JP2001034078A - Electrophotographic belt and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a low-cost electrophotographic belt giving a high precision transferred image and excellent in durability. SOLUTION: The electrophotographic belt has a structure consisting at least of two layers comprising an elastic layer 22 whose hardness is 30-95A and a core layer 21 whose hardness is 75-90D. A polyurethane stock solution to constitute the elastic layer 22 is poured into a metallic mold for centrifugal molding and the metallic mold is rotated under heating to partially cure the stock solution. A polyurethane and/or plyurea stock solution to constitute the core layer 21 is then poured on the resulting elastic layer 22, cured by heating, released from the mold and after-cured to produce the electrophotographic belt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic belt, and more particularly, to an intermediate transfer belt, a transfer conveyance belt, a fixing belt, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, a belt made of a resin such as a polyimide resin, a polyvinylidene fluoride resin, and a polycarbonate resin has been used as an electrophotographic belt such as a transfer belt and a transfer conveyance belt. Since these resin belts are hard and have low elongation, they have the advantage of no cracks.

[0003] However, these resins are not only expensive but also difficult to extrude into a seamless structure which is an essential requirement for electrophotographic belts. There is a further problem of increased cost. Also, with the recent improvement in image quality of electrophotographic apparatuses, it is required that the surface of the belt has elasticity. Since the resin belt is hard, when transferring an image to the surface of paper,
There is a problem that it is not possible to follow the unevenness of the paper and the reproducibility of a precise image is poor. Further, when a color image is transferred, if the transfer belt surface is hard, there is a problem in that the toner may lack holding properties on the belt surface and color shift may occur, and it is not possible to meet the demand for color transfer.

As a countermeasure, it is conceivable that the belt itself is made of an elastomer having elasticity. However, since the elastomer has a large stiffness even at low elongation, there is a problem that unevenness of the image due to the stiffness occurs. On the other hand, a cord or canvas can be used for the core, but the cord or canvas is formed of a twist system, and there is a problem that the belt meanders in the twist direction. A method of forming a core layer with the resin and further forming an elastic layer on the surface of the core layer is also conceivable.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electrophotographic belt which solves the above-mentioned problems, is inexpensive, can obtain a high-accuracy transfer image, and has excellent durability, and a method for manufacturing the same. It is.

[0006]

The present invention relates to an electrophotographic belt having at least a two-layer structure of an elastic layer and a core layer, wherein the elastic layer has a hardness of 30 to 95 in JIS A hardness.
And the hardness of the core layer is 75 to 9 in JIS D hardness.
It is an electrophotographic belt characterized by being at 0 degrees.

According to the present invention, the hardness of the elastic layer is in the above range. If the hardness is less than 30 degrees in JIS A hardness (hereinafter referred to as 30A), the elastic layer itself may be tacky, or the holding may be too good to generate untransferred toner, thereby increasing the cleaning property. Is inferior. If this exceeds 95A, it is impossible to follow the irregularities of the paper.

[0008] The hardness of the core layer is in the above range.
If this hardness is less than 75 degrees in JIS D hardness (hereinafter referred to as 75D), noble occurs at low elongation, which causes image displacement. If this exceeds 90D, the core layer is hard, and if it is set on a small-diameter pulley, it may crack,
Cannot be set on small diameter pulleys.

Further, the present invention is characterized in that the elastic layer and the core layer are formed by curing a liquid thermosetting polyurethane.

The present invention is also characterized in that the elastic layer is formed by curing liquid thermosetting polyurethane, and the core layer is formed by curing liquid thermosetting polyurethane or thermosetting polyurea.

According to the present invention, the elastic layer is obtained by curing a liquid thermosetting polyurethane having the above hardness range,
The core layer is obtained by curing a liquid thermosetting polyurethane and / or thermosetting polyurea having the above hardness range. By using the liquid thermosetting resin for the elastic layer and the core layer, the two layers are compatible with each other, are continuously cured, and do not cause interfacial separation. In addition, the thermal shrinkage of both layers is so close that no thermal deformation occurs after curing.

Further, according to the present invention, the thickness of the core layer is 0.05 to
0.3 mm.

According to the present invention, the thickness of the core layer is in the above range. If the thickness is less than 0.05 mm, the strength of the core layer is insufficient and the durability is poor. When this exceeds 0.3 mm,
The core layer becomes difficult to bend and cannot be wound around a small-diameter pulley.

Further, the present invention is characterized in that a surface layer is further provided on the elastic layer.

According to the present invention, a surface layer may be further provided on the elastic layer. This prevents the liquid from oozing out of the elastic layer, which is hardly practical. Further, resistance adjustment and adjustment of surface characteristics such as friction coefficient μ are also facilitated.

Further, according to the present invention, a liquid thermosetting polyurethane constituting an elastic layer is rotated at a high speed, injected into a heated centrifugal molding die and partially cured, and a core layer is formed on the cured layer. A method for producing an electrophotographic belt, comprising: injecting a liquid thermosetting polyurethane and / or polyurea to be cured, demolding and after-curing.

According to the present invention, a two-layered electrophotographic belt is manufactured by a centrifugal molding method. In this case, first, the liquid thermosetting polyurethane constituting the elastic layer is injected into the centrifugal molding die, and is partially cured by heating and rotation, and then the liquid thermosetting polyurethane and / or the liquid constituting the core layer thereon is formed. Polyurea is injected and cured by heating and rotation. This does not create a distinct layer between the two layers. Further, the elastic layer and the core layer can be continuously formed, so that the manufacturing process can be simplified.

When the surface layer is provided on the elastic layer,
Any known method such as forming a liquid coating agent by spraying or dipping after molding may be used.

When it is necessary to impart conductivity to the belt, carbon, an ionic conductive agent and the like are added to the liquid thermosetting resin constituting the elastic layer and the core layer.

[0020]

FIG. 1 is a cross-sectional view of an electrophotographic apparatus for color copying using an electrophotographic belt according to the present invention as an intermediate transfer belt 6. The photoconductor 1 is uniformly charged by the charging roller 2. The charged photoreceptor 1 is exposed by light reflected from a copy object (not shown). In the case of a color copy, the reflected light is separated into blue, green, and red by a color filter, and is separately exposed. For example, light transmitted through a blue color filter forms an electrostatic latent image on the photoreceptor 1 by yellow light, which is a complementary color of blue. The photoreceptor 1 rotates in the direction indicated by the arrow 3, comes into contact with the first developing roller 4Y, is supplied with yellow toner from the first developing roller 4Y, and the yellow component of the copy object is developed. The second to fourth developing rollers 4M, 4C, 4B are not in contact with the photoconductor 1, and the photoconductor 1 is in contact with the transfer belt 6 by the first transfer roller 5. The transfer belt 6 is moved in the direction of arrow 9 by the two pulleys 7 and 8, and the yellow image on the photoconductor 1 is transferred onto the transfer belt 6. The photoreceptor 1 is removed from the remaining yellow toner by a cleaning blade, and is discharged.

When the exposure through the yellow color filter is completed, the color filter is replaced with green, and an electrostatic latent image is formed on the photosensitive member 1 by magenta light, which is a complementary color of green. At this time, the first, third, and fourth developing rollers 4
Y, 4C, and 4B do not contact the photoconductor 1, only the second developing roller 4M contacts the photoconductor 1, and a magenta image is developed on the photoconductor 1. When the transfer of the yellow image is completed, the transfer belt 6 separates the first transfer roller 5 from the photoreceptor 1 and is rotated by the pulleys 7 and 8 in the direction opposite to the arrow 9 direction, and returns to the original position. When the magenta image on the photoconductor 1 comes to a position where it contacts the transfer belt 6, the magenta image on the photoconductor 1 is transferred to the transfer belt 6 by the first transfer roller 5.
As a result, the yellow image and the magenta image are superimposed on the transfer belt 6.

Similarly, a cyan image passed through a red color filter is developed on the photoreceptor 1 and is superimposed on the transfer belt 6. Finally, a black image is developed on the photoreceptor 1 and superimposed on the transfer belt 6 by white reflected light without using a color filter. As a result, the same color image as the object to be copied is formed on the transfer belt 6. The color image on the transfer belt 6 is transferred onto the paper 12 supplied between the second transfer roller 11 and the pulley 8. Paper 1
2 is fixed on the paper 12 by a fixing device (not shown). After the transfer belt 6 transfers the color image to the recording paper, the remaining toner is removed by the cleaning blade 13.

FIG. 2 is a perspective view of the intermediate transfer belt 6 according to one embodiment of the present invention. The intermediate transfer belt 6 includes a core layer 21 and an elastic layer 22. The core layer 21 is preferably made of a polyurethane resin and / or a polyurea resin having a hardness of 75 to 90D.
Is preferably made of a polyurethane resin having a hardness of 30 to 90A.

Example 1 Nipporan 4032 (trade name) manufactured by Nippon Polyurethane Industry Co., Ltd. was added with 0.5% of ketchin black for imparting conductivity, and dried under reduced pressure at 100 ° C. for 12 hours. 7.9 parts by weight of industrial Coronate T65 (trade name) were mixed and stirred to prepare a liquid polyurethane elastic layer stock solution.

On the other hand, 0.5% ketchin black was added to Nippon Polyurethane Industry C-700 (trade name), dried under reduced pressure at 100 ° C. for 12 hours, cooled to 40 ° C., and 100 parts by weight of Nippon Polyurethane Industry as a curing agent was added. Made DN4766
Was mixed and stirred to prepare a polyurethane core layer stock solution.

The stock solution of the elastic layer was injected into a centrifugal molding die rotating at 700 rpm by heating to 100 ° C., and the rotation speed was further increased to 1000 rpm and heating was continued for 5 minutes to partially cure the stock solution of the polyurethane elastic layer. The undiluted solution of the polyurethane core layer was poured thereon, and rotation heating was continued at 1000 rpm for 1 hour. After demolding, after-curing was performed for 12 hours to obtain a belt having an elastic layer of 0.5 mm and a core layer of 0.3 mm.

The hardness of the elastic layer was 30 A, and the hardness of the core layer was 75 D.

Example 2 Nipporan 40 containing 0.5% of ketchin black as an elastic layer
It is the same as Example 1 except that 9 parts by weight of Coronate T65 was used for 32 and 100 parts by weight. The hardness of the elastic layer was 50A.

Example 3 Nipporan 4032 as an elastic layer and Coronate T65
Instead of Nippon Polyurethane Industry Coronate 4048
Example 1 is the same as Example 1 except that 15.7 parts by weight of MOCA (trade name) manufactured by Ihara Chemical Industry was used as a curing agent for 100 parts by weight of (trade name). The hardness of the elastic layer is 95A
Met.

Example 4 C-700, 0.5% Ketchin Black added to the core layer
Example 1 is the same as Example 1 except that 50 parts by weight of DN4766 was used for 00 parts by weight. The hardness of the core layer was 82D.

Example 5 Porea R603 (trade name) 100 manufactured by Ihara Chemical Industry Co., Ltd.
Example 1 is the same as Example 1 except that a stock solution of a polyurea core layer using 82 parts by weight of DN4766 as a curing agent in parts by weight was used. The hardness of the core layer was 87D.

Examples 6 and 7 The same as Example 5 except that the thickness of the core layer was 0.05 mm and 0.15 mm.

Comparative Example 1 Nipporan 40 containing 0.5% of ketchin black in the elastic layer
The same as Example 1 except that 7 parts of Coronate T65 was added to 32 and 100 parts by weight. The hardness of the elastic layer is 2
It was 0A.

Comparative Example 2 Porea RX801 (trade name) 10 manufactured by Ihara Chemical Industry
Example 1 except that a stock solution of polyurea core layer using 70 parts by weight of DN476 as a curing agent was used with respect to 0 parts by weight.
Is the same as The hardness of the core layer was 92D.

Comparative Example 3 Porea RX201 (trade name) 10 manufactured by Ihara Chemical Industry
Example 1 except that a stock solution of polyurea core layer using 70 parts by weight of DN476 as a curing agent was used with respect to 0 parts by weight.
Is the same as The hardness of the core layer was 70D.

Comparative Examples 4 and 5 The same as Example 5 except that the thickness of the core layer was 0.02 mm and 0.5 mm.

Table 1 shows the performance of the belts produced in Examples 1 to 7 and Comparative Examples 1 to 5 when the belt was run between two pulleys having a diameter of 16 mm with a tension of 1.5 kg.

[0038]

[Table 1]

From the results shown in Table 1, it can be seen that a belt within the scope of the present invention can be suitably used for an intermediate transfer belt of an electrophotographic apparatus. On the other hand, when the hardness of the elastic layer is 20
A (less than 30A) Comparative Example 1, the hardness of the core layer is 92D
Comparative Example 2 (more than 90D), hardness of the core layer was 70D
Comparative Example 3 (less than 75D), the thickness of the core layer was 0.02 m
The belt of Comparative Example 4 having a thickness of m (less than 0.05 mm) and the belt of Comparative Example 5 having a thickness of the core layer of 0.5 mm (exceeding 0.3 mm) have problems, and clear images cannot be obtained.

FIG. 3 is a perspective view of an intermediate transfer belt 69 according to another embodiment of the present invention. The belt 69 of the present embodiment is
The surface layer 23 is provided on the surface of the elastic layer 22. Surface layer 2
No. 3 is constituted by spraying or dipping the coating agent on the belt produced in Examples 1 to 7.

In the above embodiment, the belt of the present invention is used as an intermediate transfer belt, but may be used as a transfer conveyance belt or a fixing belt.

[0042]

As described above, the electrophotographic belt according to the first aspect of the present invention has at least two layers, an elastic layer and a core layer, and the elastic layer has a hardness of 30 to 95 A and a core layer. Has a hardness of 75 to 90D. Thereby, tack does not occur in the elastic layer, image shift does not occur, and cracks do not occur in the core layer.

According to the second and third aspects of the present invention, the elastic layer is made of polyurethane and the core layer is made of polyurethane and / or polyurea. They are compatible and integrated, so that interfacial separation does not occur and there is no thermal deformation.

According to the fourth aspect of the present invention, the thickness of the core layer is set to 0.05 mm to 0.3 mm, so that the strength is insufficient and it becomes impossible to wind the core layer around a small diameter pulley. Never.

According to the fifth aspect of the present invention, a surface layer is further provided on the elastic layer, thereby preventing the liquid from seeping out of the elastic layer.

According to the present invention, the elastic layer and the core layer do not form distinct layers, the elastic layer and the core layer can be formed continuously, and the manufacturing process is simplified. Is done.

[Brief description of the drawings]

FIG. 1 shows an electrophotographic belt of the present invention as an intermediate transfer belt.
FIG. 2 is a cross-sectional view of a color copying electrophotographic apparatus used as a device.

FIG. 2 is a perspective view of the electrophotographic belt 6 according to the embodiment of the present invention.

FIG. 3 is a belt 6 for electrophotography according to another embodiment of the present invention.
It is a perspective view of a.

[Explanation of symbols]

 Reference Signs List 1 photoconductor 2 charging roller 4 developing roller 5 first transfer roller 6, 6a transfer belt 11 second transfer roller 12 paper 21 core layer 22 elastic layer 23 surface layer

Claims (6)

[Claims] 1. An electrophotographic belt having at least a two-layer structure of an elastic layer and a core layer, wherein the hardness of the elastic layer is 30 to 95 degrees in JIS A hardness, and the hardness of the core layer is JIS. D. An electrophotographic belt having a hardness of 75 to 90 degrees. 2. The electrophotographic belt according to claim 1, wherein the elastic layer and the core layer are formed by curing a liquid thermosetting polyurethane. 3. The electrophotographic apparatus according to claim 1, wherein the elastic layer is formed by curing liquid thermosetting polyurethane, and the core layer is formed by curing liquid thermosetting polyurethane or thermosetting polyurea. belt. 4. The electrophotographic belt according to claim 1, wherein the thickness of the core layer is 0.05 to 0.3 mm. 5. The electrophotographic belt according to claim 1, wherein a surface layer is further provided on the elastic layer. 6. The liquid thermosetting polyurethane constituting the elastic layer is rotated at a high speed, injected into a heated centrifugal molding die, partially cured, and the liquid thermosetting polyurethane constituting the core layer is formed on the cured layer. A method for producing an electrophotographic belt, comprising injecting and curing thermosetting polyurethane and / or polyurea, removing the mold, and performing after-curing.