PFA Fixing Member Surface Layer Wear and Release Trade-off
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Solution Overview
Problem
The existing fixing members for electrophotographic image forming apparatuses face a trade-off between wear resistance and toner release properties, where enhancing wear resistance often deteriorates the release properties of the surface layer containing PFA fluororesin.
Innovation Solution
A fixing member with a surface layer containing a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, formed by adjusting the temperature within the glass transition point range and irradiating with ionizing radiation under low oxygen conditions, followed by reheating to minimize surface energy and enhance fluidity, resulting in a crosslinked structure with improved wear resistance and toner release properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the fluororesin layer is crosslinked by heating to high temperature and irradiating with ionizing radiation to enhance wear resistance, then the wear resistance is improved, but the release properties of toner deteriorate
Solution Approach 1:
The patent applies parameter changes by controlling the temperature range during ionizing radiation irradiation. Specifically, the fluororesin layer is irradiated at temperatures between the glass transition temperature (Tg) and melting point (Tm) of PFA, rather than at higher temperatures. This temperature parameter control enables crosslinking to improve wear resistance while preventing excessive surface energy increase that would harm toner release properties. The contact angle is maintained at 67° or more to ensure adequate release properties.
Solution Approach 2:
The patent employs an inert atmosphere (oxygen concentration of 0.1 to 1000 ppm) during ionizing radiation irradiation. This controlled atmosphere prevents oxidative degradation of the fluororesin while enabling crosslinking reactions. The low oxygen environment allows the crosslinking process to proceed without generating excessive surface polar groups that would increase surface energy and deteriorate toner release properties, thus resolving the contradiction between wear resistance and release properties.
2Duration of action of stationary object
If the surface layer is made more durable through crosslinking, then the durability is improved, but the surface energy increases causing poor toner release
Solution Approach 1:
The patent controls the irradiation temperature within a specific range (Tg to Tm of PFA) to achieve partial crosslinking without excessive surface energy increase. This parameter optimization allows the surface layer to gain durability through crosslinking while maintaining adequate toner release properties by keeping the contact angle at 67° or more.
Solution Approach 2:
The patent applies partial crosslinking rather than complete crosslinking by controlling the irradiation conditions (temperature and oxygen concentration). This partial crosslinking provides sufficient durability improvement while avoiding the excessive crosslinking that would dramatically increase surface energy and prevent toner release. The contact angle specification of 67° or more indicates this partial action approach.
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 achieves a fixing member with high wear resistance and excellent toner release properties, enabling stable high-quality electrophotographic image formation.
Implementation Method 1
irradiating the uncrosslinked fluororesin layer, the temperature of the layer being adjusted, with radiation having an irradiation dose ranging from 1 to 1000 kGy under an atmosphere having an oxygen concentration of 0.1 to 1000 ppm to crosslink the uncrosslinked fluororesin
Implementation Method 2
crosslink the uncrosslinked fluororesin
Implementation Method 3
heating the fluororesin layer to a temperature ranging from the melting point (Tm) of the fluororesin to a temperature higher than the melting point by 150°C (Tm + 150°C)
Implementation Method 4
heating the fluororesin layer to a temperature ranging from the melting point (Tm) of the fluororesin
Data Source
Figure 1
Figure 2~3
AI summary
The present invention relates to a fixing member including a surface layer containing PFA, the fixing member being excellent in wear resistance and having high release properties to a toner. The fixing member includes a base member, an elastic layer provided on the surface of the base member, and a surface layer, wherein the surface layer contains a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer having a particular partial structure, and has a surface having a contact angle of 67 degrees or more as measured in a mixed liquid for a wetting tension test having a wetting tension of 31.0 mN/m.