Fixing Member Release Layer PFPE PFA Hot Offset
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Solution Overview
Problem
In electrophotographic image forming apparatuses, the high molecular mobility of perfluoropolyether (PFPE) at elevated temperatures leads to toner adhesion issues and hot offset during thermal fixation, as the PFPE in the outermost layer is depleted, causing unreliability in toner release.
Innovation Solution
A fixing member with a release layer containing both perfluoropolyether (PFPE) and tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) or tetrafluoroethylene-hexafluoropropylene copolymer (FEP), where the longitudinal relaxation time of PFPE is suppressed by ensuring a specific relationship between the relaxation times measured at different conditions, maintaining molecular mobility control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the surface temperature of the fixing member is increased to improve image forming speed, then productivity is improved, but toner releasability deteriorates due to insufficient suppression of toner adhesion
Solution Approach 1:
The patent changes the chemical composition parameters of the release layer by incorporating specific fluororesins (PFA or FEP) alongside PFPE, and controls the molecular mobility of PFPE through the specified relaxation time relationship. This allows the fixing member to operate at higher temperatures for improved productivity while maintaining sufficient toner releasability through the controlled release layer composition.
Solution Approach 2:
The release layer is constructed as a composite material containing both PFPE and either PFA or FEP fluororesins. This composite structure combines the high-temperature performance benefits of PFPE with the toner release properties of PFA or FEP, enabling the fixing member to achieve both high image forming speed and reliable toner releasability simultaneously.
2Reliability
If perfluoropolyether (PFPE) is used in the outermost layer to suppress toner adhesion, then toner releasability is improved, but hot offset occurs due to high molecular mobility at elevated temperatures
Solution Approach 1:
The patent controls the molecular mobility parameter of PFPE by establishing a specific relationship between longitudinal relaxation times (T1-1 and T1-2). By ensuring that [(T1-1)−(T1-2)]/(T1-1)≥0.1, the molecular mobility of PFPE is suppressed, preventing hot offset while maintaining toner releasability through the controlled physical state of the fluororesin.
Solution Approach 2:
The release layer exhibits local quality differentiation through its composite composition of PFPE and PFA or FEP. The PFPE component provides controlled molecular mobility characteristics in specific regions, while the PFA or FEP components contribute to toner release properties, creating a functionally differentiated structure that prevents hot offset locally while maintaining overall toner releasability.
3Reliability
If a release layer including PFA is used to suppress toner adhesion, then toner releasability is improved, but long-term reliability deteriorates due to PFPE depletion from the outermost layer
Solution Approach 1:
The release layer is pre-configured with a composite structure containing both PFPE and PFA or FEP before operation begins. This preliminary arrangement ensures that the molecular mobility of PFPE is controlled from the start, preventing the depletion phenomenon that occurs with PFPE-only outermost layers. The controlled structure is established in advance to maintain long-term toner releasability.
Solution Approach 2:
The release layer uses a composite material system where PFPE is combined with PFA or FEP in specific proportions and configurations. This composite structure prevents the depletion issues associated with pure PFPE outermost layers by distributing the functional responsibilities across multiple fluororesin components, ensuring long-term stability and sustained toner releasability throughout the service life of the fixing member.
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 prevents hot offset and ensures stable toner releasability over long-term use, contributing to high-quality electrophotographic image formation by maintaining the surface properties of the fixing member at elevated temperatures.
Implementation Method 1
when a longitudinal relaxation time of PFPE in a form of a simple substance derived from a 19F-NMR measured at a temperature of 200° C. is defined as T1−1, and a longitudinal relaxation time of PFPE contained in the release layer derived from a 19F-NMR of the release layer measured at a temperature of 200° C. is defined as T1−2
Data Source
AI summary
Provided is a fixing member in which hot offset of a toner is difficult to be generated. The fixing member has a substrate and a release layer as a surface layer, wherein the release layer includes PFPE and a second fluororesin, the second fluororesin being at least one selected from PFA and FEP, and in a 19F-NMR spectrum of the release layer measured at a temperature of 200° C., a relaxation time T1 of longitudinal relaxation of a peak derived from PFPE is 0.5 seconds or more and 3.5 seconds or less.