Polyimide Intermediate Transfer Belt for Image Quality
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Solution Overview
Problem
Intermediate transfer belts used in electrophotographic image forming apparatuses experience fine toner dots in white areas and image roughness, especially in low temperature and low humidity environments, due to issues with surface resistivity and long-term durability.
Innovation Solution
A polyimide intermediate transfer belt with a specific unit structure and composition, incorporating a tetracarboxylic acid, a diamine with a hydroxyl group, and an aromatic diamine, which maintains a predetermined surface resistivity range through controlled mol ratios and imidization, ensuring stable surface resistivity and image quality over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polyimide with carbon black filler is used, then the intermediate transfer belt can be manufactured, but fine toner dots occur in white areas and image roughness develops in low temperature and low humidity environments
Solution Approach 1:
The patent changes the chemical composition parameters of the polyimide by incorporating specific diamines with hydroxyl groups (Formula 2) and controlling the mol ratio of tetracarboxylic acid to diamine within 0.85:1.00 to 1.20:1.00. This parameter modification alters the surface properties of the polyimide, enabling it to maintain stable surface resistivity (1×10^10 to 1×10^13Ω/□) in low temperature and low humidity environments, thereby preventing fine toner dots and image roughness
Solution Approach 2:
The patent creates a composite polyimide material by combining multiple components: tetracarboxylic acid, diamine with hydroxyl group (Formula 2), and aromatic diamine without hydroxyl group. This composite structure leverages the synergistic effects of different functional groups to achieve both electrical conductivity and dimensional stability, resolving the issue of image quality degradation in challenging environmental conditions
2Duration of action of stationary object
If the surface resistivity is not properly controlled, then the intermediate transfer belt can operate, but residual charge accumulates and surface resistivity changes with long-term use
Solution Approach 1:
The patent optimizes the stoichiometric parameters of the polyimide synthesis by controlling the mol ratio of tetracarboxylic acid to the sum of diamines within 0.85:1.00 to 1.20:1.00. This precise parameter control ensures complete reaction and minimizes residual functional groups that could lead to charge accumulation. The resulting polyimide maintains stable surface resistivity over extended operational periods
Solution Approach 2:
The patent establishes a feedback mechanism through the self-regulating nature of the polycondensation reaction. By controlling the mol ratios to be within specific ranges, the reaction naturally progresses to completion, minimizing residual charges. The hydroxyl-containing diamine component provides additional feedback through hydrogen bonding that stabilizes the polymer structure and prevents surface resistivity drift during long-term use
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
The solution effectively inhibits fine toner dots in white areas and image roughness in low temperature and low humidity conditions, maintaining surface resistivity and image quality with long-term use by lowering residual charge and ensuring adequate charge distribution.
Implementation Method 1
converting the polyamic acid to the polyimide
Implementation Method 2
carbon black such as furnace black and acetylene black as conductive filler is dispersed in polyimide
Data Source
AI summary
An object is to provide an intermediate transfer belt and a method for producing the same which inhibits fine toner dots in white area in an environment of low temperature and low humidity and further, inhibits roughness of image with long-term use. An intermediate transfer belt for an electrophotographic image forming apparatus comprising a polyimide having a dispersed conductive filler, wherein the polyimide contains a unit structure represented by Formula (1);wherein X represents a group selected from Formulas (a) to (e), n, m, l each represents 0 or 1, and at least one of m and l is 1,wherein p in Formula (c) and q in Formula (e) each is an integer of 1 to 5.