13 as a belt cleaning device.

  The transfer belt unit 10 also includes a drive system (not shown) that rotationally drives the drive roller 72, and a power source and bias control as a bias application unit (not shown) that applies a primary transfer bias to the primary transfer rollers 12Y, 12M, 12C, and 12BK. Means.

  The primary transfer rollers 12Y, 12M, 12C, and 12BK press the transfer belt 11 from the back surface thereof toward the photosensitive drums 20Y, 20M, 20C, and 20BK to form primary transfer nips.

  In each primary transfer nip, a primary transfer electric field is formed between the photosensitive drums 20Y, 20M, 20C, and 20BK and the primary transfer rollers 12Y, 12M, 12C, and 12BK due to the influence of the primary transfer bias. . The toner images of the respective colors formed on the photosensitive drums 20Y, 20M, 20C, and 20BK are primarily transferred onto the transfer belt 11 due to the influence of the primary transfer electric field and nip pressure.

The driving roller 72 is in contact with the secondary transfer roller 5 via the transfer belt 11 to form a secondary transfer nip.
The cleaning counter roller 74 has a function as a tension roller as a pressure member that gives the transfer belt 11 a predetermined tension suitable for transfer.

  Although not shown in detail, the cleaning device 13 is arranged so as to face and contact the transfer belt 11, a plurality of rollers around which the cleaning belt is wound, and a cleaning that is in contact with the cleaning belt. The transfer belt 11 is cleaned by removing a foreign matter such as residual toner on the transfer belt 11 by removing the blade and a driving means for driving the roller to rotate the cleaning belt. It is like that. Foreign matter such as residual toner adhering to the cleaning belt is scraped off and removed by the cleaning blade.

The sheet feeding device 61 accommodates a plurality of transfer sheets S in a state of a stack of transfer sheets, and is disposed below the optical scanning device 8 below the main body 99. The sheet feeding device 61 has a feeding roller 3 as a sheet feeding roller pressed against the upper surface of the uppermost transfer sheet S, and the feeding roller 3 is driven to rotate counterclockwise at a predetermined timing. As a result, the uppermost transfer sheet S is fed toward the registration roller pair 4.
The transfer sheet S sent out from the sheet feeding device 61 reaches the registration roller pair 4 through the sheet feeding path and is sandwiched between the rollers of the registration roller pair 4.

  The fixing device 6 includes a heating roller 62 having a heat source therein, and a belt unit 63 pressed against the heating roller 62. The belt unit 63 includes an endless fixing belt 64 that is pressed against the heating roller 62 and three rollers 65, 66, and 67 that endlessly move the fixing belt 64 while stretching it.

  The fixing device 6 passes the transfer sheet S carrying the toner image in a manner of sandwiching the transfer sheet S between the heating roller 62 and the belt unit 63 so as to sandwich the carried toner image by the action of heat and pressure. It is fixed on the surface of the transfer paper S.

  The yellow, cyan, magenta, and black toners in the toner bottles 9Y, 9M, 9C, and 9BK are provided in the image forming units 60Y, 60M, 60C, and 60BK, respectively, by a predetermined replenishment amount through a conveyance path (not shown). 2 is supplied to the developing device 80Y shown in FIG.

  The configuration of the image forming units 60Y, 60M, 60C, and 60BK will be described as a representative of the configuration of the image forming unit 60Y that includes the photosensitive drum 20Y. Since the configurations of the other image forming units are substantially the same, in the following description, for the sake of convenience, reference numerals corresponding to the reference numerals assigned to the configuration of the image forming unit 60Y are used for the configurations of the other image forming units. The detailed description will be omitted as appropriate.

  As shown in FIG. 2, the image forming unit 60Y including the photosensitive drum 20Y includes a primary transfer roller 12Y and a cleaning device around the photosensitive drum 20Y along a rotation direction B1 that is a clockwise direction in the drawing. A cleaning device 70Y as a drum cleaning device as a means, a lubrication substance supply device 40Y as a lubricant application means, a charging device 90Y as a charging device as a charging means, and a developing device as a developing unit as a developing means A developing device 80Y.

  The photosensitive drum 20Y, the cleaning device 70Y, the lubricating substance supply device 40Y, the charging device 90Y, and the developing device 80Y are integrated to form a process cartridge 68Y. The process cartridge 68Y is detachable from the main body 99. Making a process cartridge in this way is very preferable because it can be handled as a replacement part, so that the maintainability is remarkably improved.

  The charging device 90Y is a uniform charging unit that uniformly charges the surface of the photosensitive drum 20Y, and includes a charging roller 91Y as a charging member disposed to face the surface of the photosensitive drum 20Y, and a charging roller. A brush roller 92Y disposed in contact therewith, a case 93Y housing these, and a power source (not shown) for applying an AC voltage in which an AC voltage is superimposed on a DC voltage to the charging roller 91Y.

  The charging roller 91Y is brought into contact with the surface of the photoreceptor drum 20Y, and the charging device 90Y is a contact system. The brush roller 92Y removes foreign matter adhering to the charging roller 91Y from the charging roller 91Y. Note that another cleaning member may be provided instead of the brush roller 92Y.

  The power source performs AC charging in which an AC voltage is superimposed on a DC voltage. The charging device 90Y is a charging device that performs AC charging. By superimposing the AC voltage on the DC voltage, the charged potential of the photosensitive drum 20Y can be stably and uniformly maintained.

  Although the charging device 90Y employs a contact method, a charging method may be adopted in which the charging roller 91Y is brought close to the surface of the photoconductor drum 20Y with a minute gap therebetween. In addition, a non-contact charging method using a corona charger or the like may be adopted. However, the use of the contact method or proximity method generates less oxidizing gas such as ozone and NOx, and requires a large space. Therefore, it is advantageous for downsizing the image forming apparatus and the tandem method.

  The developing device 80Y includes a developing case 85Y having an opening at a portion facing the photoconductor drum 20Y, and the photosensitive drum 20Y so as to expose a part of its peripheral surface so as to face the photoconductor drum 20Y from the opening. And a developing blade 81Y disposed in close proximity to each other and a doctor blade 82Y that regulates the developer on the developing roller 81Y to a certain height.

  The developing device 80Y is also disposed below the developing case 85Y so as to face each other, and includes a first transport screw 83Y and a second transport screw 84Y for stirring the developer and supplying the developer to the developing roller 81Y. And a partition wall 87Y provided between the first transport screw 83Y and the second transport screw 84Y.

  The developing device 80Y also rotationally drives a toner concentration sensor 86Y disposed below the second conveyance screw 84Y and a partition wall 87Y provided between the first conveyance screw 83Y and the second conveyance screw 84Y. Drive means (not shown), and bias application means (not shown) for applying a developing bias of a direct current component.

  In the developing case 85Y, the partition wall 87Y separates the first supply unit that accommodates the developing roller 81Y and the first conveyance screw 83Y and the second supply unit that accommodates the second conveyance screw 84Y. Has been.

  The first transport screw 83Y is rotationally driven by a driving unit, and supplies the developer in the first supply unit to the developing roller 81Y while transporting the developer from the back side to the front side in FIG. The developer conveyed to the vicinity of the end in the first supply unit by the first conveyance screw 83Y enters the second supply unit through an opening (not shown) formed in the partition wall 87Y.

  In the second supply unit, the second transport screw 84Y transports the developer sent from the first supply unit in the direction opposite to that of the first transport screw 83Y by being rotationally driven by the driving unit. The developer transported to the vicinity of the end of the second supply unit by the second transport screw 84Y returns to the first supply unit through another opening (not shown) provided in the partition wall 87Y.

The developer in the developing case 85Y is a two-component developer including a magnetic carrier and a negatively charged yellow toner. The developer is supplied with and supplied with yellow toner from the toner bottle 9Y. The supplied yellow toner and the developer are agitated and mixed by the conveying screw 83Y and the second conveying screw 84Y while being agitated and conveyed, frictionally charged, and supplied and carried on the developing roller 81Y.
Details of the developer will be described later.

  The developing roller 81Y whose developer carrying amount is regulated by the doctor blade 82Y and whose layer thickness is regulated is rotated between the developing roller 81Y and the photosensitive drum 20Y by the rotation in the direction of the arrow C1 and the developing bias by the bias applying means. The developer whose amount is adjusted to an appropriate amount by the doctor blade 82Y is carried to the developing area of the toner, and the yellow toner in the developer is electrostatically transferred to the electrostatic latent image formed on the surface of the photosensitive drum 20Y. The electrostatic latent image is visualized as a yellow toner image.

The developer that has consumed the yellow toner by the development is returned into the developing case 85Y as the developing roller 81Y rotates.
In this embodiment, the DC component developing bias is applied by the bias applying means. However, the developing bias may be an AC component, or an AC component superimposed on the DC component.

  The optical scanning device 8 shown in FIG. 1 includes a light source 31, a polygon mirror 32, an fθ lens 33, a reflection mirror 34, and the like. As shown in FIG. 2, the optical scanning device 8 irradiates a region between the charged region and the developing region on the photosensitive drum 20Y while scanning the light-modulated and deflected laser light L, thereby charging the device 90Y. The surface to be scanned on the surface of the photosensitive drum 20Y after being charged by the exposure is exposed by spot irradiation, and an electrostatic latent image corresponding to image information that is visualized as a yellow toner image by the developing device 80Y is written. It has become.

  The cleaning device 70Y has a cleaning case 76Y having an opening in a portion facing the photoconductor drum 20Y, and a cleaning that scrapes and collects the transfer residual toner and the carrier on the photoconductor drum 20Y in contact with the photoconductor drum 20Y. And a blade 78Y.

  The cleaning device 70Y is also rotatably supported by the cleaning case 76Y, scraped off by the cleaning blade 78Y, and a part of a discharge path (not shown) for transporting the removed transfer residual toner and the like toward the developing device 80Y. The discharge screw 79Y is configured.

  The inside of the cleaning device 70Y is a sealed space by the cleaning case 76Y, the cleaning blade 78Y, and the photosensitive drum 20Y, and has a structure in which the collected transfer residual toner and the like are not scattered inside the image forming apparatus 100.

  The lubricating substance supply device 40Y includes a case 41Y that is open only on the side facing the surface of the photoreceptor drum 20Y, a lubricating substance 42Y as a fine powder lubricant contained in the case 41Y, and a lubricating substance 42Y. An agitator 43Y as a lubrication material supply member for supplying the photosensitive drum 20Y to the photosensitive drum 20Y, and a blade 46Y as a lubrication material application blade fixedly supported by the case 41Y and having a tip abutting the photosensitive drum 20Y ing.

  The agitator 43Y rotates the rotation shaft 44Y disposed so as to extend in parallel with the rotation center axis of the photosensitive drum 20Y in the case 41Y, the blade member 45Y attached to the rotation shaft 43Y, and the rotation shaft 44Y. Thus, a driving means (not shown) for driving the agitator 43Y is provided.

The lubricating substance 42Y is accommodated in the case 41Y in a powder state with a particle size of 50 μm or less.
In addition, details of the lubricating substance supply device 40Y will be described later.

  As the photosensitive drum 20Y rotates in the B1 direction, the surface is uniformly charged by the charging device 90Y, and an electrostatic latent image corresponding to yellow is formed by exposure scanning of the laser light L from the optical scanning device 8. The electrostatic latent image is developed with yellow toner by the developing device 80Y, and the yellow toner image obtained by the development is primarily transferred to the transfer belt 11 moving in the A1 direction by the primary transfer roller 12Y. The transfer residual toner remaining after the transfer is satisfactorily removed by the cleaning device 70Y, and the lubricating material 42Y is supplied by the lubricating material supply device 40Y to be used for the next charge removal and charging by the charging device 90Y.

  Similarly, toner images of the respective colors are formed on the other photosensitive drums 20M, 20C, and 20BK, and the formed toner images of the respective colors are transferred to the A1 direction by the primary transfer rollers 12M, 12C, and 12BK. 11 is sequentially transferred to the same position on the head. As the transfer belt 11 rotates in the A1 direction, the toner image superimposed on the transfer belt 11 moves to the secondary transfer nip, which is the position facing the secondary transfer roller 5, and is in close contact with the transfer sheet S. Secondary transfer is performed on the transfer paper S by the action of the next transfer bias and the nip pressure, and a full-color image is formed on the transfer paper S.

  The transfer sheet S conveyed between the transfer belt 11 and the secondary transfer roller 5 is fed from the sheet feeding device 61 by the feeding roller 3 and fed, and is detected by the registration roller pair 4 as a detection signal by the sensor. Based on this, the leading edge of the toner image on the transfer belt 11 is sent out at a timing facing the secondary transfer roller 5.

  When the toner image of all colors is transferred and carried on the transfer paper S, the transfer paper S enters the fixing device 6 and passes through the fixing portion between the heating roller 62 and the belt unit 63 due to the action of heat and pressure. The carried toner image is fixed, and the full color image is fixed on the transfer paper S. The fixed transfer paper S that has passed through the fixing device 6 passes through the paper discharge roller 7 and is stacked on the paper discharge tray 17 at the top of the main body 99. On the other hand, the surface of the transfer belt 11 after passing through the secondary transfer nip after the secondary transfer is cleaned by the cleaning belt provided in the cleaning device 13 to prepare for the next development process.

  The configuration of the photosensitive drum 20Y will be described in detail with reference to FIG. Since the photosensitive drums 20M, 20C, and 20BK provided in the image forming units 60M, 60C, and 60BK have the same configuration, the description of the photosensitive drums 20M, 20C, and 20BK is omitted.

  As shown in FIG. 3A, the photosensitive drum 20Y includes a conductive support 21Y serving as a base, a photosensitive layer 22Y formed on the conductive support 21Y, and a protection formed on the photosensitive layer 22Y. The layer 23Y includes a flange (not shown) that is disposed at both ends, supports the main body of the photosensitive drum 20Y, and transmits rotation from the driving device. The protective layer 23Y constitutes the outermost layer of the photosensitive drum 20Y and constitutes a surface layer.

  The photosensitive layer 22Y is a normal layer type provided with a charge generation layer 24Y located on the conductive support 21Y side and a charge transport layer 25Y formed on the charge generation layer 24Y. A single layer type in which the generating material and the charge transporting material are mixed, or a reverse layer type in which the charge generating layer is provided on the charge transporting layer may be employed.

The protective layer 23Y is formed in order to improve the mechanical strength, abrasion resistance, gas resistance, cleaning properties, and the like of the photoreceptor drum 20Y.
As shown in FIG. 3B, fine particles 26Y of metal or metal oxide are dispersed in the protective layer 23Y as an inorganic filler that is a filler for increasing the mechanical strength of the protective layer 23Y.

  The fine particles 26Y are preferably 0.05 to 0.5 μm, more preferably 0.1 to 0.4 μm. By including the fine particles 26Y in the protective layer 23Y, irregularities are formed on the surface of the photoreceptor drum 20Y, and when the lubricating material 42Y is stretched by the blade 46Y, particles of 50 μm or less of the lubricating material 42Y are absorbed by the fine particles 26Y. Since it is trapped in the groove formed on the surface of the photosensitive drum 20Y, the lubricating substance 42Y is easily held on the photosensitive drum 20Y.

  Further, since the protective layer 23Y contains the fine particles 26Y, the blade 46Y does not adhere due to the irregularities on the surface of the photosensitive drum 20Y. 42Y is preferable because it can be present in a more appropriate amount and uniformly.

  An undercoat layer may be provided between the photosensitive layer 22Y and the conductive support 21Y. The undercoat layer may be a single layer or a plurality of layers. In addition, an appropriate amount of an antioxidant, a plasticizer, a leveling agent, and the like can be added to each layer such as the protective layer 23Y, the charge generation layer 24Y, and the charge transport layer 25Y if necessary.

Hereinafter, the conductive support 21Y, the charge generation layer 24Y, the charge transport layer 25Y, the protective layer 23Y, the undercoat layer, and the flange will be described in more detail.
As the conductive support 21Y, a material having a volume resistance of 10 ^ 10 Ω · cm or less, for example, metals such as aluminum, nickel, chromium, nichrome, copper, gold, silver, platinum, tin oxide, indium oxide, etc. A metal or oxide film, or a plastic film or paper coated by vapor deposition or sputtering, or a plate made of aluminum, aluminum alloy, nickel, stainless steel, etc. After forming the tube, a tube subjected to surface treatment such as cutting, super-finishing or polishing can be used.

  The conductive support 21Y may have a diameter of 20 to 150 mm, preferably 24 to 100 mm, and more preferably 28 to 70 mm. When the diameter of the conductive support 21Y is 20 mm or less, it is physically difficult to arrange the steps of charging, exposure, development, transfer, and cleaning around the photosensitive drum 20Y, and the diameter of the conductive support 21Y is 150 mm or more. Then, the image forming apparatus 100 becomes large, which is not preferable.

  In particular, since the image forming apparatus 100 is a tandem type and includes a plurality of photosensitive drums 20Y, 20M, 20C, and 20BK, the diameter is preferably 70 mm or less, and preferably 60 mm or less. An endless nickel belt and an endless stainless steel belt disclosed in JP-A-52-36016 can also be used as the conductive support 21Y.

  The charge generation material constituting the charge generation layer 24Y includes azo pigments such as monoazo pigments, bisazo pigments, trisazo pigments, tetrakisazo pigments, triarylmethane dyes, thiazine dyes, oxazine dyes, xanthene dyes. , Cyanine dyes, styryl dyes, pyrylium dyes, quinacridone pigments, indigo pigments, perylene pigments, polycyclic quinone pigments, bisbenzimidazole pigments, indanthrone pigments, squarylium pigments, phthalocyanine pigments, etc. Organic pigments and dyes, and inorganic materials such as selenium, selenium-arsenic, selenium-tellurium, cadmium sulfide, zinc oxide, titanium oxide, and amorphous silicon. Can be used.

  Examples of the charge transport material constituting the charge transport layer 25Y include an anthracene derivative, pyrene derivative, carbazole derivative, tetrazole derivative, metallocene derivative, phenothiazine derivative, pyrazoline compound, hydrazone compound, styryl compound, styryl hydrazone compound, enamine compound, butadiene Compounds, distyryl compounds, oxazole compounds, oxadiazole compounds, thiazole compounds, imidazole compounds, triphenylamine derivatives, phenylenediamine derivatives, aminostilbene derivatives, triphenylmethane derivatives, etc. can be used alone or in combination. .

  The binder resin used to form the charge generation layer 24Y and the photosensitive layer 22Y of the charge transport layer 25Y is electrically insulating, and is a known thermoplastic resin, thermosetting resin, photocurable resin, and the like. Photoconductive resins can be used, and suitable binder resins include, for example, polyvinyl chloride, polyvinylidene chloride, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer. Polymer, ethylene-vinyl acetate copolymer, polyvinyl butyral, polyvinyl acetal, polyester, phenoxy resin, (meth) acrylic resin, polystyrene, polycarbonate, polyarylate, polysulfone, polyethersulfone, ABS resin and other thermoplastic resins, Phenol resin, epoxy resin, urethane resin, melamine resin, isocyanate resin, resin Mention may be made of a kind of binder resin such as a kid resin, a silicone resin, a thermosetting resin such as a thermosetting acrylic resin, a photoconductive resin such as polyvinyl carbazole, polyvinyl anthracene, or polyvinyl pyrene, or a mixture of various kinds of binder resins. However, it is not particularly limited to these.

  Examples of the antioxidant that can be added in an appropriate amount to each layer such as the protective layer 23Y, the charge generation layer 24Y, and the charge transport layer 25Y are as follows.

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, 3-t-butyl-4-hydroxynisol 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.

High molecular phenol compound 1,1,3-tris- (2-methyl-4-hydroxy-5-tert-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 such as triphenylphosphine, tri (nonylphenyl) phosphine, tri (dinonylphenyl) phosphine, tricresylphosphine, tri (2,4-dibutylphenoxy) phosphine and the like.

  As a plasticizer that can be added in an appropriate amount to each layer such as the protective layer 23Y, the charge generation layer 24Y, and the charge transport layer 25Y, those used as a plasticizer for general resins such as dibutyl phthalate and dioctyl phthalate. It can be used as it is, and the amount used is suitably about 0 to 30 parts by weight with respect to 100 parts by weight of the binder resin.

  Among the layers such as the protective layer 23Y, the charge generation layer 24Y, and the charge transport layer 25Y, a leveling agent is added particularly in the charge transport layer 25Y. As the leveling agent, silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, polymers or oligomers having a perfluoroalkyl group in the chain are used, and the amount used is 100 parts by weight of binder resin. 0 to 1 part by weight is suitable. Leveling agents are not essential.

  As described above, the protective layer 23Y is provided to improve the mechanical strength, wear resistance, gas resistance, cleaning properties, etc. of the photosensitive drum 20Y, and the protective layer 23Y is obtained by dispersing fine particles 26Y. Can be illustrated.

  Although the protective layer 23Y improves the mechanical strength by containing the fine particles 26Y, in order to further increase the mechanical strength, the base of the protective layer 23Y in which the fine particles 26Y are dispersed is more mechanical than the photosensitive layer 22Y. As the high-strength polymer, it is preferable to use a thermosetting polymer as a thermosetting substance. Thereby, the mechanical strength of the protective layer 23Y becomes very high.

  The polymer constituting the base of the protective layer 23Y may be a thermoplastic polymer in addition to the thermosetting polymer, but the thermosetting polymer has high mechanical strength and is not worn by friction with the cleaning blade 78Y. It is more preferable because the ability to suppress is extremely high.

  If the protective layer 23Y has a thin film thickness, there is no problem even if the protective layer 23Y does not have the charge transport capability. However, if the protective layer 23Y without the charge transport capability is formed thick, the sensitivity of the photosensitive drum 20Y is reduced. Since the post potential increase and the residual potential increase are likely to occur, the protective layer 23Y may contain the above-described charge transport material, or the polymer used as the base of the protective layer 23Y may have a charge transport capability. preferable.

  Since the mechanical strength of the photosensitive layer 22Y and the protective layer 23Y is generally greatly different, the protective layer 23Y is worn by friction with the cleaning blade 78Y, and when the protective layer 23Y disappears, the photosensitive layer 22Y is worn. It is important that the protective layer 23Y has a sufficient film thickness, 0.1 to 12 μm, preferably 1 to 10 μm, and more preferably 2 to 8 μm.

  When the thickness of the protective layer 23Y is 0.1 μm or less, it is not preferable because it is too thin and easily disappears partially due to friction with the cleaning blade 78Y, and wear of the photosensitive layer 22Y proceeds from the disappeared portion.

  When the thickness of the protective layer 23Y is 12 μm or more, the sensitivity of the photosensitive drum 20Y is easily lowered, the potential after exposure is increased, and the residual potential is likely to be increased. This is not preferable because the cost of the polymer increases.

  The polymer used for the base of the protective layer 23Y is preferably a polymer that is transparent to writing light during image formation and has excellent insulating properties, mechanical strength, and adhesive properties. ABS resin, ACS resin, olefin-vinyl Monomer copolymer, chlorinated polyether, allyl resin, phenol resin, polyacetal, polyamide, polyamideimide, polyacrylate, polyallylsulfone, polybutylene, polybutylene terephthalate, polycarbonate, polyethersulfone, polyethylene, polyethylene terephthalate, polyimide, acrylic Resin, polymethylbenten, polypropylene, polyphenylene oxide, polysulfone, polystyrene, AS resin, butadiene-styrene copolymer, polyurethane, polyvinyl chloride, polyvinylidene chloride, epoxy resin, etc. And the like.

  These polymers may be thermoplastic polymers, but in order to increase the mechanical strength of the polymers, they are crosslinked with a crosslinking agent having a polyfunctional acryloyl group, carboxyl group, hydroxyl group, amino group, etc. By using a curable polymer, the mechanical strength of the protective layer 23Y increases, and wear due to friction with the cleaning blade 78Y can be significantly reduced.

  As described above, the protective layer 23Y preferably has a charge transport capability. In order to provide the protective layer 23Y with a charge transport capability, (1) the polymer used for the protective layer 23Y and the charge transport described above are used. A method of using a mixture of substances and (2) a method of using a polymer having a charge transporting capability for the protective layer 23Y are conceivable. The method (2) is a photosensitivity that has high sensitivity and little increase in potential after exposure and residual potential. The body drum 20Y can be obtained, which is preferable.

  Examples of the polymer having a charge transport layer ability include a group (formula 1) having a charge transport ability in the polymer.

（Ａｒ１は置換もしくは未置換のアリーレン基を表わす。Ａｒ２、Ａｒ３は置換もしくは未置換のアリール基を表わし、同一であっても異なってもよい。）

(Ar1 represents a substituted or unsubstituted arylene group. Ar2 and Ar3 represent a substituted or unsubstituted aryl group, which may be the same or different.)

  The group having the charge transporting ability is preferably added to a side chain of a polymer having high mechanical strength such as a polycarbonate resin or an acrylic resin, and the monomer can be easily produced, and the acrylic having excellent coatability and curability. It is preferable to use a resin.

  An acrylic resin having a charge transporting ability can form a surface layer having high mechanical strength, excellent transparency, and high charge transporting ability by polymerizing an unsaturated carboxylic acid having a group of (Formula 1). The acrylic resin has a cross-linked structure by mixing a polyfunctional unsaturated carboxylic acid, preferably a trifunctional or higher unsaturated carboxylic acid, with an unsaturated carboxylic acid having a monofunctional or monofunctional (formula 1) group. And becomes a thermosetting polymer, and the mechanical strength of the protective layer 23Y is extremely high. Although the group of (Formula 1) may be added to the polyfunctional unsaturated carboxylic acid, since the production cost of the monomer becomes high, the polyfunctional unsaturated carboxylic acid has a group of (Formula 1). Usually, it is preferable to use a photocurable polyfunctional monomer.

  Examples of the monofunctional unsaturated carboxylic acid having a group of (Formula 1) include general formula (1) and general formula (2).

  In these formulas, R1 represents a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, an aryl group which may have a substituent, a cyano group, a nitro group, Group, alkoxy group, -COOR7 (R7 is a hydrogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent or an aryl group which may have a substituent), a carbonyl halide A group or CONR8R9 (R8 and R9 represent a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, or an aryl group which may have a substituent; They may be the same or different).

Ar1 and Ar2 represent a substituted or unsubstituted arylene group, and may be the same or different.
Ar3 and Ar4 represent a substituted or unsubstituted aryl group, and may be the same or different.

X represents a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group, an oxygen atom, a sulfur atom, or a vinylene group.
Z represents a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkylene ether divalent group, or an alkyleneoxycarbonyl divalent group. m and n represent an integer of 0 to 3.

  The proportion of the polyfunctional unsaturated carboxylic acid is 5 to 75% by weight, preferably 10 to 70% by weight, more preferably 20 to 60% by weight, based on the entire protective layer 23Y. When the ratio of the polyfunctional unsaturated carboxylic acid is 5% by weight or less, the mechanical strength of the protective layer 23Y is insufficient, and when it is 75% or more, cracks are easily generated when a strong force is applied to the protective layer 23Y. Sensitivity deterioration is likely to occur, which is not preferable.

  When an acrylic resin is used for the protective layer 23Y, after applying the unsaturated carboxylic acid as a surface layer of the photoreceptor drum 20Y, electron beam irradiation or actinic rays such as ultraviolet rays are irradiated to cause radical polymerization, The protective layer 23Y can be formed. When performing radical polymerization with actinic rays, a solution obtained by dissolving a photopolymerization initiator in an unsaturated carboxylic acid is used. As the photopolymerization initiator, materials used for photocurable paints can be used.

  Thus, the thermosetting substance used for the protective layer 23Y includes a trifunctional or higher functional radical polymerizable monomer having no charge transport structure and a monofunctional radical polymerizable compound having a charge transport structure. It is desirable to form by curing.

Examples of the metal oxide used as the fine particles 26Y include titanium oxide, tin oxide, potassium titanate, TiO, TiN, zinc oxide, indium oxide, and antimony oxide. In addition, for the purpose of improving wear resistance, fluorine resins such as polytetrafluoroethylene, silicone resins, and those obtained by dispersing inorganic materials such as these resins can be added.
When the protective layer 23Y is not formed, the photosensitive layer 22Y constitutes a surface layer, and fine particles 26Y are added thereto.

  Examples of the undercoat layer include a resin or a white pigment and a resin as a main component, and a metal oxide film obtained by chemically or electrochemically oxidizing the surface of the conductive support 21Y. What has resin as a main component is preferable.

  Examples of the white pigment include metal oxides such as titanium oxide, aluminum oxide, zirconium oxide, and zinc oxide. Among them, it is most preferable to contain titanium oxide that is excellent in preventing charge injection from the conductive substrate.

  Examples of the resin include thermoplastic resins such as polyamide, polyvinyl alcohol, casein, and methyl cellulose; thermosetting resins such as acrylic, phenol, melamine, alkyd, unsaturated polyester, and epoxy; and one or various mixtures thereof. Can do.

  The flange is press-fitted into the conductive support 21Y and fixed with an adhesive or the like. Engineering plastics such as polyamide, polyacetal, polyethylene terephthalate, polyphenylene sulfide, polyether ketone, liquid crystal polymer, polycarbonate, polyphenylene ether, polyarylate, polysulfone, polyethersulfone, polyetherimide, polyamideimide, etc. with excellent mechanical strength In order to control mechanical strength, rigidity, conductivity, etc., fibers such as glass fiber, carbon fiber, fillers such as carbon, talc, kaolin, calcium carbonate, alumina, silica, and various additives are used. Used by mixing.

  The configuration and operation of the lubricating substance supply device 40Y will be described in detail. Note that the lubricating substance supply devices 40M, 40C, and 40BK provided in the image forming units 60M, 60C, and 60BK perform the same configuration and operation, and thus the description of the lubricating substance supply devices 40M, 40C, and 40BK is omitted. .

  As already described, the lubricating substance supply device 40Y includes the case 41Y, the fine powdery lubricating substance 42Y accommodated in the case 41Y, and the agitator for supplying the lubricating substance 42Y to the photosensitive drum 20Y. 43Y and a blade 46Y fixedly supported by the case 41Y and having a tip abutting against the photosensitive drum 20Y.

  The lubricating substance 42Y is for reducing the coefficient of friction between the surface of the photoreceptor drum 20Y and the blade 46Y or the substance such as yellow toner or magnetic carrier in contact with the surface. Details thereof will be described later.

  The agitator 43Y is configured to drive the agitator 43Y by rotationally driving the rotary shaft 44Y disposed so as to extend parallel to the photosensitive drum 20Y, the blade member 45Y attached to the rotary shaft 43Y, and the rotary shaft 44Y. Drive means that do not.

  When the agitator 43Y is operated, the lubricating material 42Y is blown toward the surface of the photosensitive drum 20Y by the blade member 45Y, and immediately after that, the blade 46Y is rubbed against the surface of the photosensitive drum 20Y by the blade 46Y and attached. .

  The case 41Y has an integrated structure with the cleaning case 76Y of the cleaning device 70Y, the developing case 85Y of the developing device 80Y, and the case 93Y of the charging device 90Y, and forms a process cartridge 68Y together with the photosensitive drum 20Y. Yes.

  The internal space of each case 41Y, cleaning case 76Y, developing case 85Y, and case 93Y is partitioned from each other by these case 41Y, cleaning case 76Y, developing case 85Y, case 93Y itself, blade 46Y, cleaning blade 78Y, and doctor blade 82Y. Yes.

  The lubricating substance supply device 40Y is provided outside the cleaning device 70Y by the partition. The case 41Y includes a cleaning case 76Y and a portion integrated with the case 93Y, a blade 46Y, and a cleaning blade 78Y.

  As described above, the case 41Y is opened only on the side facing the surface of the photosensitive drum 20Y, and the upstream side of the opening edge in the rotational direction B1 of the photosensitive drum 20Y is covered by the cleaning blade 78Y. It is composed. The cleaning blade 78Y is in contact with the surface of the photosensitive drum 20Y over the entire rotation center axis direction of the photosensitive drum 20Y.

  On the other hand, the blade 46Y constitutes the opening edge of the downstream portion in the rotation direction B1 of the photosensitive drum 20Y. The blade 46Y is in contact with the surface of the photosensitive drum 20Y over the entire rotation center axis direction of the photosensitive drum 20Y.

  On the other hand, the seal member (not shown) provided in the case 41Y, the cleaning case 76Y, and the case 93Y corresponding to the opening edge of the portion located at the end of the photosensitive drum 20Y in the rotation center axis direction is also the photoconductor. The drum 20Y is in contact with the surface of the photosensitive drum 2Y over the entire rotation direction B1.

  Therefore, the opening edge of the case 41Y is in contact with the surface of the photosensitive drum 20Y over the entire area. Accordingly, the internal space surrounded by the inner wall surface of the case 41Y and the surface portion of the photosensitive drum 20Y is a closed space shielded from the outside. Then, as described above, when the agitator 43Y is operated, the powder of the lubricating substance 42Y is supplied and adhered to the surface of the photosensitive drum 20Y in the closed space.

  The lubricating material 42Y adhering to the surface of the photoconductor drum 20Y passes through the contact portion between the blade 46Y and the surface of the photoconductor drum 20Y as the surface of the photoconductor drum 20Y moves, and is stretched. Form a film on top.

  By attaching the lubricating substance 42Y to the surface of the photoconductor drum 20Y, mechanical stress applied to the photoconductor drum 20Y during the above-described image forming process is greatly reduced, and the photoconductor drum is also affected by discharges caused by AC charging. 20Y is protected.

  That is, mechanical stress such as rubbing by the developer in the developing region and scraping by the cleaning blade 78Y is greatly reduced, and the surface layer of the photoreceptor drum 20Y is prevented from being oxidized and deteriorated by direct discharge. As a result, the life of the photosensitive drum 20Y is extended.

  Generally, among the various devices such as the cleaning device 70Y, the developing device 80Y, and the charging device 90Y included in the process cartridge such as the process cartridge 68Y, the life of the image carrier such as the photosensitive drum 20Y is the shortest. The replacement frequency is determined by the life of the image carrier.

  Therefore, the replacement frequency of the process cartridge 68Y is suppressed by extending the life of the photosensitive drum 20Y. Thus, other devices that have been exchanged together with the image carrier before the end of their lifetime, such as the lubricating substance supply device 40Y, the cleaning device 70Y, the developing device 80Y, and the charging device 90Y in this embodiment, can be used. The apparatus can be used effectively and user convenience can be improved.

  Further, the life of the cleaning cartridge 78Y and the charging roller 91Y may be much longer than the parts in the process cartridge 68Y due to the effect of applying the lubricant 42Y. In this case, the process cartridge 68Y is not configured. In addition, it is possible to replace each part to reduce the frequency of replacement of the expensive photoconductor drum 20Y as much as possible, or to use the photoconductor with higher durability until the life of the machine.

  Further, by attaching the lubricating substance 42Y to the surface of the photoconductor drum 20Y, the mechanical adhesion between the surface of the photoconductor drum 20Y and the toner is weakened. As a result, the transfer efficiency can be improved, and the image quality can be improved. The effect of improvement and reduction of transfer residual toner can also be obtained.

  Moreover, since the lubricating substance 42Y is supplied to the surface of the photosensitive drum 20Y in the closed space, the lubricating substance 42Y to be supplied to the photosensitive drum 20Y is not scattered inside the image forming apparatus 100, and the photosensitive drum. Any lubricious material 42Y not supplied to 20Y remains in the enclosed space.

  Further, since the lubricating substance supply device 40Y is provided outside the cleaning device 70Y, a part of the lubricating substance 42Y to be supplied to the photosensitive drum 2Y is not supplied to the photosensitive drum 2Y. There is no possibility of being collected directly by the cleaning device 70Y.

  Of the lubricating material 42Y that is blown toward the photosensitive drum 20Y by the agitator 43Y, the lubricant that has not been supplied to the photosensitive drum 20Y falls into the case 41Y and contributes again to the supply to the photosensitive drum 20Y. To do. Therefore, all of the lubricating substance 42Y accommodated in the case 41Y is used for supply to the photosensitive drum 20Y without waste.

  Since the lubricating substance supply device 40Y is arranged on the downstream side of the cleaning device 70Y in the rotation direction B1 of the photosensitive drum 20Y, the supply amount of the lubricating material 42Y is influenced by the amount of residual toner transferred to the cleaning device 70Y. Therefore, the lubricating substance 42Y is stably supplied onto the photosensitive drum 20Y.

  The lubricating substance supply device 40Y is downstream of the cleaning device 70Y in the rotational direction B1 of the photosensitive drum 20Y, upstream of the blade 46Y in the same direction B1, and upstream of the charging device 90Y in the same direction B1. Since the lubricating substance 42Y forms a film on the surface portion of the photosensitive drum 20Y that passes through the charging device 90Y and is stably applied, the lubricating substance 42Y adheres to the charging device 90Y. Has been reduced.

  The configuration in which the lubricating substance supply position of the lubricating substance supply apparatus 40Y is positioned in this way is not limited to the case where the lubricating substance supply apparatus 40Y is provided outside the cleaning apparatus 70Y, and the internal space of the case 41Y. Even if it is not a closed space shielded from the outside, it is effective.

  The blade 46Y provided at the opening edge of the case 41Y in the downstream portion in the rotation direction B1 of the photosensitive drum 20Y is in contact with the surface of the photosensitive drum 20Y over the entire rotation center axis direction of the photosensitive drum 20Y. The blade 46Y is made of urethane rubber, which is an elastic body, and its contact pressure is substantially uniform in a direction orthogonal to the direction B1.

  With such a configuration, even if the amount of the lubricating material 42Y supplied by the agitator 43Y is non-uniform on the surface of the photoconductive drum 20Y, the lubricating material 42Y on the surface of the photoconductive drum 20Y causes the blade 46Y. As it passes through the contact position, it is stretched thinly and evenly and leveled. As a result, a substantially uniform amount of the lubricating material 42Y adheres to the entire surface of the photosensitive drum 20Y.

  Further, by appropriately adjusting the contact pressure and contact angle of the blade 46Y, the number of rotations of the agitator 43Y, the number of blade members 45Y, the shape, elasticity, etc., the surface of the photosensitive drum 20Y is unnecessarily much lubricated. It is possible to prevent the substance 42Y from adhering and to attach the minimum necessary amount.

  Therefore, it is possible to minimize the amount of the lubricating material 42Y that enters the cleaning device 70Y while maintaining the functions performed by the lubricating material 42Y, such as suppressing the wear of the surface of the photosensitive drum 20Y and the cleaning blade 78Y. Become. In addition, since it is possible to minimize the amount of the lubricating material 42Y consumed per image formation, the amount of the lubricating material 42Y previously installed in the image forming apparatus 100 can be reduced. It is also possible to promote downsizing of the device.

  As the lubricating substance 42Y, a thin film is formed on the photosensitive drum 20Y to reduce the frictional force between the photosensitive drum 20Y and the cleaning blade 78Y, while absorbing the energy due to AC charging and protecting the photosensitive drum 20Y. There is no particular problem as long as it is a material that does not absorb writing light, that is, laser light L, without altering members such as the photosensitive drum 20Y or the cleaning blade 78Y.

Lubricating substance 42Y includes oils such as silicon oil and fluorine oil, fluorine resins such as polytetrafluoroethylene and polyvinylidene fluoride, zinc stearate, aluminum stearate, lead stearate, magnesium stearate, lithium oleate Examples of such metal soaps and fatty acid esters of polyhydric alcohols (sorbitan, sucrose, glycerin, propylene glycol, etc.) are easy to apply on the photosensitive drum 20Y, and the photosensitive drum 20Y and the cleaning blade 78Y A metal soap that is highly effective in reducing frictional force, has a high protective effect due to AC charging, and is inexpensive is preferably used.
Therefore, in the present embodiment, metal soap is used as the lubricating substance 42Y.

  In the image forming apparatus 100, the lubricating substance 42Y is applied not only after the start of use but also to the photosensitive drum 20Y before use. Here, the photosensitive drum 20Y before use refers to a drum on which no image is formed. The same applies to the photosensitive drums 20M, 20C, and 20BK that are other image carriers.

  As described above, when there is uneven application of the lubricant to the image carrier, the image carrier is protected from charging in a portion where the lubricant is sufficiently applied, but in a place where the lubricant is not present. The surface of the image carrier is locally deteriorated by the discharge of charging, and even if the lubricant is supplied again while forming an image on the part where the surface of the image carrier has once deteriorated, the lubricant is difficult to be held. Deterioration proceeds at the deteriorated portion.

Therefore, in the image forming apparatus 100, the lubricant 42Y is also applied to the photosensitive drum 20Y before use.
As a method of applying the lubricating substance 42Y to the photosensitive drum 20Y before use, in this embodiment, the cleaning device 70Y, the developing device 80Y, and the charging device are applied to the photosensitive drum 20Y before use in the image forming apparatus 100. 90Y, a method of operating the lubricating substance supply device 40Y in a state where the transfer belt unit 10 is not operating is adopted.

  In a system in which the cleaning device 70Y, the developing device 80Y, the charging device 90Y, and the transfer belt unit 10 are not operated, the lubricant material 42Y can be uniformly and sufficiently applied to the photosensitive drum 20Y. Due to the coating unevenness, the deterioration occurs in the portion where the lubricating substance 42Y does not exist, and the deterioration is prevented from proceeding in advance.

  When a signal for performing an image forming operation is input from the outside, the image forming apparatus 100 appropriately refers to a memory or the like in the control unit and determines whether or not this input is the first input after shipment. If it is determined that this is the case, the mode shifts to the coating mode, the cleaning devices 70Y, 70M, 70C, 70BK, the developing devices 80Y, 80M, 80C, 80BK, the charging devices 90Y, 90M, 90C, 90BK, the transfer belt unit. 10 is operated, the lubrication substance supply devices 40Y, 40M, 40C, and 40BK are operated, and the photosensitive drums 20Y, 20M, 20C, and 20BK are driven to rotate, and the lubricating substances 42Y, 42M, 42C, and 42BK are driven. Apply.

  In addition, when a signal indicating that an image forming operation is to be performed is input from the outside, the image forming apparatus 100 appropriately refers to a memory or the like in the control unit, and this input is detected by the drum detection unit and the photosensitive drums 20Y and 20M. , 20C, 20BK, or the first input after detecting the attachment / detachment of any of the image forming units 60Y, 60M, 60C, 60BK. If any of the above is determined, and if it is determined that any of the above, it shifts to the coating mode, the cleaning devices 70Y, 70M, 70C, 70BK, the developing devices 80Y, 80M, 80C, 80BK, charging. Without operating the devices 90Y, 90M, 90C, 90BK and the transfer belt unit 10, the slipping substance supply devices 40Y, 40M, 4 C and 40BK corresponding to the detected attachment / detachment are actuated, and the photosensitive drums 20Y, 20M, 20C, and 20BK corresponding to the detected attachment / detachment are rotationally driven, and the corresponding lubricating substance 42Y. 42M, 42C, 42BK are applied.

  In these cases, the operating times of the lubrication substance supply devices 40Y, 40M, 40C, and 40BK and the photosensitive drums 20Y, 20M, 20C, and 20BK are determined and recorded in the memory so as to satisfy the application amount condition described later. Yes. After the operation time has elapsed, the application mode is shifted to the normal mode for image formation, and the above-described operation is performed to perform image formation.

  Other methods may be used for applying the lubricating substance 42Y to the photosensitive drum 20Y before use. For example, the cleaning device 70Y and the developing device may be applied to the photosensitive drum 20Y before use in the image forming apparatus 100. A method of applying the lubricating material 42Y by another method without using the lubricating material supply device 40Y in a state where the device 80Y, the charging device 90Y, and the transfer belt unit 10 are not operated, and the photosensitive drum 20Y before use. A method of applying the lubricating substance 42Y using an apparatus equivalent to the lubricating substance supply apparatus 40Y outside the image forming apparatus 100, and other methods without using the lubricating substance supply apparatus 40Y outside the image forming apparatus 100. And a method of applying the lubricating substance 42Y.

  As a method of applying the lubricating substance 42Y inside or outside the image forming apparatus 100 without using the lubricating substance supply apparatus 40Y, the lubricating substance 42Y is molded into a solid bar shape as in a modification described later. Then, using the brush in contact with the lubricant solid bar, this brush is also brought into contact with the photosensitive drum 20Y, rotated, the lubricant material 42Y is scraped off from the lubricant solid bar by the brush, and the lubricant material scraped off. A method of supplying 42Y to the rotating photoconductor drum 20Y by rotation of a brush, or a method of rotating and supplying the photoconductor drum 20Y while pressing the solid lubricant bar against the photoconductor drum 20Y can be considered. Further, the powdery lubricating substance 42Y may be supplied to the photosensitive drum 20Y using a sponge roller or the like.

  In any case, during or after the application of the lubricant 42Y, the blade such as the blade 46Y is brought into contact with the photoreceptor drum 20Y to extend the lubricant 42Y to the surface of the photoreceptor drum 20Y. In this way, the step of forming a film is provided for the purpose of regulating the amount of the lubricating substance 42Y and controlling the amount of the lubricating substance 42Y in a large lump or grain, and making the lubricating substance 42Y uniform on the photosensitive drum 20Y. It is very important to paint on.

It held before start of use to the photosensitive drums 20Y surface, as a result of the evaluation in detail optimal amount of lubricating material 42Y serving metal soaps, optimal coverage of the metallic soap obtained by XPS spectrometry It was found that it was 90% or more, preferably 93% or more, and more preferably 97% or more. In the Kutsugaeritsu of lubricant material 4 2Y 90% or less by XPS analysis, where there is no coating of lubricant material 42Y in the photosensitive drums 20Y surface is not preferable for receiving the degradation due to locally AC charging.

However, the XPS analysis method can obtain the abundance only on the outermost surface. When the molecular formula of the metal soap which is the lubricating material 42Y is C _m H _n O _k M, when the lubricating material 42Y covers the surface of the photoreceptor drum 20Y 100%, the metal (M) in the lubricating material 42Y Of atomic%

となり、潤滑性物質４２Ｙの感光体ドラム２０Ｙ表面の被覆率は、

The coverage of the surface of the photosensitive drum 20Y with the lubricating material 42Y is

で表される。

It is represented by

In order to withstand AC charging, a certain amount or more of the lubricating material 42Y is required, and the optimal amount of the lubricating material 42Y retained on the surface of the photosensitive drum 20Y before the start of use is determined by another analysis method. As a result of the evaluation, the optimum abundance per unit area of the metal element in the lubricating material 42Y on the photoreceptor drum 20Y is 1.3 to 6.5 × 10 ⁻⁹ mol / cm ² , preferably 1.7 to ^{6.0 × 10 -9 mol / cm 2} , even more preferably ^{2.2~5.7 × 10 2-9 mol / cm 2} .

This is because when the abundance per unit area of the metal element in the lubricating material 42Y on the photosensitive drum 20Y is reduced to 1.3 × 10 ⁻⁹ mol / cm ² or less, the lubricating material 42Y is applied. This is because the portion that is not protected by the lubricating material 42Y on the surface of the photosensitive drum 20Y is subjected to AC charging and deteriorates.

Further, when the abundance per unit area of the metal element in the lubricating material 42Y on the photosensitive drum 20Y is 6.5 × 10 ⁻⁹ mol / cm ² or more, image blur may occur depending on image forming conditions, This is because the lubricating material 42Y is liable to adhere to the charging roller 91Y and excessive lubricating material 42Y is mixed into the developer, which is not preferable.

  As described above, by evaluating the coverage and abundance of the lubricating substance 42Y on the surface of the photosensitive drum 20Y before the start of use by two analysis methods, the film of the lubricating substance 42Y is exposed to light at the start of use of the photosensitive drum 20Y. The state in which the surface of the body drum 20Y is almost entirely covered and an optimal amount of the lubricating material 42Y is applied without being excessively diluted or too thin is defined.

  Further, if a sufficient amount of the lubricating material 42Y is applied to the photoconductive drum 20Y in advance in a state where it is not deteriorated before the start of use, the surface of the photoconductive drum 20Y when a new lubricating material 42Y is supplied. Therefore, even if the supply amount of the lubricating material 42Y is smaller than the conventional amount, an amount sufficient to protect the photosensitive drum 20Y over time is uniformly held on the photosensitive drum 20Y.

  As a method for detecting the lubricating substance 42Y, there are a fluorescent X-ray analysis method and a method in which the photosensitive layer 22Y is dissolved and the metal element in the lubricating substance 42Y is analyzed by ICP or the like.

  Although it is preferable to maintain the initial state, that is, the state before use before image formation, even after the start of image formation, the application state of the lubricating substance 42Y depends on the image formation and the like. After the subsequent 1000 sheets, that is, after the 1000-sheet image is formed, it is preferably held in the following area.

That is, the optimum amount of lubricant material 42Y present in time the photosensitive drum 20Y surface optimal coverage of the lubricant material 4 2Y obtained by XPS analysis was 92% or more, preferably 95% or more, further Preferably it is 97% or more. In XPS analysis to be Kutsugaeritsu of lubricant material 4 2Y less 92% by is not preferable because the where there is no coating of lubricant material 42Y in the photosensitive drums 20Y surface undergoes degradation due to locally AC charging.

In addition, the optimum amount of metal element present in the lubricating material 42Y on the photosensitive drum 20Y per unit area is 1.6 to 6.0 × 10 ⁻⁹ mol / cm ² , preferably 2.0 to 5. 6 × 10 ⁻⁹ mol / cm ² , more preferably 2.4 to 5.2 × 10 ⁻⁹ mol / cm ² .

This is because when the abundance per unit area of the metal element in the lubricating material 42Y on the photosensitive drum 20Y is reduced to 1.6 × 10 ⁻⁹ mol / cm ² , the application of the lubricating material 42Y is performed. This is because the portion that is not caught up and is not protected by the lubricating material 42Y on the surface of the photosensitive drum 20Y is subjected to AC charging and deteriorates.

Further, when the abundance per unit area of the metal element in the lubricating material 42Y on the photosensitive drum 20Y is 5 × 10 ⁻⁹ mol / cm ² or more, image blur may occur or lubricity may occur depending on image forming conditions. This is because the material 42Y tends to adhere to the charging roller 91Y or excessive lubricating material 42Y is mixed into the developer.

  As described above, the coating of the lubricating substance 42Y covers almost the entire surface of the photosensitive drum 20Y, and the optimum amount of the lubricating substance 42Y that is not excessively diluted or too thin is applied. In order to maintain the coating method, the coating method is within the above-described range at the start and over time, that is, for example, as described above, the contact pressure and contact angle of the blade 46Y, the rotational speed of the agitator 43Y, the blade member 45Y The number, shape, elasticity, etc. are appropriately adjusted.

In the image forming apparatus 100, when the lubricating material 42Y is supplied as a powder to the photosensitive drum 20Y, the particle size of the lubricating material 42Y is 50 μm or less, preferably 40 μm or less, and more preferably 35 μm or less. preferable. When the particle size of the lubricating material 42Y is 50 μm or more, the film of the lubricating material 42Y cannot be uniformly formed on the photosensitive drum 20Y, and large particles fly to the charging roller and are oxidized by charging, and the conductive portions of the adhered portions are electrically conductive. This is not preferable because the properties change.
The image forming apparatus 100 is configured to satisfy these conditions.

The two-component developer used in the image forming apparatus 100 will be described in detail.
The toner contained in such a developer is composed of a binder resin, a colorant, and a charge control agent as main components, and other additives as necessary. Further, for the reasons described later, the particle size of the toner is set to 10 μm or less.

  Specific examples of the binder resin used in such toner include polystyrene, chloropolystyrene, poly-α-methylstyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer, styrene. -Vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene-maleic acid copolymer, styrene-acrylic acid ester copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, Styrene-butyl acrylate copolymer, styrene-phenyl acrylate copolymer, etc.), styrene-methacrylic acid ester copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-methacrylic acid) Acid butyl copolymer, styrene-phenyl methacrylate Polymers), styrene resins (monopolymers or copolymers containing styrene or styrene substitution products) such as styrene-α-methyl chloroacrylate copolymer, styrene-acrylonitrile-acrylate ester copolymer, chloride Vinyl resin, rosin modified maleic acid resin, phenyl resin, epoxy resin, polyester resin, low molecular weight polyethylene, low molecular weight polypropylene, ionomer resin, polyurethane resin, ketone resin, ethylene-ethyl acrylate copolymer, xylene resin, polyvinyl butyral, etc. Can be mentioned.

  As coloring materials (for example, yellow, magenta, cyan and black) used for such toner, those known for toners are used. The amount of the coloring material is suitably 0.1 to 15 parts by weight, more preferably 0.15 to 9 parts by weight, with respect to 100 parts by weight of the binder resin.

  Specific examples of the charge control agent used in such a toner include nigrosine dyes, chromium-containing complexes, quaternary ammonium salts, and the like, and these are properly used depending on the polarity of the toner particles. The amount of the charge control agent is 0.1 to 10 parts by weight, more preferably 0.2 to 7 parts by weight with respect to 100 parts by weight of the binder resin.

  In addition, it is advantageous to add a fluidity imparting agent as an additive to the obtained toner particles. As the fluidity-imparting agent, fine particles of metal oxides such as silica, alumina, magnesia, zirconia, ferrite, magnetite and the like, and silane coupling agent, titanate coupling agent, zircoaluminate, quaternary ammonium salt, fatty acid, Surface treatment or coating with fatty acid metal salt, fluorine-based activator, solvent, polymer or other treatment agent, fine particles of fatty acid such as stearic acid or zinc stearate or metal salt thereof, and these fine particles with surface treatment In addition, polymer fine particles such as polystyrene, polymethyl methacrylate, and polyvinylidene fluoride, and those fine particles that are surface-treated or coated with the above-described treatment agent are used. These fluidity imparting agents have a particle size in the range of 0.01 to 3 μm.

  The addition amount of these fluidity imparting agents is preferably in the range of 0.1 to 7.0 parts by weight, particularly 0.2 to 5.0 parts by weight with respect to 100 parts by weight of the toner particles. The mixing method of the toner particles and the fluidity-imparting agent is carried out so that the powder is moved at a high speed by an air flow or mechanical force in a fluid state, and does not substantially cause pulverization. Examples of the mixer include a high-speed flow type mixer such as a Henschel mixer and a UM mixer.

  As a method for producing such a toner for a two-component developer, it can be produced by various known methods or a combination thereof. For example, in the kneading and pulverization method, a binder resin, a colorant such as carbon black, and necessary additives are dry-mixed, heated and melt-kneaded with an extruder or two-roll, three-roll, etc., and after cooling and solidification Then, the toner is pulverized by a pulverizer such as a jet mill and classified by an airflow classifier. In addition, it is possible to directly produce a toner from a monomer, a colorant, and an additive by a suspension polymerization method or a non-aqueous dispersion polymerization method. In this embodiment, such a polymerization method is used.

  The toner is preferably externally added with 0.05 to 0.2 wt% of a lubricating material such as zinc stearate. In this way, the lubricating substance externally added to the toner can be applied to the surface of the photoreceptor drum 20Y. In the image forming apparatus 100, when an image is formed, for example, a charging bias is applied by the charging device 90Y. At that time, discharge products such as ozone and nitrogen oxide are generated and adhered to the photosensitive drum 20Y. The image quality of the toner image recorded on the paper S is deteriorated. Further, as already described, it has been found that the surface layer of the photoconductive drum 20Y, which is an organic photoconductor, is oxidized by the discharge and the wear proceeds.

  On the other hand, when a lubricating substance is externally added to the toner and applied to the photosensitive drum 20Y, the lubricating substance 42Y is applied to the photosensitive drum 20Y. By forming a thin layer of the added lubricating substance, the surface energy of the photosensitive drum 20Y is reduced, filming is prevented and adhesion is difficult to adhere, and the lubricating substance layer serves as a protective layer for discharging. This prevents the surface layer of the photosensitive drum 20Y from being oxidized, and reduces the wear of the photosensitive drum 20Y. By externally adding a lubricating substance to the toner, it is possible to reduce the size and cost by eliminating the need for a dedicated lubricating substance coating apparatus.

  The toner having an average particle diameter of 10 μm or less is used to improve image quality. The supply of the lubricating substance 42Y and the lubricating substance externally added to the toner suppresses the cleaning failure that has been a problem with such small-diameter toner. Therefore, it is possible to improve the image quality while suppressing poor cleaning.

  Since the toner is manufactured by a polymerization method, its outer shape is close to a true shape, and dot reproducibility can be improved. In addition, the supply of the lubricating substance 42Y or the lubricating substance externally added to the toner suppresses the cleaning failure that has been a problem for such a toner close to the true shape. Therefore, it is possible to improve dot reproducibility while suppressing cleaning failure.

  The carrier core material contained in the developer is generally composed of the carrier core material itself or having a coating layer on the core material. Examples of the core material of the resin-coated carrier that can be used in this embodiment include ferrite and magnetite. The particle size of the core material is 20 to 65 μm, preferably about 30 to 60 μm.

  Fluorine-containing monomers can be used as the carrier coating layer. The fluorine-containing monomers include vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene, perfluoroalkyl vinyl ether, and fluorine atoms. The vinyl ether is a vinyl ketone having a fluorine atom substituted, and the polymers thereof include vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, perfluoroalkyl vinyl ether-vinylidene fluoride. Ride-tetrafluoroethylene copolymer, vinylidene fluoride polymer, tetrafluoroethylene copolymer, polymer containing vinyl ether substituted with fluorine atom, vinyl ketone substituted with fluorine atom Polymers containing emissions, fluorinated alkyl acrylate polymer, or a fluorinated alkyl methacrylate polymers.

Components that copolymerize with such fluorine-containing monomers include styrene, methylstyrene, dimethylstyrene, trimethylstyrene, acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, butyl acrylate, butyl methacrylate, and benzyl acrylate. Benzyl methacrylate, acrylic acid amide, methacrylic acid amide, cyclohexyl acrylate, cyclohexyl methacrylate, hydroxyethyl acrylate, glycidyl acrylate, glycidyl methacrylate, vinyl acetate, ethylene, propylene, and the like.
As a method for forming the coating layer, a resin may be applied to the surface of the carrier core particle by means of a spraying method, a dipping method, or the like, as in the past.

  Although the highest resolution at which the image forming apparatus 100 can form an image can perform high-quality image formation at any resolution, the highest resolution is particularly 1000 dpi or more by satisfying the various conditions described above. In high-resolution image formation of preferably 1200 dpi or more, it is excellent in high-quality image formation and highly effective.

[Modification]
A modification of the lubricating substance supply device will be described with reference to FIG. About this modification, a different point from the above-mentioned lubricating substance supply apparatus and the image forming unit will be mainly described, and the same parts are denoted by the same reference numerals and description thereof will be omitted as appropriate. Similarly to the description of the above embodiment, an image forming unit for forming a yellow toner image will be described as a representative image forming unit for forming a toner image of each color. FIG. 4 corresponds to FIG. 2 and is an enlarged view showing a schematic configuration of an image forming unit 60Y in the present modification.

  Lubricant supply device 40Y of this modification includes a brush roller 47Y which is a slipping material supply member provided in place of the agitator 43Y, a bar-like lubrication material 42Y solidified instead of fine powder, And a spring 48Y as an elastic member for urging the bar-like lubricant material 42Y toward the brush roller 47Y, and the brush roller 47Y is rotated to scrape off the lubricant material 42Y, and the scraped lubricant material This is different from the above-described embodiment in that 42Y is supplied to the surface of the photosensitive drum 20Y. Except for this point, it has the same configuration as the lubricating substance supply device 40Y of the above-described embodiment.

  The brush roller 47Y scrapes the solid lubricating substance 42Y by rubbing. Thereby, the lubricating substance 42Y in the form of fine powder adheres to the brush roller 47Y. Then, the adhering fine powdery lubricating substance 42Y is supplied to the surface of the photosensitive drum 20Y when it is conveyed to a region facing the surface of the photosensitive drum 20Y as the brush roller 47Y rotates. The lubricating substance 42Y applied to the surface of the photoreceptor drum 20Y is stretched by the blade 46Y provided in the case 41Y portion to form a lubricant film.

  The particle size and the like of the fine powdery lubricating substance 42Y generated by being scraped off by the brush roller 47Y is the same as that of the fine powdery lubricating substance 42Y accommodated in the case 41Y in the above-described embodiment. It is.

  In this embodiment, the particle size of the fine powdery lubricating substance 42Y generated by scraping off by the brush roller 47Y may be uneven. However, the solid lubricating substance 42Y is originally in the form described above. Since the density is higher than that of the lubricating substance 42Y in the form of fine powder, the volume for storing the lubricating substance 42Y is suppressed, and the lubricating substance supply device 40Y, the image forming unit 60Y, and the image forming apparatus 100 can be downsized. It is valid.

〔Example〕
An aluminum drum having a diameter of 30 mm is used as a conductive support, and an undercoat layer, a charge generation layer, a charge transport layer, and a protective layer are sequentially applied thereon, and then dried, and a 4.5 μm undercoat layer, 0. No. 1 to 28 were prepared as 28 photosensitive drums comprising a 15 μm charge generation layer, a 22 μm charge transport layer, and a protective layer of about 4.5 μm.

  Coating of the protective layer was performed by a spray method, and the others were performed by a dip coating method. 22.0% by mass of alumina having an average particle size of 0.21 μm was added to the protective layer. Plastic flanges were press-fitted into both ends of the produced photosensitive drum.

  Six sets of 24 photosensitive drums were prepared, each set consisting of 4 photosensitive drums. The remaining four were stored as spares.

<Type A>
The lubricant material was not applied to type A No. 1 to No. 4 photosensitive drums before the start of use.
On the other hand, zinc stearate as a lubricating substance was applied to the photosensitive drums Nos. 5 to 24 of the following types B to F outside the apparatus.

<Type B>
As shown in FIG. 5, type B Nos. 5 to 8 photosensitive drums were prepared by using a blade 51, a solid zinc stearate bar 52 as a lubricating material, and a brush roller 53 for applying zinc stearate. And installed in a device for applying a lubricating substance.

  The zinc stearate bar 52 was scraped by the brush roller 53 by rubbing, and the fine zinc stearate was adhered to the brush roller 53. Then, the zinc stearate adhering to the brush roller 53 was supplied to the surface of the photosensitive drum by the rotation of the brush roller 53.

  Immediately after the supply, the blade 51 was brought into contact with the trading method, and zinc stearate was applied for 5 to 10 minutes. Thereafter, the zinc stearate bar 52 and the brush roller 53 were removed, and the photosensitive drum was rotated for 5 minutes while pressing the blade 51 by a trading method.

<Type C>
The type C No. 9 to 12 photosensitive drums were also coated with zinc stearate in the same manner as type B described above.
However, only the blade pressure condition was slightly increased.

<Type D>
Zinc stearate was applied to type D Nos. 13 to 16 photosensitive drums in the same manner as type B described above.
However, only the blade pressure condition was slightly reduced.

<Type E>
Type E Nos. 17 to 20 photosensitive drums were sprinkled with 250 mg of zinc stearate powder as a lubricant on a polyurethane sponge, and the sponge was pressed while rotating the photosensitive drum.

<Type F>
Type F Nos. 21 to 24 photoconductor drums were mounted on a lubrication material coating apparatus (not shown). This apparatus is different from the apparatus for applying a lubricating substance used for type B shown in FIG. 5 in that the blade 51 is not provided.

  As in Type B, the brush roller was pressed against both the zinc stearate bar and the photosensitive drum, and the solid zinc stearate bar as a lubricating material was scraped by the brush roller by rubbing to form fine powdered stearin Zinc acid was adhered to the brush roller. And the zinc stearate adhering to this brush roller was supplied to the surface of the photoreceptor drum by rotation of the brush roller.

These types to F, the 24 kinds of the photosensitive drum immediately after the zinc stearate coating, measure the coverage of zinc stearate on the surface of the photoreceptor drum by the XPS analysis, The photosensitive drum surface by ICP measurement The amount of zinc was measured.

  Analysis by XPS analysis is performed according to the following procedure. The photoconductor drum is cut out, fixed to a sample holder, and measured by XPS analysis. Furthermore, the detected peak was analyzed and atomic% was calculated. As a measuring apparatus, a 1600S type X-ray photoelectron spectrometer manufactured by PHI was used. The measurement conditions were an X-ray source of MgKα (100 W) and an analysis region of 0.8 × 2.0 mm.

The measurement of the amount of zinc by the ICP measurement method is performed according to the following procedure. The photosensitive layer of the photosensitive drum is peeled off by a size of 2 cm × 2 cm to prepare a sample. The sample is thermally decomposed with sulfuric acid, nitric acid, and hydrochloric acid, and then dissolved in ultrapure water to prepare a test solution. Quantitative analysis of zinc in the test solution is performed by ICP-AES method. Furthermore, from the obtained quantitative results, it was converted as the amount of zinc stearate per unit area (cm 2). SP5100 type ICP-AES manufactured by SII Nano Technology was used as a measuring device.

As a result, as shown in Table 1, the variation in the detected amount of zinc in each type A to F is small, and the average value of the measurement results of the amount of zinc stearate in each type A to F is as follows: Became.

-Examples 1-3 and Comparative Examples 1-3 (initial test)

  Using such a photosensitive drum, image formation and evaluation related thereto were performed under the following conditions.

  A gap tape having a width of 10 mm and a thickness of 52 μm was attached to a position 13 mm from the end of the charging roller (Φ11.5). A charging roller is arranged right above the photosensitive drums No. 1 to 6, and the charging roller is pressed against the photosensitive drum with a spring, and the photosensitive drum is linearly moved at a linear speed of 185 mm / second between the photosensitive drum and the charging roller. In addition, an AC voltage having a frequency of 1150 Hz and an amplitude of 1200 V was applied to a DC voltage of −600 V.

  Cleaning of the transfer residual toner is performed by bringing the cleaning blade into contact with the trading method, and a solid zinc stearate bar and a zinc stearate-coated brush roller are arranged as lubricants downstream in the rotation direction of the cleaning blade, and immediately downstream thereof. A zinc stearate coating blade was placed on the surface. A charging roller was disposed downstream of the zinc stearate coating blade.

  The brush roller was pressed against both the zinc stearate bar and the photosensitive drum, and the brush roller scraped the zinc stearate bar by rubbing to adhere the finely powdered zinc stearate to the brush. The zinc stearate adhering to the brush roller was supplied to the surface of the photosensitive drum by the rotation of the brush roller. Immediately after the supply, the zinc stearate coating blade was brought into contact with the trading system to apply zinc stearate. In the toner, zinc stearate was externally added.

(Comparative Example 1)
The type A No. is added to the image forming unit for forming the black toner image. When one photoconductor drum was incorporated and five 1-by-1 halftone images of A4 were output, horizontal stripes were generated.

(Examples 1-3)
NO. Of type B to D in the image forming unit for black toner image formation. 5, NO. 9, NO. Similarly, when 13 photoconductor drums were incorporated and five 1-by-1 halftone images of A4 were output, high-quality images were obtained on all photoconductor drums.

(Comparative Example 2)
Type E NO. Is used in an image forming unit for forming a black toner image. When 17 photoconductor drums were incorporated and five A4 1-by1 halftone images were output in the same manner, high-quality images were obtained.

(Comparative Example 3)
NO. Of type F in an image forming unit for forming a black toner image. When 21 photoconductor drums were incorporated and five A4 1-by1 halftone images were output in the same manner, high-quality images were obtained.

  From these results, it was found that zinc stearate is suitable as a lubricating substance, and that a high-quality image can be obtained by applying this.

-Examples 4-5, comparative examples 4-5 (running test)

  Using the same tandem type color image forming apparatus as the image forming apparatus 100, four photosensitive drums of type B, C, E, and F are incorporated in the image forming unit of each image forming apparatus, and the same as in the initial image test. Evaluation was performed by outputting a total of 5,000 1-by-1 halftone images every five sheets, and after 100,000 sheets were output continuously, evaluation was performed again. The application conditions of the lubricating material are the same as in the initial image test.

Type B NO. After outputting 5000 and 100,000 sheets. No. 5 photosensitive drum, type C NO. No. 9 photosensitive drum, type E NO. No. 17 photosensitive drum, type F NO. With respect to 21 photoconductor drums, the zinc stearate coverage on the photoconductor drum surface was measured by XPS analysis, and the amount of zinc stearate on the photoconductor drum surface was measured by ICP measurement.

  As a result, the results shown in Table 2 as the results after 5000 sheets and the results shown in Table 3 as the results after 100,000 sheets were obtained as follows.

Example 4
A black image developed from an image forming unit for forming a black toner image in which a type B photoconductor drum was incorporated had a high quality image after outputting 5000 sheets and 100,000 sheets. Further, using this apparatus after outputting 100,000 evaluation images, when a landscape portrait was output in full color, a high-quality image was obtained.

(Example 5)
A black image developed from an image forming unit for forming a black toner image in which a type C photoconductive drum was incorporated had a high quality image after outputting 5000 sheets and 100,000 sheets. Further, using this apparatus after outputting 100,000 evaluation images, when a landscape portrait was output in full color, a high-quality image was obtained.

(Comparative Example 4)
A black image developed from an image forming unit for forming a black toner image incorporating a type E photosensitive drum has black vertical streaks after output of 5000 sheets, and many vertical streaks after output of 100,000 sheets. Occurred.

(Comparative Example 5)
A black image developed from an image forming unit for forming a black toner image incorporating a type F photosensitive drum provides a high-quality image after output of 5000 sheets, and is thin after output of 100,000 sheets. Density unevenness was observed.

  From these results, it was found that the coverage and abundance of zinc stearate affect the image quality during running, and that these values are in the above-described range contribute to the formation of high-quality images.

Example 6 and Comparative Example 6 (Tests performed by changing the conditions for applying the lubricating substance during running)
Using the stored four photosensitive drums (NO. 25-28), a type F-2 photosensitive drum was prepared in the same manner as the type F photosensitive drum. With respect to this photosensitive drum, the coverage of zinc stearate on the surface of the photosensitive drum was measured by XPS analysis, and the amount of zinc stearate on the surface of the photosensitive drum was measured by ICP.

As a result, the average value of the zinc stearate coverage on the surface of the type F-2 photosensitive drum was 72%, and the average value of the amount of zinc stearate present was 2.1 × 10 −9 mol. That is, the value was almost the same as in the case of type F.

  Using a tandem type color image forming apparatus similar to the image forming apparatus 100, a type B photosensitive drum (NO. 5 and 6) is incorporated in each of the image forming units for forming black and yellow toner images, and magenta and Each type F-2 photosensitive drum (NO. 25, 26) is incorporated into each of the image forming units for forming a cyan toner image, and in the same manner as in the above-described tests, a 1-by1 halftone image is obtained every 5 sheets for a total of 5000 sheets. The output was evaluated, and after 100,000 sheets were continuously output, the evaluation was performed again.

  At this time, the pressurizing force applied to the zinc stearate bar in order to increase the coating amount of zinc stearate as a lubricating substance was doubled as in Example 4. Other application conditions of the lubricating material are the same as in the above tests.

For the photosensitive drums of type B and type F-2 after outputting 5000 sheets and 100,000 sheets, the zinc stearate coverage on the surface of the photosensitive drum is measured by XPS analysis, and the photosensitive drum is measured by ICP measurement. The amount of zinc stearate on the body drum surface was measured.

As a result, the results shown in Table 4 as the results after 5000 sheets and the results shown in Table 5 as the results after 100,000 sheets were obtained as follows. The result was the average value of the detected amount of zinc stearate obtained from two photosensitive drums of each type.

(Example 6)
The image developed from the image forming unit for forming the black toner image and the image forming unit for forming the yellow toner image incorporating the type B photosensitive drum has a high image quality after outputting 5000 sheets and 100,000 sheets. A good image was obtained.

(Comparative Example 6)
For magenta and cyan images developed from a magenta toner image forming unit and a cyan toner image forming unit incorporating a type F-2 photosensitive drum, respectively, A high-quality image was obtained after the output, but a slight density unevenness was observed after the output of 100,000 sheets.

  From these results, it was found that if the initial lubrication material was not applied well, even if a large amount of the lubrication material was supplied over time, the image quality was not greatly improved.

Example 7 and Comparative Example 7 (Test for examining the influence of the image forming environment during running)

  The apparatus used in Example 6 and Comparative Example 6 was moved to a room with a room temperature of 10 ° C. and a humidity of 15%, and an image was output. Other conditions were the same as in Example 6 and Comparative Example 6.

(Example 7)
The image developed from the image forming unit for forming the black toner image and the image forming unit for forming the yellow toner image incorporating the type B photosensitive drum has a high image quality after outputting 5000 sheets and 100,000 sheets. A good image was obtained.

(Comparative Example 7)
For magenta and cyan images developed from a magenta toner image forming unit and a cyan toner image forming unit incorporating a type F-2 photosensitive drum, respectively, A high-quality image was obtained after output, but obvious density unevenness was seen after output of 100,000 sheets.

  From these results, it was found that the image forming environment does not significantly affect the image quality of the image to be formed when the initial lubricant application is not performed well.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the specific embodiments, and the present invention described in the claims is not specifically limited by the above description. Various modifications and changes are possible within the scope of the above.

  For example, as a modification, as shown in FIG. 6, in the rotation direction B1 of the photosensitive drum 20Y, the arrangement order of the cleaning device 70Y and the lubricating material supply device 40Y may be reversed. The arrangement position of the lubricating substance supply device 40Y may be changed as appropriate, such as a configuration in which the transfer residual toner is cleaned by the cleaning blade 78Y.

  The process cartridge only needs to include at least the image carrier and other components, and selection of other components constituting the process cartridge can be performed by selecting the image carrier, the lifetime of the component, the cost, This is appropriately performed in consideration of structural ease and the like.

  In the two forms described above, a two-component developer is used, but the same effect can be obtained even if the developer is a one-component developer. In addition, the present invention is not a so-called tandem image forming apparatus such as the image forming apparatus 100, but sequentially forms toner images of each color on a single photosensitive drum and sequentially superimposes the color toner images to form a color image. The present invention can be similarly applied to a so-called one-drum type image forming apparatus, and can also be applied to a monochrome image forming apparatus instead of a color image forming apparatus.

  The effects described in the embodiments of the present invention are only the most preferable effects resulting from the present invention, and the effects of the present invention are limited to those described in the embodiments of the present invention. is not.

1 is a schematic front view of an image forming apparatus to which the present invention is applied. FIG. 2 is a schematic front view showing a configuration around one image carrier among a plurality of image carriers provided in the image forming apparatus shown in FIG. 1. FIG. 2 is an enlarged sectional view of a surface structure of an image carrier provided in the image forming apparatus shown in FIG. 1. It is a schematic front view of an apparatus for applying a lubricant to an image carrier. FIG. 5 is a schematic front view showing a modification of the configuration around the image carrier shown in FIG. 2. FIG. 10 is a schematic front view showing still another modified example of the configuration around the image carrier shown in FIG. 2.

Explanation of symbols

20Y, 20M, 20C, 20BK Image carrier 23Y, 23M, 23C, 23BK Surface layer 26Y, 26M, 26C, 26BK Filler 40Y, 40M, 40C, 40BK Lubricant coating means 42Y, 42M, 42C, 42BK Lubricant, metal soap 68Y, 68M, 68C, 68BK Process cartridge 90Y, 90M, 90C, 90BK Charging unit 100 Image forming apparatus

Claims (9)

Having an image carrier,
The image carrier before use is one in which a lubricant is applied outside the apparatus,
The lubricant is zinc stearate ;
The amount of the zinc stearate applied to the image carrier before use is such that the abundance per unit area on the image carrier is 3.1 × 10 ⁻⁹ to 4.8 × 10 ⁻⁹ mol / An image forming apparatus having a cm ² and a zinc stearate coverage of 91% or more by XPS analysis. The image forming apparatus according to claim 1.
Charging means for charging the image carrier,
The charging method of the image carrier by the charging means is a contact method or a proximity method,
The image forming apparatus , wherein the charging unit performs AC charging in which an AC voltage is superimposed on a DC voltage . The image forming apparatus according to claim 1 or 2,
The lubricant is supplied to the image carrier in a powder state with a particle size of 50 μm or less,
An image forming apparatus , wherein the image carrier contains a filler of 0.05 to 0.5 μm in a surface layer thereof . The image forming apparatus according to any one of claims 1 to 3,
An image forming apparatus, wherein a surface layer of the image carrier is formed of a thermosetting substance . The image forming apparatus according to claim 4.
The thermosetting substance includes a trifunctional or higher-functional radical polymerizable monomer having no charge transporting structure and a monofunctional radical polymerizable compound having a charge transporting structure;
An image forming apparatus , wherein the surface layer is formed by curing the thermosetting substance . 6. The image forming apparatus according to claim 4 , wherein the surface layer has a thickness of 1 to 10 [mu] m . The image forming apparatus according to any one of claims 1 to 6 ,
An image forming apparatus having a maximum resolution of 1000 dpi or more . A process cartridge used in the image forming apparatus according to claim 1 , wherein the process cartridge includes at least the image carrier . An image forming method for forming an image using the image forming apparatus according to claim 1 or the process cartridge according to claim 8 .

Images