Polyimide Annular Belt Production via Precursor Sheet Joining
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Solution Overview
Problem
The centrifugal molding method for producing polyimide annular belts results in nonuniform film thickness and surface roughness due to gravitational and temperature influences, leading to productivity issues and insufficient uniformity, which affects image quality in electrophotographic applications.
Innovation Solution
A method involving the formation of an annular belt by joining polyimide precursor sheets and performing an imidizing reaction to achieve uniformity in film thickness and surface roughness, using a casting or extrusion molding method to produce the sheets with specific solvent content and molecular weight, and then integrating the ends to form a seamless belt.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the centrifugal molding method is used to produce polyimide annular belts, then the belt can be formed as a seamless annular structure, but the film thickness and surface roughness become nonuniform due to gravitational and temperature influences
Solution Approach 1:
The polyimide precursor sheet is prepared in advance with controlled thickness and uniform properties before forming. The sheet is pre-dried to reduce solvent content to 5 wt% or less, ensuring dimensional stability during the subsequent imidizing reaction and forming processes, thereby preventing thickness nonuniformity
Solution Approach 2:
The invention changes the physical and chemical parameters of the material during processing. The polyimide precursor is transformed into polyimide through imidizing reaction at controlled temperatures (gradually increased to final temperature not exceeding 500°C), and the solvent content is reduced to 5 wt% or less, ensuring uniform film properties without gravitational distortion
2Shape
If the centrifugal molding method is used, then the annular belt can be produced, but the productivity becomes poor due to the need to rotate the mold until solvent evaporation is complete
Solution Approach 1:
The polyimide precursor sheet is pre-dried before forming to reduce solvent content to 5 wt% or less. This preliminary drying action eliminates the need for prolonged rotation during solvent evaporation, significantly improving productivity while maintaining annular belt formation
Solution Approach 2:
The production process is segmented into distinct steps: (1) preparing polyimide precursor sheet with controlled solvent content, (2) joining ends to form annular shape, and (3) performing imidizing reaction. This segmentation allows each step to be optimized independently, improving overall productivity
3Temperature
If the film is applied to a cylindrical mold for centrifugal molding, then solvent evaporation can occur, but slight sagging of the applied film occurs making thickness uniformity insufficient
Solution Approach 1:
The polyimide precursor sheet is pre-dried to reduce solvent content to 5 wt% or less before forming. This preliminary action ensures that minimal solvent remains to cause sagging during subsequent heating, maintaining film thickness uniformity while still allowing complete evaporation
Solution Approach 2:
The solvent content parameter is controlled to 5 wt% or less in the polyimide precursor sheet. This parameter change reduces the harmful effects of solvent evaporation (sagging) while maintaining the ability to achieve complete evaporation for uniform final product
4Shape
If the centrifugal molding method is used, then the annular belt can be formed, but vibration occurs during mold rotation affecting surface roughness uniformity
Solution Approach 1:
The polyimide precursor sheet is prepared with controlled properties and pre-dried before forming. This preliminary preparation ensures the material has sufficient stability to withstand the imidizing reaction and forming process without vibration-induced surface roughness variations
Solution Approach 2:
The invention changes the processing approach by using pre-prepared polyimide precursor sheets with controlled molecular weight and solvent content, transforming the material properties to eliminate vibration sensitivity during forming while maintaining annular structure
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enhances the productivity and uniformity of polyimide annular belts, ensuring consistent film thickness, surface roughness, and electrical conductivity, thereby improving image quality in electrophotographic applications such as transfer and fixing belts.
Implementation Method 1
performing an imidizing reaction of the polyimide precursor
Data Source
AI summary
The present invention relates to a method for producing an annular belt made of polyimide comprising;a) joining both ends of a sheet made of a polyimide precursor to form an annular belt; andb) performing an imidizing reaction of the polyimide precursor.