JP7175742B2 - Intermediate transfer belt and image forming apparatus - Google Patents

Description

The present invention relates to an intermediate transfer belt used in image forming apparatuses such as copiers, printers, and facsimile machines using an electrophotographic method or an electrostatic recording method, and the image forming apparatus.

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 photoreceptor is primarily transferred onto an intermediate transfer belt, which is an endless belt-like intermediate transfer member, and then recorded on paper or the like. An intermediate transfer method for secondary transfer onto 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 an "elastic intermediate transfer belt") is sometimes used 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 section (primary transfer section, secondary transfer section). Therefore, it is known that the elastic intermediate transfer belt is effective in suppressing the hollow phenomenon in which a part of the toner image is not transferred. Also, 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 toner images on general paper, but also improves the transferability of toner images on thick paper and the transferability of toner images on uneven recording materials such as embossed paper. is also known to be effective.

It is known to use a crosslinked 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. In the case of a crosslinked rubber material, low-molecular-weight components contained in the elastic layer, such as the plasticizer, the unreacted rubber component, and the conductive agent component, which are compounding components, migrate to the surface of the belt. phenomena are known to occur. In particular, when silicone rubber is used as the rubber material, or when an ion conductive agent or the like is added to the rubber material, bleeding tends to become noticeable. If the bleeding component migrates to the surface of the intermediate transfer belt, the image quality may be affected.

Patent Literature 1 describes that the occurrence of bleeding is suppressed by promoting cross-linking of a cross-linkable material. Further, Patent Document 2 describes that the cross-linking suppresses the molecular motion of the resin and suppresses the movement of the ions of the ion conductive material.

JP 2015-125226 A JP 2004-258395 A

On the other hand, the manufacturing process of the intermediate transfer belt generally includes a step of cutting the widthwise edge of the intermediate transfer belt so that the intermediate transfer belt has a predetermined width (hereinafter also referred to as "edge cutting"). Normally, edge cutting is performed at both widthwise end portions of the intermediate transfer belt. In this process, a metal blade directly cuts the edge of the intermediate transfer belt.

However, if the degree of cross-linking of the rubber material is increased in order to suppress bleeding, the shrinkage of the elastic layer increases, which may lead to a decrease in adhesion between the base layer and the elastic layer. Therefore, when the edge of the elastic intermediate transfer belt is cut, as shown in FIG. There is a risk that peeling (hereinafter also referred to as “edge peeling”) may occur. If peeling occurs at the edge, the peeling progresses toward the image area where the toner of the elastic intermediate transfer belt can be transferred, which may affect the image quality or reduce the durability of the intermediate transfer belt. .

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an intermediate transfer belt and an image forming apparatus having the same, which can suppress the bleeding of the components contained in the elastic layer and suppress peeling at the edges.

The above objects are achieved by an intermediate transfer belt and an image forming apparatus according to the present invention. In summary, the present invention has a base layer, an elastic layer laminated above the base layer, and a surface layer laminated above the elastic layer, wherein the elastic layer contains silicone rubber as an elastic body. The degree of swelling of the elastic layer in the first area outside the image area to which the toner can be transferred in the width direction of the intermediate transfer belt is measured by the toluene swelling method, which is defined as the first swelling. The first swelling degree is 169% or more, where 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. and wherein 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 comprising the intermediate transfer belt of the present invention.

According to the present invention, it is possible to provide an intermediate transfer belt capable of suppressing peeling at the edges while suppressing bleeding of components contained in the elastic layer, and an image forming apparatus having the same.

1 is a schematic cross-sectional view of an example of an image forming apparatus; FIG. 2 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. FIG. 4 is a schematic diagram for explaining an example of a method for manufacturing an intermediate transfer belt; It is a schematic diagram for explaining a problem.

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 cross-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 employs an intermediate transfer method and is capable of forming a full-color image using an electrophotographic method.

The image forming apparatus 100 of this example forms yellow (Y), magenta (M), cyan (C), and black (K) images 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. For elements having the same or corresponding functions or configurations in the image forming units PY, PM, PC, and PK, the suffixes Y, M, C, and K are omitted from the symbols indicating that they are elements for one of the colors. may be described in a comprehensive manner. In this example, the image forming section P includes 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.

A photosensitive drum 101, which is a drum-shaped (cylindrical) photosensitive member (electrophotographic photosensitive member) as an image bearing member, is rotationally driven in the counterclockwise direction indicated by the arrow in the drawing. The photosensitive drum 101 has a structure in which a charge generating layer, a charge transporting layer and a surface protective layer are sequentially laminated on a substrate formed of an aluminum cylinder. The surface of the rotating photosensitive drum 101 is uniformly charged to a predetermined potential with a predetermined polarity (negative polarity in this example) by a charging roller 102 which is a roller-type charging member as charging means. A predetermined charging voltage (charging bias) is applied to the charging roller 102 during the charging process. The charged surface of the photosensitive drum 101 is scanned and exposed according to image information by an exposure device (laser scanner) 103 as an exposure unit, and static color components corresponding to each image forming portion P are 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 developing means, and a toner image (developer image) is formed on the photosensitive drum 101 . be done. The developing device 104 includes a developing container containing toner, a developing roller as a developer carrying member, a regulating blade as a developer amount regulating member for regulating the amount of toner on the developing roller, and the like. Developing devices 104Y, 104M, 104C, and 104K for yellow, magenta, cyan, and black contain yellow, magenta, cyan, and black toner, respectively. The developing roller is lightly pressed against the photosensitive drum 101 at the developing portion, 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, a charge having the same polarity as the charge polarity of the photosensitive drum 101 (negative polarity in this example) is applied to the exposed portion of the photosensitive drum 101 where the absolute value of the potential is lowered by exposure after being uniformly charged. Charged toner adheres.

An endless intermediate transfer belt (elastic intermediate transfer belt) 1 is arranged as an intermediate transfer member so as to be in contact with the four photosensitive drums 101Y, 101M, 101C, and 101K. The intermediate transfer belt 1 is stretched over a driving roller 121, a tension roller 122, and a secondary transfer counter roller 123 as a plurality of stretching rollers (supporting rollers) with a predetermined tension. When the drive roller 121 is rotationally driven, the intermediate transfer belt 1 is transmitted with a driving force, and rotates (circulates) in the clockwise direction indicated by the arrow in the drawing. On the inner peripheral surface side of the intermediate transfer belt 1 , primary transfer rollers 105 , which are roller-type primary transfer members as primary transfer means, are arranged corresponding to the respective photosensitive drums 101 . A primary transfer roller 105 is pressed toward the photosensitive drum 101 via the intermediate transfer belt 1 to form a primary transfer portion T1 where the photosensitive drum 101 and the intermediate transfer belt 1 are in 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 normal charge polarity of the toner (charge polarity during development), is applied to the primary transfer roller 105 . be done. For example, when a full-color image is formed, yellow, magenta, cyan, and black toner images formed on the respective photosensitive drums 101Y, 101M, 101C, and 101K are sequentially superimposed on the intermediate transfer belt 1. Primary transfer is performed.

A secondary transfer roller 108 , which is a roller-type secondary transfer member as a secondary transfer means, is arranged at a position facing the secondary transfer opposing roller 123 on the outer peripheral surface side of the intermediate transfer belt 1 . The secondary transfer roller 108 is pressed toward the secondary transfer opposing roller 123 via the intermediate transfer belt 1, forming a secondary transfer portion T2 where the intermediate transfer belt 1 and the secondary transfer roller 108 are in contact with each other. The toner image formed on the intermediate transfer belt 1 as described above is nipped and conveyed 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. is secondarily transferred onto the recording material S. During the secondary transfer process, the secondary transfer roller 108 is applied with a predetermined secondary transfer voltage (secondary transfer bias) that is a DC voltage having a polarity opposite to the normal charge polarity of the toner. Usually, a secondary transfer voltage of several kV is applied in order to ensure sufficient secondary transfer efficiency. A recording material (recording medium, transfer material, sheet) S is accommodated in a cassette 112 and is supplied from the cassette 112 to a conveying path by a pickup roller 113 . The recording material S supplied to the conveying path is conveyed to the secondary transfer portion T2 in timing with the toner image on the intermediate transfer belt 1 by the conveying roller pair 114 and the registration roller pair 115 . The recording material S is typically 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 onto which the toner image has been transferred is conveyed to a fixing device 109 as fixing means. The fixing device 109 has a fixing roller 191 having a heating means and a pressure roller 192 that presses against the fixing roller 191 . The fixing device 109 heats and presses the recording material S bearing an unfixed toner image with a fixing roller 191 and a pressure roller 192, thereby fixing (melting or fixing) the toner image onto the recording material S. . The recording material S on which the toner image has been fixed is discharged (output) to the outside of the image forming apparatus 100 by the pair of conveying rollers 116, the pair of discharge rollers 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 from the photosensitive drum 101 by the developing device 104 and collected. Toner (secondary transfer residual toner) remaining on the intermediate transfer belt 1 without being transferred to the recording material S during the secondary transfer process and paper dust are removed by a belt cleaning device 111 as intermediate transfer body cleaning means. 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 such an image forming apparatus 100, the bleeding component generated from the elastic layer 12 (FIG. 2) is prevented from migrating to the surface of the intermediate transfer belt 1. Suppressed. As a result, high quality images can be formed. Further, by using the intermediate transfer belt 1 according to the present invention, peeling of the intermediate transfer belt 1 can be suppressed for a long period of time.

2. Intermediate Transfer Belt Next, an embodiment of an 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 laminate having four layers: a base layer 11, an elastic layer 12, an intermediate layer 13, and a surface layer . Note that 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 a laminate of these three layers, for example.

<Base layer>
The base layer (base material) 11 will be described. The base layer 11 is a roll-shaped or belt-shaped seamless type cylindrical one. Materials suitable for forming the base layer 11 include, for example, resin materials such as polyetheretherketone, polyethylene terephthalate, polybutylene naphthalate, polyester, polyimide, polyamide, polyamideimide, polyacetal, and polyphenylene sulfide.

Conductive powder such as metal powder, conductive oxide powder, or conductive carbon may be added to the resin forming the base layer 11 to impart conductivity.

As the resin constituting the base layer 11, polyether ether ketone or polyimide to which carbon black is added is particularly preferable from the viewpoint of mechanical strength and conductivity.

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 remarkably lowered. On the other hand, if the thickness of the base layer 11 is more than 500 μm, it may become difficult to use as an intermediate transfer member due to excessive rigidity.

<Elastic layer>
The elastic layer 12 will be explained. The elastic layer 12 needs to have appropriate flexibility in order to follow the surface shape of the recording material S. As shown in FIG. In the present invention, silicone rubber is used as the material of the elastic body forming the elastic layer 12 because of its low 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 thickness of the elastic layer 12 is too thin, sufficient flexibility may not be obtained, and if the thickness of the elastic layer 12 is too thick, it may become difficult to use as an intermediate transfer body. The JIS-A hardness of the elastic layer 12 is preferably 14 degrees or more and 60 degrees or less, 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.

The elastic layer 12 may contain an electronic conductive agent or an ionic conductive agent as a conductive agent. Examples of the electron conductive agent include conductive carbon black such as acetylene black and ketjen black, graphite, graphene, carbon fiber, and carbon nanotube. Examples of electronic conductive agents include powders of metals such as silver, copper, and nickel, conductive zinc oxide, conductive calcium carbonate, conductive titanium oxide, conductive tin oxide, and conductive mica. Among these, conductive carbon black is preferable from the viewpoint of ease of control of electric resistance. Examples of ion conductive agents include lithium salts, potassium salts, pyridine-based, alicyclic amine-based, and aliphatic amine-based ionic liquids. 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 ratio for the elastic layer 12 is preferably 35 parts by mass or less, more preferably 25 parts by mass or less per 100 parts by mass of the silicone rubber. Thereby, the elastic layer 12 is provided with a stable conductivity suitable for the intermediate transfer body.

In addition, the elastic layer 12 contains a filler, a cross-linking accelerator, a cross-linking retarder, a cross-linking aid, an anti-scorch agent, an anti-aging agent, a softening agent, a heat stabilizer, a flame retardant, an auxiliary flame retardant, an ultraviolet absorber, an anti- Additives such as rust agents may be included. In particular, fillers include reinforcing fillers such as fumed silica, crystalline silica, wet silica, fumed titanium oxide, cellulose nanofibers, and the like. Reinforcing fillers include organoalkoxysilanes, organohalosilanes, organosilazanes, diorganosiloxane oligomers whose molecular chain ends are blocked with silanol groups, and cyclic organosiloxanes, from the standpoint of being easily dispersed in silicone rubber. It may be surface-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. From the viewpoint of reducing cohesive failure in the primer layer, the thickness of the primer layer is preferably 0.1 μm or more and 2 μm or less.

In addition, as shown in FIG. 3, the intermediate transfer belt 1 of the present embodiment has low-crosslinking regions in which the degree of cross-linking of the elastic layer 12 is lower than that of the non-low-crosslinking region 16 at the center in the width direction at both ends in the width direction. A region 15 is provided. As a result, peeling of the edge between the base layer 11 and the elastic layer 12 after the edge of the intermediate transfer belt 1 is cut can be suppressed. 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 using the degree of swelling (measurement method will be described later), which is a characteristic value for judging the degree of cross-linking. The degree of swelling of the elastic layer 12 in the low-crosslinking regions 15 arranged at the ends in the width direction of the intermediate transfer belt 1 needs to be 169% or more from the viewpoint of adhesion between the base layer 11 and the elastic layer 12 . be. If the degree of swelling of the elastic layer 12 in the low cross-linking region 15 is lower than 169%, that is, if the degree of cross-linking of the silicone rubber is high, there is a risk that the edge will peel off from the position where the edge is cut. In addition, the degree of swelling of the elastic layer 12 in the non-low-crosslinked region 16 arranged in the central portion in the width direction of the intermediate transfer belt 1 needs to be 127% or more and 155% or less from the viewpoint of suppression of bleeding. . If the degree of swelling of the elastic layer 12 in the non-low cross-linked region 16 is lower than 127%, that is, if the degree of cross-linking of the silicone rubber is high, decomposition products due to heating during the cross-linking (vulcanization) process will increase and become bleeding components. As a result, image defects due to bleeding may occur. In addition, when the degree of swelling of the elastic layer 12 in the non-low cross-linked region 16 is greater than 155%, that is, when the degree of cross-linking of the silicone rubber is low, the intermolecular free volume of the silicone rubber increases, resulting in an increase in the bleed component. image defects 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 is required to be 58% or less, preferably 40% or less, and 39% or less. is more preferable. If this difference is too large, the distortion of the intermediate transfer belt 1 due to the difference in shrinkage between the low cross-linking regions 15 and the non-low cross-linking regions 16 will increase, and image defects such as color misregistration may occur.

<Middle layer>
The intermediate layer 13 will be explained. The intermediate layer 13 is a layer that enhances adhesion between the elastic layer 12 and the surface layer 14 , and is required to use a material that has a high affinity for the elastic layer 12 and the surface layer 14 . Such materials include polyurethane (urethane resin), polyamide resin, polyvinylidene chloride resin, fluororesin, phenol resin, cellulose acetate resin, and the like. If the affinity between the elastic layer 12 and the surface layer 14 is sufficiently high and there is no problem in adhesion, the intermediate layer 13 is not particularly necessary.

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. If the thickness of the intermediate layer 13 is too thin, the effect of increasing the adhesiveness may be reduced, and poor adhesion may occur between the elastic layer 12 and the surface layer 14 . Also, if the intermediate layer 13 is too thick, the elastic function of the elastic layer 12 may be hindered.

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

<Surface layer>
The surface layer 14 will be explained. 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 to improve the transferability of the toner onto the recording material S and the releasability of the toner from the intermediate transfer belt 1, and is required to have low adhesion. be. As a material for forming the surface layer 14, any material having low adhesion can be used without any particular limitation. Such materials include fluorine resin, fluorine-containing urethane resin, fluorine rubber, and siloxane-modified polyimide. Among these, 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. If the thickness of the surface layer 14 is less than 1 μm, it tends to disappear due to abrasion. Moreover, if the thickness of the surface layer 14 is more than 4 μm, the elastic function of the elastic layer 12 may be impaired.

The surface layer 14 may contain a conductive agent similar to that described above, if necessary. From the viewpoint of adhesion and mechanical strength, 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 (fluorine-containing urethane resin, etc.) of the surface layer 14 .

<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. It is more preferably 0×10 ¹³ Ω·cm or less. Further, 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. 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 region 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 can be performed. Secondary transfer can be stably performed.

The surface resistivity of the intermediate transfer belt 1 was measured using a circular electrode (trade name: Hiresta UP, manufactured by Mitsubishi Chemical Analytic Tech). The intermediate transfer belt 1 to be measured is placed on a plate made of an insulating material, a voltage of 1000 V is applied, and the value is read 10 seconds after the application. Measurements are taken at arbitrary 16 points within a single belt surface, and the average value thereof is taken as the surface resistivity of the intermediate transfer belt 1 to be measured. The volume resistivity measuring method is substantially the same as the surface resistivity measuring method except that the object to be measured is placed on a metal plate.

3. Configuration of Intermediate Transfer Belt of Examples and Comparative Examples Next, the effects of the present invention will be further described using Examples 1 to 5 and Comparative Examples 1 to 7 below.

<Method for measuring the thickness of each layer>
Here, a method for 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, surface layer 14) of the intermediate transfer belt 1 is determined by using a cross-section polisher to prepare a vertical section from the surface of the intermediate transfer belt 1, and then making It was obtained by observing the cut cross section with a scanning electron microscope.

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

[Example 1]
In Examples and Comparative Examples, some of the materials of the mixed dispersion are diluted and dispersed with a solvent. , means the amount excluding solvent (volatile matter).

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

The above materials were charged into a twin-screw kneader using a weight feeder so that the polyetheretherketone content was 80% by mass and the acetylene black content was 20% by mass. The set temperatures of the cylinders of the twin-screw kneader were 320° C. at the material charging section and 360° C. at the downstream side of the cylinder and the die. The screw rotation speed of the twin-screw kneader was set to 300 rpm, and the material supply amount was set to 8 kg/h.

Next, the obtained pellets were subjected to cylindrical extrusion molding to obtain a belt. 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. Using a gravimetric feeder, the pellets were fed into the single screw extruder at a feed rate of 4 kg/h. The set temperature of the cylinder of the single-screw extruder was 320°C at the material charging portion, and 380°C at the downstream side of the cylinder and the cylindrical die. The molten resin discharged from the single-screw extruder was passed through a gear pump, extruded from a cylindrical die, and taken up at a speed of 85 μm in thickness by a cylindrical take-up machine. The molten resin was cooled and solidified by coming into contact with a cooling mandrel provided between the cylindrical die and the cylindrical take-up machine during the take-off process. The solidified resin was cut into a width of 380 mm by a cylindrical cutting machine installed at the bottom of the cylindrical take-up machine to obtain a crystalline thermoplastic resin belt.

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

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

As shown in FIG. 5, in a state in which the crystalline thermoplastic resin belt 20 coated with the mixed solution is attached to the core 21, a temperature control ring 22 is provided at a position corresponding to the end of the belt 20 in the width direction. placed in the heating furnace. The temperature control ring 22 has a ring-shaped structure having a predetermined width in the width direction of the belt 20 and accommodating a circular temperature control tube 23 therebetween. The temperature adjustment pipe 23 is connected to a hot water circulation device (not shown), and hot water at a predetermined temperature is made to flow through the temperature adjustment pipe 23 . This makes it possible to adjust the heating temperature of the widthwise end portion of the belt 20 corresponding to the low cross-linking region 15 (FIG. 3) of the intermediate transfer belt 1 .

In the cross-linking (vulcanization) step using a heating furnace, the primary firing was performed at 130° C. for 10 minutes, and the secondary firing was performed at 180° C. for 180 minutes to cross-link the rubber. At the time of secondary baking, hot water of 55°C was flowed through the temperature control tube 23 to set the surface temperature of the belt 20 at predetermined positions at both ends in the width direction of the belt 20 to 155°C. This predetermined position was the edge 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.

After cooling, the belt was removed from the core to obtain a belt laminated with the elastic layer 12 .

<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., Ltd.) emitting a single wavelength of 172 nm as an excimer UV irradiation unit. went.

The belt provided with the elastic layer 12 was fitted in a cylindrical core, placed 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 rotational speed of 5 rpm. Inside, excimer UV irradiation was performed for 30 minutes.

<Preparation of intermediate layer>
As a material for the intermediate layer 13, a polyurethane resin paint (trade name: Hydran 201, manufactured by DIC Corporation) was used. The belt laminated with the surface-modified elastic layer 12 is fitted to the core, and while rotating at 90 rpm, the polyurethane resin solution is sprayed using a spray gun (trade name: W-101, manufactured by Anest Iwata Co., Ltd.). was applied. The amount of paint 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 liquid, the belt was naturally dried for 15 minutes while being rotated at 90 rpm with the belt fitted in the core. 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 a material for the surface layer 14, a fluorine-containing polyurethane resin liquid (trade name: Emralon T-861, manufactured by Henkel Japan Ltd.) in which polytetrafluoroethylene is dispersed in a polyurethane dispersion was used. The belt laminated with the intermediate layer 13 was fitted to the core, and while rotating at 90 rpm, the urethane resin liquid was applied using a spray gun (trade name: W-101, manufactured by Anest Iwata Co., Ltd.). The amount of paint discharged during application was set so that the thickness of the surface layer 14 after drying was 3 μm.

After applying the resin liquid, the substrate was placed in a heating furnace at 130° C. and left for 30 minutes. After being removed from the heating furnace and cooled, the intermediate transfer belt 1 of Example 1 was obtained.

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

<Range of low cross-linking region>
The range of the low cross-linking region 15 can be adjusted by changing the width of the temperature adjustment 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, viewed along the normal direction to the surface of the intermediate transfer belt 1 . Lb in FIG. 4 is the width of the belt before edge cutting. Also, Lc is the width of the belt after the end portion is cut. Li is the width of the image area (the area where the toner image on the surface of the intermediate transfer belt 1 can be transferred). Also, Ll is the width of the low cross-linking region 15 . Also, Lh is the width of the non-low-crosslinked region 16 . In this embodiment, the dimensions of widths Lb, Lc, Li, Ll, and Lh are set as follows. This set value is obtained when the intermediate transfer belt 1 is steered to the maximum when conveying the intermediate transfer belt 1 in the image forming apparatus 100 (when the intermediate transfer belt 1 moves from one end side to the other end side in the width direction at the maximum). case), the image area width Li is set so as not to exceed the non-low-crosslinked 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-crosslinking area 16 in the width direction of the intermediate transfer belt 1 .
Belt width before edge cutting Lb: 380 mm
Belt width after edge cut Lc: 360mm
Image area width Li: 298mm
Low cross-linking region width Ll: 30 mm
Non-low cross-linked region 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, and the temperature of the warm water circulated through the temperature control pipe 23 during the secondary firing is set to 80°C to cut the edge of the belt. The surface temperature was set at 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, and the temperature of the warm water circulated through the temperature adjustment pipe 23 during the secondary firing is set to 70°C to cut the belt at the edge cut position. The surface temperature was set at 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, and the temperature of the warm water circulated through the temperature control pipe 23 during the secondary firing is set to 80°C to cut the edge of the belt. The surface temperature was set at 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, and the temperature of the warm water circulated through the temperature control pipe 23 during the secondary firing is set to 75°C to cut the edge of the belt. The surface temperature was set at 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 baking temperature of the elastic layer 12 is set to 190° C., and the temperature of the hot water circulated through the temperature adjustment pipe 23 during the secondary baking is set to 50° C. to cut the edge of the belt. The surface temperature was set at 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 baking temperature of the elastic layer 12 is set to 180° C., and the temperature of the hot water circulated through the temperature control pipe 23 during the secondary baking is set to 50° C. to cut the edge of the belt. The surface temperature was set at 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 baking temperature of the elastic layer 12 is set to 170° C., and the temperature of the hot water circulated through the temperature control pipe 23 during the secondary baking is set to 65° C. to cut the edge of the belt. The surface temperature was set at 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 baking temperature of the elastic layer 12 is set to 160° C., and the temperature of the hot water circulated through the temperature control pipe 23 during the secondary baking is set to 70° C. to cut the edge of the belt. The surface temperature was set at 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 elastic layer 12 was secondarily baked by setting the secondary baking temperature of the elastic layer 12 to 150.degree.

[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, and the temperature of the warm water circulated through the temperature adjustment pipe 23 during the secondary firing is set to 70°C to cut the belt at the end cut position. The surface temperature was set at 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, and the temperature of the warm water circulated through the temperature control pipe 23 during the secondary firing is set to 45°C to cut the edge of the belt. The surface temperature was set at 140°C.

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

<Method for Measuring Degree of Swelling of Elastic Layer>
The degree of swelling of the elastic layer 12 was measured using the following method of estimating the degree of cross-linking. That is, a test piece (test piece) cut out from a rubber product is immersed in toluene at room temperature for a certain period of time, and the degree of swelling of the test piece before and after immersion (volume change rate = volume after immersion / volume before immersion ) was used to compare the "toluene swelling method".

The volume was measured according to JIS K 6258:2016. A test piece was obtained by extracting only the elastic layer 12 so as to have a length and width of 10±0.1 cm and a thickness of 0.02±0.005 cm. In addition, in order to set the immersion time to a time when the volume after immersion is generally saturated, the volume change rate is obtained by measuring every 24 hours, and the volume change rate is within 5% compared to the volume change rate obtained 24 hours before. When the difference was , the finally obtained volume change rate was used as the measured value of the degree of swelling.

As test pieces of the intermediate transfer belt 1 to be evaluated, the end portions in the width direction corresponding to the low cross-linking regions 15 and the central portion in the width direction corresponding to the non-low cross-linking regions 16 were obtained. Specifically, the edge test piece was obtained so as to include the edge cut position (that is, the edge of the intermediate transfer belt 1 after edge cutting) of the intermediate transfer belt 1 to be evaluated. Further, the test piece for 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 value of the degree of swelling of the elastic layer 12 at the end portion and the central portion of the intermediate transfer belt 1 to be evaluated was obtained by performing measurement a plurality of times (for example, at five points in the circumferential direction of the belt). It can be represented by the mean of the values.

<Cross-cut test (edge peeling degree)>
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. A cross-cut test was performed according to JIS K5600-5-6. In addition, this cross-cut test was performed so that a position 5 mm inside along the width direction of the intermediate transfer belt 1 from the edge cut position of the intermediate transfer belt 1 to be evaluated was included in 25 cells. Then, the degree of edge peeling was evaluated according to the following criteria.
◯ (good): Not even one of the 25 squares was peeled off.
x (defective): 1 square or more of 25 squares were peeled off.

<Method for evaluating bleeding>
The intermediate transfer belt 1 of Example or Comparative Example was attached in place of the intermediate transfer belt attached to a full-color electrophotographic image forming apparatus (trade name: imagePRESS C800, manufactured by Canon Inc.). Then, the photosensitive drum 101K of the image forming unit PK for black was brought into contact with the intermediate transfer belt 1 to be evaluated for 10 minutes in a high temperature and high humidity (temperature of 30° C., relative humidity of 80%) environment. After that, 100 black solid images (images at the maximum density level) were output on A3 size plain paper (trade name: GF-C081A3, manufactured by Canon Inc.). For image formation, a black developer mounted in the print cartridge of the electrophotographic image forming apparatus was used. The image output was performed in a high temperature and high humidity environment (temperature of 30° C., relative humidity of 80%).

After image output, 100 solid images obtained were evaluated by the following procedure. Streak-like image deterioration along the width direction of the intermediate transfer belt 1 due to bleeding of the intermediate transfer belt 1 in the area corresponding to the area of the photosensitive drum 101K for black that is in contact with the intermediate transfer belt 1 before image formation. Visual observation was made to see at which output image the dots disappeared. Then, the degree of bleeding was evaluated according to the following criteria. This streak-like image deterioration is caused by the bleed component that migrates to the surface of the intermediate transfer belt 1 and adheres to the surface of the photosensitive drum 101K. latent image flow). Further, it is considered that this streaky image deterioration is improved by, for example, removing the bleeding component from the photosensitive drum 101K by continuing image output.
Rank A: Rank at which image deterioration disappears with 10 or less output images B: Rank at which image deterioration disappears with 11 to 50 output images C: Rank D at which image deterioration disappears with 51 to 100 output images : Image degradation does not disappear with 100 output images

<Color deviation evaluation>
The intermediate transfer belt 1 of Example or Comparative Example was attached in place of the intermediate transfer belt attached to a full-color electrophotographic image forming apparatus (trade name: imagePRESS C800, manufactured by Canon Inc.). Then, a continuous image output test of 10,000 sheets was performed using A3 size plain paper (trade name: GF-C081A3, manufactured by Canon Inc.) in a high-temperature and high-humidity (temperature of 30° C., relative humidity of 80%) environment. .

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 were formed on A3 size plain paper (trade name: GF-C081A3). , Canon). Then, the color misregistration was evaluated according to the following criteria.
Rank A: Good. No color shift Rank B: Color shift occurs partially Rank C: Color shift occurs over the entire surface

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

As can be seen from the results in Table 1, peeling at the edges between the base layer 11 and the elastic layer 12 is suppressed when the degree of swelling of the elastic layer 12 at the edges 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 when the degree of swelling of the elastic layer 12 in the central portion in the width direction 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 degree of swelling at the end portion and the degree of swelling at the center portion are within the above ranges, the difference in swelling degree between the end portion and the center portion is small. If it is not 58% or less, color misregistration may occur remarkably. This is probably because the difference in swelling degree between the end portions and the center portion was too large, and the distortion of the intermediate transfer belt 1 due to the difference in contraction between the end portions and the center portion became large. . As can be seen from the results in Table 1, the difference in swelling degree between the edge and the center is preferably 39% or less.

That is, the degree of swelling of the elastic layer 12 in the first region outside the image region in the width direction of the intermediate transfer belt 1 is defined as the first degree of swelling. Further, the swelling degree of the elastic layer 12 in the second area within the image area in the width direction of the intermediate transfer belt 1 is defined as a second swelling degree. 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% ), it is possible to suppress edge peeling while suppressing image defects caused by bleeding in the image area and image defects caused by distortion of the intermediate transfer belt 1 .

As described above, according to the present embodiment, edge peeling can be suppressed while suppressing the occurrence of image defects.

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

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

REFERENCE SIGNS LIST 1 intermediate transfer belt 11 base layer 12 elastic layer 13 intermediate layer 14 surface layer 15 low cross-linking region 16 non-low cross-linking region

Claims (5)

An intermediate transfer device comprising 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 using silicone rubber as an elastic body. in the belt
The swelling degree measured by the toluene swelling method of the elastic layer in the first area outside the image area where the toner can be transferred in the width direction of the intermediate transfer belt is the first swelling degree, and the swelling degree in the width direction of the intermediate transfer belt is The first swelling degree is 169% or more, and the second swelling degree is 127%, where the swelling degree measured by the toluene swelling method of the elastic layer in the second region within the image region is defined as the second swelling degree. 155% or less, and the difference between the first swelling degree and the second swelling degree is 58% or less. 2. The intermediate transfer belt according to claim 1, wherein the difference between said first swelling degree and said second swelling degree is 39% or less. 3. The intermediate transfer belt according to claim 1, wherein the elastic layer contains an ion conductive agent. 4. The intermediate transfer belt according to any one of claims 1 to 3, further comprising an intermediate layer provided between the elastic layer and the surface layer. An image forming apparatus comprising the intermediate transfer belt according to claim 1 .

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