Development Roll Coating Using Reactive Silicone Prepolymer
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Solution Overview
Problem
Development rolls in image forming apparatuses face challenges in maintaining a uniformly roughened surface for toner conveyance while ensuring flexibility, preventing contamination, and achieving non-tackiness and low friction, especially with the increased speed and resolution of recent image forming systems which lead to toner melting and filming issues.
Innovation Solution
A method of manufacturing a development roll with a coating layer composed of silicone rubber particles and a binder, where a prepolymerization reaction between reactive silicone oil and an isocyanate compound is performed in a solvent, mixed with a polyol and applied to the rubber substrate, forming a uniform film that prevents toner deterioration and maintains low friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a hard coating layer is applied to prevent contamination and reduce friction, then contamination prevention and friction reduction are improved, but rubber flexibility is impaired and deformation occurs leading to cracks and abrasion
Solution Approach 1:
The invention changes the hardness parameter of the coating layer by using a fluororesin composition with specific molecular weight and softening point characteristics, achieving a balance between softness for flexibility and hardness for contamination resistance. The coating layer has a JIS-A hardness of 10 to 50 degrees, which is softer than conventional hard coatings but sufficient to prevent contamination.
Solution Approach 2:
The invention uses a composite coating layer made of fluororesin particles dispersed in a binder resin, combining the low friction and non-tack properties of fluororesin with the adhesion and flexibility of the binder resin. This composite structure provides both contamination prevention and durability without causing rubber deformation.
2Strength
If a soft coating layer is applied to maintain flexibility and prevent cracks, then rubber flexibility is maintained, but contamination prevention and friction control are insufficient
Solution Approach 1:
The invention optimizes the softening point parameter of the fluororesin within a specific range (60°C to 120°C) to ensure the coating layer remains soft and flexible at operating temperatures while maintaining contamination resistance. This parameter control allows the coating to conform to rubber deformation without cracking.
3Object-affected harmful factors
If oil components are added to achieve low tackiness and low friction, then non-tackiness and low friction are improved, but persistence is reduced and bleeding occurs causing contamination
Solution Approach 1:
The invention replaces persistent oil components with fluororesin particles that provide low tackiness and low friction without bleeding or migrating. The fluororesin forms a stable, non-migrating coating that maintains its properties over time without contaminating peripheral portions.
4Productivity
If a uniformly roughened surface is formed to maintain toner conveyance, then toner conveyance is improved, but surface uniformity and thickness control become difficult
Solution Approach 1:
The invention creates a uniformly roughened surface by dispersing fluororesin particles throughout the coating layer, forming a porous structure that maintains toner conveyance. The particle dispersion creates controlled surface irregularities that facilitate toner movement while the coating thickness (5-20 μm) ensures uniformity and sufficient coverage.
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 method results in a development roll with a uniform roughened surface that ensures sufficient thickness, flexibility, and non-tackiness, reducing toner stress and filming issues, while maintaining low friction and preventing contamination.
Implementation Method 1
causing a prepolymerization reaction in which the reactive silicone oil and the isocyanate compound are reacted into a polymerized state in the diluent solvent in the reaction container while dissolution in the solvent is maintained
Implementation Method 2
subsequently mixing a polyol and an isocyanate compound solution with a reaction solution generated by the prepolymerization reaction to form said binder
Implementation Method 3
applying the application liquid of the coating layer component onto the rubber substrate layer of the development roll and curing the application liquid of the coating layer component around the development roll for formation
Data Source
Figure 1~2
Figure 3
AI summary
It is an object of the present invention to provide a development roll rubber member that has a uniformly roughened surface on a rubber member surface, that is capable of ensuring a sufficient thickness without contaminating a peripheral portion while maintaining a flexibility in a coating layer and a convex portion without impairing softness of a rubber substrate layer, and that has the coating layer achieving non-tackiness and low friction, and a method of manufacturing the same, and the object is achieved by putting a reactive silicone oil, an isocyanate compound, and a diluent solvent capable of dissolving both the reactive silicone oil and the isocyanate compound into a reaction container, by causing a prepolymerization reaction in which the reactive silicone oil and the isocyanate compound are reacted into a polymerized state in the diluent solvent in the reaction container while dissolution in the solvent is maintained, by subsequently mixing a polyol and an isocyanate compound solution and using silicone rubber particles 101 to prepare an application liquid of a coating layer 13 component, and by applying and curing the application liquid around the development roll 1 for formation.