JPH04303872A - Endless belt for intermediate transfer - Google Patents

Abstract

PURPOSE:To improve the surface state, the circumferntial length accuracy and the thickness accuracy of an endless belt for intermadiate transfer by finishing the outside peripheral surface thereof becoming a transfer surface being a specular surface whose gloss is >=50 and setting the average error of the thickness thereof to be <=20%. CONSTITUTION:The endless belt 17 for intermediate transfer is basically endless and annular. Besides, it is loaded in a full-color electrophotographic copying machine. Then, the outside peripheral surface X of the belt 17 is finished being the specular surface whose gloss is >=50 and the average error of the thickness thereof is set to be <=20%. In such a case, when the gloss is under 50 or the average error of the thickness is over 20% it is not favarable because the smoothness of the transfer surface of the belt is lost, large rugged difference is provided and toner is left, fused and attached in a recessed part. By setting the gloss and the average thickness is such a way, transfer efficiency is accurately uniformized at any part and the irregularity of transfer is prevented from occurring.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention relates to an intermediate transfer endless belt for transferring a toner image formed on a photoreceptor onto its own outer circumferential surface and retransferring it onto copy paper in an electrophotographic copying machine or the like. It is related to.

0002

[Prior Art] A full-color toner image formed on a photoreceptor is first transferred onto the outer peripheral surface of an intermediate transfer endless belt made of thermoplastic resin, and then transferred again to copy paper. A modern full-color electrophotographic copying machine is usually configured as shown in FIG. That is, this electrophotographic copying machine includes an optical device 12 that guides light reflected from an original 11, a filter 13 that separates the reflected light from the original into three primary colors of red, green, and blue, and a belt-shaped photoreceptor having photoconductivity. 14, a developing device 15, an intermediate transfer endless belt 17 that once transfers the toner image formed on the photoconductor 14 onto its own outer peripheral surface before copying it onto copy paper 16, and a fixing device 18. There is. More specifically, a charger 19 is provided near the starting end of the photoconductive belt-like photoreceptor 14, and three developing units 15a, 15b, 15c are provided in the middle of the photoreceptor 14. is provided. The belt-shaped photoreceptor 14 is charged by the charger 19 and then exposed to light reflected from the original projected from the optical device 12, so that an electrostatic latent image is formed thereon. In this case, a filter 13 is provided on the projection path of the optical device 12 that projects the reflected light from the original onto the photoreceptor 14, and the filter 13 separates the reflected light from the original into three primary colors of red, green, and blue. For example, the red color is guided first, then the green color, and so on, in order, onto the belt-shaped photoreceptor 14 to form respective electrostatic latent images. The three developing units 15a, 15b, and 15c provided in the developing device 15 store toners of three types of colors corresponding to the separated three primary colors, respectively. The latent image formed by the color-separated light is colored and developed with toner corresponding to the color. That is, a colored toner image is formed for each color using the toners of the above three colors, and this is sequentially transferred to the outer peripheral surface of the endless intermediate transfer belt 17 by the action of the primary transfer roller 20. Forms a full-color toner image. In this way, the copying machine sequentially transfers colored toner images formed for each color onto copy paper 16, and instead of forming colored toner images on copy paper 16, the copying machine expands and contracts due to humidity, etc. A colored toner image is once formed on the endless intermediate transfer belt 17. The toner image is then transferred to the copy paper 1 supplied from the paper cassette 21.
6, the image is retransferred by the action of the secondary transfer roller 22, and as the copy paper 16 is conveyed, it is sent to the fixing device 18 where it is fixed, and then sent out from the copying machine as shown by the arrow. 23 is a conveyor belt.

As described above, in the electrophotographic copying machine described above, toner is once transferred from the photoreceptor 14 to the endless intermediate transfer belt 17 and then retransferred from the endless intermediate transfer belt 17 to the paper 16. Therefore, the intermediate transfer endless belt 1
In addition to the electrical resistivity of the semiconductor region (108 to 109 Ωcm), 7 has no local unevenness, circumferential or axial lines or wrinkles, and preferably has a mirror surface. In addition, from the perspective of circumferential accuracy, the belt must have an accuracy of ±0.5 mm when installed on the machine, for example in the case of a diameter of 200 mm, and from the perspective of thickness accuracy, the machine For example, if the thickness is 200 μm, the thickness should be ±2 to prevent local uneven contact with the photoreceptor 14 or the paper 16 during installation.
It is required to have an accuracy of 0 μm. However,
If the intermediate transfer endless belt 17 is manufactured by blow molding, the surface condition in the axial direction will be poor due to mold parting, and if it is manufactured by inflation molding, the accuracy of the circumferential length will be poor. For this reason, the intermediate transfer endless belt 17 is manufactured by an extrusion molding method, particularly by an inside mandrel method which can obtain good circumferential length accuracy.

0004

[Problem to be solved by the invention] However, the thickness 5
When manufacturing a particularly thin intermediate transfer endless belt 17 such as 0 to 500 μm by extrusion molding, even if the above-mentioned inside mandrel method is used, uneven linear velocity of the extruded resin, uneven flow inside the extrusion die, and take-up speed may occur. The actual situation is that even slight fluctuations in unevenness cause non-uniform circumferential length and thickness, making it impossible to obtain an endless intermediate transfer belt 17 that satisfies the above requirements. Furthermore, the extrusion molding method has a problem in that streaks such as die scars occur in the extrusion direction. Therefore, it is conceivable to mirror-finish the conveying surface after extrusion molding, but the intermediate transfer endless belt 17 usually contains carbon black in order to give it semi-conductivity, and is polished. However, the carbon black was exposed on the surface, resulting in a rough surface that could not be mirror-finished.

[0005] In the intermediate transfer endless belt 17 which has a poor surface condition and is uneven in circumference and thickness, the unevenness of the transfer surface is large, so that toner tends to remain in the concave portions and uneven cleaning tends to occur. In this state, the secondary transfer roller 2
When a current flows from the intermediate transfer endless belt 17, an excessive current flows in the convex portion of the surface of the endless intermediate transfer belt 17, and the residual toner melts into a lump or a film and adheres to the transfer surface. For this reason,
The problem is that clear images cannot be obtained.

The present invention was made in view of the above circumstances, and an object of the present invention is to provide an intermediate transfer endless belt that is free from irregularities on its outer circumferential surface and can provide copied images of excellent quality.

[0007]

[Means for Solving the Problems] In order to achieve the above object, an intermediate transfer endless belt of the present invention provides an intermediate transfer belt that retransfers a toner image transferred from a photoreceptor to its own outer peripheral surface onto copy paper. The belt is an endless belt, and the outer circumferential surface has a mirror finish with a gloss of 50 or more, and the average thickness error is 20.
% or less.

[0008]

[Operation] That is, the present inventors conducted a series of studies in order to obtain an intermediate transfer endless belt that is excellent in terms of surface condition, circumferential length accuracy, and thickness accuracy. As a result, if the above numerical range is satisfied, there will be no unevenness on the belt transfer surface and no local sagging of the belt, which will lead to the melting of the residual toner as described above and the resulting deterioration of image quality. We have discovered that this is an excellent endless intermediate transfer belt, and have arrived at this invention.

Next, the present invention will be explained in detail based on examples.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a partial sectional view showing an embodiment of the present invention. The intermediate transfer endless belt 17 has a basic overall shape of an endless ring like a normal intermediate transfer endless belt, and is attached to a full-color electrophotographic copying machine as shown in FIG.

However, this intermediate transfer endless belt 17 is
The outer peripheral surface X is finished to a mirror surface with a gloss of 50 or higher, and the average thickness error is set to 20% or less. This is,
This is a major feature of this invention. In other words, if the gloss is less than 50 or the average error in thickness exceeds 20%, the belt transfer surface loses its smoothness and has a large difference in unevenness, so as mentioned above, toner remains in the recesses. This is because the film will melt and adhere, making it impossible to obtain clear image quality.

[0012] The above-mentioned gloss meter (manufactured by Pacific Scientific Co., Ltd., Glass Guard II)
The average error in thickness is calculated by a thickness meter.

Therefore, in the intermediate transfer endless belt 17 of the present invention, the outer circumferential surface Efficiency is uniform with high accuracy maintained in all parts, and uneven transfer does not occur during transfer and retransfer of toner images.

The intermediate transfer endless belt 17 as described above is
For example, it can be created as follows. That is, first, a thermoplastic resin such as polycarbonate or polypropylene is extruded to form an annular endless belt 1 having a thickness of about 50 to 500 μm. Next, as shown in FIG. 2, this endless belt 1 is inserted into a steel pipe 2 whose inner circumferential surface 2a has a mirror finish with a gloss of 50 or more. The heated load roller 3 presses the outer circumferential surface of the endless belt against the inner circumferential surface of the steel pipe 2 from inside. In this state, the steel pipe 2 and heating load roller 3 are rotated in the same direction by rotating the guide roller 4 that contacts them from below in the same direction. As a result, the outer circumferential surface of the endless belt 1 is softened by the heating from the heating load roller 3, and is mirror-finished by the mirror-finished inner circumferential surface 2a of the steel pipe 2. In addition, the heating load roller 3 has a heat-resistant elastic body 3b such as silicone rubber formed on the outer circumferential surface of a core metal 3a that serves as a rotating shaft.
Furthermore, a heating means such as a nichrome wire is built inside. 3c is a rotating shaft portion of the core bar 3a.

The intermediate transfer endless belt 17 thus obtained has a mirror surface on its outer circumferential surface X (see FIG. 1), and the mirror surface degree and thickness accuracy satisfy the above-mentioned numerical range. In addition, the circumference accuracy is also excellent (normally, the circumference is 6
(within ±500μm for 30mm). Therefore, when this product is incorporated into a full-color electrophotographic copying machine as shown in FIG. 10, no overcurrent will occur on the transfer surface (outer circumferential surface The occurrence of melt adhesion and filming can be prevented. Therefore, it is possible to prolong the life of the belt 17 and to obtain a copy image of excellent image quality.

In the above manufacturing method, it is desirable that the inner circumferential surface of the mirror-finished steel pipe 2 is coated with silicone so that the thermoplastic resin eluted from the outer circumferential surface of the endless belt 1 does not adhere thereto. Further, the heating temperature of the heating load roller 3 is preferably set to 160 to 190°C when the endless belt 1 is made of polycarbonate, and 150 to 180°C when the endless belt 1 is made of polypropylene. It is preferable to set it to . Further, the rotational speed of the steel pipe 2 is set at a linear speed of about 0.5 m/min, and the weight of the heating load roller 3 is set at about 100 to 1000 g/cm.

In the above manufacturing method, the finishing accuracy also changes depending on how much difference is set between the circumferential length of the steel pipe 2 and the circumferential length of the endless belt 1. In order to obtain a product that satisfies the numerical values of this invention, the circumference of the endless belt 1 should be 100 to 97% of the circumference of the steel pipe 2, more preferably 100 to 9%.
It is preferable to set it to 9%.

Furthermore, in the above manufacturing method, the heating load roller 3
As a result, the endless belt 1 is heated and the steel pipe 2 is pressed against the inner circumferential surface 2a at the same time. However, as shown in FIG. A hot air blowing nozzle 9 that blows hot air toward the inner peripheral surface of the endless belt 1 may be inserted into the belt 1 so that the endless belt 1 is softened by the hot air.

Furthermore, in order to shape the outer circumferential surface of the endless belt 1 into a mirror surface, the method is not limited to the above method. For example, as shown in FIG. A load roller 5 is inserted into the endless belt 1 from the outside, and a heating roller 3' whose outer circumferential surface has a mirror finish with a gloss of 50 or higher is inserted into the endless belt 1.
It may be made to come into pressure contact with the outer circumferential surface of. The structure of the heating roller 3' is similar to that of the heating load roller 3 shown in FIG. 2, and the same parts are given the same numbers. Also, 6
is a first cold roller, and 7 is a second cold roller. The second cold roller 7 is movable as shown by arrow A, and functions to separate the heating roller 3' from the endless belt 1. Then, the heating roller 3'
The outer peripheral surface of the endless belt 1 is preferably coated with silicone so that the thermoplastic resin eluted from the surface of the endless belt 1 does not adhere thereto. Further, in this manufacturing method, it is preferable that the circumferential length of the endless belt 1 is set to 100 to 103% of the circumferential length of the steel pipe 2.

As described above, when pressing the heating roller 3' onto the outer circumferential surface of the endless belt 1 to form a mirror surface, as shown in FIG. The endless belt 1 may be sandwiched between only the loaded rollers 5 and shaped into a mirror surface. However, also in this case, the first cold roller 6 and the second cold roller 7 are provided in the same manner as in the case of FIG. 4 above.

In addition, in the above method, a heating roller 3' is used for shaping the mirror surface, but as shown in FIG. 6, the heating roller 3' is not used, but a guide roller 8 at room temperature is used, Alternatively, the outer peripheral surface of the endless belt 1 may be heated by blowing hot air from a hot air blowing nozzle 9 provided on the outside. Alternatively, as shown in FIG. 7, mirror-finishing may be performed without using the steel pipe 2 while blowing hot air from a hot air blowing nozzle 9 provided below.

Furthermore, as a method for shaping the outer peripheral surface of the endless belt 1 into a mirror surface, it is also possible to use a heat-resistant sheet whose one side is mirror-finished. That is, as shown in FIG. 8, a steel pipe 2 is inserted inside the endless belt 1, a load roller 5 is further inserted inside the steel pipe 2, and the endless belt 1 is pressed against the heating roller 3' provided below. do. And endless belt 1
A heat-resistant sheet 10, one side of which has been mirror-finished, is passed between the heating roller 3' and the heating roller 3' with its mirror-finished surface touching the outer peripheral surface of the endless belt 1. In this way,
By pressing against the heat-resistant sheet 10, a mirror surface is formed on the outer peripheral surface of the endless belt 1. Alternatively, as shown in FIG.
Mirror finishing can be performed in the same manner as above without using the steel pipe 2. In these figures, 11a is a supply roller that supplies the heat-resistant sheet 10, and 12a is a take-up roller for the heat-resistant sheet 10. In this method, the heat-resistant sheet 10 used is usually
A material having a heat shrinkage rate matching that of the material of the endless belt 1 is used. For example, when the endless belt 1 is made of polypropylene or polycarbonate, a polyimide film is used.

Next, FIG. 10 shows the intermediate transfer endless belt (example product) obtained by the method shown in FIG. 2 above, and comparative example products 1 and 2 having the characteristics shown in Table 1 below. Built into a full-color electrophotographic copying machine for continuous copying (20
00 times) and observed the unevenness of density in the copied image. The results are also shown in Table 1 below.

[0024]

[Table 1]

From the above results, the Example products are Comparative Examples 1 and 2.
It can be seen that it is possible to obtain a copy image that is superior to that of the original.

[0026]

[Effects of the Invention] As described above, in the intermediate transfer endless belt of the present invention, the outer peripheral surface, which is the transfer surface, is finished to a mirror finish with a gloss of 50 or more, and the average thickness error is also set to a very low value. , the transfer surface is smooth and the transfer efficiency is almost uniform in all parts. Therefore, when the endless intermediate transfer belt of the present invention is incorporated into a full-color electrophotographic copying machine, extremely clear images can be obtained without causing image shading, and high quality products can be provided. can. Furthermore, since the toner does not melt and adhere to the endless intermediate transfer belt itself, it is possible to extend the life of the belt.

[Brief explanation of the drawing]

FIG. 1 is a partially enlarged sectional view showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram of the manufacturing method of the above embodiment.

FIG. 3 is an explanatory diagram of another manufacturing method of the above embodiment.

FIG. 4 is an explanatory diagram of another manufacturing method of the above embodiment.

FIG. 5 is an explanatory diagram of another manufacturing method of the above embodiment.

FIG. 6 is an explanatory diagram of another manufacturing method of the above embodiment.

FIG. 7 is an explanatory diagram of another manufacturing method of the above embodiment.

FIG. 8 is an explanatory diagram of another manufacturing method of the above embodiment.

FIG. 9 is an explanatory diagram of another manufacturing method of the above embodiment.

FIG. 10 is a configuration diagram of a full-color copying machine incorporating an endless intermediate transfer belt.

[Explanation of symbols]

1 Endless belt 17 Intermediate transfer endless belt

Claims (1)

[Claims] 1. A semiconductive intermediate transfer endless belt containing carbon black for retransferring a toner image transferred from a photoreceptor to its outer peripheral surface onto copy paper, wherein the outer peripheral surface has a gloss of 50 or more. An endless intermediate transfer belt that has a mirror finish and has an average thickness error of 20% or less.