Process of making an endless belt

Details Process of making an endless belt Process of making an endless belt

1999-07-27

2001-10-16

Tentoni, Leo B. (Department: 1732)

Plastic and nonmetallic article shaping or treating: processes

Direct application of fluid pressure differential to...

Production of continuous or running length

C264S150000, C264S171260, C264S171270, C264S209100

Reexamination Certificate

active

06303072

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a process for producing an endless belt, and more particularly, to a process for producing an endless belt used in, e.g., intermediate transfer members and transfer material carrying members for electrophotography. This invention also relates to an image forming apparatus having an endless belt formed by such production process.
2. Related Background Art
Compared with image forming apparatus in which images are transferred from a first image bearing member to a second image bearing member (transfer material) fastened or attracted onto a transfer drum (Japanese Patent Application Laid-open No. 63-301960), image forming apparatus making use of intermediate transfer belts have an advantage that a variety of second image bearing members can be selected without regard to their width and length, including thin paper (40 g/m
2
paper) and up to thick paper (200 g/m
2
paper) such as envelopes, post cards and labels. This is because any processing or control (e.g., the transfer material is held with a gripper, attracted, and made to have a curvature) is not required for the second image bearing member transfer material.
Because of such an advantage, color copying machines and color printers making use of intermediate transfer belts have already begun to be available in the market.
Color image forming apparatus are also proposed which have a plurality of recording assemblies in which electrostatic latent images are formed on photosensitive members, the electrostatic latent images formed are developed and the developed images are transferred to a transfer material, where a color image is formed by transferring individual color images superimposingly to the transfer material while transporting it successively to the respective recording assemblies by means of a transfer material carrying member (transfer belt). Such image forming apparatus have an advantage that images can be reproduced in a short time because the color image is formed through one step.
Because of such an advantage, color copying machines and color printers making use of transfer belts have already begun to be available in the market.
Various processes for producing such intermediate transfer belts and transfer belts are already known in the art. For example, Japanese Patent Application Laid-open No. 3-89357 and No. 5-345368 disclose a process for producing a semiconducting belt by extrusion.
Japanese Patent Application Laid-open No. 5-269849 also discloses a process in which a belt is obtained by joining both ends of a sheet to bring it into a cylindrical form. Japanese Patent Application Laid-open No. 9-269674 discloses a process in which a belt is obtained by forming a multi-layer coating film on a cylindrical substrate and finally removing the substrate. Meanwhile, Japanese Patent Application Laid-open No. 5-77252 discloses a seamless belt obtained by centrifugal molding.
For example, in the extrusion, the production of an endless belt having a thickness of 100 &mgr;m or smaller involves considerable difficulties, tending to cause uneven wall thickness and uneven electrical resistance. Also, in the case when both ends of a sheet are joined, the difference in height and decrease in tensile strength at the joint come into question. Still also, processes making use of solvents as in cast molding, coating and centrifugal molding require many steps of preparing a coating solution, coating it and removing the solvent, resulting in a high cost.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a process for producing an endless belt which can make the life of photosensitive members longer and can be rich in variety, and which process can enjoy a low cost, having a small number of steps.
Another object of the present invention is to provide a process for producing an endless belt which does not cause any faulty transfer of very small image areas (i.e., blank areas caused by poor transfer) and enables formation of good images without dependence on the type of paper or OHP sheet, the second image bearing member, and also to provide an image forming apparatus having an endless belt obtained by such a production process.
The present invention provides a process for producing an endless belt comprising the step of melt-extruding an extrusion material into a cylinder by means of an extruder; the extrusion material being a material having a tensile break strength of 400 kgf/cm
2
or above and a breaking extension of from 3.0% to 250%, and being extruded in an extrusion ratio of from 1.05 to 2.80 by blowing a gas to the inside of the melt-extruded cylindrical product while being melt-extruded.
The present invention also provides an image forming apparatus having an endless belt produced by the process described above.


REFERENCES:
patent: 4698196 (1987-10-01), Fabian
patent: 5258154 (1993-11-01), Okuyama et al.
patent: 63-301960 (1988-12-01), None
patent: 3-89357 (1991-04-01), None
patent: 5-77252 (1993-03-01), None
patent: 5-269849 (1993-10-01), None
patent: 5-345368 (1993-12-01), None
patent: 9-269674 (1997-10-01), None

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