JPH0531820A - Manufacture of semiconductive endless belt - Google Patents

Abstract

PURPOSE:To constitute the above method so that neither an offset in running nor creases are generated by simple structure. CONSTITUTION:A heat-resistant resin pipe 3 which possesses the higher coefficient of thermal expansion than that of a steel pipe 2 and is in a state of a drum is arranged within the steel pipe 2 and at least the resin pipe 3 and a thermoplastic sheet 1 are heated under a state where the thermoplastic 1 molded into a state of an endless belt is arranged on the outer circumference of the resin pipe 3. Then, the thermoplastic sheet 1 is softened and the resin pipe 3 is expanded by this heating and the thermoplastic sheet 1 is pressurized by placing the thermoplastic sheet 1 between the resin pipe 3 and steel pipe 2. Then, the same is cooled, the resin pipe 3 is separated from the steel pipe 2 under a state where the thermoplastic sheet 1 is stuck close to the resin pipe 3 and the thermoplastic sheet 1 is made into a state of almost a drum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a semiconductive endless belt such as an intermediate transfer belt, a photosensitive belt and a contact developing sleeve used in various OA equipment such as an electrophotographic copying machine.

[0002]

2. Description of the Related Art An electrophotographic copying machine, particularly a full-color electrophotographic copying machine, temporarily transfers a full-color toner image formed on a photosensitive member onto an outer peripheral surface of an intermediate transfer endless belt made of a thermoplastic resin endless belt. It is designed to be re-transferred to copy paper. Such a full-color electrophotographic copying machine is usually constructed as shown in FIG. That is, the electrophotographic copying machine includes an optical device 12 that guides reflected light of a document 11, a filter 13 that separates the reflected light of the document into three primary colors of red, green, and blue, and a belt-shaped photoconductor having photoconductivity. 14, a developing device 15, and a photoconductor 14
Intermediate transfer endless belt 17 for temporarily transferring the toner image formed on the outer peripheral surface of the copy paper 16 before copying the toner image onto the copy paper 16.
And a fixing device 18. More specifically,
A charging charger 19 is provided in the vicinity of the start end side portion of the belt-shaped photoconductor 14 having photoconductivity, and three developing portions 15a to 15c are provided in the middle part of the photoconductor 14. The belt-shaped photoconductor 14 is charged by the charging charger 19 and then exposed by the reflected light of the document projected from the optical device 12, and an electrostatic latent image is formed thereon. In this case, in the projection path of the optical device 12 for projecting the reflected light of the original onto the photoconductor 14, the filter 13 for separating the reflected light of the original into the three primary colors of red, green and blue as described above.
The primary color lights separated by the above are sequentially guided to the belt-shaped photoconductor 14 in the order of, for example, red is first, and then green, and each electrostatic latent image is formed. The developing device 15 includes three developing units 15a, 15b, and 15c so as to correspond to the above-mentioned three types of primary colors, and respectively stores toners of three types of colors corresponding to the above-described separated three primary colors. .. Then, the latent image formed by the color-separated light is color-developed with the toner corresponding to the color. That is, a colored toner image is formed for each color by the toners of the above three types of colors, and this is the primary transfer roller 20.
By this action, the toner images are sequentially transferred to the outer surface of the intermediate transfer endless belt 17, and a full-color toner image is formed on the intermediate transfer endless belt 17. As described above, the copying machine sequentially transfers the colored toner image formed for each color onto the copy paper 16,
An intermediate transfer endless belt 17 that does not form a colored toner image on the copy paper 16 and does not expand or contract due to humidity or the like.
First, a colored toner image is formed. Then, the toner image is transferred onto the copy paper 16 supplied from the paper cassette 21.
Then, it is retransferred by the action of the secondary transfer roller 22. The retransferred full-color toner image is sent to the fixing device 18 as the copy paper 16 is conveyed and fixed, and the copy paper 16 on which the toner image has been fixed is sent out from the copying machine as indicated by an arrow. The toner remaining on the intermediate transfer endless belt 17 is collected by the cleaning blade 25 of the cleaning device 24 after the transfer and is ready for the next transfer. Two
3 is a conveyor belt.

[0003] Such an intermediate transfer endless belt 17, by an extrusion molding method, polycarbonate (PC), polypropylene a dispersion of (PP) conductive material such as carbon black in thermoplastic resin such as, 10 ⁸ to 10 It is obtained by extrusion molding into a semi-conductive endless belt-like sheet (cylindrical sheet) of ¹¹ Ωcm, and the length of the inner circumferential surface in the circumferential direction (inner circumferential length) is the same over the entire length in the axial direction. Has been formed.

[0004]

However, the intermediate transfer endless belt 17 has a problem in the straight running property of the belt. The intermediate transfer endless belt 17 is a roller (see FIG.
In this case, if the intermediate transfer endless belt 17 is formed to have the same inner circumferential length as a whole, in this case, the inner circumferential length of the belt may vary slightly. Even if the wrinkles occur in the center portion 17b, which is the image area, due to uneven running and wrinkles on the belt, the image becomes defective. For this reason, rubber positioning guides are fixed to the inner surfaces of both ends along the circumference with double-sided adhesive tape, and these guides are fitted into the guide grooves formed in the circumferential direction at the both ends of each roller to prevent deviation. Although it is being prevented, in this case, the cost is increased due to post-processing, and the fixing force of the adhesive tape is weak,
The problem remains that the guide itself shifts to one side and the position shift still occurs during traveling.

The present invention has been made in view of the above circumstances, and can easily manufacture a semiconductive endless belt which has a simple structure, can be manufactured at low cost, and is free from running deviations and wrinkles. The purpose is to provide a method.

[0006]

In order to achieve the above object, the method for manufacturing a semiconductive endless belt according to the present invention has a coefficient of thermal expansion larger than that of the outer cylinder in the outer cylinder. A substantially drum-shaped inner cylinder is provided, and at the outer periphery of the inner cylinder, a thermoplastic sheet formed into an endless belt is provided, and at least the inner cylinder and the thermoplastic sheet are heated, This heating softens the thermoplastic sheet and expands the inner cylinder body, sandwiches the thermoplastic sheet between the inner cylinder body and the outer cylinder body, pressurizes, and then cools, and the inner cylinder body is cooled by this cooling. With the thermoplastic sheet in close contact with the body, the inner cylindrical body is separated from the outer cylindrical body, and the thermoplastic sheet has a substantially drum shape.

[0007]

That is, according to the present invention, first, an inner cylindrical body such as a substantially drum-shaped heat-resistant resin pipe having a coefficient of thermal expansion larger than that of the outer cylindrical body is provided in the outer cylindrical body such as a steel pipe. Set up. Then, prior to the above-mentioned disposition of the inner cylinder or after the disposition, a thermoplastic sheet formed into an endless belt shape by an extrusion molding method or the like is disposed on the outer periphery of the inner cylinder. Next, in that state, at least the inner cylindrical body and the thermoplastic sheet are heated. As a result, the thermoplastic sheet is softened, and at the same time, the inner cylindrical body is expanded. Due to this expansion, the softened thermoplastic sheet is sandwiched between the outer cylindrical body and the inner cylindrical body and pressed. After that, cool. By this cooling, the inner cylindrical body and the outer cylindrical body are contracted and separated from each other, and the inner cylindrical body is contracted while the thermoplastic sheet is in close contact with the inner cylindrical body. Due to this adhesion, the thermoplastic sheet is formed into a shape substantially the same as the shape of the outer peripheral surface of the inner cylindrical body, that is, the inner peripheral length thereof increases steplessly from both end portions toward the central portion. At the same time, the inner peripheral surface of the outer cylindrical body, for example, a mirror surface is transferred and formed on the outer peripheral surface thereof.

As described above, since the semiconductive endless belt obtained by the present invention is formed so that the inner peripheral length increases steplessly from both ends toward the center,
By tensioning this on a drum-shaped roller, the tension uniformly acts on the entire roller, and it is possible to prevent deviation of the running of the belt. Moreover, since only the shape of the belt is changed, the post-processing can be omitted and the belt can be manufactured at low cost.

The present invention will be described in detail.

The manufacturing method of the semiconductive endless belt of the present invention is as follows.
A substantially drum-shaped inner cylindrical body is arranged in the outer cylindrical body, and is formed into an endless belt shape on the outer circumference of the inner cylindrical body before or after the arrangement of the inner cylindrical body. A thermoplastic sheet is provided, and heating is performed in that state, followed by cooling.

Polypropylene (PP), polycarbonate (PC) and the like are used as the material of the thermoplastic sheet. The thickness of the sheet is set to 100 to 200 μm. Moreover, PP has a coefficient of thermal expansion of 0.9 to 1.5 × 1.
0 ^-4 (5 to 10 times that of metal), PC is 0.75 x 1
It is 0 ⁻⁴ (4 to 5 times that of metal).

A steel pipe is used as the outer cylinder. The thermal expansion coefficient of this steel pipe is 1.2 × 10 ⁻⁵ . The outer surface temperature (correction temperature) of PP is 160 to 170 ° C.
In the case of PC, the temperature is set to 170 to 180 ° C. The inner peripheral surface of this steel pipe is mirror-finished. As a method of finishing to a mirror surface, a method of honing the inner peripheral surface and then hard chrome plating, a method of coating a heat resistant resin such as silicon, polyimide, or polyethersulfone (PES) on the inner peripheral surface, a method of combining the two, etc. There is. Further, the outer cylindrical body is not limited to the steel pipe, and may be made of a material having a thermal expansion coefficient smaller than that of the inner cylindrical body.

The material of the inner cylinder has heat resistance that can withstand the heating temperature described below and a coefficient of thermal expansion of about 1 × 10 ^-4 (about the same as the coefficient of thermal expansion of the thermoplastic sheet). It is necessary to use fluorinated resin (Teflon). In particular, PTFE (tetrafluoroethylene resin)
In the case of, the continuous maximum operating temperature of 260 ° C. can be used, and the core temperature rises to 140 to 150 ° C. to expand about 2 to 3 mm / diameter 200, and the coefficient of thermal expansion is 1 × 10. ^-4, which is preferable. It is also possible to use aluminum. The coefficient of thermal expansion of aluminum is 2.4
Although it is as small as × 10 ^-5 , it rises to 140 to 150 ° C and expands about 0.4 to 0.6 mm in diameter / 200 in diameter. Due to the Teflon coating on the outer surface of the aluminum pipe, the endless belt having a larger coefficient of thermal expansion (larger contraction) can be demolded.

As the heating means, for example, a conventionally known oven is used.

As the cooling means, for example, conventionally known air supply means (air blowing pipe, etc.) is used.

The semiconductive endless belt of the present invention is manufactured, for example, as follows. That is, a cylindrical sheet (made of a thermoplastic resin) extruded into an endless belt by an extrusion molding method is covered on the outer side of a substantially drum-shaped heat-resistant resin pipe and inserted into a steel pipe. Then, the whole is heated uniformly in an oven or the like. As a result, the thermoplastic sheet is softened, and at the same time, the steel pipe and the resin pipe are expanded. During this expansion, the coefficient of thermal expansion of the resin pipe is larger than the coefficient of thermal expansion of the steel pipe, so the degree of diameter enlargement of the resin pipe relative to the steel pipe increases, and the above-mentioned softened thermoplastic sheet is sandwiched between the steel pipe and the resin pipe. It is pressurized. Next, it cools and the said thermoplastic sheet is removed from a steel pipe. In this case, if the temperature of the steel pipe is too high, peeling marks remain on the outer peripheral surface of the thermoplastic sheet. At this time, if the cooling rate of the steel pipe is set to be higher than that of the thermoplastic sheet, it is preferable that air is blown around the steel pipe to cool the steel pipe because the peeling traces do not remain. Further, at the time of the cooling, the thermoplastic sheet and the resin pipe are reduced in diameter in a state of being in close contact with each other, and the state returns to the initial state. As a result, the shape of the thermoplastic sheet is the same as the outer peripheral surface of the substantially drum-shaped resin pipe, that is, the inner peripheral length increases steplessly from both ends toward the center. Then, air is blown between the thermoplastic sheet and the resin pipe to float the thermoplastic sheet from the outer peripheral surface of the resin pipe and remove it. During the step of blowing air around the steel pipe and the step of removing the thermoplastic sheet while blowing air between the thermoplastic sheet and the resin pipe, the steel pipe and the resin pipe around which the thermoplastic sheet is wound are loosened. It is preferable to rotate (1 rpm). In this way, the desired semiconductive endless belt is obtained.

Next, examples will be described.

[0018]

1 is a perspective view of an endless belt forming apparatus showing an embodiment of the present invention, and FIG. 2 is a sectional view thereof. In the figure, 1 is a sheet-shaped thermoplastic resin extruded into an endless belt by an extruder (not shown),
The thickness is set to 150 to 200 μm and the width L ₂ is set to 360 mm. PP is used as this thermoplastic resin. 2 is a steel pipe with an inner diameter of 202 mm and a width of 38
It is set to 0 mm. The inner peripheral surface of this steel pipe 2 is finished to a mirror surface by honing, and after this mirror surface finishing, the surface is coated with silicon, polyimide, polyethersulfone, etc., and the molten thermoplastic resin is applied to the surface. You may make it not adhere. Reference numeral 3 denotes a heat-resistant resin pipe, which is formed in a substantially drum shape as shown in FIG. That is, both ends 3a, 3c in the axial direction
Has an outer diameter D ₁ of 200 mm and a central portion 3 b has an outer diameter D ₂ of 20
0.2-202mm (+0.1 for both ends 3a, 3c
To + 1.0%). 20 is desirable
0.6 ~ 201mm (+0.3 for both ends 3a, 3c
~ + 0.5%). Also, the width L ₁
Is set to 370 mm. PTFE is used as a material for the heat resistant resin pipe.

In the above construction, first, the thermoplastic sheet 1 formed into an endless belt by extrusion molding is put on the outside of the heat resistant resin pipe 3 and inserted into the steel pipe 2. Then, the whole is uniformly heated to 175 ° C. in an oven. As a result, as shown in FIG. 4, the thermoplastic sheet 1 is softened and the resin pipe 3 is expanded, and the softened thermoplastic sheet 1 is sandwiched between the expanded steel pipe 2 and the resin pipe 3. It is pressed in the state. After the pressure welding, air is blown onto the outer peripheral surface of the steel pipe 2 to remove the steel pipe 2 as shown in FIG.
The resin pipe 3 is separated from. At this time, the resin pipe 3
The thermoplastic sheet 1 is closely attached to. Next, air is blown between the thermoplastic sheet 1 and the resin pipe 3 to separate the thermoplastic sheet 1 and the resin pipe 3. As a result, the desired semiconductive endless belt 9 as shown in FIG. 6 is obtained. In this semiconductive endless belt 9, the outer diameter D ₃ of both ends 9a and 9c in the axial direction is 200 mm, and the outer diameter D ₄ of the central portion 9b is 200.2 to 202 mm (+0.1).
To + 1.0%). 20 is desirable
It is to be set to 0.6 to 201 mm (+0.3 to + 0.5%).

As shown in FIG. 7, even if the semiconductive endless belt 9 thus obtained is used for a long time in a state of being stretched over both rollers, the belt is not biased.
Moreover, the occurrence of wrinkles in the central portion 9b was reduced, and the image defect was eliminated. Further, there is an advantage that the outer peripheral surface of the semiconductive endless belt 1 is finished to be a mirror surface.

In the above embodiment, the inner peripheral surface of the steel pipe 2 is mirror finished, but the invention is not limited to this, and the inner peripheral surface of the steel pipe 2 may be finished in a satin finish by shot blasting.

[0022]

As described above, according to the manufacturing method of the present invention, it is possible to easily manufacture a semi-conductive endless belt having an outer peripheral surface, for example, a mirror surface and an overall shape like a drum. In the obtained semi-conductive endless belt, the rollers formed in a drum shape are bridged over each other, whereby the tension can be kept uniform over the entire belt, and deviation of the running of the belt does not occur. Moreover, since only the shape of the belt is changed, the post-processing can be omitted and the belt can be manufactured at low cost.

[Brief description of drawings]

FIG. 1 is a perspective view of an endless belt forming apparatus showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the device.

FIG. 3 is a perspective view of a resin pipe used in the above apparatus.

FIG. 4 is a cross-sectional view showing a heating state in the above apparatus.

FIG. 5 is a cross-sectional view showing a cooling state in the above apparatus.

FIG. 6 is a perspective view of a semiconductive endless belt obtained by the above device.

FIG. 7 is an explanatory view showing a usage state of the semiconductive endless belt.

FIG. 8 is a configuration diagram of a full-color copying machine incorporating an intermediate transfer endless belt.

[Explanation of symbols]

 1 Thermoplastic sheet 2 Steel pipe 3 Heat resistant resin pipe

Claims (1)

1. A substantially drum-shaped inner cylinder having a coefficient of thermal expansion larger than that of the outer cylinder is disposed in the outer cylinder, and the outer periphery of the inner cylinder is defined. In the state where the thermoplastic sheet formed into an endless belt is arranged, at least the inner cylinder and the thermoplastic sheet are heated, and the inner cylinder is expanded while softening the thermoplastic sheet by this heating, The thermoplastic sheet is sandwiched between the inner cylinder and the outer cylinder to apply pressure, and then cooled,
By this cooling, the inner cylindrical body is separated from the outer cylindrical body in a state where the thermoplastic sheet is closely attached to the inner cylindrical body, and the thermoplastic sheet is formed into a substantially drum shape. Manufacturing method.