JP2014203003A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of filming even when an intermediate transfer belt manufactured by extrusion molding and having no coat layer on the surface is cleaned with a blade member, and to polish the surface of the intermediate transfer belt over time to reduce the roughness on the surface smaller than the initial state.SOLUTION: An intermediate transfer belt 3 is manufactured by extrusion molding and is a resin belt of a single-layer structure having no coat layer on the surface. A blade member 21 includes a cleaning blade 222 that is formed of an elastic body and brings, into contact with the surface of the intermediate transfer belt 3, an edge part including a ridge line 22c of the tip part located on the intermediate transfer belt 3 side to clean the surface of the intermediate transfer belt 3. The cleaning blade 222 has a mixed layer 22d of an acrylic resin and urethane rubber being a base material of the cleaning blade formed in a thickness of 1.0 μm or more from the surface of the tip part toward the inside, and has a surface layer 223 composed of an acrylic resin formed in a thickness of 0.1 μm or more on the surface of the tip part, where the surface layer contains polishing agent particles.

Description

  The present invention relates to an image forming apparatus using an electrophotographic system, such as a copying machine, a facsimile machine, a printer, a plotter, or a multi-function machine having a plurality of functions.

  Conventionally, a toner image is formed on a photoconductor as an image carrier, transferred to an endless belt-shaped intermediate transfer body (hereinafter, described as an “intermediate transfer belt” as a specific example), and further transferred to the intermediate 2. Description of the Related Art Image forming apparatuses that transfer a toner image on a transfer body onto transfer paper as a recording medium are widely known. In recent years, in response to the demand for colorization, a tandem (for example, four drums) that has a plurality of image forming portions that form toner images on an image carrier and forms toner images of a plurality of colors on an intermediate transfer member at once. ) Type electrophotographic image forming apparatus is widely used.

  As an intermediate transfer member used in these image forming apparatuses, a resin belt having a high elastic modulus (Young's modulus) with polyimide (hereinafter referred to as “PI”) as the head is often used (for example, Patent Document 1). reference). On the other hand, since a low-cost image forming apparatus is desired, there is an increasing demand for a low-cost intermediate transfer member. Polyamideimide (hereinafter referred to as “PAI”), which is lower in cost than PI, or polyfluoride Vinylidene (hereinafter referred to as “PVDF”), polycarbonate (hereinafter referred to as “PC”), polyphenylene sulfide (hereinafter referred to as “PPS”), and the like are also used. Hereinafter, although an intermediate transfer belt will be described as a specific example of the intermediate transfer member, it is also simply referred to as a belt unless confusion occurs.

  Patent Document 1 discloses a blade member in an image forming apparatus in which a magnetic brush is installed prior to a cleaning process of an intermediate transfer body for the purpose of improving the removal of residual toner components on a resin belt-shaped intermediate transfer body. A material in which the contact surface with the intermediate transfer member is made of a resin and the surface hardness and Young's modulus are smaller than the resin of the intermediate transfer member is disclosed.

  Not all low-cost intermediate transfer belts have low elasticity, but in reality, low-cost intermediate transfer belts have low elasticity. The reason PVDF and PC are low in cost is that they are manufactured by extrusion molding, which is a continuous molding, even though the material cost is high. It depends. The thermoplastic resin that is the material of these intermediate transfer belts has low heat resistance and low elastic modulus.

  On the other hand, the reason for the high cost of the PI belt is that, in addition to the high material cost, it is generally manufactured by a centrifugal molding method. That is, because centrifugal molding is a batch process, the production efficiency is low, and because the heat resistance is high, the drying temperature is high and the production time is long.

  However, since the productivity is high, a belt manufactured by extrusion molding, which is known as a low-cost manufacturing method, has a larger surface roughness than those manufactured by centrifugal molding such as PI and PAI. Therefore, when performing so-called process control in which a toner patch is created on the intermediate transfer belt, the toner amount is detected by an optical detection means, and image forming conditions are changed based on the detection result, the problems described below are performed. There has occurred.

  That is, in an image forming apparatus such as an electrophotographic copying machine or a laser beam printer, a density detection toner pattern is formed on an image carrier such as an intermediate transfer belt in order to always obtain a stable image density. (Hereinafter also referred to as “P pattern”). Then, the density of the P pattern is detected by an optical detection means, and the development potential is changed based on the detection result (specifically, the exposure power, charging bias, and development bias are changed) to affect the image density. The development density is controlled.

  In the case of the two-component development method, image density control is performed such that the maximum target adhesion amount (adhesion amount for obtaining a target ID) becomes a target value by changing the toner density control target value in the developing device. It is carried out. A process control operation (hereinafter also referred to as a “procedure operation”) is executed in order to optimize the image density of each color when the power is turned on or after a predetermined number of sheets have passed.

  In this process control operation, a P pattern corresponding to a standard detection object composed of gradation patterns for each color toner is created on the intermediate transfer belt by sequentially switching the charging bias and developing bias at appropriate timing. Image. Then, the output voltage of these P patterns is set to a density arranged near one of the driving rollers of the intermediate transfer belt, at a position where the respective photoconductors are arranged side by side, and outside the position where the intermediate transfer belt has passed. It is detected by a detection sensor (hereinafter abbreviated as “P sensor”). Although not described in detail below, the output value of the P sensor is converted by the adhesion amount conversion algorithm (powder adhesion amount conversion method) to calculate the development γ and Vk representing the current developing ability, Based on this, control for changing the development bias value and the toner density control target value is performed.

  Such a P pattern detection means is a reflection type in which an LED (light emitting diode) as a light emitting element (light emitting means) and a PD (photodiode) or PTr (phototransistor) as a light receiving element (light receiving means) are combined. An optical sensor is generally used. As a reflection type optical sensor, a configuration in which only specular reflection light from the P pattern (density detection toner pattern) is a detection target, a configuration in which only diffuse reflection light from the P pattern is a detection target, and reflection of both of these. A configuration in which light is a detection target is known.

In any configuration, it is necessary to accurately detect the amount of reflected light, and when the glossiness of the intermediate transfer belt is lowered due to filming or scratches on the surface of the intermediate transfer belt, the detection performance may be deteriorated. In addition, when the surface roughness of the surface of the intermediate transfer belt is large, the detection performance is deteriorated. Therefore, it is preferable that the surface roughness is small.
For this reason, an intermediate transfer belt having a high glossiness and a small surface roughness has been used in order to maintain the above detection accuracy. In the intermediate transfer belt manufactured by centrifugal molding, the surface roughness of the surface of the intermediate transfer belt is determined by the roughness of the mold at the time of molding. Therefore, the surface roughness of the intermediate transfer belt can be controlled by controlling the surface roughness of the mold. It is possible to manage the surface roughness. As for glossiness, PI and PAI belts manufactured by centrifugal molding have sufficient glossiness for optical detection when they are new.
However, PI and PAI belts have high material costs and low production efficiency due to batch processing, high heat resistance, high drying temperature, and long production time. It is.

  On the other hand, intermediate transfer belts manufactured by extrusion molding may vary in surface roughness due to temperature variations across the entire belt as well as manufacturing process reasons, and surface roughness is generally not as small as that of centrifugally molded belts. Is. For this reason, an intermediate transfer belt for extrusion molding may be subjected to surface polishing or surface coating to maintain the smoothness and glossiness of the surface. Increase.

  In the above-described reflection type optical sensor, the specular reflection output (hereinafter referred to as “Vsg”) of the background portion of the intermediate transfer belt (where no toner adheres) becomes a predetermined value (for example, 4.0 ± 0.5 V). The LED current is adjusted. This adjustment operation is called “Vsg adjustment”, and the LED current determined by the Vsg adjustment operation is defined as “Vsg adjustment current” or “Ifsg”.

  Here, with reference to FIG. 6 to FIG. 9, problems and problems of the prior art will be described based on the above-described background art contents. FIG. 6 is a graph obtained by measuring the Vsg fluctuation of an intermediate transfer belt α made of PI manufactured by centrifugal molding over a belt circumferential length of 100 mm. FIG. 7 is a graph in which the Vsg variation of an intermediate transfer belt β made of PPS manufactured by extrusion molding is measured over a belt circumferential length of 100 mm. FIG. 8 is a graph showing a result of measuring 10 P patterns on the intermediate transfer belt α with 10 kinds of gradations and measuring the regular reflection output (belt initial stage) with a reflection type optical sensor. FIG. 9 is a graph showing the result of measuring 10 regular P patterns on the intermediate transfer belt β and measuring the regular reflection output (belt initial stage) with a reflective optical sensor.

The test and measurement results shown in FIG. 6 to FIG. 9 are components of related parts using imagio MP C2201 (corresponding to the basic configuration of the image forming apparatus shown in FIG. 1 described later) manufactured by Ricoh Co., Ltd.・ It was obtained by changing specifications.
Both the intermediate transfer belt α and the intermediate transfer belt β are adjusted to Vsg so that Vsg is 4.0 V. Ifsg of the intermediate transfer belt α is 8.6 mA, and Ifsg of the intermediate transfer belt β is 7.0 mA. It was. The surface roughness of the intermediate transfer belt α was Rz: 0.85 [μm], whereas the surface roughness Rz of the intermediate transfer belt β was 0.80 [μm]. Regarding the glossiness (measured at 20 °), the intermediate transfer belt α was 140 and the intermediate transfer belt β was 107. From these, it can be seen that the smaller the surface roughness and the higher the glossiness of the belt surface, the better the stability of Vsg.

  The surface roughness Rz is measured in accordance with the ten-point average roughness Rz defined in JIS B0601: 1982. That is, in the part extracted by the reference length from the cross-sectional curve, the value of the difference between the average value of the highest altitude of the peak from the highest to the fifth and the average value of the altitude of the valley from the deepest to the fifth is expressed in μm. Is. Further, the glossiness (20 ° measurement) was measured using a glossmeter for the specular glossiness according to JIS Z 8741: 1997.

  The detection accuracy of the intermediate transfer belt β having a large Vsg variation shown in FIGS. 7 and 9 is worse than the intermediate transfer belt α having a small Vsg variation shown in FIGS. 6 and 8, but the peak voltage Max of the Vsg of the intermediate transfer belt β. The difference between Min and Min is about 0.5 V, and the minimum detection accuracy can be secured within this range. Therefore, it was found that the intermediate transfer belt β can secure the minimum detection accuracy in the initial state.

  On the other hand, for the purpose of power saving, image forming apparatuses are proceeding with low-temperature fixing of toner. When such toner is used, the toner tends to melt on the surface of the intermediate transfer belt. If the toner melts in a part of the extrusion belt (hereinafter referred to as “toner filming”), the Vsg detection is not performed accurately, which is worse than the minimum detection accuracy secured in the initial belt. Become. As described above, there is a problem in that the amount of light is not accurately detected due to the occurrence of filming, and thus the image density control is not accurately performed.

  From the test results described above and the contents described with reference to FIG. 10 described later, filming is considered to occur for the following reasons. When the surface of the intermediate transfer belt in the filming portion was analyzed, toner, paper powder, and additives were detected, but other material components of the intermediate transfer belt were also detected in a large proportion. If images having a low image area ratio are continuously formed, there is almost no toner on the intermediate transfer belt, and it is considered that friction is continuously generated between the intermediate transfer belt and the blade member. Therefore, in the case of a single-layer blade, the amount of stick-slip, which is a vibration phenomenon that occurs on the sliding surface, is large, the blade member is worn, and the fine powder is rubbed against the surface of the intermediate transfer belt while scraping the surface. It is thought that is generated.

With reference to FIG. 10, the contact state between the blade member of the conventional image forming apparatus and the intermediate transfer belt will be described. FIG. 10A is a cross-sectional view for explaining the behavior of the blade member, and FIG. 10B is a contact portion of the edge portion of the cleaning blade in FIG. It is an expanded sectional view explaining a state.
In the example shown in FIG. 10, a conventional blade member 40 is constituted by a cleaning blade 41 and a holder 42, and the cleaning blade 41 is brought into contact with an intermediate transfer belt 43 made of PPS manufactured by extrusion molding. In this example, the cleaning blade 41 is made of urethane rubber having a single layer and a 100% modulus value of 2.5 [Mpa].
Here, the “100% modulus value” means that a certain strain (100% in this case) is applied to an elastic body such as rubber (the force that the object tries to resist to keep the original shape). This means the stress of the same (hereinafter the same).

As shown in FIG. 10B, since the strength of the cleaning blade 41 is low, the blade tip surface 41a, which is a contact portion with the surface of the intermediate transfer belt 43, is greatly deformed, and the amount of stick slip increases. The behavior of the tip surface 41a becomes unstable. For this reason, the cleaning property is deteriorated, and toner, toner additive, paper powder and the like are rubbed on the surface, and filming occurs. Further, the vibration of the blade member 40 is increased, and the nip width formed on the blade front end surface 41a, which is the edge portion including the ridge line, is increased by contact with the surface of the intermediate transfer belt 43, and the wear amount of the cleaning blade 41 is increased. Will be.
On the other hand, when the contact pressure of the cleaning blade 41 is increased for the purpose of preventing the occurrence of filming, the frictional force between the intermediate transfer belt 43 and the blade tip surface 41a increases, so that the filming is not improved. In addition, when the hardness of the blade material was increased, the belt surface was damaged when the intermediate transfer belt had a low elastic modulus.

  The present invention has been made in view of the above circumstances, and prevents filming from occurring even when an endless belt-shaped intermediate transfer body produced by extrusion molding and having no coating layer on the surface is cleaned with a blade member. An object of the present invention is to provide an image forming apparatus capable of polishing the surface by use over time and reducing the roughness of the surface of the intermediate transfer member from the initial state.

In order to solve the above problems and achieve the above object, the present invention employs the following characteristic means / invention specific items (hereinafter referred to as “configuration”).
The present invention provides an endless belt-shaped intermediate transfer member for transferring a toner image formed on an image carrier, and a toner image formed on the intermediate transfer member after being transferred to a recording medium, In the image forming apparatus comprising a blade member for removing the transfer residual toner, the intermediate transfer body is a resin belt having a single layer structure which is manufactured by extrusion molding and has no coating layer on the surface thereof. The blade member is a cleaning blade body formed of an elastic body that cleans the surface of the intermediate transfer body by bringing an edge portion including a ridge line of a tip portion located on the intermediate transfer body side into contact with the surface of the intermediate transfer body. The cleaning blade body is directed from the surface of the tip portion to the inside, and at least one of an acrylic resin and a methacrylic resin and a base of the cleaning blade body. And a surface layer made of at least one of the acrylic resin and the methacrylic resin on the surface of the tip portion. The layer thickness is 0.1 μm or more, and abrasive particles are contained in the surface layer.

  According to the present invention, in an image forming apparatus using an endless belt-shaped intermediate transfer body produced by extrusion molding having no coating layer on the surface, the blade member having the above-described structure for polishing the surface without causing stick-slip is provided. By using it, it is possible to reduce the surface roughness of the intermediate transfer body having a large surface roughness in the initial state while preventing filming by using it over time.

1 is a schematic overall configuration diagram of an image forming apparatus showing a first embodiment. (A) is sectional drawing of the blade member used for 1st Embodiment, (b) is an expanded sectional view of the front-end | tip part of the blade member, (c) is a perspective view of the blade member. It is a side view which shows the base material of the blade member used for 1st Embodiment. (A) is sectional drawing explaining the behavior of the blade member used for 1st Embodiment, (b) is a contact part with the intermediate transfer belt of the edge part of the cleaning blade of (a) (enclosed by a round broken line) It is an expanded sectional view explaining the state of). (A) is sectional drawing explaining the behavior of the blade member used for 2nd Embodiment, (b) is a contact part with the intermediate transfer belt of the edge part of the cleaning blade of (a) (enclosed with a round broken line) It is an expanded sectional view explaining the state of). It is a figure explaining the subject of a prior art, Comprising: It is the graph which measured the Vsg fluctuation | variation of the intermediate transfer belt (alpha) made from PI manufactured by centrifugal molding over the belt circumferential direction length. It is a figure explaining the subject of a prior art, Comprising: It is the graph which measured the Vsg fluctuation | variation of the intermediate transfer belt (beta) made from PPS manufactured by extrusion molding over the belt circumferential direction length. It is a figure explaining the subject of a prior art, Comprising: It is a graph which shows the result of having created P pattern on the intermediate transfer belt (alpha) with 10 types of gradations, and having measured the regular reflection output (belt initial stage) with the reflection type optical sensor is there. It is a figure explaining the subject of a prior art, Comprising: It is a graph which shows the result of having produced P pattern on the intermediate transfer belt (beta) in 10 types of gradations, and measuring the regular reflection output (belt initial stage) with the reflection type optical sensor. is there. It is a figure explaining the subject of a prior art, (a) is sectional drawing explaining the behavior of a blade member, (b) is a contact part with the intermediate transfer belt of the edge part of the cleaning blade of (a) (circle broken line) It is an enlarged sectional view explaining the state of (enclosed by).

  Hereinafter, embodiments of the present invention including examples will be described in detail with reference to the drawings. In each embodiment and the like, components (members and components) having the same function and shape are described once unless they are confused, and the description thereof is omitted by giving the same reference numerals.

(First embodiment)
A first embodiment of the present invention will be described with reference to FIGS. The image forming apparatus according to the first embodiment uses, as an endless belt-shaped intermediate transfer body, a resin belt having a single-layer structure that is manufactured by extrusion molding and does not have a coat layer on the surface. The blade member for removing the transfer residual toner on the body has the following characteristics.
The blade member is made of urethane rubber which is a one-layer or two-layer elastic body that cleans the surface of the intermediate transfer body by bringing the edge portion including the ridge line of the tip portion positioned on the intermediate transfer body side into contact with the surface of the intermediate transfer body. The cleaning blade body is provided. The cleaning blade body is a mixed layer of at least one of acrylic resin and methacrylic resin having a layer thickness (film thickness) of 1.0 μm or more from the surface of the tip portion to the inside and the base material of the cleaning blade body. Is formed. Furthermore, a surface layer made of at least one of acrylic resin and methacrylic resin of 0.1 μm or more is formed on the surface of the tip of the cleaning blade body, and the surface layer contains abrasive particles. is there.

  First, the overall configuration of the image forming apparatus according to the first embodiment will be described with reference to FIG. FIG. 1 is a schematic overall configuration diagram of an image forming apparatus showing a first embodiment of the present invention. An image forming apparatus 30 shown in FIG. 1 is a tandem type color printer, and includes first to fourth photoconductors 1a, 1b, 1c, and 1d as a plurality of image carriers disposed in an apparatus main body 31. Is provided.

  Different color toner images are formed on the photoreceptors 1a, 1b, 1c, and 1d, respectively. A black toner image, a cyan toner image, a magenta toner image, and a yellow toner image are formed on the photoreceptors 1a, 1b, 1c, and 1d, respectively. Note that each of the photoconductors 1a, 1b, 1c, and 1d shown in FIG. 1 is formed in a drum shape, but an endless belt-like photoconductor that is wound around a plurality of rollers and driven to rotate may be used. it can.

  An intermediate transfer belt 3 as an intermediate transfer member made of an endless belt and made of a resin belt is disposed opposite to the photosensitive members 1a, 1b, 1c, and 1d. It is in contact with the surface of the transfer belt 3. The intermediate transfer belt 3 has an annular shape and is wound around a support roller 4, a tension roller 5, a backup roller 6, and an entrance roller 7. One of the rollers, for example, the support roller 4 is configured as a driving roller driven by a driving source (not shown), and the intermediate transfer belt 3 is rotationally driven in the direction of arrow A by the driving of this roller.

The intermediate transfer belt 3 has a surface roughness Rz: 0.3 μm or more, and is effective for a belt obtained by extrusion molding. Here, the surface roughness Rz is a ten-point average roughness Rz defined in JIS B0601: 1982.
As the material of the intermediate transfer belt 3, a material using PVDF, PC, thermoplastic elastomer (TPE), PPS, polyetherimide resin (PEI), polyethersulfone resin (PES) or the like is suitable. Alternatively, a mixture of these materials may be used.

  The formation of toner images on the photoreceptors 1a, 1b, 1c, and 1d and the transfer of each toner image to the intermediate transfer belt 3 are substantially the same in each of the photoreceptors 1a, 1b, 1c, and 1d. The only difference is the color of the toner image. Therefore, only the formation of the black toner image on the photosensitive member 1a and the transfer of the toner image to the intermediate transfer belt 3 will be described.

  The photoconductor 1a is driven to rotate clockwise as indicated by an arrow C in FIG. 1. At this time, the surface of the photoconductor 1a is irradiated with light from a static eliminator (not shown), and the surface potential of the photoconductor 1a is initially set. It becomes. The initialized photoreceptor 1a is uniformly charged by the charging device 8 to a predetermined polarity, in this example, a negative polarity. The charged surface is irradiated with a light-modulated laser beam L emitted from the exposure device 9, and an electrostatic latent image corresponding to the writing information is formed on the surface of the photoreceptor 1a. In the image forming apparatus shown in FIG. 1, an exposure apparatus 9 including a laser writing apparatus that emits a laser beam is used. However, an exposure apparatus having an LED array and an image forming unit can also be used.

  The electrostatic latent image formed on the photoreceptor 1 a is visualized as a black toner image by the developing device 10. On the other hand, on the inner side of the intermediate transfer belt 3, a primary transfer roller 11a as a primary transfer unit is disposed at a position facing the photoreceptor 1a with the intermediate transfer belt 3 interposed therebetween. The primary transfer roller 11 a comes into contact with the back surface of the intermediate transfer belt 3, and an appropriate transfer nip between the photoreceptor 1 a and the intermediate transfer belt 3 is formed.

The primary transfer roller 11a is applied with a transfer voltage having a polarity opposite to the toner charging polarity of the toner image formed on the photoreceptor 1a, in this example, a positive polarity. As a result, a transfer electric field is formed between the photoreceptor 1a and the intermediate transfer belt 3, and the black toner image on the photoreceptor 1a is electrostatically applied to the intermediate transfer belt 3 that is rotationally driven in synchronization with the photoreceptor 1a. Is transcribed. Transfer residual toner adhering to the surface of the photoreceptor 1a after the black toner image is transferred to the intermediate transfer belt 3 is removed by the cleaning device 12, and the surface of the photoreceptor 1a is cleaned.
Similarly, a cyan toner image, a magenta toner image, and a yellow toner image are respectively formed on the other photoreceptors 1b, 1c, and 1d, and the toner images of the respective colors are transferred to the intermediate transfer belt to which the black toner image is transferred. Electrostatic transfer is performed by sequentially superimposing on 3.

  The image forming apparatus 30 is driven in two modes: a full color mode using four color toner images and a black single color mode using only a black single color. In the full color mode, the intermediate transfer belt 3 and all the photoreceptors 1a, 1b, 1c, and 1d come into contact with each other, and four color toner images are transferred onto the intermediate transfer belt 3. On the other hand, in the black monochrome mode, only the photoreceptor 1 a contacts the intermediate transfer belt 3, and only black toner is transferred to the intermediate transfer belt 3. At this time, the intermediate transfer belt 3 and the cyan, magenta, and yellow photoconductors 1b, 1c, and 1d are not in contact with the intermediate transfer belt 3, and the primary transfer rollers 11b, 11c, and 11d are moved by a contact / separation mechanism (not shown). The photoconductors 1b, 1c, and 1d are separated from each other. At that time, the profile of the intermediate transfer belt 3 is changed by moving the backup roller 6 in order to reliably separate the intermediate transfer belt 3 from the cyan, magenta, and yellow photoreceptors 1b, 1c, and 1d.

  As shown in FIG. 1, a sheet feeding device 14 is disposed at the lower part of the apparatus main body 31. In the paper feeding device 14, the recording medium P made of transfer paper, for example, is sent out in the arrow B direction by the rotation of the paper feeding roller 15. The fed recording medium P is a portion of the intermediate transfer belt 3 that is wound around the support roller 4 at a predetermined timing by the registration roller pair 16 and a secondary transfer device that is arranged in correspondence therewith. It is conveyed between the rollers 17. At this time, a predetermined transfer voltage is applied to the secondary transfer roller 17, whereby the toner image superimposed and transferred on the intermediate transfer belt 3 is secondarily transferred to the recording medium P.

  The recording medium P on which the toner image is secondarily transferred is further conveyed upward and passes through the fixing device 18. At this time, the toner image on the recording medium P is fixed by the fixing device 18 by heat and pressure. The recording medium P that has passed through the fixing device 18 is discharged to, for example, a paper discharge tray disposed outside the image forming apparatus by a pair of paper discharge rollers 19 provided in the paper discharge unit.

  Next, the intermediate transfer belt 3 will be described. The intermediate transfer belt 3 has, for example, the following configuration and uses two types of intermediate transfer belts # 1 and # 2 manufactured by extrusion molding.

(1) Intermediate transfer belt # 1
Material: PPS
Young's modulus: 3200 MPa
Thickness dimension: 80μm
Line speed: 256mm / s
Tension: 1.3N / cm

(2) Intermediate transfer belt # 2
Material: PVDF
Young's modulus: 950 MPa
Thickness dimension: 140μm
Line speed: 120mm / s
Tension: 1.3N / cm

  Next, toner used in the image forming apparatus 30 of the first embodiment will be described. As the toner used in the image forming apparatus 30 of the present embodiment, a polymerized toner manufactured by a suspension polymerization method, an emulsion polymerization method, or a dispersion polymerization method, which is easy to increase the circularity and the particle size, is used to improve the image quality. It is preferable. In particular, it is preferable to use a polymerized toner having a circularity of 0.97 or more and a volume average particle size of 5.5 [μm] or less. By using a material having an average circularity of 0.97 or more and a volume average particle size of 5.5 [μm], a higher resolution image can be formed.

  The “circularity” here is an average circularity measured by a flow type particle image analyzer FPIA-2000 (trade name, manufactured by Toa Medical Electronics Co., Ltd.). Specifically, a surfactant, preferably an alkylbenzene sulfonate, is added in an amount of 0.1 to 0.5 [ml] as a dispersant in 100 to 150 [ml] of water from which impure solids have been removed in advance. Further, about 0.1 to 0.5 [g] of a measurement sample (toner) is added. Thereafter, the suspension in which the toner is dispersed is subjected to a dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes so that the concentration of the dispersion becomes 3000 to 1 [10,000 / μl]. To measure the shape and distribution of the toner. Based on the measurement result, C2 / C1 when C1 is the outer peripheral length of the actual toner projection shape, S is the projected area, and C2 is the outer peripheral length of a perfect circle showing the same area as the projected area S. The average value was determined as the circularity.

  Further, the toner suitably used for the color printer can be obtained by the following method. That is, a polyester prepolymer having a functional group containing at least a nitrogen atom, a polyester, a colorant, and a toner material liquid in which a release agent is dispersed in an organic solvent are subjected to a crosslinking and elongation reaction in an aqueous solvent. At least one reaction is performed.

  Next, process control in the image forming apparatus 30 of the first embodiment will be described. In the image forming apparatus 30 of the first embodiment, apart from the normal image forming mode as described above, a process control operation is performed to optimize the image density of each color when the power is turned on or after a predetermined number of sheets have passed. Executed. In this process control operation, a density detection toner pattern (P pattern) corresponding to a standard detection object having a gradation pattern for each color toner is sequentially switched between charging bias and development bias at appropriate timing. As a result, an image is formed on the intermediate transfer belt 3. At this time, the output voltage of these P patterns is detected by the density detection sensor 13 arranged at the position shown in FIG. In the density detection sensor 13, the intermediate transfer belt 3 passes through a position near the entrance roller 7 between the support roller 4 and the entrance roller 7, which is a driving roller of the intermediate transfer belt 3, where the respective photoconductors are arranged side by side. The downstream intermediate transfer belt 3 is arranged outside and outside.

  Then, the output value from the density detection sensor 13 is converted by an adhesion amount conversion algorithm (powder adhesion amount conversion method) to calculate development γ and Vk representing the current developing ability, and based on this calculated value, Control for changing the development bias value and the toner density control target value is performed.

Here, a supplementary explanation will be given regarding development γ and Vk representing the current development capability. In an electrophotographic image forming apparatus, the characteristics of a developer or a photoconductor as an image carrier change depending on the usage environment, deterioration with time, etc., so that a plurality of patch patterns (P patterns) are statically formed on the image carrier. An electrostatic latent image is formed and the patch pattern is developed by a developing device. There are known methods for calculating various potentials such as a developing bias potential and a charging potential of the image carrier from the developing potential of the patch pattern and the toner adhesion amount. For example, the relationship between the development potential (V) on each patch pattern and the toner adhesion amount (mg / cm ² ) is linearly approximated. Next, a development potential capable of obtaining a predetermined maximum toner adhesion amount is obtained from the development γ that is the slope of the linear approximation formula and the development start voltage (Vk) that is an intercept between the linear approximation formula and the potential axis, and the development potential Methods for obtaining various potentials from values are known.

The density detection sensor 13 is a member used for executing the development density control method according to the present embodiment, and includes an LED built in the element holder, a regular reflection light receiving element, and a diffuse reflection light receiving element. Then, the density detection sensor 13 reflects the reflected light of the light emitted from the light emitting element (the reflected component of the irradiated light) to the P pattern (density detection toner pattern) using the toner pattern formed on the detection target surface. Are detected by each light receiving element.
Note that a phototransistor or a photodiode is used as the light receiving element. As described above, the density detection sensor 13 is composed of a reflection type optical sensor, and functions as a reflected light amount detection unit having a light emitting element that irradiates light on the surface of the intermediate transfer belt 3 and a light receiving element that receives reflected light.

Next, the belt cleaning device 20 will be described in detail. The transfer residual toner adhering to the intermediate transfer belt 3 after the toner image transfer is removed by the belt cleaning device 20. In the image forming apparatus 30 of the present embodiment, the blade member 21 is used for the belt cleaning apparatus 20.
Hereinafter, the blade member 21 will be described with reference to FIG. 2A and 2B show a blade member used in a belt cleaning device of an image forming apparatus. FIG. 2A is a sectional view of the blade member, and FIG. 2B is an enlarged sectional view of a tip portion of the blade member. FIG. 2C is a perspective view of the blade member. 2A, 2B, and later-described FIGS. 4A and 5A, the surface layer 223 has a very thin layer thickness (film thickness) as described later. In Fig. 1, the features are exaggerated and enlarged to clearly show their characteristics.
As shown in FIGS. 2A and 2C, the blade member 21 includes a rectangular parallelepiped holder 221 made of a rigid material such as metal or hard plastic as a support member, and a rectangular parallelepiped shape as a cleaning blade body. And a cleaning blade 222. The cleaning blade 222 is fixed to one end side of the holder 221 with an adhesive or the like, and the other end side of the holder 221 is cantilevered by the case 20 a of the belt cleaning device 20.

  The cleaning blade 222 has a structure including a plurality of layers, in this embodiment, a two-layer structure. That is, as shown in FIG. 2, the cleaning blade 222 is disposed on the intermediate transfer belt 3 side and has a contact layer 224 on which an edge portion including a ridge line 22c that contacts the intermediate transfer belt 3 is formed. And a backup layer 225 connected and fixed to the holder 221.

  FIG. 3 is a side view showing the base material of the blade member 21. The cleaning blade 222 is manufactured by forming the mixed layer 22d and the surface layer 223 on the tip 22e of the base material 23 composed of two layers of the contact layer 224 and the backup layer 225 shown in FIG. The mixed layer 22d is shown with hatching in FIG. 2, and the surface layer 223 is shown with a granular pattern in FIG.

  The contact layer 224 and the backup layer 225 constituting the base material 23 are formed of urethane rubber that is an elastic body. The contact layer 224 is set to be stronger than the backup layer 225. The contact layer 224 has a 100% modulus value larger than the backup layer 225. Thereby, the edge part which is the front-end | tip part of the blade member 21 is stabilized, and cleaning performance can be improved.

In this embodiment, a urethane rubber material having a 100% modulus at 23 ° C. of 6 Mpa to 12 Mpa, more preferably 6 to 7 MPa, is used for the contact layer 224. Further, a urethane rubber material having a 100% modulus at 23 ° C. of 4 to 5 MPa can be used for the backup layer 225.
The cleaning blade 222 is not limited to two layers, and may be three or more layers. At this time, the 100% modulus values of the plurality of layers are different, and the 100% modulus value of the contact layer is maximized among the plurality of layers.

Further, the contact layer 224 and the backup layer 225 are made of urethane rubber and measured with a rubber hardness meter, the contact layer 224 has a rubber hardness of 80 degrees (JIS-A scale), and the backup layer 225 has a rubber hardness of 75 degrees (JIS-). The same effect can be obtained by using the (A scale) type.
The characteristics of the contact layer 224 and the backup layer 225 can be changed depending on the toner, the speed of the intermediate transfer belt 3, and the like. Further, the thickness of the contact layer 224 can be 0.5 mm and the thickness of the backup layer 225 can be 1.3 mm, but the ratio of the thicknesses of both can be changed by selecting the rubber hardness.

  Since the backup layer 225 has lower strength than the contact layer 224, it is possible to prevent sag due to long-term use and a decrease in contact pressure. For this reason, good cleaning performance can be obtained over a long period of time.

  The mixed layer 22d extends in the longitudinal direction of the cleaning blade 222 from the surface of the tip 22e toward the inside from the blade tip 22a at the edge on the side of the cleaning blade 222 that contacts the intermediate transfer belt 3 to a predetermined dimension. Formed along. In this example, the mixed layer 22d is formed on the three surfaces of the tip 22e so as to have a film thickness of 1.0 μm or more, as shown by hatching.

  Further, the surface layer 223 is formed on the two surfaces of the front end portion 22e of the cleaning blade 222 on the front side of the mixed layer 22d, the blade front end surface 22a and the blade lower surface 22b that is in contact with the intermediate transfer belt 3. It is formed along the longitudinal direction of 222. The surface layer 223 is formed so that the film thickness becomes 0.1 μm or more.

Next, a method for manufacturing the cleaning blade 222 will be described.
First, in FIG. 3, the contact layer 224 and the backup layer 225 are bonded as the base material 23. Next, the mixed layer 22d is formed on the tip portion 22e from the blade tip surface 22a of the base material 23 to a predetermined dimension. The mixed layer 22d is a mixed layer of urethane rubber and acrylic resin constituting the contact layer 224 and the backup layer 225 which are the base material 23 of the cleaning blade 222, or a mixture of urethane rubber and methacrylic resin, or urethane rubber and acrylic. It consists of a mixture of resin and methacrylic resin.
The predetermined dimension of the mixed layer 22d is preferably at least 2 mm or more from the blade tip surface 22a at the edge portion. If the mixed layer 22d is too large, the cost is increased, and if the mixed layer 22d is smaller than 2 mm, the edge portion that is in contact with the intermediate transfer belt becomes smaller and unstable.

  In order to form the mixed layer 22d, the tip 22e portion of the base material 23 is immersed in a material constituting the mixed layer 22d for a predetermined time. Thereby, the mixed layer 22d of the urethane rubber of the base material 23 and at least one of acrylic resin and methacrylic resin is formed. The material constituting the mixed layer is, for example, a mixture of an acrylate monomer and a polymerization initiator in a solvent. The thickness dimension (film thickness) of the mixed layer 22d is performed by controlling the immersion time. The cross-linking reaction of the tip 22e is performed by applying heat and light energy after the coating of the surface layer 223 described later.

  The surface layer 223 is formed by spray coating a material liquid of the surface layer 223 in which abrasive particles described later are added to the base material 23 on which the mixed layer 22d is formed. The material liquid of the surface layer 223 is, for example, a mixture of an acrylate monomer, an abrasive, and a polymerization initiator in a solvent. In this embodiment, cerium oxide is used as the abrasive particles, but the present invention is not limited to this. Thus, the surface layer 223 including abrasive particles in at least one of acrylic resin and methacrylic resin is formed on the base material 23 on which the mixed layer 22d is formed. The surface layer 223 was formed by performing a photocrosslinking reaction by ultraviolet irradiation or a thermal crosslinking reaction by heating. The film thickness of the surface layer 223 is controlled by controlling spray coating conditions (discharge amount, coating speed).

  Specifically, the volume occupancy of the abrasive particles on the contact surface is preferably 50% or more and 90% or less. When the volume occupancy ratio of the abrasive particles on the contact surface is less than 50%, the amount of abrasive particles contacting the surface of the intermediate transfer belt is small, and filming on the intermediate transfer belt cannot be efficiently removed. Absent. On the other hand, if the volume occupancy exceeds 90%, it is not preferable because abrasive particles appearing on the surface are easily peeled off.

Next, the problem of cleaning the surface of the intermediate transfer belt using a conventional blade member when performing image formation over time with an extrusion-molded belt without a surface coat, and the blade member of this embodiment that eliminates the problem The behavior of will be described.
When a conventional blade member is used as a cleaning member and an image with a low image area ratio (image area ratio of 1% or less) is repeatedly formed, the degree of occurrence of filming on the intermediate transfer belt deteriorates. If filming of the intermediate transfer belt occurs sparsely on the belt, an abnormal image due to a change in surface resistance due to partial filming of the intermediate transfer belt may occur. Alternatively, when the pattern density of the P pattern or toner patch created on the intermediate transfer belt is detected by an optical detection means (for example, the reflection type optical sensor described above), a problem occurs when the development potential is changed based on the detection result. Arise. Specifically, when changing the development potential, so-called process control is performed in which the LD power, the charging bias, and the development bias are changed to control the development density that affects the image density. At this time, the glossiness of the belt is lowered due to filming of the intermediate transfer belt, and the detection performance may be lowered.
Since the detection performance is originally minimal in the initial state, when filming occurs, the Vsg fluctuation (regular reflection output of the background portion of the intermediate transfer belt (where no toner adheres)) is worse than the initial state, and detection is performed. It becomes impossible.

  The cause of filming when the conventional blade is used is considered as follows because the material component of the intermediate transfer belt is detected from the analysis result of the surface of the intermediate transfer belt in the filming portion. In the case of using a single-layer cleaning blade that has been used conventionally, there is almost no toner on the intermediate transfer belt if images with a low image area ratio are continuously formed. The blade continues to cause friction. Therefore, in the case of a single-layer cleaning blade that has been used conventionally, the stick slip amount as described above becomes large, causing blade wear, and scraping the surface of the intermediate transfer belt while scraping the fine powder onto the surface of the intermediate transfer belt. Therefore, it is presumed that filming occurs.

  Further, the problem from the beginning that the extrusion belt without a surface coat has a large surface roughness in the initial state can reduce the surface roughness over time by providing the cleaning blade with a function of uniformly polishing. Therefore, to uniformly polish the surface of the intermediate transfer belt with the cleaning blade, it is necessary to stabilize the behavior of the cleaning blade at the nip, that is, to reduce the stick slip amount. Therefore, the cleaning blade 222 as described above was created to make the cleaning blade behavior as shown in FIGS. 4A and 4B described later.

The contact state of the blade member of the first embodiment with the intermediate transfer belt and the cleaning blade behavior will be described with reference to FIG. FIG. 4 shows the contact state of the blade member of the image forming apparatus according to the first embodiment with the intermediate transfer belt. FIG. 4A is a cross-sectional view for explaining the behavior of the blade member. FIG. 4B is an enlarged cross-sectional view illustrating a state of a contact portion (enclosed by a broken line) of the edge portion of the cleaning blade in FIG.
In this embodiment, as shown in FIG. 4B, the deformation and vibration of the edge portion (tip portion) contacting the intermediate transfer belt 3 are reduced by the action of the surface layer 223 and the mixed layer 22d of the cleaning blade 222. Minimized and the nip behavior is very stable. As a result, the surface of the intermediate transfer belt 3 can be uniformly polished by the abrasive particles contained in the surface layer 223 of the blade member 21 for cleaning. Further, since the polished polishing powder does not behave like rubbing against the surface of the intermediate transfer belt 3, filming of the intermediate transfer belt 3 can be prevented. In addition, very good cleaning properties can be obtained, and vibration is minimized, so that the amount of wear of the cleaning blade 222 is minimized.

  The above test results were obtained with the above-described intermediate transfer belt # 1, but similar test results were obtained with the other intermediate transfer belt # 2.

As described above, according to the first embodiment, in the image forming apparatus using the endless belt-shaped intermediate transfer body manufactured by extrusion molding having no coating layer on the surface, the surface is formed without causing stick slip. By using the blade member having the above-described structure for polishing, it is possible to reduce the surface roughness of the intermediate transfer body having a large surface roughness in the initial state while preventing filming by using with time.
The effects described from time to time including the above basic effects are obtained by using imgio MP C2201 (corresponding to the basic configuration of the image forming apparatus shown in FIG. 1) manufactured by Ricoh Co., Ltd. It should be noted that the content is based on the results obtained by performing tests and measurements by changing the content of the embodiment including the examples.

(Second Embodiment)
A second embodiment of the present invention will be described with reference to FIG. FIG. 5 shows the contact state of the blade member of the image forming apparatus according to the second embodiment with the intermediate transfer belt. FIG. 5A is a cross-sectional view for explaining the behavior of the blade member, and FIG. FIG. 6 is an enlarged cross-sectional view illustrating a state of a contact portion (enclosed by a broken line) of the edge portion of the cleaning blade in FIG. 5A with the intermediate transfer belt.
In the second embodiment, as compared with the first embodiment, instead of the cleaning blade 222 having a two-layer structure, as shown in FIG. The point which uses the board member which is the elastic body of this is different. Then, a mixed layer 22 d of urethane rubber and acrylic resin and a surface layer 223 made of acrylic resin containing abrasive particles are formed on the cleaning blade 222. Except for these differences, the second embodiment is the same as the image forming apparatus of the first embodiment.

Hereinafter, a method for creating the cleaning blade 222 will be described. The substrate 23 of the cleaning blade 222 was made using the following materials.
[Base material]
Urethane rubber: 72 degree rubber hardness (JIS-A scale), rebound resilience: 31 [%] (manufactured by Toyo Tire & Rubber)

The mixed layer 22d was formed using the following materials.
[Mixed layer material]
Monomer: 10 parts of PETIA (Daicel Cytec) Polymerization initiator: Irgacure 184 (manufactured by Ciba Specialty Chemicals) 1 part Solvent: 149 parts of tetrahydrofuran

The surface layer 223 was formed using the following materials.
[Surface layer material]
Monomer: PETIA (Daicel Cytec) 10 parts Abrasive particles: Cerium oxide 5 parts Polymerization initiator: Irgacure 184 (manufactured by Ciba Specialty Chemicals) 1 part Solvent: 2-butanone 89 parts

[Formation method]
The substrate 23 of the cleaning blade 222 having a single layer structure made of the same material is immersed in the mixed layer material for 60 seconds, and the surface layer material is spray-coated to a thickness of 0.8 μm. Using a metal halide lamp manufactured by Denki Co., Ltd., UV curing was performed by ² J / cm ² UV irradiation. The blade member 21 according to the first embodiment is formed by this method except that the contact layer 224 and the backup layer 225 are made of urethane rubber having different hardnesses and bonded to form the base material 23. Can be created.

  By using the blade member 21 formed by the above method, it is possible to suppress the ridgeline 22c of the cleaning blade 222 that is in contact with the surface of the intermediate transfer belt 3 from moving in the moving direction. Furthermore, even when the inside is exposed due to surface layer wear over time, the deformation can be similarly suppressed by forming the mixed layer 22d inside the edge layer.

The surface layer 223 is preferably covered with a material having a pencil hardness of 7H or higher. Further, since the surface layer 223 is a member having a hardness higher than that of the cleaning blade 222, the surface layer 223 is rigid and thus hardly deformed, and the turning of the ridge line 22 c of the blade member 21 can be suppressed. The hardness here can be, for example, Martens hardness measured using a microhardness meter H-100 manufactured by Fischer. In the present embodiment, the cleaning blade 222 is about 1 [N / mm ² ], but when a material having a pencil hardness of 7H to 9H used for the surface layer 223 is cured on a glass substrate and measured, it is 100 to 300. It was [N / mm ² ], and the hardness was 100 times or more.

  Next, the behavior of the blade member 21 in the image forming apparatus according to the second embodiment will be described. As in the first embodiment, the blade member 21 of the second embodiment can also reduce the deformation and vibration of the tip / edge portion of the cleaning blade 222 as shown in FIG. The nip behavior can be stabilized.

The surface of the intermediate transfer belt 3 can be uniformly polished by the abrasive particles contained in the surface layer 223 of the blade member 21 for cleaning. Further, since the polished polishing powder does not behave like rubbing against the surface of the intermediate transfer belt 3, filming of the intermediate transfer belt 3 can be prevented. In addition, very good cleaning performance is obtained and vibration is minimized. In addition, the nip width between the edge portion of the cleaning blade 222 and the surface of the intermediate transfer belt 3 is also reduced, so that the amount of blade wear is minimized. Is done.
However, since the base material of the blade member 21 is a single layer, the contact pressure (contact pressure) with respect to the intermediate transfer belt 3 is a single elasticity compared to the first embodiment, so that the contact condition adjustment is difficult. The amount of filming and the amount of scraping the intermediate transfer belt 3 tend to be too little or too much, so there is a disadvantage that the margin for setting the contact condition is low, but there is an advantage that the cost is low. is there.

  Next, the reason why the mixed layer 22d is provided on the cleaning blade 222 of the blade member 21 will be described in detail. This reason similarly applies to the blade member 21 used in the image forming apparatus of the first embodiment. As described above, the blade member 21 of the second embodiment is provided with the surface layer 223 that is harder than the cleaning blade 222 to reduce the friction coefficient between the ridge line 22 c and the surface of the intermediate transfer belt 3. For comparison, a case will be described in which the mixed layer 22d is not formed on the base material 23 of the cleaning blade 222 but only the surface layer 223 having a hardness higher than that of the base material 23 is formed.

  Even if only the surface layer 223 is provided to reduce the friction coefficient, the surface layer 223 wears and decreases over time. At this time, if the surface layer 223 is made thick so as to withstand long-term use, there is a possibility that the elastic deformation at the ridge line 22c of the cleaning blade 222 is inhibited, resulting in cleaning failure. On the other hand, if the surface layer 223 is thin so as not to hinder the elastic deformation at the ridge line 22c of the cleaning blade 222, the surface layer 223 is worn to the extent that the substrate is exposed in a short time. When the low-hardness base material is exposed and directly contacts the surface of the intermediate transfer belt 3, the friction coefficient between the blade member 21 and the surface of the intermediate transfer belt 3 increases, and abnormal wear and noise occur.

  The blade member 21 is present so that at least one of acrylic resin and methacrylic resin has an inclination with respect to the base material of the inner cleaning blade 222 having the surface layer 223 having high hardness. As a result, the mechanical strength and rigidity of the urethane rubber as the base material are moderately strengthened, and the behavior of the tip and edge portions of the cleaning blade 222 during sliding with the surface of the intermediate transfer belt 3 can be moderately suppressed. And it is possible to perform good cleaning, and it is possible to exhibit high wear resistance by suppressing the occurrence of abnormal wear and abnormal noise.

  In addition, if only the surface layer 223 having a high hardness is provided on the base material of the cleaning blade 222, the hardness changes suddenly at the boundary between the high hardness layer and the base material layer, stress concentrates, and the cleaning blade 222 may be damaged. There is. On the other hand, by causing a gradient in the content of the base material of the cleaning blade 222, it is possible to suppress a sudden change in hardness at the boundary between the high hardness layer and the base material layer, resulting in stress concentration. Thus, the cleaning blade 222 can be prevented from being damaged.

  Compared with this, Patent Document 2 describes a configuration in which only the surface layer is provided, or a configuration in which the substrate of the cleaning blade is simply impregnated with a resin material. The problem described above occurs when only the surface layer is provided. Further, if the structure is only impregnated with a resin material, the hardness of the portion of the blade member that comes into contact with the image carrier at the beginning of use cannot be as high as that provided with a surface layer, and wear resistance is reduced. It becomes insufficient. Further, the resin used has a pencil hardness of B to 6H, and even if this is used as a surface layer, the pencil hardness is not sufficient and the durability is poor. If the surface layer is made thick in order to compensate for this durability, the posture control of the edge part including the ridge line is impaired, and the durability is lowered.

Patent Document 3 describes a configuration in which a base material of a cleaning blade is impregnated with a silicone-containing crosslinked resin with a gradient, and the surface of the cleaning blade is covered with the resin.
Furthermore, since the blade member described in Patent Document 3 covers the surface of the cleaning blade with a crosslinked resin to be impregnated, it is different from the blade member 21 of the present embodiment in which a surface layer is provided separately from the impregnated one. Further, the silicone-containing crosslinked resin is inferior in durability as compared with the resin used for the surface layer of the present embodiment. Furthermore, if the impregnation is performed for 12 hours as in the impregnation operation described in Patent Document 3, the amount of the impregnated cross-linked resin becomes excessive, the base rubber swells too much, the rubber network structure is destroyed, and the mechanical strength is reduced. The durability is lowered.

  In the blade member 21 according to the second embodiment, the surface is covered with a surface layer 223 made of a resin having a pencil hardness of 7H or more, and further, an acrylic resin is formed as a mixed layer 22d inside the urethane rubber forming the base material of the cleaning blade 222. Exists with a slope. According to the second embodiment, since the cleaning blade 222 contains a resin to increase the hardness, durability over time can be ensured even if the thickness of the surface layer 223 is reduced. With the very thin film thickness and high pencil hardness of the surface layer 223, it becomes possible to simultaneously exhibit the posture control of the ridge line 22c and impart durability, and high durability can be achieved. In addition, by suppressing the content of the resin to be contained in the cleaning blade 222, it is possible to achieve both reduction in rubber mechanical strength due to swelling of the base rubber and reinforcement of the network structure due to infiltration of a hard resin material. .

  As described above, since the hardness is increased by having the mixed layer 22d on the ridge line 22c of the cleaning blade 222, the ridge line 22c of the cleaning blade 222 is not easily deformed. When the surface layer 223 having a hardness higher than that of the cleaning blade 222 is formed on the entire surface of the blade lower surface 22b of the cleaning blade 222, the surface layer 223 formed on the blade lower surface 22b is applied to the surface of the intermediate transfer belt 3 on the ridge line 22c of the cleaning blade 222. It will inhibit the elastic deformation. For this reason, it is almost impossible to obtain a restoring force against the elastic deformation acting in the direction of increasing the contact pressure on the surface of the intermediate transfer belt 3 at the ridge line 22c.

  As a result, the ridge line 22c cannot follow the eccentricity or minute waviness of the intermediate transfer belt 3, and the contact pressure with respect to the intermediate transfer belt 3 varies. For this reason, when a contact pressure is reduced under severe conditions such as receiving a large pressing force from the toner capped on the ridge line 22c, such as during continuous solid image formation, the toner slips from the blade member 21 and causes poor cleaning. There is a fear.

  For such a problem, it may be considered that the surface layer 223 is not formed on the blade lower surface 22 b of the cleaning blade 222. However, when the surface layer 223 is not formed on the blade lower surface 22b, the ridge line 22c of the cleaning blade 222 is greatly elastically deformed in the direction of surface movement of the intermediate transfer belt 3, and the ridge line 22c is turned over, resulting in turning wear. There is a fear.

  In the cleaning blade 222 of the second embodiment, the surface layer 223 is formed on both the blade tip surface 22a and the blade lower surface 22b so that the film thickness becomes 1 μm or less at a position of 50 μm from the ridge line 22c. Accordingly, it is possible to suppress the elastic deformation of the ridge line 22c of the cleaning blade 222 from being inhibited as compared with the case where the surface layer 223 is formed only on the blade tip surface 22a. Then, the ridge line 22 c of the cleaning blade 222 can be elastically deformed in the surface movement direction of the intermediate transfer belt 3 to such an extent that the ridge line 22 c is not turned.

  Thereby, even when the tension roller 5 shown in FIG. 1 is decentered, the ridge line 22c is made to follow the surface of the intermediate transfer belt 3 by the restoring force against the elastic deformation of the ridge line 22c of the cleaning blade 222. Cleanability can be maintained.

  The layer thickness of the surface layer 223 is preferably 1 μm or less when measured at a distance of 50 μm from the ridgeline 22c. When the thickness of the surface layer 223 is larger than 1 μm, the rigidity of the surface layer 223 becomes too strong, and the ridgeline 22c of the blade member 21 slides on the surface of the intermediate transfer belt 3 (means sliding in contact). The behavior may be too small. As a result, the concentration of vibration energy on the ridge line 22c is not preferable because unpleasant noise is likely to occur and the wear rate is increased, which may make it impossible to use the device at an early stage.

As described above, according to the second embodiment, the same basic effects as those of the first embodiment can be obtained. Furthermore, according to the second embodiment, the following effects can be achieved by providing the mixed layer 22d and the surface layer 223.
First, toner removal performance is greatly improved.
Second, the wear of the cleaning blade 222 in the blade member 21 is reduced, and the cleaning performance can be maintained over a long period of time.

Third, the coefficient of friction between the cleaning blade 222 and the intermediate transfer belt 3 is reduced, and the behavior of the tip portion (edge portion) of the cleaning blade 222 is moderately suppressed during sliding with the surface of the intermediate transfer belt 3. As a result, the abrasive particles contained in the surface layer 223 can stably come into contact with the surface of the intermediate transfer belt 3, so that the surface of the intermediate transfer belt 3 can be uniformly polished in the axial direction, and the state of the initial belt The surface roughness at can be reduced over time.
Fourth, since the cleaning blade 222 does not rub toner additives or the like onto the surface of the intermediate transfer belt 3, filming does not occur.

The embodiments and the like described above are examples of the present invention, and the present invention has a specific effect for each of the following modes.
[Aspect 1]
An intermediate transfer member such as an endless belt-shaped intermediate transfer belt 3 for transferring a toner image formed on an image carrier such as the photoreceptors 1a, 1b, 1c, and 1d, and a toner image formed on the intermediate transfer member. In an image forming apparatus such as the image forming apparatus 30 provided with a blade member such as the blade member 21 for removing transfer residual toner on the intermediate transfer body after being transferred to the recording medium, an intermediate transfer such as the intermediate transfer belt 3 is performed. The body is a resin belt having a single layer structure which is manufactured by extrusion molding and does not have a coating layer on the surface, and the blade member such as the blade member 21 is an edge including the ridge line 22c of the tip portion located on the intermediate transfer body side. A cleaning blade body such as a cleaning blade 222 formed of an elastic body for cleaning the surface of the intermediate transfer body by bringing the portion into contact with the surface of the intermediate transfer body, The blade body has a layer thickness of 1... Such as a mixed layer 22 d of at least one of acrylic resin and methacrylic resin and the base material of the cleaning blade body facing from the surface of the tip portion to the inside. A surface layer such as a surface layer 223 made of at least one of an acrylic resin and a methacrylic resin is formed on the surface of the tip portion so as to have a thickness of 0.1 μm or more. In addition, the surface layer contains abrasive particles.

  According to this aspect 1, as described in the above-described embodiments including examples, in an image forming apparatus using an endless belt-shaped intermediate transfer body manufactured by extrusion molding having no coating layer on the surface, the stick By using the blade member configured as described above that polishes the surface without causing slipping, the surface roughness of the intermediate transfer body having a large surface roughness in the initial state is reduced by using over time while preventing the occurrence of filming. be able to.

[Aspect 2]
In [Aspect 1], the cleaning blade body such as the cleaning blade 222 is formed by stacking a plurality of layers including a contact layer such as the contact layer 224 on which the ridge line such as the ridge line 22c is formed. The% modulus values are different, and the contact layer has the highest 100% modulus value among the layers.
According to this aspect 2, as described in the above-described embodiments including examples, in order to stabilize the behavior of the edge portion which is the tip portion of the cleaning blade body, the strength is relatively high and 100% modulus is obtained. On the other hand, a material having a large value is used, and a material having a relatively low strength and a small 100% modulus value is used for the backup layer in the plurality of layers, as compared with the edge layer. It is possible to prevent settling and contact pressure drop during use.

[Aspect 3]
In [Aspect 2], the contact layer such as the contact layer 224 is formed of a material having a 100% modulus value at 23 ° C. of 6 Mpa to 12 Mpa.
[Aspect 4]
In [Aspect 1], the cleaning blade body such as the cleaning blade 222 is formed of one elastic body made of the same material.

[Aspect 5]
In any one of [Aspect 1] to [Aspect 4], a density detection sensor 13 having a light emitting element for irradiating light on a surface of an intermediate transfer member such as the intermediate transfer belt 3 and a light receiving element for receiving reflected light, etc. A reflected light amount detecting means is provided.
[Aspect 6]
In any one of [Aspect 1] to [Aspect 5], the abrasive particles are cerium oxide.

  Although the present invention has been described with respect to specific embodiments, the technical contents disclosed by the present invention are not limited to those exemplified in the above-described embodiments. That is, it may be configured by appropriately combining them, and it will be apparent to those skilled in the art that various embodiments, modifications, and examples can be configured within the scope of the present invention according to the necessity and application. It is.

1a, 1b, 1c, 1d photoconductor (an example of an image carrier)
3 Intermediate transfer belt (an example of an intermediate transfer member)
8 Charging device 9 Exposure device 10 Developing devices 11a, 11b, 11c, 11d Primary transfer roller 12 Cleaning device 13 Density detection sensor (an example of reflected light amount detection means)
14 Feeder 17 Secondary transfer roller 18 Fixing device 20 Belt cleaning device 21 Blade member 22a Blade tip surface 22b Blade bottom surface 22c Edge line 22d Mixed layer 22e Tip portion 23 Base material 30 Image forming device 31 Device body 221 Holder 222 Cleaning blade ( Example of cleaning blade body)
223 Surface layer 224 Contact layer 225 Backup layer P Recording medium

JP 2005-024937 A Japanese Patent No. 3602898 JP 2004-233818 A

Claims (6)

An endless belt-shaped intermediate transfer member for transferring a toner image formed on the image carrier, and a transfer residual toner on the intermediate transfer member after transferring the toner image formed on the intermediate transfer member to a recording medium An image forming apparatus comprising: a blade member for removing
The intermediate transfer body is a resin belt having a single layer structure which is manufactured by extrusion molding and does not have a coating layer on the surface,
The blade member is a cleaning blade body formed of an elastic body that cleans the surface of the intermediate transfer body by bringing an edge portion including a ridge line of a tip portion located on the intermediate transfer body side into contact with the surface of the intermediate transfer body. With
The cleaning blade body is:
A mixed layer of at least one of an acrylic resin and a methacrylic resin and the base material of the cleaning blade body is formed so as to have a layer thickness of 1.0 μm or more from the front surface to the inside. With
A surface layer made of at least one of the acrylic resin and the methacrylic resin is formed on the surface of the tip portion so that the layer thickness is 0.1 μm or more, and the surface layer is polished. An image forming apparatus comprising agent particles. The cleaning blade body is:
A plurality of layers including a contact layer on which the ridgeline is formed are formed to be overlapped,
The plurality of layers have different 100% modulus values,
The image forming apparatus according to claim 1, wherein the contact layer has a maximum 100% modulus value among the plurality of layers.   The image forming apparatus according to claim 2, wherein the contact layer is formed of a material having a 100% modulus value at 23 ° C. of 6 Mpa to 12 Mpa.   The image forming apparatus according to claim 1, wherein the cleaning blade body is composed of one elastic body made of the same material.   5. The image forming apparatus according to claim 1, further comprising a reflected light amount detection unit having a light emitting element that irradiates light on a surface of the intermediate transfer member and a light receiving element that receives reflected light. .   The image forming apparatus according to claim 1, wherein the abrasive particles are cerium oxide.

Images