JP2004279523A - Transfer belt and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an intermediate transfer belt structure which prevents the stuck part of the reinforcement member from flaring like a bell and has excellent durability free of meanders in the intermediate transfer belt made of a synthetic resin stuck a reinforcement member for reinforcing ends of the belt, and to provide a method for manufacturing the belt. <P>SOLUTION: The intermediate transfer belt 1 in the form of an annular seamless belt has an inner bend part 1a as a small diameter part whose diameter in an image formation area gradually decreases toward one end, in the vicinity of the right and left ends in the axial direction of its cylinder, and an outward bend part 1b as a large diameter part whose diameter gradually increases towards the other end. The reinforcement member 2 is stuck to the external surface of the inner bend part 1a, and a guide rubber 3 for preventing meander is stuck to the internal surface of the part. In the method of the production of it, an annular belt intermediate body is mounted inside a mold having a shape corresponding to the inner and outer bend parts 1a and 1b, and is heated to a temperature right above the glass transition point of a resin forming the belt intermediate transfer body, thereby transferring the shape of the mold to the belt intermediate body. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a transfer belt used for an image forming apparatus such as an electrophotographic copying machine or a printer, and a method for manufacturing the same.
[0002]
[Prior art]
2. Description of the Related Art In an image forming apparatus such as a conventional electrophotographic copying machine or printer, a photosensitive member is uniformly charged, and an image is exposed thereon to form an image latent image. Then, the formed image latent image is developed with toner to form a toner image of the image, which is transferred to an intermediate transfer belt, which is an annular seamless belt, and further transferred to a recording medium, and the transferred toner image is transferred. In some cases, an image is formed by performing a heat fixing process using a fixing device. Hereinafter, an outline of an image forming apparatus using the above-described intermediate transfer belt will be described.
[0003]
FIG. 4 is a diagram for explaining the outline of the configuration of the monochrome image forming apparatus. The image forming apparatus 10 includes a photoconductor 11 as a center, a charging device, an exposure optical system, a developing device, and a residual surface of the photoconductor. In FIG. 4, a cleaner for cleaning the toner and other members are arranged. In FIG. 4, the photosensitive member 11, the charging device 12, the exposure optical system 13, the developing device 14, and the intermediate transfer belt 15 arranged in contact with the photosensitive member 11 Only shown.
[0004]
The photoconductor 11 is configured to rotate in a direction indicated by an arrow a at a constant speed by a driving mechanism (not shown). The intermediate transfer belt 15 is provided between a driving roller 16a, a driven roller 16b also serving as a primary transfer roller, and a driven roller 16c. The driven roller 16b is disposed close to the photoconductor 11, and the intermediate transfer belt 15 moves in the direction of arrow b while being in contact with the photoconductor 11 by the driving of the driving roller 16a.
[0005]
A secondary transfer roller 17 is disposed at a position facing the driven roller 16c with an intermediate transfer belt 15 interposed therebetween, and feeds a sheet (not shown) toward a nip portion between the intermediate transfer belt 15 and the secondary transfer roller 17. The recording medium P is transported from the mechanism.
[0006]
The operation of the above configuration will be described. When the power is turned on, the photoconductor 11 starts rotating in the direction of arrow a at a constant speed by a drive mechanism (not shown), and the intermediate transfer belt 15 moves in the direction of arrow b at the same speed as the peripheral speed of the photoconductor 11. After the surface of the photoconductor 11 is uniformly charged by the charging device 12, a laser beam modulated with an image signal is projected from the exposure optical system 13 onto the surface of the photoconductor 11, and an image latent image is formed.
[0007]
The image latent image on the surface of the photoconductor 11 is developed with the toner loaded in the developing device 14 to form a toner image. The toner image on the surface of the photoconductor 11 is transferred to the intermediate transfer belt 15 at a position of a driven roller 16b also serving as a primary transfer roller. The recording medium P is transported from a paper feed mechanism (not shown) to a transfer position in accordance with the timing at which the toner image comes on the secondary transfer roller 17 by the movement of the intermediate transfer belt 15 in the direction of the arrow b. Is transferred to the recording medium P.
[0008]
Thereafter, the toner image on the recording medium P is fixed by a fixing device (not shown), and the image recording operation is completed.
[0009]
FIG. 5 is a diagram schematically illustrating the configuration of the full-color image forming apparatus. The image forming apparatus 20 includes a photosensitive member 21, a charging device 22 arranged in contact with the photosensitive member 21, an exposure optical system 23, and a predetermined developing device. Developing units 24Y, 24M, 24C, 24K of yellow (Y), magenta (M), cyan (C), and black (K) mounted on a rotating drum 24 capable of setting the developing device at a developing position. The intermediate transfer belt 25 placed in contact with the photoconductor 21 is bridged between a driving roller 26a, a primary transfer roller 26b, a pressing roller 26c, and a driven roller 26d. Further, a secondary transfer roller 27 is disposed at a position facing the pressing roller 26c with an intermediate transfer belt 25 interposed therebetween, and a nip portion between the intermediate transfer belt 25 and the transfer roller 27 is fed from a paper feed mechanism (not shown) to a recording medium. A configuration is provided in which P is transported.
[0010]
Next, the outline of the full-color image forming operation will be described. When the power is turned on, the photoconductor 21 starts rotating in the direction of arrow a at a constant speed by a drive mechanism (not shown), and the intermediate transfer belt 25 moves in the direction of arrow b at the same speed as the peripheral speed of the photoconductor 21.
[0011]
First, a toner image corresponding to the first color component, yellow (Y), is formed. After the surface of the photoconductor 21 is cleaned and the surface of the photoconductor 21 is uniformly charged by the charging device 22, the surface of the photoconductor 21 is modulated by the image signal of the first color component from the exposure optical system 23. The emitted laser light is projected to form an image latent image. The image latent image is developed by the yellow (Y) developing device 24Y set at the developing position, and the yellow (Y) toner image is transferred to the intermediate transfer belt 25 by the primary transfer roller 26b.
[0012]
Next, a toner image corresponding to magenta (M) as the second color component is formed. After the surface of the photoconductor 21 is cleaned and the surface of the photoconductor 21 is uniformly charged by the charging device 22, the surface of the photoconductor 21 is modulated with an image signal of the second color component from the exposure optical system 23. The emitted laser light is projected to form an image latent image. The image latent image is developed by a magenta (M) developing device 24M set at a development position, and the magenta (M) toner image is formed by a primary transfer roller 26b on a yellow (Y) toner image on the intermediate transfer belt 25. Is transferred in a superimposed manner.
[0013]
Hereinafter, similarly, a cyan (C) toner image is formed on the surface of the photoconductor 21, and the yellow (Y) and magenta (M) toner images on the intermediate transfer belt 25 are superimposed on the toner image. And a black (K) toner image is formed on the surface of the photoreceptor 21, and further superimposed and transferred onto the superimposed toner image on the intermediate transfer belt 25, and the four color toner images are superimposed. A full-color toner image is formed.
[0014]
By the movement of the intermediate transfer belt 25 in the direction of the arrow b, the recording medium P is conveyed to a transfer position from a paper feed mechanism (not shown) at a timing at which a full-color toner image comes on the secondary transfer roller 27. The upper full-color toner image is transferred to the recording medium P. Thereafter, the toner image on the recording medium P is fixed by a fixing device (not shown), and the image recording operation is completed.
[0015]
In addition, there is a full-color image forming apparatus having a configuration called a tandem type full-color image forming apparatus. This means that, along the intermediate transfer belt, four units of yellow (Y), magenta (M), cyan (C), and black (K), each having a charging device, a photoconductor, an exposure device, and a developing device. In this configuration, the image forming units are arranged in a line. The operation is such that yellow (Y), magenta (M), cyan (C), and black (K) toner images are sequentially superimposed and transferred on the intermediate transfer belt to form a full-color toner image. The transferred full-color toner image is further transferred to the recording medium P by the secondary transfer means. However, since the structure and operation are known structures, detailed description will be omitted.
[0016]
In the image forming apparatus having the configuration shown in FIGS. 4 and 5, the intermediate transfer belt is provided between the drive roller and the driven roller so that a tension of 40 to 60 N (Newton) acts on the intermediate transfer belt. Is a speed equal to the peripheral speed of the photoconductor, for example, 80 to 150 m / sec. It is.
[0017]
As described above, the intermediate transfer belt is driven in a state where a tension of 40 to 60 N (Newton) is applied, and is driven while repeatedly contacting and separating from the drive roller, the driven roller, the intermediate roller, and the like. In particular, due to the repetitive tension acting on the edge of the intermediate transfer belt in the longitudinal direction, that is, the belt edge in the direction perpendicular to the moving direction of the intermediate transfer belt (hereinafter, referred to as “cylindrical axis direction” in the present invention), the belt edge It is known that cracks and fractures occur in the belt, and that the belt is meandering due to a change in the diameter of the intermediate transfer belt in the cylindrical axis direction.
[0018]
As a countermeasure, a reinforcing member such as a tape made of Teflon (registered trademark) or a polyethylene-based material is stuck on the surface of the intermediate transfer belt edge, or on the front and back surfaces thereof, to prevent the edge from cracking and breaking. A device with improved durability has been proposed (Patent Document 1). Further, a belt has been proposed in which the amount of change in the diameter of the intermediate transfer belt in the longitudinal direction, that is, in the cylindrical axis direction is regulated within a predetermined range, for example, within ± 0.5 mm, thereby preventing the belt from meandering (Patent Document 2).
[0019]
[Patent Document 1]
JP-A-5-345369.
[0020]
[Patent Document 2]
Japanese Patent No. 2886505.
[0021]
[Problems to be solved by the invention]
However, in the case where the reinforcing member is attached to the surface of the edge of the intermediate transfer belt, or to both the front and back surfaces, the member attached to the back of the belt edge is used to ride on the end of the roller around which the belt edge is wound. The meandering force is larger than the combined strength of the belt base material and the reinforcing member, and the inconvenience that the belt edge portion expands like a trumpet occurs.
[0022]
Furthermore, even if the amount of change in the diameter of the intermediate transfer belt in the cylindrical axis direction is restricted to a predetermined range and the accuracy of the cylinder is increased, if there is a member (such as a guide rubber) attached to the back surface of the belt edge, the above-mentioned case will be considered. Similarly, the force of climbing over the end of the roller being wound and trying to meander becomes greater than the combined strength of the belt base material and the reinforcing member, the cylindrical accuracy of the belt collapses, and the edge becomes a trumpet shape. An inconvenience of spreading occurs.
[0023]
An object of the present invention is to solve the above problems.
[0024]
[Means for Solving the Problems]
The present invention solves the above-mentioned problems, and the invention of claim 1 is an annular transfer belt formed of a resin composition, wherein the left and right edges of the transfer belt located outside the image forming area in the cylindrical axis direction are provided. In the vicinity of the portion, a small diameter portion in which one diameter is gradually reduced toward the edge with respect to the diameter of the image forming area of the transfer belt, and a large diameter portion in which the other diameter is gradually enlarged toward the edge are provided. A transfer belt.
[0025]
The change in the diameter of the edge between the small-diameter portion and the large-diameter portion is set to be -0.6 mm or more for the small-diameter portion and +1.0 mm or less for the diameter of the image forming area. .
[0026]
Further, the amount of change in the diameter of the large-diameter portion can be set to +0.6 mm or more and +1.0 mm or less with respect to the diameter of the image forming area.
[0027]
Further, outside the image forming area of the transfer belt near the edge where the small-diameter portion is formed, a reinforcing member made of a resin composition is adhered to the outer surface of the transfer belt, and the inner surface of the transfer belt is made of a rubber material. A guide member is adhered.
[0028]
According to a fifth aspect of the present invention, there is provided an annular belt formed of a resin composition, wherein a small-diameter portion in which the diameter near one edge is reduced toward the edge with respect to the diameter of the image forming area, and the other edge. A method for producing a transfer belt for providing a shape having a large diameter portion in which a diameter near a portion is enlarged toward an edge, comprising the following steps:
Mounting an annular belt formed of a resin composition inside a cylindrical mold having the predetermined shape to be transferred to the annular belt, and pressurizing air by sealing an end of the mold. And transferring the shape of the mold to the annular belt by heating the mold to a temperature just above the glass transition point of the resin composition.
[0029]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described. FIG. 1 is a perspective view illustrating the shape of an intermediate transfer belt according to an embodiment of the present invention, and FIG. 2 is an enlarged sectional view of an edge of the intermediate transfer belt.
[0030]
As shown in FIGS. 1 and 2, the intermediate transfer belt 1 is an annular seamless belt, and has one diameter near the left and right edges in the cylindrical axis direction of the transfer belt with respect to the diameter of the image forming area of the transfer belt. An inner bent portion 1a which is a small diameter portion whose diameter is gradually reduced toward the edge and an outer bent portion 1b which is a large diameter portion whose other diameter is gradually enlarged toward the edge are formed.
[0031]
Then, the reinforcing member 2 is attached over the entire circumference of the inner bent portion 1a and the outer surface of the belt body following the inner bent portion 1a, and the entire circumference of the inner surface of the inner bent portion 1a to which the reinforcing member 2 is attached is provided. A guide rubber 3 having a rectangular section is attached to prevent the meandering of the intermediate transfer belt.
[0032]
The dimension A in the width direction from the edge of the inner bent portion 1a, which is a small-diameter portion, is about 4.5 mm, and the size B, which is the amount of change in the diameter of the edge of the inner bent portion 1a, is the diameter of the image forming area of the intermediate transfer belt. It is configured to be 0.6 mm or more in diameter. The dimension C in the width direction from the edge of the outer bent portion 1b, which is a large-diameter portion, is about 4.5 mm, and the size D, which is the diameter change amount of the edge of the outer bent portion 1b, is the image forming area of the intermediate transfer belt. It is configured to have a large diameter of 1.0 mm or less than the diameter of. At this time, the dimension D may be configured to be larger than the diameter of the image forming area of the intermediate transfer belt by 0.6 mm or more and +1.0 mm or less.
[0033]
The material that forms the intermediate transfer belt 1 is a polyphenylene sulfide (PPS) that is a thermoplastic resin, and a mixed composition (PBT / PC) of polycarbonate and polyethylene terephthalate that are thermoplastic resins, and neutral carbon as a conductive material. Use the one with black added.
[0034]
The method of manufacturing the intermediate transfer belt according to the above-described embodiment includes the following steps. First, a material in which a conductive material is added to the above-described thermoplastic resin material is heated and melted, and extruded using a known seamless belt molding die to form an annular belt intermediate having a thickness of about 150 μm.
[0035]
Next, a cylindrical second mold having an inner diameter about 0.5 mm larger than the outer diameter of the annular belt intermediate is prepared. The second molding die has an inner surface mirror-finished, and a small-diameter portion having an inner diameter gradually reduced from near 4.5 mm away from the edge toward the edge near one edge in the cylindrical axis direction. Is formed. Near the other edge in the cylindrical axis direction, a large diameter portion whose inner diameter gradually increases like a trumpet is formed from the vicinity of 4.5 mm from the edge to the edge. The small diameter portion is a portion of the molding die corresponding to the inner bent portion 1a of the intermediate transfer belt 1, and the large diameter portion is a portion of the molding die corresponding to the outer bent portion 1b of the intermediate transfer belt 1.
[0036]
The previously formed annular belt intermediate body is mounted on the above-described second molding die, and both ends of the second molding die are sealed and air is sealed in a state where the annular belt intermediate body is mounted, and the internal pressure is reduced. After 0.6 MPa, the temperature is just above the glass transition point of the resin composition constituting the belt intermediate, that is, 100 ° C. when the thermoplastic resin is PPS, and 120 ° C. when the thermoplastic resin is PBT / PC. Then, the shapes of the small-diameter portion and the large-diameter portion of the second mold are transferred to the belt intermediate.
[0037]
By the above processing, the belt intermediate body is formed with the inner bent portion 1a at one edge portion in the cylindrical axis direction and the outer bent portion 1b at the other edge portion. The reinforcing member 2 is applied over the entire outer surface of the belt body, and the guide rubber 3 having a rectangular cross section is applied over the entire inner surface of the inner bent portion 1a to which the reinforcing member 2 is applied. The transfer belt 1 is completed.
[0038]
The reinforcing member 2 is formed by applying a pressure-sensitive adhesive to a polyimide tape (Nitto Denko Corporation: Apical) or polyethylene terephthalate (Teijin DuPont: Neotex) film. A member can be used.
[0039]
The guide rubber 3 is a urethane rubber having a hardness of 70 degrees, which is the hardness of Asker A hardness meter manufactured by Kobunshi Keiki Co., Ltd., which is configured according to JISk6253.
[0040]
Next, the evaluation of the durability performance of the intermediate transfer belt of this embodiment and the results thereof will be described.
[0041]
FIG. 3 is a diagram illustrating the evaluation results of the durability performance of the intermediate transfer belt. The evaluation of the durability performance was performed by applying a tension using an acceleration tester capable of applying a tension equal to the tension applied to the intermediate transfer belt for a long time in an image forming apparatus using the intermediate transfer belt of this embodiment. The time until the intermediate transfer belt was damaged was measured.
[0042]
In the evaluation of the durability performance, for each type of the material of the intermediate transfer belt and the material of the reinforcing member 2, the diameter change amount B of the inner bent portion 1a formed near the end in the cylindrical axis direction of the intermediate transfer belt and the outer bent portion Tests were performed on four examples (Examples 1 to 4) in which the diameter change amount D of the portion 1b was different. Although the diameter of the effective image area of the intermediate transfer belt of the embodiment in the direction of the cylindrical axis is preferably originally constant, the diameter slightly changes due to a manufacturing error. The diameter variation due to manufacturing error (variation) is in the range of ± 0.3 mm.
[0043]
As a comparative example, the diameter change amount B of the inner bent portion 1a and the diameter change amount D of the outer bent portion 1b formed at the end of the intermediate transfer belt in the cylindrical axis direction are the diameters of the effective image area in the cylindrical axis direction. Two comparative examples were prepared, one having the same variation of ± 0.3 mm and the other having a variation of diameter of ± 1.5 mm.
[0044]
In Example 1, the material of the intermediate transfer belt was polyphenylene sulfide (PPS), the material of the reinforcing member was polyimide (PI), the diameter change B of the inner bent portion 1a was -0.6 mm, and the diameter change amount of the outer bent portion 1b. D indicates an intermediate transfer belt of +0.6 mm, and the time until breakage is 600 hours (Hr).
[0045]
In Example 2, the material of the intermediate transfer belt was polyphenylene sulfide (PPS), the material of the reinforcing member was polyethernitrile (PEN), the diameter change B of the inner bent portion 1a was -0.6 mm, and the diameter of the outer bent portion 1b was This indicates that the intermediate transfer belt having a change amount D of +1.0 mm takes 500 hours (Hr) until breakage.
[0046]
In Example 3, the material of the intermediate transfer belt is a mixture of polycarbonate and polyethylene terephthalate (PBT / PC), the material of the reinforcing member is polyimide (PI), the amount of change B in the diameter of the inner bent portion 1a is -1.0 mm, and the outer bent portion is formed. This shows that the intermediate transfer belt in which the diameter change amount D of the portion 1b is +0.6 mm was 480 hours (Hr) until breakage.
[0047]
In Example 4, the material of the intermediate transfer belt was a mixture of polycarbonate and polyethylene terephthalate (PBT / PC), the material of the reinforcing member was polyether nitrile (PEN), and the diameter change B of the inner bent portion 1a was -1.0 mm. This indicates that the intermediate transfer belt in which the diameter change amount D of the outer bent portion 1b is +1.0 mm was 550 hours (Hr) until breakage.
[0048]
In Comparative Example 1, the material of the intermediate transfer belt was polyphenylene sulfide (PPS), the material of the reinforcing member was polyimide (PI), the diameter change B of the inner bent portion 1a was -0.3 mm, and the diameter change amount of the outer bent portion 1b. D indicates that the intermediate transfer belt was +0.3 mm, and the time until breakage was 350 hours (Hr).
[0049]
In Comparative Example 2, the material of the intermediate transfer belt was a mixture of polycarbonate and polyethylene terephthalate (PC / PBT), the material of the reinforcing member was polyimide (PI), the diameter change B of the inner bent portion 1a was -1.5 mm, This shows that the intermediate transfer belt in which the diameter change amount D of the bent portion 1b is +1.5 mm was 200 hours (Hr) until breakage.
[0050]
In Examples 1 to 4, the time until breakage was 480 hours or more, indicating that the intermediate transfer belt was not damaged within the time corresponding to the life of the image forming apparatus.
[0051]
In Comparative Example 1, the time required for the inner bent portion 1a to expand in a trumpet shape and to be broken by meandering is short, and when the intermediate transfer belt is mounted on the winding roller in the outer bent portion 1b, it is easy to be caught and the frequency of breakage is high. It turned out to be high.
[0052]
Further, in Comparative Example 2, it was found that the inner bent portion 1a was easily buckled and cracked, and the outer bent portion 1b was repeatedly bent when passing through the drive roller, so that the time to crack was short.
[0053]
【The invention's effect】
As described in detail above, according to the first aspect of the present invention, one side of the intermediate transfer belt near the left and right edges in the cylindrical axial direction located outside the image forming area with respect to the diameter of the image forming area. Is provided with a small-diameter portion (inner bent portion) whose diameter gradually decreases toward the edge and a large-diameter portion (outer bent portion) whose diameter of the other gradually increases toward the edge. Even when the reinforcing member is attached to the back surface of the small diameter portion, this portion does not spread like a trumpet, and the intermediate transfer belt does not meander. Further, by providing the large-diameter portion at the edge of the other belt, when the intermediate transfer belt is mounted on the winding roller, the intermediate transfer belt can be easily mounted and is not damaged.
[0054]
According to the fifth aspect of the present invention, the small-diameter portion (inner bent portion) and the large-diameter portion (outer bent portion) near the left and right edges in the cylindrical axis direction located outside the image forming area of the intermediate transfer belt. Can be easily formed, and the productivity can be improved.
[Brief description of the drawings]
FIG. 1 is a perspective view illustrating the shape of an intermediate transfer belt according to an embodiment of the present invention.
FIG. 2 is an enlarged sectional view of an edge portion of the intermediate transfer belt shown in FIG.
FIG. 3 is a diagram illustrating evaluation results of durability performance of an intermediate transfer belt.
FIG. 4 is a diagram schematically illustrating the configuration of a monochrome image forming apparatus.
FIG. 5 is a diagram schematically illustrating the configuration of a full-color image forming apparatus.
[Explanation of symbols]
1 Intermediate transfer belt (annular transfer belt)
1a Inner bent portion 1b Outer bent portion 2 Reinforcement member 3 Guide rubber

Claims (5)

An annular transfer belt formed of a resin composition, wherein one of the diameters of the transfer belt located outside the image forming area is in the vicinity of the left and right edges in the cylindrical axis direction of the transfer belt with respect to the diameter of the image forming area of the transfer belt. A transfer belt having a small-diameter portion whose diameter gradually decreases toward the edge and a large-diameter portion whose other diameter gradually increases toward the edge. The diameter change amount at the edge between the small diameter portion and the large diameter portion is set so that the small diameter portion is set to −0.6 mm or more and the large diameter portion is set to +1.0 mm or less with respect to the diameter of the image forming area. The transfer belt according to claim 1, wherein: 2. The transfer belt according to claim 1, wherein the amount of change in the diameter of the edge of the large diameter portion is set to be not less than +0.6 mm and not more than +1.0 mm with respect to the diameter of the image forming area. Outside the image forming area of the transfer belt near the edge where the small diameter portion is formed, a reinforcing member made of a resin composition is adhered to the outer surface of the transfer belt, and a guide made of a rubber material is provided on the inner surface of the transfer belt. The transfer belt according to claim 1, wherein the member is attached. An annular belt formed of a resin composition has a small-diameter portion in which the diameter near one edge is reduced toward the edge with respect to the diameter of the image forming area, and the diameter near the other edge is the edge. A method for producing a transfer belt that imparts a shape having a large diameter portion that is enlarged toward the printing apparatus, comprising the following steps:
Mounting an annular belt formed of a resin composition inside a cylindrical mold having the predetermined shape to be transferred to the annular belt, and pressurizing air by sealing an end of the mold. And transferring the shape of the mold to the annular belt by heating the mold to a temperature just above the glass transition point of the resin composition.

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