WO2003010608A1 - Cylindrical developer carrier and production method thereof - Google Patents

Abstract

A cylindrical developer carrier which is provided with an alumite layer covering a uniformly-roughened conductive substrate surface, the alumite layer being uniformly provided with pores reaching the substrate, whereby allowing toner to be sufficiently friction-electrified on a developer sleeve and to be carried and conveyed as a deviation-free, uniform layer after repeated uses, and causing no difference in developing capability independently of a developing history.

Description

TECHNICAL FIELD The present invention relates to a cylindrical developer carrier and a method for producing the same.

 The present invention relates to a cylindrical developer carrier mounted on an electrophotographic apparatus such as an electrophotographic printer, a copying machine, and a facsimile. Background art

 Electrophotographic devices such as laser printers, LED printers, and plain paper copiers form images by the so-called Carlson process. The Carlson process is a cycle of an electrophotographic process using members such as charging, exposure, toner development, transfer, and charge removal arranged on the peripheral surface of a cylindrical photoreceptor with a photosensitive layer having a photoconductive function. This is an image forming method for outputting by fixing the toner image transferred to the printer.

 In this process, when the electrostatic latent image formed on the surface of the photoreceptor by the charging and exposure is visualized by the next toner development, the toner in the developing device is cylindrically developed. The latent image on the surface of the photoreceptor is carried and conveyed to the vicinity of the surface of the photoreceptor by using an electrostatic force through an agent carrier, that is, a developing sleeve. In order to obtain a good image by such a developing method, it is extremely important that the toner on the developing sleeve is carried on a uniform layer without any unevenness on the developing sleeve.

Also, if the toner layer on the developing sleeve is too thick or too thin, good images cannot be expected in terms of development density. For this reason, it is necessary to separately provide a member for regulating the thickness of the toner on the developing sleep. However, the surface condition is also important to uniformly and uniformly distribute the toner on the surface of the developing sleep. With such surface condition Therefore, a smooth surface is not always the best, and it is said that it is better to provide unevenness of an appropriate size to provide an appropriate frictional force between the sleeve and the toner. However, the convexity has a problem that, depending on the hardness of the developing sleeve material, it is worn after repeated use and the image gradually deteriorates. Therefore, improvement of abrasion resistance is required. When the developing sleeve material is an aluminum alloy, its Vickers hardness is as small as about 7 OHv, so after forming M convex on the surface, the Vickers hardness is as large as about 200 Hv to 400 Hv. It is known that when an alumite surface layer is formed by arsenic, the abrasion resistance 1 to the raw material is improved (see JP-A-5-46008). On the other hand, when the alumite layer is provided on the surface of the developing sleeve, the surface resistance increases due to the insulating properties of the alumite layer. However, if the surface resistance is high, the charge of the toner corresponding to the image forming portion during the previous image forming process is not sufficiently moved from the developing sleeve side to the photosensitive member surface side, and tends to remain. The charge amount of the image forming corresponding portion is larger than the charge amount of the non-image forming corresponding portion. Then, when a new image is formed in the next developing process, the developing agent is more strongly attracted to the portion of the developing sleeve having a high charge amount, so that it is difficult for the image forming corresponding portion to move to the photosensitive member surface side. As a result, a density difference having a pattern corresponding to the image in the previous development process, a so-called ghost image, was found on the developed image of the photoreceptor j-law. In the present invention, this is also referred to as memory).

In view of the problems described above, according to the present invention, even after repeated use, the toner is sufficiently triboelectrically charged on the developing sleeve, and can be carried and transported as a uniform layer without bias. It is an object of the present invention to provide a cylindrical developer carrier that does not cause a difference in developing ability according to the history, and a method for manufacturing the same. Disclosure of the invention According to the present invention, there is provided a cylindrical developer carrier having an alumite layer coated on a uniformly roughened surface of a conductive substrate, wherein the alumite layer uniformly has micropores reaching the substrate. The object is achieved by making the body.

 According to another aspect of the present invention, it is preferable that the conductive substrate is a cylindrical developer carrier mainly composed of an aluminum-based metal material.

 According to the following invention, it is more preferable to use a cylindrical developer carrier in which the alumite layer is an alumite layer formed by an anodizing method.

 According to the next invention, it is desirable that the alumite layer is a cylindrical developer carrier having an alumite layer sealed with nickel acetate.

 According to the following invention, it is more desirable to use a cylindrical developer carrier having an alumite layer thickness of 2 to 5 μm.

 According to the following invention, it is more preferable that the cylindrical developer carrier according to any one of claims 1 to 4, wherein the micropores have an area of 10 to 50% of an alumite layer forming region. .

 According to another embodiment of the present invention, the surface of the conductive substrate is uniformly roughened by blasting with spherical fine particles, and after forming an alumite layer by anodic oxidation, the diameter of the conductive substrate is larger than that of the spherical fine particles. It is appropriate to use a method for producing a cylindrical developer carrying member that is blasted with shaped fine particles.

 According to the next invention, the surface of the conductive substrate is blasted using glass beads as the spherical fine particles, and after the alumite layer is formed by anodic oxidation, the diameter of the aluminum oxide is larger than that of the spherical fine particles. It is more appropriate to use a method for producing a cylindrical developer carrier that is blasted with amorphous particles as a component.

According to the next invention, the surface of the conductive substrate is subjected to blast treatment using glass beads as spherical fine particles, so that irregularities having an average surface roughness Ra = 0.8 to 1.5 μm are obtained. After forming an alumite layer by P-polarization, blasting is performed with amorphous fine particles having aluminum oxide as a main component and having a diameter larger than that of the spherical fine particles. That is even more appropriate. BRIEF DESCRIPTION OF THE FIGURES

 FIG. 1 is a perspective view of a developer carrier according to the present invention.

 FIG. 2 is a partially enlarged sectional view of the developer carrier according to the present invention.

 FIG. 3 is a schematic configuration diagram of an image forming apparatus equipped with the developer carrier according to the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

 Hereinafter, specific examples of the cylindrical developer carrier according to the present invention will be described in detail with reference to the drawings.

 The present invention is not limited to the embodiments described below.

 FIG. 1 is a perspective view of a cylindrical developer carrier, that is, a developing sleeve 11 according to the present invention, FIG. 2 is a partially enlarged sectional view of the developing sleeve 11, and FIG. 3 is a view of the developing sleeve 11 according to the present invention. FIG. 1 is a schematic configuration diagram of an image forming apparatus 100 to be mounted, a developing device including a roller charging member 3, an exposure source 4, a developing container 5 and a developing sleep 11 on an outer peripheral surface of a photoconductor 10, a transfer device 6, This indicates that an electrophotographic process member such as the static eliminator 7 is provided.

In the image forming apparatus 100 using the contact (roller) charging method shown in FIG. 3, the electrophotographic processes are sequentially performed by the members arranged on the peripheral surface of the cylindrical electrophotographic organic photoconductor 10. The image formation is performed. In this image forming method, first, a voltage is applied to a roller charging member 3 arranged in contact with the electrophotographic photoreceptor 10 to charge the surface of the photoreceptor 10, and the image exposure means 4 corresponds to the original. Photoreceptor 1 An image is exposed to 0 to form an electrostatic latent image. Next, the electrostatic latent image on the photoconductor 10 is transferred by electrostatically transferring the toner stirred and charged in the developing container 5 to the surface of the photoconductor 10 via the development sleep 11 and attaching the toner. Develop (visualize). Further, the toner image formed on the photoconductor 10 is transferred by a transfer charger 6 onto a transfer material such as paper supplied through a paper feed roller and a paper feed guide, and is not transferred to the transfer material by a cleaner. Then, the remaining toner remaining on the photoconductor 10 is collected. If residual charges remain inside the photoreceptor, it is better to apply an appropriate voltage to the photoreceptor 10 by the charge removing means 7 to remove the charge or remove the charge using light. On the other hand, the transfer material on which the toner image has been formed is sent to a fixing device (not shown) by the transport unit, where the toner image is fixed and output as an image.

 In this image forming apparatus 100, the light g of the image exposing means 4 can be halogen light, fluorescent light, laser light, or the like. Other auxiliary processes may be added as needed. This image forming apparatus 100 can be widely applied not only to copying machines but also to electrophotographic application fields such as laser beam printers and electrophotographic plate making systems.

Meanwhile, as shown in the perspective view of FIG. 1, the developing sleeve 11 according to the present invention has a shape having a sleeve supporting portion on both sides of a sleeve-shaped conductive base 1 having a diameter of 20 mm, and is made of aluminum alloy. Is used. This diameter may be appropriately changed depending on the device to be mounted. Usually, the diameter is often in the range of 10 to 25 mm. In this example, the composition of the alloy used was JIS standard A6063 material, but may be A5506 material or 3003 material. The surface of the aluminum sleep base 1 is smoothened by cutting or grinding the surface of a raw tube formed by extrusion and drawing of an aluminum alloy ingot using a cutting tool or a grindstone. Next, using a spherical glass bead having an average particle diameter of 44 μm or less (# 600), the surface of the sleeve substrate 1 was blasted, and the average surface roughness Ra was determined. 0.8 to 1.5 m. If the average roughness is larger than 1.5 μm, the toner will remain in the concave and convex portions, and if the average roughness is smaller than 0.8 m, the toner will be too smooth, causing insufficient triboelectric charging of the toner and insufficient toner concentration. In other words, there is a problem that an appropriate image density cannot be obtained. Further, there is a problem that the toner layer is liable to be biased due to slippage of the toner and it is difficult to form a uniform layer.

 Next, the anodized aluminum layer 2 is formed on the surface of the sleeve substrate 1 on which the irregularities having the predetermined size are formed by the anodizing method, and the sealing process is performed. The sealing treatment is preferably a Huckel acetate sealing, but the effect of the present invention can also be obtained by a sealing treatment using a croaker. The thickness of the alumite layer is preferably in the range of 2 to 5 μm. If it is thicker than 5 μm, it will be difficult to uniformly and innumerably form the fine holes 21 reaching the aluminum substrate 1 according to the present invention later. If the thickness is less than 2 μm, the alumite layer wears quickly and the durability deteriorates.

 The formation of the fine pores 21 after the formation of the alumite layer 2 is performed by a plast treatment of amorphous aluminum oxide (alumina) fine particles having a higher hardness than alumite. Fine particles of other materials may be used as long as they are harder than alumite. The particle size of the alumina fine particles (for example, # 320) having a diameter larger than that of the glass beads (for example, # 600) is used. The purpose of the blast treatment after the formation of the alumite layer 2 is to remove as much as possible the alumite layer 2 on the protrusions of the alumite layer 2 and to provide countless and uniform micro holes 21 reaching the aluminum substrate 1. Further, by uniformly providing a myriad of leak sites for the charge of the toner, the surface resistance of the alumite layer 2 is reduced, and the above-described problem of the difference in developing ability according to the development history is solved.

The following experiment was conducted in order to obtain an appropriate area ratio of the fine pores formed mainly in the projections of the above-described irregularities of the alumite layer 2 to the entire alumite layer 2 formation region. Each of the developing sleeves 1 having a total area ratio of the micropores 21 to the layer 2 area of 5%, 10%, 20%, 40%, 50%, 60%, 70%, 100% One sample was prepared, and image evaluation and sleeve life were examined.

 The total micropore area ratio was determined by using the difference in the light reflectance between the alumite layer 2 region and the micropore 21. Specifically, it was determined by using a light reflectometer and a calibration curve created from a sample known in advance. Alternatively, the area ratio may be obtained from an enlarged photograph of the sleeve surface. The results are shown in the table below.

 The image density was measured with a Macbeth densitometer, with a value of 1.3 or more marked as 〇, a value of 1.2 to 1.3 as △, and a value of 1.2 or less as X. From this image density evaluation, it can be seen that the toner is sufficiently triboelectrically charged on the developing sleeve, and is carried and transported as a uniform layer without bias.

 In the image memory, no occurrence was indicated by 〇, slight occurrence was indicated by △, and occurrence was indicated by X. From this image memory evaluation, it can be seen that the developing sleeve is in a surface state having an appropriate leak site where there is no difference in developing ability according to the developing history.

 The life of the sleeve was rated 〇 for durability of 20,000 or more, 〇 for 10,000 to 20,000, and X for 10,000 or less. From this life, it is possible to determine whether there is a change (or deterioration) in the characteristics of the previous two evaluations after initial use and after repeated use of a predetermined number of sheets.

In the overall evaluation, all three items were rated as Δ, and if there was at least one X, the overall evaluation was also X.

【table 1】

From the above table, when the ratio of the area of the micropores according to the present invention to the alumite layer region on the surface of the developing sleeve is 10 to 50%, all three items are evaluated as 〇, and the overall evaluation is also 〇. It is clear that. Industrial applicability

 According to the present invention, there is provided a cylindrical developer carrier having an alumite layer coated on a uniformly roughened conductive substrate surface, wherein the alumite layer uniformly has micropores reaching the substrate. Therefore, even after repeated use, the toner is sufficiently triboelectrically charged on the developing sleeve, and can be carried and transported as a uniform layer without deviation, and there is no difference in developing ability according to the development history. A cylindrical developer carrier can be provided.

Claims

The scope of the claims 1. A cylindrical developer carrier having an alumite layer coated on a uniformly roughened surface of a conductive substrate, wherein the alumite layer is uniformly provided with micropores reaching the substrate. 2. The cylindrical developer carrier according to claim 1, wherein the conductive substrate is mainly made of an aluminum-based metal material. 3. The cylindrical developer carrier according to claim 1, wherein the alumite layer is an alumite layer formed by an anodic oxidation method. 4. The cylindrical developer carrier according to claim 1, wherein the alumite layer is a nickel oxide-sealed alumite layer. 5. The cylindrical developer carrier according to claim 3, wherein the alumite layer is an alumite layer sealed with nickel acetate. 6. The cylindrical developer carrier according to claim 1, wherein the thickness of the alumite layer is 2 to 5 μm. 7. The cylindrical developer carrier according to claim 5, wherein the thickness of the alumite layer is 2 to 5 m. 8. The cylindrical developer carrier according to claim 1, wherein the micropores reaching the substrate have an area of 10 to 50% of an alumite layer forming region. 9. The cylindrical developer carrier according to claim 7, wherein the micropores reaching the substrate have an area of 10 to 50% of the alumite layer forming region. 10. After the surface of the conductive substrate is roughened by blasting with spherical fine particles and an alumite layer is formed by anodic oxidation, the surface of the conductive substrate is subjected to plasting with irregularly shaped fine particles having a diameter larger than that of the spherical fine particles. For producing a cylindrical developer carrier. 11. After conducting a blast treatment on the surface of the conductive substrate using glass beads as the spherical fine particles and forming an alumite layer by anodic oxidation, the non-crystalline aluminum oxide having a larger diameter than the spherical fine particles as a main component. 12. The method for producing a cylindrical developer carrier according to claim 10, wherein the blast treatment is performed by using fixed fine particles. 12. The surface of the conductive substrate was blasted using glass beads as spherical fine particles to provide irregularities with an average surface roughness Ra = 0.8 to 1.5 m, and the alumite layer was formed by anodic oxidation. 21. The method for producing a cylindrical developer carrier according to claim 11, wherein blasting is performed by using irregular shaped fine particles mainly composed of aluminum oxide having a diameter larger than that of the spherical fine particles.