JP2020098254A - Intermediate transfer belt and image forming apparatus - Google Patents

Abstract

To provide an intermediate transfer belt that can prevent peeling at the ends, while preventing bleed of a component contained in an elastic layer, and an image forming apparatus including the same.SOLUTION: An intermediate transfer belt 1 has a base layer 11, an elastic layer 12 stacked on the base layer 11, and a surface layer 14 stacked above the elastic layer 12, and the elastic layer 12 is formed with the use of silicone rubber as an elastic body. When a first degree of swelling is a degree of swelling of the elastic layer 12 measured by a toluene swelling method in first areas outside an image area in a width direction of the intermediate transfer belt 1 where a toner may be transferred, and a second degree of swelling is a degree of swelling of the elastic layer 12 measured by the toluene swelling method in a second area in the image area in the width direction of the intermediate transfer belt 1, the first degree of swelling is 169% or more and the second degree of swelling is 127% or more and 155% or less, and the difference between the first degree of swelling and the second degree of swelling is 58% or less.SELECTED DRAWING: Figure 2

Description

The present invention relates to an intermediate transfer belt used in an image forming apparatus such as a copying machine, a printer, and a facsimile apparatus, which uses an electrophotographic method or an electrostatic recording method, and an image forming apparatus thereof.

Conventionally, in an image forming apparatus using an electrophotographic method or the like, a toner image formed on an image bearing member such as a photoconductor is primarily transferred onto an intermediate transfer belt which is an endless belt-shaped intermediate transfer member, and then recorded on paper or the like. An intermediate transfer method in which secondary transfer is performed on a material is widely used.

In such an image forming apparatus, an intermediate transfer belt having at least one elastic layer (hereinafter, also referred to as “elastic intermediate transfer belt”) may be used in order to further improve image quality. Since the elastic intermediate transfer belt has at least one elastic layer, it is relatively soft and can reduce the pressure acting on the toner in the transfer portion (primary transfer portion, secondary transfer portion). Therefore, it is known that the elastic intermediate transfer belt is effective in suppressing a hollow phenomenon in which a part of the toner image is not transferred. Further, the elastic intermediate transfer belt has good adhesion to the recording material in the secondary transfer portion. Therefore, the elastic intermediate transfer belt not only improves the transfer efficiency of a toner image on general paper, but also improves the transferability of a toner image on thick paper and the transferability of a toner image on a recording material having irregularities such as embossed paper. Is also known to be effective.

It is known to use a cross-linked rubber material as an elastic body forming the elastic layer of such an elastic intermediate transfer belt. When a crosslinked rubber material is used, the hardness and elongation of the elastic layer can be adjusted by the degree of crosslinking. Further, in the crosslinked rubber material, a low molecular weight component contained in the elastic layer such as a compounding component such as a plasticizer, an unreacted rubber component, and a conductive component is transferred to the surface of the belt, which is called “bleed”. It is known that a phenomenon occurs. In particular, when silicone rubber is used as the rubber material, or when an ionic conductive agent or the like is added to the rubber material, bleeding tends to be remarkable. If the bleeding component migrates to the surface of the intermediate transfer belt, it may affect the image quality.

Patent Document 1 describes that generation of bleeding is suppressed by promoting crosslinking of the crosslinkable material. Further, Patent Document 2 describes that molecular movement of the resin is suppressed by cross-linking and migration of ions of the ion conductive material is suppressed.

JP, 2005-125226, A JP, 2004-258395, A

On the other hand, the manufacturing process of the intermediate transfer belt generally includes a step of cutting an end portion in the width direction so that the intermediate transfer belt has a predetermined width (hereinafter, also referred to as “end portion cutting”). Usually, end cutting is performed at both ends of the intermediate transfer belt in the width direction. In this step, the end of the intermediate transfer belt is directly cut with a metal blade.

However, if the degree of cross-linking of the rubber material is increased to suppress bleeding, the elastic layer shrinks greatly, which may lead to a decrease in adhesion between the base layer and the elastic layer. Therefore, when the end portion of the elastic intermediate transfer belt is cut, as shown in FIG. 6, when stress is applied to the end portion after the end portion is cut in the direction of peeling the elastic layer from the base layer, the gap between the base layer and the elastic layer is May cause peeling (hereinafter, also referred to as “edge peeling”). When the edge peeling occurs, the peeling may affect the image quality by advancing toward the image area where the toner of the elastic intermediate transfer belt can be transferred, or the durability of the intermediate transfer belt may be deteriorated. ..

Therefore, an object of the present invention is to provide an intermediate transfer belt capable of suppressing bleeding of components contained in an elastic layer and suppressing edge peeling, and an image forming apparatus including the intermediate transfer belt.

The above object is achieved by the intermediate transfer belt and the image forming apparatus according to the present invention. In summary, the present invention comprises a base layer, an elastic layer laminated above the base layer, and a surface layer laminated above the elastic layer, wherein the elastic layer comprises silicone rubber as an elastic body. In the intermediate transfer belt formed by using the first swelling, the swelling degree of the elastic layer in the first area outside the image area where the toner in the width direction of the intermediate transfer belt can be transferred is measured by the toluene swelling method. When the swelling degree measured by the toluene swelling method of the elastic layer in the second area in the image area in the width direction of the intermediate transfer belt is defined as the second swelling degree, the first swelling degree is 169% or more. The second swelling degree is 127% or more and 155% or less, and the difference between the first swelling degree and the second swelling degree is 58% or less. ..

According to another aspect of the present invention, there is provided an image forming apparatus including the intermediate transfer belt of the present invention.

According to the present invention, it is possible to provide an intermediate transfer belt that can suppress edge peeling while suppressing bleeding of components contained in the elastic layer, and an image forming apparatus including the intermediate transfer belt.

FIG. 3 is a schematic cross-sectional view of an example of an image forming apparatus. FIG. 3 is a schematic cross-sectional view of an intermediate transfer belt. FIG. 3 is a schematic perspective view of an intermediate transfer belt. FIG. 3 is a schematic side view of an intermediate transfer belt. FIG. 6 is a schematic diagram for explaining an example of a method for manufacturing an intermediate transfer belt. It is a schematic diagram for demonstrating a subject.

Hereinafter, the intermediate transfer belt and the image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

1. Image Forming Apparatus First, an example of an image forming apparatus that can use the intermediate transfer belt according to the present invention will be described. FIG. 1 is a schematic sectional view of an image forming apparatus 100 of this example. The image forming apparatus 100 of this example is a tandem type laser printer that can form a full-color image using an electrophotographic method and that employs an intermediate transfer method.

The image forming apparatus 100 of the present example forms images of respective colors of yellow (Y), magenta (M), cyan (C), and black (K) along the moving direction of the flat portion of the intermediate transfer belt 1. It has four image forming units PY, PM, PC, and PK. Regarding the elements having the same or corresponding functions or configurations in each of the image forming sections PY, PM, PC, PK, Y, M, C, K at the end of the reference numerals indicating the elements for any color are omitted. There is a general explanation. In this example, the image forming portion P is configured to include a photosensitive drum 101, a charging roller 102, an exposure device 103, a developing device 104, a primary transfer roller 105, etc., which will be described later.

The photosensitive drum 101, which is a drum type (cylindrical) photoconductor (electrophotographic photoconductor) as an image bearing member, is rotationally driven in a counterclockwise direction indicated by an arrow in the figure. The photosensitive drum 101 is configured by sequentially stacking a charge generation layer, a charge transport layer, and a surface protection layer on a base body formed of an aluminum cylinder. The surface of the rotating photosensitive drum 101 is uniformly charged to a predetermined potential of a predetermined polarity (negative polarity in this example) by a charging roller 102 which is a roller type charging member as a charging means. During the charging process, a predetermined charging voltage (charging bias) is applied to the charging roller 102. The surface of the photosensitive drum 101 that has been subjected to the charging process is scanned and exposed according to image information by an exposure device (laser scanner) 103 as an exposure unit, and the static component of the color component corresponding to each image forming portion P is formed on the photosensitive drum 101. An electric image (electrostatic latent image) is formed. The electrostatic image formed on the photosensitive drum 101 is developed (visualized) by supplying toner as a developer by a developing device 104 as a developing unit, and a toner image (developer image) is formed on the photosensitive drum 101. To be done. The developing device 104 includes a developing container that stores toner, a developing roller that serves as a developer bearing member, and a regulating blade that serves as a developer amount regulating member that regulates the amount of toner on the developing roller. The yellow, magenta, cyan, and black developing devices 104Y, 104M, 104C, and 104K contain toners of yellow, magenta, cyan, and black, respectively. The developing roller is lightly pressed against the photosensitive drum 101 in the developing section, and is rotationally driven with a speed difference in the forward direction with respect to the photosensitive drum 101. The toner conveyed to the developing section by the developing roller adheres to the electrostatic image formed on the photosensitive drum 101 by applying a predetermined developing voltage (developing bias) to the developing roller. In this example, in the exposed portion on the photosensitive drum 101 where the absolute value of the potential is lowered by being uniformly charged and then exposed, the charging polarity of the photosensitive drum 101 is the same polarity (negative polarity in this example). The charged toner adheres.

An intermediate transfer belt (elastic intermediate transfer belt) 1 composed of an endless belt as an intermediate transfer member is arranged so that it can contact the four photosensitive drums 101Y, 101M, 101C, and 101K. The intermediate transfer belt 1 is stretched around a drive roller 121, a tension roller 122, and a secondary transfer counter roller 123, which are a plurality of stretching rollers (supporting rollers), and is stretched with a predetermined tension. The driving force is transmitted to the intermediate transfer belt 1 when the driving roller 121 is rotationally driven, and the intermediate transfer belt 1 rotates (rotates) in a clockwise direction indicated by an arrow in the figure. On the inner peripheral surface side of the intermediate transfer belt 1, a primary transfer roller 105, which is a roller-type primary transfer member as a primary transfer unit, is arranged corresponding to each photosensitive drum 101. The primary transfer roller 105 is pressed toward the photosensitive drum 101 via the intermediate transfer belt 1 and forms a primary transfer portion T1 where the photosensitive drum 101 and the intermediate transfer belt 1 come into contact with each other. The toner image formed on the photosensitive drum 101 as described above is primarily transferred onto the rotating intermediate transfer belt 1 by the action of the primary transfer roller 105 at the primary transfer portion T1. During the primary transfer process, a predetermined primary transfer voltage (primary transfer bias), which is a DC voltage having a polarity opposite to the regular charging polarity of toner (charging polarity at the time of development), is applied to the primary transfer roller 105. To be done. For example, when forming a full-color image, the toner images of yellow, magenta, cyan, and black formed on the photosensitive drums 101Y, 101M, 101C, and 101K are sequentially superposed on the intermediate transfer belt 1 so as to be superimposed on each other. Primary transfer is performed.

On the outer peripheral surface side of the intermediate transfer belt 1, a secondary transfer roller 108, which is a roller-type secondary transfer member as a secondary transfer unit, is arranged at a position facing the secondary transfer counter roller 123. The secondary transfer roller 108 is pressed toward the secondary transfer counter roller 123 via the intermediate transfer belt 1 and forms a secondary transfer portion T2 where the intermediate transfer belt 1 and the secondary transfer roller 108 contact each other. The toner image formed on the intermediate transfer belt 1 as described above is conveyed by being sandwiched between the intermediate transfer belt 1 and the secondary transfer roller 108 by the action of the secondary transfer roller 108 at the secondary transfer portion T2. The secondary transfer is performed on the recording material S. During the secondary transfer process, a predetermined secondary transfer voltage (secondary transfer bias), which is a DC voltage having a polarity opposite to the regular charging polarity of the toner, is applied to the secondary transfer roller 108. Normally, a secondary transfer voltage of several kV is applied in order to ensure a sufficient secondary transfer efficiency. The recording material (recording medium, transfer material, sheet) S is accommodated in the cassette 112, and is supplied from the cassette 112 to the conveyance path by the pickup roller 113. The recording material S supplied to the conveyance path is conveyed to the secondary transfer portion T2 by the conveyance roller pair 114 and the registration roller pair 115 in time with the toner image on the intermediate transfer belt 1. The recording material S is typically paper (paper), but may be synthetic paper made of resin such as waterproof paper, plastic sheet such as OHP sheet, or cloth.

The recording material S to which the toner image is transferred is conveyed to the fixing device 109 as a fixing unit. The fixing device 109 includes a fixing roller 191 including a heating unit, and a pressure roller 192 that is in pressure contact with the fixing roller 191. The fixing device 109 fixes (melts and fixes) the toner image on the recording material S by heating and pressing the recording material S carrying the unfixed toner image with the fixing roller 191 and the pressure roller 192. .. The recording material S on which the toner image is fixed is discharged (output) to the outside of the apparatus main body of the image forming apparatus 100 by the conveying roller pair 116, the discharging roller pair 117, and the like.

Further, the toner remaining on the photosensitive drum 101 without being transferred to the intermediate transfer belt 1 during the primary transfer process is removed and collected from the photosensitive drum 101 by the developing device 104 in this example. In addition, the toner (secondary transfer residual toner) and paper dust remaining on the intermediate transfer belt 1 without being transferred to the recording material S during the secondary transfer process are intermediately transferred by a belt cleaning device 111 as an intermediate transfer member cleaning unit. It is removed from the belt 1 and collected.

By using the intermediate transfer belt 1 according to the present invention as the intermediate transfer belt 1 in the image forming apparatus 100, transfer of the bleeding component generated from the elastic layer 12 (FIG. 2) to the surface of the intermediate transfer belt 1 can be prevented. Suppressed. As a result, a high quality image can be formed. Further, by using the intermediate transfer belt 1 according to the present invention, peeling off of the end portion of the intermediate transfer belt 1 can be suppressed for a long period of time.

2. Intermediate Transfer Belt Next, an embodiment of the intermediate transfer belt (elastic intermediate transfer belt) according to the present invention will be described. As shown in FIG. 2, the intermediate transfer belt 1 of the present embodiment is composed of a laminated body having four layers of a base layer 11, an elastic layer 12, an intermediate layer 13, and a surface layer 14. The intermediate transfer belt 1 only needs to have the base layer 11, the elastic layer 12, and the surface layer 14, and may be composed of, for example, a laminate of these three layers.

<Base layer>
The base layer (base material) 11 will be described. The base layer 11 is a roll type or belt type seamless type cylindrical type. Suitable materials for forming the base layer 11 include, for example, resin materials such as polyether ether ketone, polyethylene terephthalate, polybutylene naphthalate, polyester, polyimide, polyamide, polyamide imide, polyacetal, and polyphenylene sulfide.

The resin forming the base layer 11 may be provided with conductivity by adding conductive powder such as metal powder, conductive oxide powder, and conductive carbon.

From the viewpoints of mechanical strength and conductivity, the resin forming the base layer 11 is particularly preferably carbon black-added polyether ether ketone or polyimide.

The thickness (film thickness) of the base layer 11 is preferably 10 μm or more and 500 μm or less. If the thickness of the base layer 11 is less than 10 μm, the mechanical strength may be significantly reduced. If the thickness of the base layer 11 is larger than 500 μm, the rigidity becomes too strong, which may make it difficult to use as an intermediate transfer member.

<Elastic layer>
The elastic layer 12 will be described. The elastic layer 12 needs to have appropriate flexibility in order to follow the surface shape of the recording material S. In the present invention, silicone rubber is used as the material of the elastic body forming the elastic layer 12 because of its small compression set and excellent ozone resistance.

The thickness of the elastic layer 12 is preferably 100 μm or more and 1000 μm or less, more preferably 200 μm or more and 500 μm or less. If the elastic layer 12 is too thin, sufficient flexibility may not be obtained, and if the elastic layer 12 is too thick, it may be difficult to use it as an intermediate transfer member. The JIS-A hardness of the elastic layer 12 is preferably 14 degrees or more and 60 degrees or less, and more preferably 22 degrees or more and 55 degrees or less. If the JIS-A hardness of the elastic layer 12 is too low, bleeding tends to occur, and if the JIS-A hardness of the elastic layer 12 is too high, the transferability of the toner to the recording material S having irregularities may deteriorate.

The elastic layer 12 may include an electronic conductive agent or an ionic conductive agent as a conductive agent. Examples of the electronic conductive agent include conductive carbon black such as acetylene black and Ketjen black, graphite, graphene, carbon fiber, and carbon nanotube. Examples of the electronic conductive agent include metal powder such as silver, copper and nickel, conductive zinc white, conductive calcium carbonate, conductive titanium oxide, conductive tin oxide and conductive mica. Of these, conductive carbon black is preferable from the viewpoint of easy control of electric resistance. Examples of the ionic conductive agent include pyridine-based, alicyclic amine-based, and aliphatic amine-based ionic liquids as well as lithium salts and potassium salts. Of these, ionic liquids are preferable from the viewpoint of environmental stability and suppression of polarization due to durability. From the viewpoint of mechanical strength, the compounding recipe for the elastic layer 12 is preferably 35 parts by mass or less, and more preferably 25 parts by mass or less, relative to 100 parts by mass of the silicone rubber. Thereby, the elastic layer 12 is provided with stable conductivity suitable for the intermediate transfer member.

The elastic layer 12 includes a filler, a cross-linking accelerator, a cross-linking retarder, a cross-linking aid, a scorch inhibitor, an anti-aging agent, a softening agent, a heat stabilizer, a flame retardant, a flame retardant aid, an ultraviolet absorber, and a protective agent. It may contain an additive such as a rusting agent. In particular, examples of the filler include reinforcing fillers such as fumed silica, crystalline silica, wet silica, fumed titanium oxide, and cellulose nanofiber. Reinforcing fillers include organoalkoxysilanes, organohalosilanes, organosilazanes, diorganosiloxane oligomers in which both molecular chain ends are blocked with silanol groups, and cyclic organosiloxanes from the viewpoint of being easily dispersed in silicone rubber. The surface may be modified with an organosilicon compound.

A primer layer (not shown) may be provided between the base layer 11 and the elastic layer 12 if necessary. The thickness of the primer layer is preferably 0.1 μm or more and 2 μm or less from the viewpoint of reducing cohesive failure in the primer layer.

In addition, as shown in FIG. 3, the intermediate transfer belt 1 of the present embodiment has low cross-linking at both ends in the width direction, in which the elastic layer 12 has a lower degree of cross-linking than the non-low cross-linking region 16 at the center in the width direction. Area 15 is provided. As a result, it is possible to suppress the peeling of the end portion between the base layer 11 and the elastic layer 12 after the end portion of the intermediate transfer belt 1 is cut. The degree of cross-linking in each of the low cross-linking region 15 and the non-low cross-linking region 16 will be described by the swelling degree (a measuring method will be described later) that is a characteristic value for determining the degree of cross-linking. From the viewpoint of the adhesion between the base layer 11 and the elastic layer 12, the degree of swelling of the elastic layer 12 in the low cross-linking region 15 arranged at the end of the intermediate transfer belt 1 in the width direction needs to be 169% or more. is there. When the degree of swelling of the elastic layer 12 in the low cross-linking region 15 is lower than 169%, that is, when the degree of cross-linking of the silicone rubber is high, the end peeling may occur from the position where the end cut is made. Further, the swelling degree of the elastic layer 12 in the non-low-crosslinking region 16 arranged in the widthwise central portion of the intermediate transfer belt 1 needs to be 127% or more and 155% or less from the viewpoint of suppressing bleeding. .. If the degree of swelling of the elastic layer 12 in the non-low crosslinked region 16 is lower than 127%, that is, if the silicone rubber has a high degree of crosslinking, decomposition products due to heating during the crosslinking (vulcanization) process increase, and this becomes a bleed component. As a result, an image defect due to bleeding may occur. When the swelling degree of the elastic layer 12 in the non-low crosslinked region 16 is higher than 155%, that is, when the silicone rubber has a low degree of crosslinking, the intermolecular free volume of the silicone rubber increases, so that the bleeding component increases and the bleeding increases. There is a risk that an image defect may occur due to. Furthermore, the difference in swelling degree of the elastic layer 12 between the low cross-linking region 15 and the non-low cross-linking region 16 needs to be 58% or less, preferably 40% or less, and 39% or less. Is more preferable. If this difference is too large, distortion of the intermediate transfer belt 1 due to the difference in contraction between the low cross-linking region 15 and the non-low cross-linking region 16 becomes large, and image defects such as color misregistration may occur.

<Middle layer>
The intermediate layer 13 will be described. The intermediate layer 13 is a layer that enhances the adhesion between the elastic layer 12 and the surface layer 14, and it is required to use a material having a high affinity for the elastic layer 12 and the surface layer 14. Examples of such a material include polyurethane (urethane resin), polyamide resin, polyvinylidene chloride resin, fluororesin, phenol resin, and cellulose acetate resin. The intermediate layer 13 is not particularly required when the affinity between the elastic layer 12 and the surface layer 14 is sufficiently high and there is no problem in the adhesiveness.

The thickness of the intermediate layer 13 is preferably 0.8 μm or more and 16 μm or less, more preferably 1 μm or more and 15 μm or less. When the thickness of the intermediate layer 13 is too thin, the effect of enhancing the adhesiveness is weakened, and there is a possibility that poor adhesion may occur between the elastic layer 12 and the surface layer 14. If the intermediate layer 13 is too thick, the elastic function of the elastic layer 12 may be hindered.

The intermediate layer 13 may include additives such as a curing agent, a plasticizer, and a conductive agent, if necessary. The amount of the additive is not particularly limited as long as it has a sufficient mechanical strength.

<Surface layer>
The surface layer 14 will be described. The surface layer 14 constitutes the surface of the intermediate transfer belt 1 (the surface carrying the toner image). The surface layer 14 is a layer provided for improving the transferability of the toner to the recording material S and improving the releasability of the toner from the intermediate transfer belt 1, and it is necessary that the surface layer 14 has a low adhesive property. is there. The material forming the surface layer 14 is not particularly limited as long as it has a low adhesive property. Examples of such a material include a fluororesin, a fluorine-containing urethane resin, a fluororubber, and a siloxane-modified polyimide. Of these, a fluorine-containing urethane resin is preferable from the viewpoint of not impairing the elastic function of the elastic layer 12.

The thickness of the surface layer 14 is preferably 1 μm or more and 4 μm or less. When the thickness of the surface layer 14 is less than 1 μm, it tends to disappear due to wear. If the thickness of the surface layer 14 is larger than 4 μm, the elastic function of the elastic layer 12 may be hindered.

The surface layer 14 may include the same conductive agent as described above, if necessary. The amount of the conductive agent is preferably 30 parts by mass or less with respect to 100 parts by mass of the main component of the surface layer 14 (fluorine-containing urethane resin or the like) from the viewpoint of adhesiveness and mechanical strength.

<Electrical resistance of intermediate transfer belt>
The volume resistivity of the intermediate transfer belt 1 is preferably 1.0×10 ⁶ Ω·cm or more and 1.0×10 ¹⁴ Ω·cm or less, and 1.0×10 ⁸ Ω·cm or more, 1. It is more preferably 0×10 ¹³ Ω·cm or less. The surface resistivity of the intermediate transfer belt 1 measured from the surface layer 14 side is preferably 1.0×10 ⁶ Ω/□ or more and 1.0×10 ¹⁴ Ω/□ or less, and 1.0×10 ¹⁴ Ω/□ or less. It is more preferably 10 ⁹ Ω/□ or more and 1.0×10 ¹³ Ω/□ or less. By setting the electric resistance of the intermediate transfer belt 1 within the range of the semiconductive area as described above, the primary transfer of the toner image from the photosensitive drum 101 and the transfer of the toner image from the intermediate transfer belt 1 to the recording material S are performed. Secondary transfer can be performed stably.

The surface resistivity of the intermediate transfer belt 1 was measured using a circular electrode (trade name: Hiresta UP, manufactured by Mitsubishi Chemical Analytech Co., Ltd.). The intermediate transfer belt 1, which is an object to be measured, is placed on a plate made of an insulator, a voltage of 1000 V is applied, and the value 10 seconds after the application is read. The surface resistivity of the intermediate transfer belt 1 to be measured is determined by measuring 16 arbitrary points within a single belt surface. The method for measuring the volume resistivity is substantially the same as the method for measuring the surface resistivity, except that the measurement target is placed on a plate made of metal.

3. Configurations of Intermediate Transfer Belts of Examples and Comparative Examples Next, the effects of the present invention will be further described using the following Examples 1 to 5 and Comparative Examples 1 to 7.

<Measurement method of thickness of each layer>
Here, a method of measuring the thickness of each layer of the intermediate transfer belt 1 will be described. The thickness of each layer (base layer 11, elastic layer 12, intermediate layer 13, and surface layer 14) of the intermediate transfer belt 1 was measured by using a cross section polisher to make a vertical cross section from the surface of the intermediate transfer belt 1, and then making the cross section. It was determined by observing the cross section obtained with a scanning electron microscope.

Specifically, a cross-section polisher (trade name: SM-09010, manufactured by JEOL Ltd.) was used for accelerating voltage 4 kV, current value 70 μA, and using argon gas for 15 hours to obtain a cross section perpendicular to the surface. It was made. Thereafter, this cross section was observed with a scanning electron microscope (trade name: XL-300-SFEG, manufactured by FEI) at an accelerating voltage of 3 kV and a magnification of 1,500, and any three points were observed. Was calculated, and the average value was used as the thickness (average thickness, average film thickness) of each layer of the evaluation object.

[Example 1]
In Examples and Comparative Examples, some of the materials of the mixed dispersion are those diluted and dispersed by a solvent, but the amount of each material used (parts by mass) is the amount related to the nonvolatile content unless otherwise specified. , Means the amount excluding the solvent (volatile matter).

<Preparation of base layer>
The following materials were kneaded using a biaxial kneader (trade name: PCM30, manufactured by Ikegai Co., Ltd.) to obtain pellets.
-Polyether ether ketone (trade name: VICTREX PEEK450G, manufactured by Victorex)
・Acetylene black (Brand name: Denka Black granular product, manufactured by Denka)

Each of the above materials was introduced into a biaxial kneader using a weight feeder so that the polyether ether ketone content was 80% by mass and the acetylene black content was 20% by mass. The cylinder set temperature of the twin-screw kneader was 320° C. at the material feeding part and 360° C. at the cylinder downstream side and the die. The screw rotation speed of the twin-screw kneader was 300 rpm, and the material supply rate was 8 kg/h.

Next, the obtained pellets were subjected to cylindrical extrusion molding to obtain a belt. The cylindrical extrusion molding was performed using a single-screw extruder (trade name: GT40, manufactured by Plastic Engineering Laboratory Co., Ltd.) and a cylindrical die having a circular opening with a diameter of 300 mm and a gap of 1 mm. The pellets were fed to the single-screw extruder at a feed rate of 4 kg/h using a weight feeder. The cylinder set temperature of the single-screw extruder was 320° C. at the material feeding part, and 380° C. at the cylinder downstream and the cylindrical die. The molten resin discharged from the single-screw extruder was extruded from a cylindrical die through a gear pump, and was taken up by a cylindrical take-out machine at a speed of 85 μm in thickness. The molten resin was cooled and solidified by coming into contact with a cooling mandrel provided between the cylindrical die and the cylindrical taker in the process of being taken out. The solidified resin was cut into a width of 380 mm by a cylindrical cutting machine installed in the lower part of the cylindrical take-up machine to obtain a crystalline thermoplastic resin belt.

<Preparation of elastic layer>
As the conductive agent, an ionic liquid type antistatic agent (trade name: FC-4400, manufactured by 3M Japan Co., Ltd.) was used. Addition of 0.2 parts by mass of the above conductive agent to 100 parts by mass of addition curable liquid silicone rubber (trade name: TSE3450 A/B, manufactured by Momentive Performance Materials), a planetary stirring defoaming device (Brand name: HM-500, manufactured by Keyence Corporation) was stirred and defoamed to obtain a mixed solution.

Next, the crystalline thermoplastic resin belt serving as the base layer 11 was attached to a cylindrical core, and a ring nozzle for discharging rubber was attached coaxially with the core. The liquid silicone rubber mixed liquid was supplied to a ring nozzle using a liquid feed pump and discharged from a slit to apply the mixed liquid on the base layer 11. At this time, the relative moving speed of the ring nozzle and the discharge amount of the liquid feed pump were adjusted so that the cured silicone rubber layer had a thickness of 220 μm.

As shown in FIG. 5, a temperature adjusting ring 22 is provided at a position corresponding to an end portion in the width direction of the belt 20 in a state where the crystalline thermoplastic resin belt 20 coated with the mixed liquid is attached to the core 21. It was put into a heating furnace. The temperature adjustment ring 22 has a ring-shaped structure having a predetermined width in the width direction of the belt 20, which houses the circular temperature adjustment tube 23 so as to sandwich it. The temperature adjusting pipe 23 is connected to a hot water circulating device (not shown), and hot water having a predetermined temperature is flown into the temperature adjusting pipe 23. This makes it possible to adjust the heating temperature of the widthwise end portion of the belt 20 in the portion corresponding to the low cross-linking area 15 (FIG. 3) of the intermediate transfer belt 1.

In the cross-linking (vulcanization) step in a heating furnace, the rubber was cross-linked by heating at 130° C. for 10 minutes for the first firing and 180° C. for 180 minutes for the second firing. At the time of the secondary firing, hot water of 55° C. was caused to flow through the temperature adjusting pipe 23, and the surface temperature of the belt 20 at predetermined positions at both ends in the width direction of the belt 20 was set to 155° C. This predetermined position was the end cut position of the intermediate transfer belt 1, and the surface temperature of the belt 20 at this predetermined position was measured by attaching a thermocouple to the predetermined position.

Then, after cooling, the belt was removed from the core to obtain a belt on which the elastic layer 12 was laminated.

<Surface modification of elastic layer>
In order to improve the adhesiveness between the elastic layer 12 and the intermediate layer 13, the surface of the elastic layer 12 is modified by using an excimer lamp (manufactured by M.D.com Co.) that emits a single wavelength of 172 nm as an excimer UV irradiation unit. I went.

The belt provided with the elastic layer 12 was fitted into a cylindrical core, arranged at a distance of about 1 mm from the surface of the excimer lamp, and a space into which nitrogen gas and air were introduced while rotating the core at a rotation speed of 5 rpm. Inside, the excimer UV irradiation was performed for 30 minutes.

<Preparation of intermediate layer>
As a material for the intermediate layer 13, a polyurethane resin coating (trade name: Hydran 201, manufactured by DIC) was used. The belt on which the elastic layer 12 subjected to the surface modification is laminated is fitted to the core, and while rotating at 90 rpm, a spray gun (trade name: W-101, manufactured by Anest Iwata Co., Ltd.) is used to produce the polyurethane resin liquid. Was applied. The amount of coating material discharged during application was set so that the thickness of the intermediate layer 13 after drying was 8 μm.

After the application of the resin solution, the belt was fitted to the core, and naturally dried for 15 minutes while rotating at 90 rpm. After drying, a belt in which the polyurethane intermediate layer 13 was laminated on the elastic layer 12 was obtained.

<Preparation of surface layer>
As the material of the surface layer 14, a fluorine-containing polyurethane resin liquid (trade name: Emralon T-861, manufactured by Henkel Japan) in which polytetrafluoroethylene was dispersed in a polyurethane dispersion was used. The urethane resin solution was applied using a spray gun (trade name: W-101, manufactured by Anest Iwata Co., Ltd.) while fitting the belt having the intermediate layer 13 laminated on the core and rotating the core at 90 rpm. The amount of coating material discharged during coating was set so that the thickness of the surface layer 14 after drying was 3 μm.

After applying the resin solution, the resin solution was placed in a heating furnace at 130° C. and left for 30 minutes. After being taken out of the heating furnace and cooled, an intermediate transfer belt 1 of Example 1 was obtained.

<Thickness>
Regarding the thickness of each layer of the intermediate transfer belt 1 of Example 1, the base layer 11 was 85 μm, the elastic layer 12 was 220 μm, the intermediate layer 13 was 8.0 μm, and the surface layer 14 was 3.0 μm.

<Range of low bridge area>
The range of the low cross-linking region 15 can be adjusted by changing the width of the temperature adjusting ring 22 (the width in the direction corresponding to the width direction of the intermediate transfer belt 1). In this embodiment, as shown in FIG. 4, the range of the low cross-linking region 15 in the width direction of the intermediate transfer belt 1 is set. FIG. 4 is a schematic side view of the intermediate transfer belt 1 of FIG. 3 viewed from the side, that is, a side view of the surface of the intermediate transfer belt 1 taken along a direction normal to the surface. Lb in FIG. 4 is the width of the belt before the end cutting. Lc is the width of the belt after the end portion is cut. Further, Li is the width of the image area (area where the toner image on the surface of the intermediate transfer belt 1 can be transferred). Ll is the width of the low cross-linking region 15. Further, Lh is the width of the non-low-bridge region 16. In this embodiment, the dimensions of the widths Lb, Lc, Li, Ll, and Lh are set as follows. This set value is set when the steering during conveyance of the intermediate transfer belt 1 is maximized in the image forming apparatus 100 (the intermediate transfer belt 1 is moved from one end side in the width direction to the other end side to the maximum. Even in the case), the image area width Li is set so as not to exceed the non-low bridge area width Lh. That is, the toner image transferred onto the intermediate transfer belt 1 is always transferred within the range of the non-low cross-linking region 16 in the width direction of the intermediate transfer belt 1.
Belt width before end cutting Lb: 380 mm
Belt width after end cutting Lc: 360 mm
Image area width Li: 298 mm
Low bridge area width Ll: 30 mm
Non-low bridge area width Lh: 320 mm

[Example 2]
An intermediate transfer belt 1 of Example 2 was obtained in the same manner as in Example 1 except for the following changes. In the preparation of the elastic layer 12, the secondary firing temperature of the elastic layer 12 is set to 170° C., the temperature of the hot water circulated in the temperature adjusting pipe 23 during the secondary firing is set to 80° C. The surface temperature was set to 150°C.

[Example 3]
An intermediate transfer belt 1 of Example 3 was obtained in the same manner as in Example 1 except for the following changes. In the preparation of the elastic layer 12, the secondary firing temperature of the elastic layer 12 is set to 170° C., the temperature of the hot water circulated in the temperature adjustment pipe 23 during the secondary firing is set to 70° C. The surface temperature was set to 145°C.

[Example 4]
An intermediate transfer belt 1 of Example 4 was obtained in the same manner as in Example 1 except for the following changes. In the preparation of the elastic layer 12, the secondary firing temperature of the elastic layer 12 is set to 160° C., the temperature of the hot water circulated in the temperature adjusting pipe 23 during the secondary firing is set to 80° C. The surface temperature was set to 150°C.

[Example 5]
An intermediate transfer belt 1 of Example 5 was obtained in the same manner as in Example 1 except for the following changes. In the preparation of the elastic layer 12, the secondary firing temperature of the elastic layer 12 is set to 160° C., the temperature of the hot water circulated in the temperature adjusting pipe 23 during the secondary firing is set to 75° C. The surface temperature was set to 145°C.

[Comparative Example 1]
An intermediate transfer belt 1 of Comparative Example 1 was obtained in the same manner as in Example 1 except for the following changes. In the preparation of the elastic layer 12, the secondary firing temperature of the elastic layer 12 is set to 190° C., the temperature of the hot water circulated in the temperature adjusting pipe 23 during the secondary firing is set to 50° C. The surface temperature was set to 150°C.

[Comparative example 2]
An intermediate transfer belt 1 of Comparative Example 2 was obtained in the same manner as in Example 1 except for the following changes. In the preparation of the elastic layer 12, the secondary firing temperature of the elastic layer 12 is set to 180° C., the temperature of the hot water circulated in the temperature adjusting pipe 23 at the time of the secondary firing is set to 50° C. The surface temperature was set to 145°C.

[Comparative Example 3]
An intermediate transfer belt 1 of Comparative Example 3 was obtained in the same manner as in Example 1 except for the following changes. In the preparation of the elastic layer 12, the secondary firing temperature of the elastic layer 12 is set to 170° C., the temperature of the hot water circulated in the temperature adjusting pipe 23 at the time of the secondary firing is set to 65° C. The surface temperature was set to 140°C.

[Comparative Example 4]
An intermediate transfer belt 1 of Comparative Example 4 was obtained in the same manner as in Example 1 except for the following changes. In the preparation of the elastic layer 12, the secondary firing temperature of the elastic layer 12 is set to 160° C., the temperature of the hot water circulated in the temperature adjusting pipe 23 during the secondary firing is set to 70° C. The surface temperature was set to 140°C.

[Comparative Example 5]
An intermediate transfer belt 1 of Comparative Example 5 was obtained in the same manner as in Example 1 except for the following changes. In the preparation of the elastic layer 12, the secondary firing temperature of the elastic layer 12 was set to 150° C. with the temperature adjustment ring 22 removed, and the secondary firing of the elastic layer 12 was performed.

[Comparative Example 6]
An intermediate transfer belt 1 of Comparative Example 6 was obtained in the same manner as in Example 1 except for the following changes. In the preparation of the elastic layer 12, the secondary firing temperature of the elastic layer 12 is set to 180° C., the temperature of the hot water circulated in the temperature adjusting pipe 23 during the secondary firing is set to 70° C. The surface temperature was set to 155°C.

[Comparative Example 7]
An intermediate transfer belt 1 of Comparative Example 7 was obtained in the same manner as in Example 1 except for the following changes. In the preparation of the elastic layer 12, the secondary firing temperature of the elastic layer 12 is set to 190° C., the temperature of the hot water circulated in the temperature adjusting pipe 23 at the time of the secondary firing is set to 45° C. The surface temperature was set to 140°C.

4. Evaluation of Intermediate Transfer Belts of Examples and Comparative Examples Next, with respect to the intermediate transfer belts 1 of Examples and Comparative Examples, the results of examining the swelling degree of the elastic layer 12, the degree of edge peeling, bleeding, and color misregistration will be described.

<Method of measuring swelling degree of elastic layer>
The swelling degree of the elastic layer 12 was measured using the following method for estimating the degree of crosslinking. That is, a test piece cut out from a rubber product is immersed in toluene at room temperature for a certain period of time, and the swelling degree of the test piece before and after the immersion (volume change rate = volume after immersion/volume before immersion) The “toluene swelling method” for comparing

The above-mentioned volume was measured according to JIS K 6258:2016. Further, the test piece was obtained by extracting only the elastic layer 12 so that the length and the width were 10±0.1 cm and the thickness was 0.02±0.005 cm. Further, in order to set the immersion time to a time when the volume after the immersion is almost saturated, measurement is performed every 24 hours to obtain the above-mentioned volume change rate, and within 5% as compared with the volume change rate obtained 24 hours ago. When the difference was, the volume change rate finally obtained was used as the measurement value of the swelling degree.

In addition, the test piece of each intermediate transfer belt 1 to be evaluated was obtained at the end portion in the width direction corresponding to the low cross-linking region 15 and the center portion in the width direction corresponding to the non-low cross-linking region 16. Specifically, the test piece at the end was obtained so as to include the end cut position of the intermediate transfer belt 1 to be evaluated (that is, the edge of the intermediate transfer belt 1 after the end cut). Further, the test piece in the central portion was obtained so as to include the central position in the width direction of the intermediate transfer belt 1. Further, the measured values of the swelling degree of the elastic layer 12 at the end portion and the central portion of the intermediate transfer belt 1 to be evaluated are obtained by performing the measurement a plurality of times (for example, 5 points in the circumferential direction of the belt). It can be represented by an average value.

<Cross-cut test (degree of edge peeling)>
The degree of edge peeling between the base layer 11 and the elastic layer 12 was evaluated using a cross-cut test as a method for evaluating the degree of film peeling. The cross cut test was performed according to JIS K5600-5-6. Further, this cross-cut test was carried out such that a position 5 mm inside from the end cut position of the intermediate transfer belt 1 to be evaluated along the width direction of the intermediate transfer belt 1 was included in 25 squares. Then, the degree of edge peeling was evaluated according to the following criteria.
◯ (Good): No peeled part is seen in 25 squares.
Poor (poor): The number of peeled-off spots was 1 or more in 25.

<Bleed evaluation method>
Instead of the intermediate transfer belt mounted on the full-color electrophotographic image forming apparatus (trade name: imagePRESS C800, manufactured by Canon Inc.), the intermediate transfer belt 1 of the example or the comparative example was mounted. Then, the photosensitive drum 101K of the black image forming portion PK was brought into contact with the intermediate transfer belt 1 to be evaluated in a high temperature and high humidity (temperature 30° C., relative humidity 80%) environment for 10 minutes. After that, 100 black solid images (images of maximum density level) were output onto A3 size plain paper (trade name: GF-C081A3, manufactured by Canon Inc.). The black developer loaded in the print cartridge of the electrophotographic image forming apparatus was used to form an image. The image output was performed under a high temperature and high humidity environment (temperature 30° C., relative humidity 80%).

After the image output, the obtained 100 solid images were evaluated by the following procedure. In a region of the black photosensitive drum 101K corresponding to a region in contact with the intermediate transfer belt 1 before image formation, streak image deterioration along the width direction of the intermediate transfer belt 1 due to bleeding of the intermediate transfer belt 1 It was visually observed how many output images had disappeared. Then, the degree of bleeding was evaluated according to the following criteria. In this streak-like image deterioration, the bleed component transferred to the surface of the intermediate transfer belt 1 adheres to the surface of the photosensitive drum 101K, and the electrostatic image is disturbed due to fluctuations in the electric resistance of the surface of the photosensitive drum 101K ( Latent image flow) is considered to occur. Further, it is considered that the streak-like image deterioration is improved by continuing the image output and removing the bleed component from the photosensitive drum 101K.
Rank A: Image deterioration disappeared with 10 or less output images Rank B: Image deterioration disappeared with 11 to 50 output images Rank C: Rank D with image deterioration disappeared from 51 to 100 output images : Image deterioration does not disappear with 100 output images

<Evaluation of color shift>
Instead of the intermediate transfer belt mounted on the full-color electrophotographic image forming apparatus (trade name: imagePRESS C800, manufactured by Canon Inc.), the intermediate transfer belt 1 of the example or the comparative example was mounted. Then, under a high temperature and high humidity (temperature of 30° C., relative humidity of 80%) environment, a continuous image output test of 10,000 sheets was performed using A3 size plain paper (trade name: GF-C081A3, manufactured by Canon Inc.). ..

Next, a blue character image and line image using cyan and magenta developers, and a green character image and line image using cyan and yellow developers are printed on A3 size plain paper (trade name: GF-C081A3). , Manufactured by Canon Inc.). Then, the color misregistration was evaluated according to the following criteria.
Rank A: Good. No color shift Rank B: Partial color shift occurs Rank C: Color shift occurs on the entire surface

<Evaluation result>
Table 1 shows the measurement results or evaluation results of the swelling degree of the elastic layer 12, the presence or absence of edge peeling, bleeding, and color misregistration for the intermediate transfer belt 1 of the example or the comparative example.

As can be seen from the results in Table 1, peeling of the end portion between the base layer 11 and the elastic layer 12 is suppressed when the swelling degree of the elastic layer 12 at the end portion in the width direction of the intermediate transfer belt 1 is 169% or more. can do.

Further, as can be seen from the results in Table 1, bleeding in the image area is suppressed if the swelling degree of the elastic layer 12 in the widthwise central portion of the intermediate transfer belt 1 corresponding to the image area is 127% or more and 155% or less. can do.

On the other hand, as can be seen from the results in Table 1, even when the swelling degree of the end portion and the swelling degree of the central portion are in the above ranges, the difference in swelling degree between the end portion and the central portion is If it is not less than 58%, color misregistration may occur remarkably. It is considered that this is because the difference in the degree of swelling between the end portion and the central portion is too large, so that the distortion of the intermediate transfer belt 1 due to the difference in the contraction between the end portion and the central portion becomes large. .. As can be seen from the results in Table 1, the difference in swelling degree between the end portion and the central portion is preferably 39% or less.

That is, the swelling degree of the elastic layer 12 in the first area outside the image area in the width direction of the intermediate transfer belt 1 is defined as the first swelling degree. In addition, the degree of swelling of the elastic layer 12 in the second area in the image area of the intermediate transfer belt 1 in the width direction is referred to as the second degree of swelling. At this time, the first swelling degree is 169% or more, the second swelling degree is 127% or more and 155 or less, and the difference between the first swelling degree and the second swelling degree is 58% or less (preferably 39% By the following, it is possible to suppress edge peeling while suppressing image defects due to bleeding in the image area and image defects due to distortion of the intermediate transfer belt 1.

As described above, according to the present embodiment, it is possible to suppress edge peeling while suppressing the occurrence of image defects.

[Other]
Although the present invention has been described above with reference to the specific embodiments, the present invention is not limited to the above embodiments.

In the above-described embodiment, the low cross-linking regions are provided at both ends in the width direction of the intermediate transfer belt to suppress the end peeling at both ends, but the present invention is not limited to this. For example, when it is known that one end portion in the width direction of the intermediate transfer belt is significantly peeled off, a low cross-linking region should be provided only in one end portion in the width direction of the intermediate transfer belt. You may

1 Intermediate Transfer Belt 11 Base Layer 12 Elastic Layer 13 Intermediate Layer 14 Surface Layer 15 Low Cross-Linking Area 16 Non-Low Cross-Linking Area

Claims (5)

An intermediate transfer having a base layer, an elastic layer laminated above the base layer, and a surface layer laminated above the elastic layer, wherein the elastic layer is formed by using silicone rubber as an elastic body. In the belt,
The swelling degree of the elastic layer in the first area outside the image area where the toner in the widthwise direction of the intermediate transfer belt can be transferred is defined as a first swelling degree, the swelling degree in the widthwise direction of the intermediate transfer belt. When the swelling degree of the elastic layer in the second area in the image area measured by the toluene swelling method is defined as the second swelling degree, the first swelling degree is 169% or more and the second swelling degree is 127%. The intermediate transfer belt is 155% or more and the difference between the first swelling degree and the second swelling degree is 58% or less. The intermediate transfer belt according to claim 1, wherein a difference between the first swelling degree and the second swelling degree is 39% or less. The intermediate transfer belt according to claim 1 or 2, wherein the elastic layer contains an ionic conductive agent. The intermediate transfer belt according to any one of claims 1 to 3, wherein an intermediate layer is provided between the elastic layer and the surface layer. An image forming apparatus comprising the intermediate transfer belt according to claim 1.

Images