JP2020024307A - Intermediate transfer belt and image formation apparatus and method of manufacturing intermediate transfer belt - Google Patents

Abstract

To provide an intermediate transfer belt for electrophotography capable of improving productivity in manufacture while securing wear resistance and an image formation apparatus with the same and a method of manufacturing the intermediate transfer belt.SOLUTION: An intermediate transfer belt 7 has a base layer and a surface layer formed on an outer peripheral side of the base layer. The hardness of a surface of the surface layer measured in a nano-indentation method is 160-340 N/mmin a first region Lm including the entire maximum image region in a belt width direction. Further, the hardness of the surface of the surface layer is 70-120 N/mmin a second region Lr including an end part of the intermediate transfer belt outside the first region in the belt width direction.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an intermediate transfer belt for electrophotography, an image forming apparatus including the same, and a method of manufacturing an intermediate transfer belt.

  2. Description of the Related Art An electrophotographic image forming apparatus includes an intermediate transfer type in which a toner image formed on a surface of a photoreceptor is primarily transferred to an intermediate transfer belt, and a toner image carried on the intermediate transfer belt is secondarily transferred to a recording material. It has been known. As the intermediate transfer belt, an endless belt made of resin to which appropriate conductivity is imparted is widely used.

The intermediate transfer belt is required to have high abrasion resistance because it comes into contact with a cleaning blade for cleaning the belt surface, a photoconductor, a transfer roller, a recording material, and the like. Patent Literature 1 discloses a laminated belt for an image forming apparatus in which a coat layer containing a thermo-crosslinkable resin is formed on a base material layer, and the surface hardness of the coat layer is 250 N / mm ² or more and 700 N / mm ² or less. Has been described.

JP 2017-40871 A

  Incidentally, the manufacturing process of the intermediate transfer belt includes a process of cutting a side portion of the belt-shaped workpiece with a metal blade and forming the belt-shaped workpiece to a predetermined belt width. However, when manufacturing an intermediate transfer belt having a layer having a high hardness on the surface like the belt member described in the above-mentioned document, damage is accumulated on the metal blade during repeated cutting, and deterioration proceeds. Then, it is necessary to frequently replace the metal blade, which may lead to a reduction in productivity during manufacturing.

  Therefore, an object of the present invention is to improve the productivity during manufacturing while ensuring the wear resistance of the intermediate transfer belt.

One embodiment of the present invention is an intermediate transfer belt for electrophotography, which has a base layer and a surface layer formed on an outer peripheral side of the base layer, and has a surface hardness of the surface layer measured by a nanoindentation method. but in the belt width direction, the first region including the whole area of the maximum image forming region is at 160 N / mm ² or more 340 N / mm ² or less, the intermediate transfer be outside than the first region in the belt width direction in the second region including the end portion of the belt is 70N / mm ² or more 120 N / mm ² or less, wherein the.

Another aspect of the present invention is a method for manufacturing an intermediate transfer belt for electrophotography, comprising: a base layer forming step of forming a base layer in a belt shape; and a photocurable resin material on an outer peripheral side of the base layer. A coating step of applying a coating liquid containing the coating liquid, an irradiation step of irradiating light to the surface of the belt-shaped workpiece coated with the coating liquid, and the belt-shaped workpiece irradiated with light, in the belt width direction And a cutting step of cutting the side portion. The hardness of the surface of the intermediate transfer belt measured by the nanoindentation method is 160 N / mm ² or more and 340 N / in the first region including the maximum image forming region in the belt width direction. becomes mm ² or less, so that the a 70N / mm ² or more 120 N / mm ² or less if there in the belt width direction from the first region outside the second region including the cutting position in said cutting step The amount of light irradiated to the second region of the belt-shaped workpiece in the irradiation step is set to a value smaller than the amount of light irradiated to the first region.

  ADVANTAGE OF THE INVENTION According to this invention, the productivity at the time of manufacture can be improved, ensuring the wear resistance of an intermediate transfer belt.

1 is a schematic diagram of an image forming apparatus according to the present disclosure. FIG. 4 is a cross-sectional view of the intermediate transfer belt. FIG. 4 is a diagram for explaining a method of curing a surface layer when manufacturing an intermediate transfer belt. FIG. 4 is a view for explaining dimensions of the intermediate transfer belt.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic diagram illustrating an image forming apparatus 100 according to the present embodiment. The image forming apparatus 100 is a full-color printer including a so-called tandem-type intermediate transfer type image forming engine in which four image forming units PY, PM, PC, and PK are arranged along the rotation direction of the intermediate transfer belt 7.

  Each of the image forming units PY to PK includes a photosensitive drum 1, which is a photosensitive member, a charging device 2, a developing device 4, an exposing device 3, and a drum cleaner 6, and executes an electrophotographic process. A yellow, magenta, cyan and black toner image is formed. That is, the surface of the photosensitive drum 1 is uniformly charged by the charging device 2, and the photosensitive drum 1 is exposed by the laser beam emitted from the exposure device 3. At this time, the laser beam is modulated and output based on data obtained by decomposing the image to be output into a single-color image, and an electrostatic latent image corresponding to the single-color image is formed on the surface of the photosensitive drum 1. The developing device 4 stirs the developer containing the toner inside the container, causes the charged toner particles to be carried on a developer carrier such as a developing sleeve, and supplies the toner particles to the photosensitive drum 1. The electrostatic latent image carried on the photosensitive drum 1 is developed by the toner supplied from the developing device 4, and the toner image is visualized.

  The toner images formed by the image forming units PY to PK are transferred to the recording material P via the intermediate transfer unit 15. The intermediate transfer unit 15 is configured such that an intermediate transfer belt 7 as an intermediate transfer member is stretched around a driving roller 8, a tension roller 9, and a driven roller 10. The drive roller 8 is driven to rotate by a drive source, and rotates the intermediate transfer belt 7 in a direction along the rotation direction of the photosensitive drum 1 (counterclockwise direction in the figure). The tension roller 9 applies an appropriate tension to the intermediate transfer belt 7 and tilts the rotation axis of the tension roller 9 with respect to the rotation axis of the drive roller 8 to reduce the deviation (bias in the belt width direction) of the intermediate transfer belt 7. Also serves as a correction roller for correction.

  On the inner peripheral side of the intermediate transfer belt 7, primary transfer rollers 5 are disposed at positions corresponding to the respective photosensitive drums 1 with the intermediate transfer belt 7 interposed therebetween, and serve as a nip portion between the photosensitive drum 1 and the intermediate transfer belt 7. A primary transfer portion T1 is formed. The toner image carried on the photosensitive drum 1 is primarily transferred by the primary transfer roller 5 so as to overlap with the intermediate transfer belt 7 at the primary transfer portion T1. Deposits such as toner remaining on the primary transfer remaining on the photosensitive drum 1 without being transferred to the intermediate transfer belt 7 are removed by the drum cleaner 6.

  A secondary transfer roller 12 is disposed at a position facing the drive roller 8 with the intermediate transfer belt 7 interposed therebetween, and a secondary transfer portion T2 is formed as a nip portion between the intermediate transfer belt 7 and the secondary transfer roller 12. ing. The secondary transfer roller 12 is a transfer unit of the present embodiment for transferring a toner image from the intermediate transfer belt 7 to the recording material P. The recording material P fed from a storage unit such as a cassette or a tray is subjected to secondary transfer by the registration roller pair 13 at the timing when the toner image carried on the intermediate transfer belt 7 reaches the secondary transfer unit T2. It is sent to the section T2. In the secondary transfer portion T2, the toner image is secondarily transferred from the intermediate transfer belt 7 to the recording material P by the secondary transfer roller 12.

  The intermediate transfer unit 15 includes a belt cleaner 16 that cleans the surface of the intermediate transfer belt 7. The belt cleaner 16 is a cleaning unit of the present embodiment. The belt cleaner 16 is made of an elastic material such as urethane rubber, has a cleaning blade 11 that is a blade member that comes into contact with the intermediate transfer belt 7 at a tip portion, and cleans the belt surface as the intermediate transfer belt 7 rotates. . Deposits such as toner remaining on the secondary transfer remaining on the intermediate transfer belt 7 without being transferred to the recording material P are scraped off by the cleaning blade 11 and removed, and collected in a collection container.

  The recording material P to which the toner image has been transferred is then conveyed to a fixing device. The fixing device includes a pair of rollers for nipping and transporting the recording material P, and a heat source such as a halogen lamp, and applies heat and pressure to the toner image. As a result, the toner is fused and mixed and fixed to the recording material P, so that a fixed image fixed to the recording material P is obtained. The recording material P that has passed through the fixing device is discharged to the outside of the image forming apparatus 100.

[Intermediate transfer belt]
The configuration of the intermediate transfer belt 7 for electrophotography will be described. As shown in FIG. 2, the intermediate transfer belt 7 according to the present embodiment has a layer structure including a base layer 31 and a surface layer 32 (coat layer) formed on the outer peripheral side of the base layer 31. The surface 7a of the surface layer 32 is the outer peripheral surface of the intermediate transfer belt 7 that carries the toner image or contacts the photosensitive drum 1, the secondary transfer roller 12, the cleaning blade 11, and the recording material P (see FIG. 1).

(Base layer)
As a material constituting the base layer 31, a resin having mechanical strength and bending resistance as an intermediate transfer member is preferable. Specifically, polyamide, polyacetal, polyarylate, polycarbonate, polyphenylene ether, polyethylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polysulfone, polyether sulfone, polyphenyl sulfide, polybutylene terephthalate, polyether ether ketone, polyfluoride Vinylidene, polyvinyl fluoride, polyether amide copolymer, polyurethane copolymer, polyimide, polyamide imide and the like. It is formed from one of these resins or a mixture thereof. The base layer 31 is made of a material whose hardness does not change (or change is negligible) in response to the method of curing the surface layer 32 (ultraviolet rays in this embodiment).

A conductive substance can be added to the base layer 31 in order to impart conductivity. Examples of the conductive material include carbon-based inorganic conductive particles such as carbon black, carbon fiber, and carbon nanotubes, and conductive particles such as metal oxides such as zinc antimonate, zinc oxide, tin oxide, and titanium oxide. By adding such a conductive substance as needed, the volume resistance value of the base layer 31 is adjusted in the range of 10 ⁸ to 10 ¹² [Ω · cm]. If the volume resistance is too large, the primary transferability or the secondary transferability due to application of a predetermined transfer bias may be reduced. If the volume resistance is too small, the resistance unevenness tends to be remarkable, and And the like, and image defects are likely to occur. The thickness of the base layer 31 is preferably 40 μm or more and 200 μm or less from the viewpoint of mechanical strength and bending resistance.

(Surface layer)
The surface layer 32 is mainly composed of a photocurable resin material, a photopolymerization initiator, a conductive substance, and the like. Further, in order to improve the releasability, a fluorine resin or the like may be added. Examples of the photocurable resin material include ultraviolet curable resins such as urethane resin, acrylic resin, epoxy resin, polyester resin, methacrylic resin, maleimide resin, oxetane resin, polyether resin, and polyvinyl ether resin. Above all, in consideration of the surface layer 32 rubbing against other members such as a photoconductor and a cleaning blade, an acrylic resin having high hardness is particularly preferable. Such an ultraviolet curable resin can be obtained by curing an ultraviolet curable monomer, oligomer, prepolymer, or the like.

  As a photopolymerization initiator, benzophenone, thioxanthone-based compound, benzyldimethyl ketal, α-hydroxyketone, α-hydroxyalkylphenone, α-aminoketone, α-aminoalkylphenone, monoacylphosphine oxide, bisacylphosphine oxide, Radical-generating photopolymerization initiators such as hydroxybenzophenone, aminobenzophenone, titanocene, oxime ester, and oxyphenyl acetate are exemplified.

  Examples of the conductive substance include carbon-based inorganic conductive particles such as carbon black, carbon fiber, and carbon nanotubes, and metal oxides such as zinc antimonate, zinc oxide, tin oxide, and titanium oxide.

  It is desirable that the thickness of the surface layer 32 be 1 μm or more and 20 μm or less. If the thickness of the surface layer 32 is less than 1 μm, the original performance of the intermediate transfer belt 7 may be impaired because the surface layer 32 is worn due to friction with the cleaning blade 11 or the like and the cumulative use time is increased. There is. If the thickness of the surface layer 32 is larger than 20 μm, the flexibility of the intermediate transfer belt 7 may be insufficient, and the bending resistance may not be satisfied, for example, the surface layer 32 may be cracked.

(Production method)
The intermediate transfer belt 7 can be manufactured by the following procedure.
(A) First, a belt-shaped workpiece in which the above-described constituent material of the base layer 31 is formed into an endless belt-shaped film is obtained (base layer forming step). As a forming method of the base layer 31, a known method such as extrusion molding, inflation method, and centrifugal molding method can be used.
(B) Next, the surface layer coating solution obtained by dissolving and dispersing the constituent material of the surface layer 32 in an appropriate organic solvent is applied to the base layer 31 by any method such as ring coating, dip coating, spray coating and the like. Is applied to the outer peripheral surface of the belt-shaped workpiece having the above (application step).
(C) The belt-shaped workpiece coated with the surface layer coating liquid is dried for the purpose of removing the organic solvent. The drying step can be performed in an environment of about 30 to 60 ° C. so as not to induce a radical reaction.
(D) The belt-shaped workpiece is irradiated with ultraviolet rays using an ultraviolet irradiator to cure the resin material, thereby obtaining a belt-shaped workpiece on which the surface layer 32 is formed (irradiation step).
(E) The belt-shaped workpiece is cut to a predetermined length in the belt width direction, and the cut pieces are removed to obtain the intermediate transfer belt 7 (cutting step).

  Here, in the cutting step, the side of the belt-shaped workpiece in the belt width direction is cut by a metal blade such as tungsten steel. However, when the surface layer 32 is made of a resin having high hardness as in the present embodiment, the cutting process is repeated, and damage is accumulated in the blade edge, so that it is necessary to frequently replace the metal blade, thereby lowering productivity. I will.

  Therefore, in the present embodiment, by setting the surface hardness at both end positions in the belt width direction of the surface layer 32 smaller than the surface hardness at the center position, the advantage of using the high hardness surface layer 32 is not impaired. Improving productivity. The “end position” here is an end position of the intermediate transfer belt 7 obtained in the cutting step, and indicates a position adjacent to the cut surface.

[Configuration Example of Intermediate Transfer Belt and Its Evaluation]
Hereinafter, a configuration example (example) of the intermediate transfer belt 7 according to the present embodiment, and results of evaluation tests performed using the example and the comparative example will be described. The method of producing the intermediate transfer belt 7 used in the evaluation test is as follows.

(Base layer forming step)
The base layer 31 is made of a polyetheretherketone resin having a thickness of 100 μm, a volume resistivity ρv = 5 × 10 ⁹ [Ω · cm] and a surface resistivity ρs = 5 × 10 ¹² [Ω / □] containing a conductive substance. A cylindrical film was used. This tubular film was prepared by tubular extrusion molding, and the film was cut to a desired length to obtain a tubular endless belt.

(Coating process)
The coating liquid for forming the surface layer 32 was prepared according to the following formulation.
8.0 parts by mass of dipentaerythritol hexaacrylate 17.0 parts by mass of pentaerythritol tetraacrylate 5.0 parts by mass of pentaerythritol triacrylate 47.0 parts by mass of methyl ethyl ketone 45.0 parts by mass of ethylene glycol 15.0 parts by mass antimony-doped tin oxide fine particles (Ishihara Sangyo Co., Ltd.) SN-100P)
6.0 parts by mass Photopolymerization initiator (Irgacure 184 manufactured by Ciba Geigy)
2.0 parts by mass

  After these materials were mixed and dispersed with a stirring homogenizer, they were further dispersed by a dispersing device Nanomizer (manufactured by Yoshida Kikai Kogyo Co., Ltd.) to obtain a mixed dispersion. This mixed dispersion was applied to the cylindrical endless belt by a ring coating method. The belt-shaped workpiece coated with the coating solution was put into a drying oven at 80 ° C. for 1 minute to evaporate the solvent.

(Irradiation process)
Thereafter, as shown in FIG. 3, the belt-shaped workpiece W was fitted and held on the core 41, and was cured by irradiating ultraviolet rays while rotating the core 41 in the circumferential direction D1. At this time, the integrated value (integrated light amount) of the amount of ultraviolet light applied to the low hardness regions 21 and 21 of the belt-shaped workpiece W was set to be smaller than the integrated light amount of the high hardness region 22. However, the low hardness regions 21 and 21 are regions on both sides of the belt-shaped workpiece W in the belt width direction D2, and include a cutting position in the cutting process. The high-hardness region 22 is a region that is located between the low-hardness regions 21 and 21 and serves as a holding surface that holds the toner image when mounted on the image forming apparatus. The larger the integrated amount of ultraviolet light, the more the crosslinking reaction of the resin material proceeds, and the higher the surface hardness.

One of the following two methods can be used to reduce the integrated light amount of the low hardness regions 21 and 21 compared to the integrated light amount of the high hardness region 22.
(1) By adjusting the installation position and angle of a mirror that constitutes an optical system that guides ultraviolet light emitted from a light source toward a belt-shaped workpiece W, the distribution of the irradiation amount of ultraviolet light in the belt width direction is made non-uniform. how to.
(2) A method in which a filter is arranged between the light source and the belt-shaped workpiece W so as to cover the low hardness region 21, and the ratio of ultraviolet rays reaching the low hardness region 21 is reduced as compared with the high hardness region 22.

In the first embodiment, the amount of light applied to the belt-shaped workpiece is made uneven by the arrangement of the mirror, and the integrated light amount of the high hardness region 22 is set to 2.8 J / cm ² , and the integrated light amount of the low hardness region 21 is set to 1 0.3 J / cm ² . At this time, the resulting surface hardness of the intermediate transfer belt 7, 160 N / mm ² at the center position of the belt width direction was 120 N / mm ² at the end positions. The method for measuring the surface hardness will be described later.

In Example 2, 3.5 J / cm ² the integrated light quantity of the high-hardness region 22, and sets the integrated light quantity of the low hardness region 21 to 0.5 J / cm ^2. At this time, the resulting surface hardness of the intermediate transfer belt 7, 340 N / mm ² at the center position of the belt width direction, was 70N / mm ² at the end positions.

In Comparative Examples 1 to 3, unlike Examples 1 and 2, optical design was performed so that the belt-shaped workpiece W was uniformly irradiated with ultraviolet rays in the belt width direction. In Comparative Example 1, the integrated light amount was set to 1.3 J / cm ^2, and an intermediate transfer belt having a surface hardness of 120 N / mm ² was obtained. In Comparative Example 2, the integrated light amount was set to 2.8 J / cm ^2, and an intermediate transfer belt having a surface hardness of 160 N / mm ² was obtained. In Comparative Example 3, an integrated light amount was set to 4.0 J / cm ^2, and an intermediate transfer belt having a surface hardness of 480 N / mm ² was obtained.

(Cutting process)
The belt-shaped workpiece obtained by the irradiation step is fitted to a core, and while rotating the core at 2 rpm, a tungsten steel circular blade having a blade thickness of 0.3 mm is made to penetrate, so that both ends of the belt-shaped workpiece are inserted. Cut. Then, the cut pieces were removed to obtain an intermediate transfer belt.

The dimensions at the time of manufacture were set as follows in common for each sample (see FIG. 4). Here, a sample having medium hardness regions 23, 23 between the low hardness regions 21 and 21 and the high hardness region 22 and having the integrated light quantity adjusted so that the surface hardness is intermediate between the two is used. I have.
Width of belt-shaped workpiece before cutting L: 410 mm
Width of intermediate transfer belt after cutting Lb: 360 mm
Cutting width (cut allowance) of belt-shaped workpiece La: 25 mm
Width of high hardness region Lm: 312 mm
Width of low hardness region Lr: 31 mm
Width of medium hardness area Ls ... 18mm
Maximum image width Li: 298 mm
Non-image area width Ln: 31 mm
Cleaning blade width Lc: 328 mm

  However, the maximum image width Li refers to the maximum length in the belt width direction of the toner image that can be formed by the image forming units PY to PK, that is, the width of the maximum image forming area in which an image can be formed on the intermediate transfer belt. The non-image area refers to an area on the surface of the intermediate transfer belt that does not carry a toner image (that is, an area outside the range of the maximum image width). Further, the width Lc of the cleaning blade refers to the length of the tip of the cleaning blade 11 that contacts the intermediate transfer belt.

(Measurement of surface hardness)
The surface hardness of the intermediate transfer belt manufactured by the above steps was measured by a nanoindentation method based on ISO14577 using a micro hardness tester (product name: HM2000) manufactured by Fisher Scope. The measurement conditions were a maximum pushing load of 0.2 mN and a pushing time of 5 seconds. In addition, in consideration of the dispersion of the measurement results, the same location was measured three times, and the average value was adopted as the hardness measurement value.

(Evaluation method)
In order to evaluate each sample of the intermediate transfer belt, evaluation was performed from the viewpoint of ease of cutting (cutting property), abrasion resistance and coat cracking.

The cut property was evaluated by measuring the cut step and straightness of the obtained intermediate transfer belt every time the belt-shaped workpiece W was cut in the cutting step, and evaluated according to the following criteria. However, the cut step represents the presence or absence of a step on the cut surface, and is obtained by measuring the cut position (the position of the cut surface in the belt width direction) at a predetermined number of measurement points arranged at equal intervals in the circumferential direction. , The absolute value of the difference between the measurement values of adjacent measurement points. Straightness refers to the degree of variation in the cutting positions when measuring the cutting positions at a predetermined number of measurement points arranged at equal intervals in the circumferential direction.
○: When 100 intermediate transfer belts were cut, the number of cut steps or straightness did not satisfy the specified value is less than 30 sheets. ×: When 100 intermediate transfer belts were cut, the cut step or straightness was the specified value. If more than 30 samples do not satisfy the conditions

  The standard values in the evaluation tests shown in Table 1 are as follows. Regarding the cut step, the number of measurement points was set to 3100, and the standard value was satisfied when the cut step between adjacent measurement points was 100 μm or less (the maximum cut step was 100 μm or less). Regarding the straightness, the number of measurement points was 31300, and the variation of the cutting position in the belt width direction was 150 μm or less (for a coordinate axis extending in one direction in the belt width direction, the difference between the maximum value and the minimum value of the cutting position was 150 μm In the following case, the standard value was satisfied.

The abrasion resistance was evaluated by mounting each sample of the intermediate transfer belt on an evaluation device and performing a durability test for forming images on a large number of recording materials. The evaluation environment was a high temperature and high humidity (32.5 ° C./85% RH) environment. As an evaluation apparatus, a color MFP (product name: iRC2620) manufactured by Canon Inc. was used, and the intermediate transfer belt of the present embodiment was mounted instead of the polyimide intermediate transfer belt assembled in the apparatus. After the image output of 100,000 sheets, the scraping of the surface layer 32 of the intermediate transfer belt was evaluated according to the following criteria.
：: The decrease in the thickness of the surface layer 32 is less than 1 μm compared to before the endurance test.

  The pressing force (linear pressure) per unit length in the longitudinal direction (belt width direction) at the contact portion between the intermediate transfer belt 7 and the cleaning blade 11 made of urethane rubber is set to be 580 mN / cm. did. Further, the cleaning blade 11 was not applied with the lubricant applied in the iRC2620. The weight average particle diameter of the used toner was 5.0 μm, and the average circularity was 0.985.

  The coating crack was evaluated by visually observing the surface of the intermediate transfer belt obtained in the cutting step, and when the cracks on the surface layer 32 could not be visually recognized, it was evaluated as O, and when cracks could be visually recognized, it was evaluated as X. Table 1 summarizes the evaluation results of each sample.

As shown in Table 1, in Examples 1 and 2, the cuttability at the time of manufacture and the wear resistance at the time of use were good, and no surface coat cracking occurred. On the other hand, in the intermediate transfer belt of Comparative Example 1 in which the surface hardness at the center position is less than 160 N / mm ² , although the cut property is good, the amount of decrease in the film thickness of the surface layer 32 is large. Was inferior in wear resistance. Further, the intermediate transfer belt of Comparative Example 2 in which the surface hardness at the end portion exceeds 120 N / mm ² has high abrasion resistance, but the metal blade deteriorates quickly, and is compared with Examples 1 and 2. The productivity during production was poor. Further, in the intermediate transfer belt of Comparative Example 3 having a surface hardness of more than 340 N / mm ² , coat cracking occurred. Note that the abrasion resistance of Comparative Example 3 was not evaluated because the one having a coat crack is not suitable for use as an intermediate transfer belt.

From the above, to set the surface hardness of the first region including the maximum image formation area of the intermediate transfer belt 160 N / mm ² or more 340 N / mm ² or less, and the surface hardness of the second region including the end portion of the intermediate transfer belt 70N / mm ² or more 120 N / mm ² or can be seen that by setting the following. With such a setting, it is possible to provide an intermediate transfer belt that can improve productivity during manufacturing while ensuring wear resistance.

Further, it is preferable to set the average value of the surface hardness within the range of the maximum image width Li of the toner image intermediate transfer belt carries the 160 N / mm ² or more 340 N / mm ² or less. In the above Examples 1 and 2, the hardness over the high hardness region 22 having a width Lm than the maximum image width Li is set to a constant (160 N / mm ² or 340 N / mm ^2), satisfy this condition ing. In the present embodiment, the variation in hardness (standard deviation of the measured value of hardness) in the high hardness region 22 is set to 30 N / mm ² or less. Further, the variation in hardness is preferably 20 N / mm ² or less, and more preferably the variation in hardness is 10 N / mm ² or less. With such a setting, the wear of the intermediate transfer belt 7 is reduced by the surface layer 32 having a high hardness at least in the region serving as the toner image carrying surface, so that the performance of the intermediate transfer belt 7 is maintained for a long period of time. It becomes possible.

  Further, the intermediate transfer belt of the present embodiment has a first area (high-hardness area 22) including the center position in the belt width direction and an outer side of the first area, and an end position of the belt (the cutting position in the cutting step). ) (Low-hardness regions 21 and 21). The hardness of the surface of the first region can be regarded as constant except for the tolerance during manufacturing. At this time, the ratio of the area occupied by the first region is set to be at least half (Lm / L ≧ 1/2) of the surface of the entire intermediate transfer belt. This makes it possible to provide an intermediate transfer belt having high abrasion resistance and having a first area suitable as a surface for carrying a toner image. It is more preferable to set the length (Lm) of the first region in the belt width direction to a size widely used as a recording material (for example, 297 mm, which is the long side length of A4).

  In the present embodiment, the width Lb of the intermediate transfer belt is greater than the width Lc of the cleaning blade, and the end position of the intermediate transfer belt 7 is located outside the cleaning blade 11 in the belt width direction (see FIG. 4). . Normally, the hardness is distributed with a gradient from the set hardness of the high hardness region 22 to the set hardness of the low hardness region 21. For this reason, it is preferable that the range of contact with the cleaning blade 11 is set at least in a region where the hardness is higher than the low hardness region 21. In other words, both ends of the leading end of the cleaning blade 11 in the belt width direction are disposed inside the inner ends of the low hardness regions 21 and 21, and do not contact the cleaning blade 11 in the low hardness region 21. Is preferred.

  In the present embodiment, a medium hardness region 23 is provided between the high hardness region 22 and the low hardness region 21, and the end of the cleaning blade 11 contacts the medium hardness region 23. The hardness of the middle hardness region 23 is set so as to satisfy a relationship of “hardness of the low hardness region 21 <hardness of the middle hardness region 23 <hardness of the high hardness region 22”. However, the range of the medium hardness region may be narrower than the illustrated range. Alternatively, the high hardness region 22 may be extended without providing the middle hardness region 23 so that the end of the cleaning blade 11 contacts the high hardness region 22.

In the present embodiment, the target hardness of the low hardness region 21 and the target hardness of the high hardness region 22 are respectively set, and a configuration is adopted in which the variation of the measured value of the hardness with respect to the target hardness is allowed within a predetermined value or less. However, the hardness of the belt surface may be continuously changed. That is, when the hardness of the belt surface is measured along the width direction of the belt, the graph may have a smooth curve instead of a step-like shape. In this case, the first region includes the entire area of the maximum image forming region refers to a region measured value of hardness of 160 N / mm ² or more 340 N / mm ² or less. Further, the second region includes an end portion of the intermediate transfer belt, it refers to a region measured value of hardness of 70N / mm ² or more 120 N / mm ² or less.

  Further, in the present embodiment, a photocurable resin is used as a constituent material of the surface layer 32, but the present invention is not limited to this, and a thermosetting resin may be used as a constituent material of the surface layer 32, for example. In this case, by controlling the temperature distribution in the curing reaction, the surface hardness at the cutting position of the belt-shaped workpiece can be set lower than at the center position.

DESCRIPTION OF SYMBOLS 1 ... Photoconductor / 7 ... Intermediate transfer belt / 11 ... Blade member (cleaning blade) / 12 ... Transfer means (secondary transfer roller) / 16 ... Cleaning means (belt cleaner) / 21 ... Second area (low hardness area) / 22: First area (high hardness area) / 31: Base layer / 32: Surface layer / 100: Image forming apparatus / Li: Maximum image width / PY, PM, PC, PK ... Image forming part / W: Belt-shaped workpiece

Claims (6)

An intermediate transfer belt for electrophotography,
A base layer,
And a surface layer formed on the outer peripheral side of the base layer,
Hardness of the surface of the surface layer measured by a nanoindentation method,
In the belt width direction, the first region including the whole area of the maximum image forming region is at 160 N / mm ² or more 340 N / mm ² or less, of the intermediate transfer belt be outside than the first region in the belt width direction in the second region including the end portion is 70N / mm ² or more 120 N / mm ² or less,
An intermediate transfer belt, characterized in that: The surface layer includes a photocurable resin material,
The intermediate transfer belt according to claim 1, wherein: The surface layer has a surface hardness variation of 30 N / mm ² or less in the first region.
The intermediate transfer belt according to claim 1 or 2, wherein: An image forming unit having a photoconductor, and forming a toner image on the surface of the photoconductor,
The intermediate transfer belt according to any one of claims 1 to 3, wherein the toner image formed by the image forming unit is transferred.
Transfer means for transferring the toner image carried on the intermediate transfer belt to a recording material,
The average hardness of the surface layer of the surface at the maximum image formation area, is 160 N / mm ² or more 340 N / mm ² or less,
An image forming apparatus comprising: A cleaning unit that has a blade member that abuts on the intermediate transfer belt at a front end portion, and that cleans a surface of the intermediate transfer belt with rotation of the intermediate transfer belt,
In the belt width direction, both ends of the tip portion of the blade member are arranged more inside than the end portion inside the second region,
The image forming apparatus according to claim 4, wherein: A method for manufacturing an intermediate transfer belt for electrophotography,
A base layer forming step of forming the base layer into a belt shape,
An application step of applying a coating liquid containing a photocurable resin material on the outer peripheral side of the base layer,
An irradiation step of irradiating light to the surface of the belt-shaped workpiece coated with the coating liquid,
A cutting step of cutting a side portion in the belt width direction of the belt-shaped workpiece irradiated with light,
Hardness of the surface of the intermediate transfer belt was measured by nanoindentation method is said be 160 N / mm ² or more 340 N / mm ² or less in the belt width direction in a first region including the maximum image forming region, it said in the belt width direction first as a 70N / mm ² or more 120 N / mm ² or less in the second region including the cutting position in the cutting step there than one region outside, irradiating the second region of the belt-like workpiece in the irradiation step The amount of light to be set to a value smaller than the amount of light applied to the first region,
A method for producing an intermediate transfer belt.

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