JP2009162803A - Intermediate transfer body and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an intermediate transfer body obtaining a high quality transfer image at high transfer efficiency even on a recording medium having recesses and projections on its surface and achieving stable electrostatic transfer for long term use regardless of an environmental change or durability and without causing electrode contact failure, etc., caused by soiling with developer, and to provide an image forming apparatus using the intermediate transfer body. <P>SOLUTION: In the intermediate transfer body, an elastic layer, a conductive layer and a surface resistance layer are disposed on a conductive substrate. In addition, the conductive layer is directly formed on the axial ends of the conductive substrate without through the elastic layer. A transfer voltage is applied thereto from the substrate side. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus that primarily transfers a toner image formed on an image carrier onto an intermediate transfer member, and further transfers the toner image onto a recording medium from the intermediate transfer member, and the intermediate transfer member.

  Conventionally, there has been known an image forming apparatus that develops an electrostatic latent image on the surface of an image carrier with a dry or wet developer containing toner particles, and transfers the toner image formed by the development to a recording medium to obtain a final image. It has been.

  In addition, the toner image formed by development with the developer is primarily transferred to an intermediate transfer member, a plurality of toner images are superimposed on the surface of the intermediate transfer member, and then the superimposed toner images are collectively transferred to a recording medium. An image forming apparatus that obtains a final image is also known.

  In particular, a wet image forming apparatus using a wet developing device has an advantage that cannot be realized by a dry image forming apparatus, and its value is being reviewed in recent years.

  For example, since a very fine toner of submicron size can be used, high image quality can be realized and a texture equivalent to printing can be obtained. Particularly, in recent years, with the increase in the speed of image forming apparatuses, a wet developer in which toner particles are dispersed at a high concentration in a highly viscous carrier liquid tends to be used.

  Here, for the transfer of a toner image onto a recording medium in a dry type or wet type image forming apparatus, an electrostatic transfer method using an electrostatic force has been generally used instead of a thermal transfer in order to avoid an influence on a photosensitive member. . The toner particles are precharged, and the toner particles move to the recording medium due to the electrostatic force generated by applying a voltage having the opposite polarity to the toner particles to a transfer roller provided on the back side of the recording medium. The toner image is transferred.

  The recording medium is usually paper, and various sizes and types of transfer sheets are used, and appropriate transfer conditions are set according to the transfer sheets. However, when transferring to high-quality paper or embossed paper whose surface is uneven, it may not be possible to obtain good transferability only by adjusting such electrostatic transfer conditions. In order to improve the transferability by bringing the toner image closer to the uneven transfer paper surface, for example, a transfer method using an intermediate transfer body provided with a rubber elastic layer has been devised.

  However, if a high-resistance rubber elastic layer is interposed, the electric field of the bias does not work efficiently. Therefore, in order to efficiently perform electrostatic transfer, for example, a technique for making a rubber elastic body conductive is required.

  In fact, a technique using a conductive rubber elastic layer has also been proposed (see, for example, Patent Document 1).

  In Patent Document 1, a drum-shaped intermediate transfer body serving as a base is covered with a blanket having a configuration in which an elastic layer and a conductor layer are stacked, and conductive at the end in the direction perpendicular to the axial direction of the blanket. Techniques have been proposed in which the extension of the body layer is joined to the conductive substrate.

  However, although the elastic layer and the conductor layer can play their respective roles, the conductive rubber layer is subject to changes in resistance due to environmental fluctuations and durability against energization, and electrostatic secondary transfer onto transfer paper. The optimum transfer conditions in the are easily changed.

  An intermediate transfer member has been developed in which a conductive layer is separately provided on a non-conductive rubber elastic layer instead of imparting conductivity to the rubber elastic layer itself (see, for example, Patent Document 2). .

  In Patent Document 2, a cloth layer in which conductive weft yarn and non-conductive warp yarn are knitted and a surface resistance layer are provided on an insulating rubber elastic layer of an intermediate transfer member, and an axial end portion is exposed. A technique for applying a transfer voltage by bringing an electrode member into contact with the weft portion has been proposed.

A voltage in the vicinity of the surface (under the surface resistance layer) can be applied while having elasticity. Further, since it is a weft, it is possible to apply a voltage only to the nip portion. However, the weft portion is not electrically connected to the base portion of the intermediate transfer member, and it is necessary to bring the electrode member into contact with the weft. That is, an exposed portion of the weft must be provided, and in the long term, that portion is contaminated with a developer or the like, and contact failure tends to occur.
US Pat. No. 5,745,829 JP-A-8-202174

  As described above, although an intermediate transfer body provided with an elastic layer can be expected to have good transferability with respect to a recording medium having an uneven surface, an elastic body is used to stabilize electrostatic transfer conditions. It is required to hold a conductor layer for applying a transfer voltage separately from the layer.

  However, the electrode contact portion is easily contaminated, particularly when a wet developer is used, such as when the electrode portion for voltage application is exposed, and causes poor contact with respect to environmental changes and durability. It was easy to disturb.

  The present invention has been made in view of the above technical problems, and an object of the present invention is to obtain a high-quality transfer image with high transfer efficiency even for a recording medium having irregularities on the surface. Intermediate transfer body that can realize stable electrostatic transfer against environmental changes and durability without causing electrode contact failure due to contamination by developer even for long-term use, and intermediate transfer thereof An image forming apparatus using a body is provided.

  In order to solve the above problems, the present invention has the following features.

  1. An intermediate transfer body on which a toner image formed on an image carrier is primarily transferred and secondarily transferred onto a recording medium. An elastic layer, a conductor layer, and a surface resistance layer are arranged in this order on a conductive substrate. An intermediate transfer member characterized in that at least one axial end portion has a region where the conductive layer is formed on the conductive substrate without the elastic layer interposed therebetween. .

  2. 2. The intermediate transfer member according to 1, wherein the surface resistance layer is formed so as to cover the conductor layer.

  3. 3. The intermediate transfer member according to 1 or 2, wherein the conductor layer is in contact with the conductive substrate so as to cover a surface of the elastic layer and an end side surface thereof.

  4). 4. The intermediate transfer member according to any one of 1 to 3, wherein the conductive substrate has a drum shape or a belt shape.

  5). The elastic layer has a rubber hardness of 10 degrees or more and 60 degrees or less in JIS-A, and the conductor layer has a surface resistivity of 1E + 4Ω / □ or less. The intermediate transfer member according to item 1.

  6). An image, wherein the toner image formed on the image carrier is primarily transferred to the intermediate transfer member according to any one of 1 to 5 and then secondarily transferred from the intermediate transfer member onto a recording medium. Forming equipment.

  According to the intermediate transfer body and the image forming apparatus according to the present invention, in the intermediate transfer body, an elastic body layer, a conductor layer, and a surface resistance layer are provided on the conductive substrate, thereby adjusting the electrical resistance of the elastic body layer. Therefore, a high-quality transfer image can be obtained stably with high transfer efficiency even for a recording medium having a surface with irregularities. In addition, the conductive layer is formed directly on the conductive substrate without passing through the elastic layer in the end region in the axial direction, and the transfer voltage is applied from the substrate side. Electrostatic transfer that is stable against environmental changes and durability can be realized without causing electrode contact failure.

  Embodiments of the present invention will be described below with reference to the drawings.

(Overall configuration of image forming apparatus)
FIG. 1 is a diagram illustrating a schematic configuration example of an image forming apparatus including an intermediate transfer member according to an embodiment of the present invention. A schematic configuration of the image forming apparatus will be described with reference to FIG. Details of the configuration of the intermediate transfer member will be described later with reference to FIG.

  FIG. 1 shows an example of a wet image forming apparatus. Although a wet image forming apparatus will be described as an example, the present invention can be similarly applied to a dry image forming apparatus.

  Around the photosensitive member 1 as an image carrier, a charging device 2, an exposure device 3, developing devices 4Y, 4M, 4C, and 4K, an intermediate transfer member 5, and a cleaning device 6 are arranged in order in the rotation direction indicated by the arrows. A cleaning device 7 and a transfer roller 8 are disposed around the intermediate transfer member 5.

  Each of the four sets of developing devices 4Y, 4M, 4C, and 4K is provided so as to be detachable from the photoreceptor 1, and each has a developer tank (not shown) and a developer on the surface thereof, and the surface of the photoreceptor 1 And a developing roller 41 for developing the electrostatic latent image.

  Here, the toner of the developing device 4Y is a yellow toner, the toner of the developing device 4M is a magenta toner, the toner of the developing device 4C is a cyan toner, and the toner of the developing device 4K is a black toner. A full-color image can be formed by forming an image, superimposing on the surface of the intermediate transfer member 5, and then transferring the image onto the recording medium 9 at once.

(Operation function of image forming apparatus)
The operation of the image forming apparatus in FIG. 1 will be described in order.

  The photoreceptor 1 rotates in the direction indicated by the arrow. First, the surface of the photoconductor 1 is uniformly charged to a predetermined surface potential by the charging device 2, and then image information is exposed by the exposure device 3 to form an electrostatic latent image on the surface of the photoconductor 1. .

  Next, the developing device 4Y is opposed to the photoreceptor 1, and a developer carried on the surface of the developing roller 41 is brought into contact with the photoreceptor 1 to develop the electrostatic latent image, whereby yellow toner is developed on the surface of the photoreceptor 1. An image is formed.

  Assuming the case of a wet image forming apparatus, the wet developer used in the developing devices 4Y, 4M, 4C, and 4K is obtained by dispersing toner particles in an insulating carrier liquid. It may contain a function-imparting agent such as an agent.

  The concentration and viscosity of the wet developer are not particularly limited, but a solid component such as toner particles is dispersed at a rate of 10 to 50% by mass, and the viscosity at 25 ° C. is 0.01 Pa · s to 10 Pa · s. It is particularly suitable when a wet developer having a high concentration and high viscosity in the range is used.

  The toner particles are previously charged positively by a toner charging means (not shown).

  When the photosensitive member 1 further rotates, the toner image on the surface moves to a primary transfer region where the photosensitive member 1 and the intermediate transfer member 5 are in contact with each other. A negative voltage is applied to the intermediate transfer member 5 by a power source (not shown), and the toner moves by the electric field generated by the applied voltage, so that the toner image on the surface of the photoreceptor 1 is primarily applied to the surface of the intermediate transfer member 5. Transcribed.

  After the primary transfer, the developer remaining on the photoconductor 1 is removed by the cleaning device 6, and the surface of the photoconductor 1 is uniformly charged to a predetermined surface potential again by the charging device 2. The intermediate transfer member 5 may have a drum shape or a belt shape.

  Subsequently, an electrostatic latent image is formed again on the surface of the photoconductor 1 and developed by the developing device 4M, so that a magenta toner image is formed on the surface of the photoconductor 1. Thereafter, the magenta toner image is primarily transferred onto the surface of the intermediate transfer member 5, and the yellow toner image and the magenta toner image are superimposed on the surface of the intermediate transfer member 5.

  Similarly, the cyan toner image developed by the developing device 4 </ b> C and the black toner image developed by the developing device 4 </ b> K are superimposed to form a full-color toner image on the surface of the intermediate transfer member 5.

  The full-color toner image formed on the surface of the intermediate transfer member 5 moves to a secondary transfer region where the intermediate transfer member 5 and the recording medium 9 abut when the intermediate transfer member 5 rotates in the direction of the arrow.

  In the secondary transfer region, a linear pressure is applied between the intermediate transfer member 5 and the recording medium 9 by the transfer roller 8 on the back surface of the recording medium 9, and a negative voltage is applied to the transfer roller 8 by a power source (not shown). Applied.

  By applying this voltage, the surface of the recording medium 9 facing the intermediate transfer member 5 also has a negative potential, and the toner image is recorded on the recording medium 9 by the potential difference between the surface potential of the recording medium 9 and the surface potential of the intermediate transfer member 5. In this state, when the recording medium 9 is conveyed in the direction of the arrow and exits the secondary transfer area, the secondary transfer of the toner image onto the recording medium 9 is completed.

  The recording medium 9 onto which the toner image has been transferred is subjected to a fixing process by the fixing device 10 to complete image output. After the secondary transfer, the developer remaining on the intermediate transfer member 5 is removed by the cleaning device 7.

(Configuration of intermediate transfer member)
FIG. 2 is a diagram showing a schematic configuration of the intermediate transfer member 5 in FIG. 1, that is, an embodiment of the intermediate transfer member according to the present invention, and shows a cross section of one end portion in the axial direction. A schematic configuration of the intermediate transfer member will be described with reference to FIG.

  Reference numeral 51 denotes a conductive substrate of the intermediate transfer member. The intermediate transfer member 5 is configured by coating the following layers on the surface of the drum-shaped conductive substrate.

  The conductive substrate 51 may have a belt shape (the configuration of the intermediate transfer belt and the image forming apparatus including the belt are shown in FIGS. 5 and 6). The material is preferably a highly conductive material such as a metal drum or metal sheet. Further, a non-conductive material coated with a metal may be used, and if it is highly conductive, a resin dispersed in carbon may be used. The surface resistivity ρs2 of the conductive substrate 51 is preferably 1E + 3Ω / □ or less.

  52 is an elastic body layer. For example, a rubber layer having an appropriate elasticity is provided on the conductive substrate 51 in order to improve the adhesion to the recording medium 9, that is, the transfer paper, at the nip portion with the transfer roller 8.

  The rubber layer of the elastic body layer 52 is preferably 10 to 60 degrees in terms of rubber hardness JIS-A. Rubber having a rubber hardness of less than 10 degrees is difficult to manufacture. If it exceeds 60 degrees, the effect as an elastic body is lost, and the transfer efficiency on a paper having an uneven surface is deteriorated.

  The thickness of the rubber layer is preferably 0.1 mm to 10 mm, more preferably 1 mm to 5 mm. The volume resistivity ρv2 of the elastic layer 52 need not be controlled. Carbon may be contained in consideration of physical durability.

  53 is a conductor layer. It is provided as an upper layer of the elastic layer 52 and functions as an electrode layer for applying a transfer voltage between the transfer roller 8 and the nip portion with the transfer roller 8.

  The thickness of the conductor layer 53 is preferably thick in order to obtain moderate conductivity, but thin in order not to impair the adhesion of the lower elastic layer 52 to the recording medium 9. . Specifically, 0.01 to 100 μm is preferable, and 0.01 to 10 μm is more appropriate.

  The surface resistivity ρs1 of the conductor layer 53 is preferably 1E + 4Ω / □ or less, and more preferably 1E + 3Ω / □ or less. When ρs1 exceeds 1E + 4Ω / □, the applied voltage becomes unstable and the transfer efficiency is not stable. The material is preferably a metal, other inorganic material, or a resin imparted with conductivity.

  54 is a surface resistance layer. By providing on the conductor layer 53, it functions as an appropriate barrier layer between the toner image formed on the surface.

  Accordingly, the surface resistance layer 54 should have an appropriate thickness for maintaining an appropriate resistance value. However, the surface resistance layer 54 is appropriately thin so as not to impair the adhesion to the recording medium 9 due to the elasticity of the elastic layer 52. Better. Specifically, 1 to 100 μm is preferable, and 5 to 30 μm is more appropriate. The volume resistivity ρv1 of the surface resistance layer 54 is preferably 1E + 8 to 1E + 12 Ω · cm.

  The elastic body layer 52, the conductor layer 53, and the surface resistance layer 54 are laminated and provided on the surface of the conductive substrate 51 in the order described above. In this way, the function is shared. In particular, the function sharing between the elastic layer 52 and the conductor layer 53 eliminates the need for the elastic layer 52 to have an electric resistance adjusting function, and the recording medium has irregularities on the surface. 9, the degree of adhesion at the nip portion with the transfer roller 8 is increased, and a high-quality transfer image can be obtained stably with high transfer efficiency.

  On the other hand, since the conductor layer 53 is separately provided, it is necessary to consider how to conduct the conductor layer 53, which is the upper layer of the elastic layer 52. That is, the conductor layer 53 functions as an electrode layer for applying a transfer voltage to and from the transfer roller 8 at the nip portion with the transfer roller 8, and therefore needs to be electrically connected from the power source 59. For this reason, in this embodiment, the configuration described below is adopted.

  As shown in FIG. 2, the elastic layer 52 is not formed on the conductive substrate 51 at at least one axial end of the drum-shaped intermediate transfer member 5, that is, directly without the elastic layer 52. There is a region where the conductive layer 53 is formed on the conductive substrate 51 (the region indicated by X in FIG. 2).

  In this region, the conductor layer 53 is electrically connected to the conductive substrate 51. The conductive substrate 51 has a rotating shaft, for example, and can be electrically connected to the power source 59 through an electrode (not shown) from an arbitrary position on the shaft. A voltage can be applied from the power source 59 to the conductor layer 53 through such a path.

  Of course, the recording medium 9 is not interposed between the transfer roller 8 and the region X in which the conductive layer 53 is directly formed on the conductive base 51 without the elastic layer 52 interposed therebetween. This is the end region. There is no need to worry about insufficient adhesion to the recording medium 9 due to the absence of the elastic layer 52.

  In this way, the conductive layer 53 is directly connected to the conductive base 51 to establish a connection with the power source 59. Therefore, it is not necessary to expose a part of the conductive layer 53 or to contact the electrode member. Even for long-term use, there is no electrode contact failure due to contamination by the developer, and stable electrostatic transfer can be realized against environmental changes and durability.

  Further, in the vicinity of the region X, the conductor layer 53 plays a role of conducting with the conductive substrate 51 and reaches its terminal portion. In the configuration shown in FIG. 2, the end portion in the axial direction of the conductor layer 53 is formed so as to cover the end portion in the axial direction of the elastic layer 52 which is the lower layer. The part is formed so as to cover the end part in the axial direction of the lower conductor layer 53.

  This also applies to the opposite axial end. That is, the conductor layer 53 is all covered with the surface resistance layer 54 and is not exposed.

  As a result, the conductive layer 53 is not exposed, and naturally, the conductive layer 53 is not contaminated by the developer even for long-term use, and stable electrostatic transfer is realized against environmental changes and durability. can do.

  Further, in the vicinity of the region X, the conductor layer 53 is in contact with the conductive substrate 51 in the region X so as to cover the surface and end side surfaces of the elastic layer 52. That is, the surface of the conductor layer 53 and the surface resistance layer 54 covering the layers up to the end of the elastic layer 52 is flat, and a step portion (hereinafter referred to as Y) on the outer end surface thereof, that is, the region X part. Is done.

  In particular, in an image forming apparatus using a wet developer, the stepped portion Y can be used to collect the wet developer remaining at the time of transfer and prevent the end of the intermediate transfer member from being stained. FIG. 3 shows a state in which a cleaner blade for cleaning the remaining developer is arranged in the configuration of FIG.

  In FIG. 3, 61 is a cleaner blade. The cleaner blade 61 is provided up to the end of the elastic layer 52, and excess wet developer can be dropped onto the stepped portion Y at the end. The wet developer 11 that has fallen on the stepped portion Y can be recovered by, for example, the developer recovery member 62 or the like.

  In this way, the step portion Y formed by contacting the conductive base 51 in the region X in such a manner that the conductive layer 53 covers the surface of the elastic layer 52 and the side surface of the end thereof is positively utilized. In addition, surplus wet developer 11 can be recovered, thereby preventing the end of the intermediate transfer member from being stained.

  When a drum-shaped metal roller is used for the conductive substrate 51, an end configuration as shown in FIG. 4 can be adopted.

  FIG. 4 shows an example in which the same portion as shown in FIG. In this example, the elastic layer 52 is formed up to the end of the conductive substrate 51, that is, the drum-shaped axial end. However, the conductor layer 53 is formed so as to cover the side of the conductor layer 53 and further to the side surface of the end portion in the axial direction of the conductive substrate 51.

  In this example, the region X exists on the side surface of the end portion of the conductive substrate 51. Naturally, the surface resistance layer 54 also wraps around the end side surface and covers the conductor layer 53.

  Such a configuration is also possible. Also in this case, the function sharing between the elastic body layer 52 and the conductor layer 53 eliminates the need for the elastic body layer 52 to maintain the function of adjusting the electric resistance. The degree of adhesion at the nip portion with the transfer roller 8 is increased, and a high-quality transfer image can be obtained stably with high transfer efficiency. In addition, the entire length of the intermediate transfer member can be used effectively.

  Similarly, there is no need to expose a part of the conductor layer 53 or to contact the electrode member, and there is no electrode contact failure due to contamination by the developer even for long-term use. And stable electrostatic transfer with respect to durability.

  In addition, for example, in accordance with the shape of the intermediate transfer member, there is a region where the conductive layer is formed on the conductive substrate without the elastic layer at the end in at least one axial direction. Various stacked configuration embodiments are possible.

  In the above-described embodiment, the intermediate transfer member 5 is made of metal and has a drum shape. The transfer roller 8 is also a metal roller. The transfer roller 8 may be an elastic roller or a belt-like member. The intermediate transfer member 5 may also have a belt shape.

  FIG. 5 is a diagram illustrating a schematic configuration example of an image forming apparatus including the belt-shaped intermediate transfer member 5. According to the shape of the intermediate transfer member 5, four image forming units including the photosensitive member 1 are provided for four colors, and the respective color toner images on the photosensitive members 1Y, 1M, 1C, and 1K are respectively provided on the intermediate transfer member. Transcribed and overlaid. This is the difference from the image forming apparatus of FIG. 1, and the other components are the same as those of FIG.

  In FIG. 1, an image forming apparatus having a configuration in which four sets of developing devices 4Y, 4M, 4C, and 4K are disposed around one photoconductor 1 has been described as an example. However, as shown in FIG. The same applies to the case of an image forming apparatus in which four sets of photoconductors 1Y, 1M, 1C, and 1K are disposed along the periphery of the intermediate transfer body 5 and each photoconductor is provided with one developing device. The description of can be applied. Also, the operation functions are almost common, and the description is omitted.

  FIG. 6 shows a schematic configuration example of the belt-shaped intermediate transfer member 5 using the metal belt in FIG. A schematic configuration example of the belt-shaped intermediate transfer member will be described with reference to FIG.

  As in the case of the drum-shaped intermediate transfer member in FIG. 2, an elastic layer 52, a conductor layer 53, and a surface resistance layer 54 are laminated on a conductive substrate 51 of a metal belt.

  FIG. 6B shows a cross section of the one end portion of the belt viewed from the traveling direction. As shown in FIG. 6B, the elastic body layer 52 is not formed on the conductive substrate 51 at at least one axial end of the belt-shaped intermediate transfer body 5, that is, through the elastic body layer 52. The region X in which the conductor layer 53 is formed directly on the conductive substrate 51 is also present as in the case of the drum-shaped intermediate transfer member in FIG.

  Therefore, FIG. 6A shows a cross section parallel to the belt traveling direction, and it is possible to establish electrical continuity with the power source 59 via, for example, the electrode roller 55 from the back side of the belt free from contamination by the developer. Thus, there is no need to expose a part of the conductor layer 53 or contact the electrode member, and there is no electrode contact failure due to contamination by the developer even for long-term use. As in the case of the drum-shaped intermediate transfer body, it is possible to realize electrostatic transfer that is stable against environmental changes and durability.

(Example)
The configuration of the intermediate transfer member according to the present invention was implemented using the wet image forming apparatus provided with the drum-shaped intermediate transfer member shown in FIG. However, monochrome image formation was performed. Images were actually formed, and transfer efficiency was measured to evaluate durability stability.

  Table 1 shows the structure of the intermediate transfer member used. Example 1, the comparative example 1, and the comparative example 2 which are this Embodiment were implemented.

  FIG. 7 shows a layered structure at the end of the intermediate transfer member of Comparative Example 1. The intermediate transfer member of Comparative Example 1 is obtained by providing the elastic layer 52 with conductivity without providing a conductor layer. It can be said that the elastic layer 52 also serves as the conductor layer 53. The elastic layer 52 is a PU rubber layer having ionic conductivity, and the volume resistivity ρv2 is 1E + 8 Ω · cm.

  FIG. 8 shows a laminated structure at the end of the intermediate transfer member of Comparative Example 2. The intermediate transfer member of Comparative Example 2 has the same stacked structure as that of Example 1, but there is no region where the conductive layer 53 is in direct contact with the conductive substrate 51 and is instead covered with the surface resistance layer 54. An exposed region is provided, and the electrode roller 55 is brought into contact with the exposed portion of the conductor layer 53 to conduct with the power source 59.

  The developer used is a wet developer in which a toner in which a pigment is dispersed in a resin is dispersed in a non-volatile insulating solvent. A small amount of dispersant was added. The volume average particle diameter of the toner is 2 μm to 3 μm, and the toner concentration is 20 to 30% by mass with respect to the mass of the developer.

  In the evaluation method, the durability stability was evaluated by comparing the transfer efficiency in the initial stable state, the transfer efficiency after continuous driving for 24 hours, and the transfer efficiency after driving for one month. The evaluation sheet is Jpaper.

  The transfer efficiency was calculated from the amount of toner before transfer on the intermediate transfer body and the amount of toner remaining after transfer on a single color solid image. In order to ensure image quality, the transfer efficiency of 95% or more was determined to be OK, and less than 95% was determined to be NG. The transfer voltage from the intermediate transfer member to the paper is 500V.

  The durability stability evaluation results obtained by measuring the transfer efficiency are also shown in Table 1.

  In Example 1, the transfer efficiency was OK, that is, a transfer efficiency of 95% or more was obtained in the initial state, after continuous driving for 24 hours, and after driving for one month. In addition, the image quality was good, and there was no problem.

  In Comparative Example 1, the transfer efficiency was OK in the initial state. However, after 24 hours of continuous driving and after 1 month of driving, the transfer efficiency was NG. In Comparative Example 1, the conductor layer is not provided, and the elastic body layer is made conductive to conduct with the conductive base and voltage is applied. Therefore, the conductivity of the elastic body layer depends on the environment and durability. The reason is that it fluctuated and was not stable. It would be necessary to provide a conductor layer to obtain stable conduction.

  In Comparative Example 2, the transfer efficiency was OK in the initial state and after 24 hours of continuous driving. However, the transfer efficiency was NG after driving for one month. In Comparative Example 2, the conductive layer is not electrically connected to the conductive base, and an electrode roller is brought into contact with the exposed portion of the conductive layer to apply a voltage. When the exposed portion of the conductor layer in contact with the electrode roller was seen, it was soiled with the developer. This contact failure due to contamination is presumed to be the cause of the failure to maintain a stable transfer state.

  When the exposed portion of the conductor layer was wiped and evaluated again, the transfer efficiency was good. However, scratches were generated on the exposed surface of the conductor layer every time it was wiped, and the transfer efficiency was NG after wiping several times. It seems that poor contact due to scratches has occurred. Contamination of the electrode portion itself should be prevented, and a conduction mechanism that does not require the conductor layer to be exposed is desired.

  Compared to these, in Example 1, the conductor layer is formed directly on the conductive substrate without going through the elastic layer, and is directly connected to the conductive substrate, and the transfer voltage is applied through the conductive substrate. The conduction state does not vary greatly depending on the environment and durability, and contact failure due to developer contamination or the like cannot occur. Actually, in Example 1, good transfer efficiency is obtained in the initial state, after continuous driving for 24 hours, and after driving for one month.

  As described above, according to the intermediate transfer body and the image forming apparatus according to the present embodiment, in the intermediate transfer body, the elastic body layer, the conductor layer, and the surface resistance layer are provided on the conductive substrate, whereby the elastic body layer is provided. Is not used for adjusting the electric resistance, so that a high-quality transfer image can be obtained stably and with high transfer efficiency even for a recording medium having irregularities on the surface. In addition, the conductor layer is formed directly on the conductive substrate without passing through the elastic layer at the end in the axial direction. By applying a transfer voltage from the substrate, the electrode contacts due to contamination by the developer even for long-term use. It is possible to realize electrostatic transfer that is stable against environmental changes and durability without causing defects.

  The scope of the present invention is not limited to the above embodiment. Unless it deviates from the meaning of this invention, those changed forms are also included in the range.

1 is a diagram illustrating a schematic configuration example of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a schematic configuration example of an intermediate transfer member 5 in FIG. 1. FIG. 4 is a diagram showing a situation where a cleaner blade for removing the developer remaining on the surface of the intermediate transfer member 5 is arranged. FIG. 3 is a diagram illustrating an example of a different stacked configuration with respect to the configuration of the intermediate transfer member 5 illustrated in FIG. 1 is a diagram illustrating a schematic configuration example of an image forming apparatus including a belt-shaped intermediate transfer member. FIG. 6 is a diagram illustrating a schematic configuration example of a belt-shaped intermediate transfer member 5 in FIG. 5. 6 is a diagram illustrating an example of a stacked configuration at an end portion of an intermediate transfer member of Comparative Example 1. FIG. 6 is a diagram illustrating an example of a stacked configuration at an end portion of an intermediate transfer member of Comparative Example 2. FIG.

Explanation of symbols

1, 1Y, 1M, 1C, 1K photoconductor 2 charging device 3 exposure device 4, 4Y, 4M, 4C, 4K developing device 5 intermediate transfer member 6 cleaning device (for photoconductor)
7 Cleaning device (for intermediate transfer member)
DESCRIPTION OF SYMBOLS 8 Transfer roller 9 Recording medium 10 Fixing device 11 Wet developer 41 Developing roller 51 Conductive substrate 52 Elastic body layer 53 Conductor layer 54 Surface resistance layer 55 Electrode roller 59 Power supply 61 Cleaner blade 62 Recovery member

Claims (6)

An intermediate transfer member that is primarily transferred to a toner image formed on an image carrier and then secondarily transferred onto a recording medium,
It is configured by laminating an elastic layer, a conductor layer, and a surface resistance layer in this order on a conductive substrate,
An intermediate transfer member, wherein at least one end portion in the axial direction has a region where the conductive layer is formed on the conductive substrate without the elastic layer interposed therebetween. The intermediate transfer member according to claim 1, wherein the surface resistance layer is formed so as to cover the conductor layer. The intermediate transfer member according to claim 1, wherein the conductive layer is in contact with the conductive base so as to cover a surface of the elastic layer and a side surface of the end portion. The intermediate transfer member according to any one of claims 1 to 3, wherein the conductive substrate has a drum shape or a belt shape. The elastic layer has a rubber hardness of 10 degrees or more and 60 degrees or less in JIS-A,
The intermediate transfer member according to claim 1, wherein the conductor layer has a surface resistivity of 1E + 4Ω / □ or less. A toner image formed on an image carrier is primarily transferred to the intermediate transfer member according to any one of claims 1 to 5, and further transferred to a recording medium from the intermediate transfer member. Image forming apparatus.

Images