EPDM Rubber Composition for Sheet Conveying Roller
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Solution Overview
Problem
Sheet conveying rollers in image forming apparatuses face issues with reduced friction coefficient and hardness due to sulfur blooming and increased permanent elongation, leading to rotative slippage and abrasion resistance problems when using conventional crosslinking agents and filler blends.
Innovation Solution
A rubber composition combining higher and lower ethylene content EPDMs with a peroxide crosslinking system, where the higher ethylene content EPDM is between 30-80 mass% and the lower ethylene content EPDM is balanced to maintain proper hardness and reduce permanent elongation, preventing slip torque reduction and friction coefficient loss, while avoiding filler-induced abrasion resistance deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If sulfur is used as a crosslinking agent for EPDM, then crosslinking is achieved, but sulfur blooms on the outer surface reducing friction coefficient
Solution Approach 1:
The patent extracts the harmful sulfur blooming effect by replacing sulfur crosslinking agents with peroxide crosslinking agents. This substitution eliminates the source of sulfur blooming while maintaining the crosslinking function, thereby resolving the contradiction between achieving crosslinking and preventing harmful surface blooming.
Solution Approach 2:
The patent changes the chemical parameter of the crosslinking agent from sulfur-based to peroxide-based. This parameter change fundamentally alters the crosslinking mechanism to avoid sulfur blooming while preserving the essential crosslinking function, thus resolving the technical contradiction.
2Object-generated harmful factors
If peroxide crosslinking agent is used to avoid sulfur blooming, then friction coefficient is maintained, but hardness of the sheet conveying roller is reduced
Solution Approach 1:
The patent employs a composite material system combining peroxide crosslinking agents with specific filler materials (silica, carbon black) and processing aids. This composite approach compensates for the hardness reduction caused by peroxide crosslinking while maintaining the benefit of sulfur blooming prevention, thus resolving the contradiction.
Solution Approach 2:
The patent adjusts multiple parameters including the type and amount of fillers, the specific peroxide compound used, and processing conditions to optimize both hardness and blooming prevention. By changing these parameters, the patent achieves a balance where peroxide crosslinking provides blooming-free surfaces while fillers and processing adjustments maintain adequate hardness.
3Strength
If higher ethylene content EPDM is used to prevent hardness reduction, then hardness is maintained, but permanent elongation increases causing through-hole diameter increase
Solution Approach 1:
The patent changes the ethylene content parameter of EPDM to an optimized range (40-70%) rather than using high ethylene content material. This parameter adjustment prevents excessive permanent elongation while maintaining adequate hardness, resolving the contradiction between these two properties.
Solution Approach 2:
The patent applies different filler materials and amounts to specific regions or functions within the rubber composition. By locally optimizing the filler distribution and type, the patent achieves balanced performance in both hardness and permanent elongation resistance without requiring extreme ethylene content.
4Stability of the object's composition
If lower ethylene content EPDM is used to reduce permanent elongation, then through-hole diameter stability is improved, but abrasion resistance is reduced due to greater filler blending
Solution Approach 1:
The patent uses a carefully designed composite material system with specific filler combinations (silica, carbon black) in optimized proportions. This composite approach provides adequate permanent elongation control while maintaining excellent abrasion resistance, resolving the contradiction between through-hole stability and abrasion resistance that plagues conventional formulations.
Solution Approach 2:
The patent optimizes the ethylene content parameter within a specific range (40-70%) and adjusts filler content and type parameters to achieve a balance where permanent elongation is controlled without excessive filler addition, thereby maintaining abrasion resistance.
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 provides a sheet conveying roller with improved hardness, reduced permanent elongation, and enhanced abrasion resistance, preventing rotative slippage and maintaining friction coefficient stability over time.
Implementation Method 1
a peroxide crosslinking agent; crosslinking the rubber of the tubular body
Implementation Method 2
rotatable in contact with a sheet to frictionally transport the sheet
Implementation Method 3
a predetermined slip torque is provided between the sheet conveying roller and the shaft by an interference defined by a diameter difference
Data Source
AI summary
A rubber composition contains a higher ethylene content EPDM and a lower ethylene content EPDM as a rubber component. The proportion of the higher ethylene content EPDM is 30 to 80 mass % based on the overall amount of the rubber component. The rubber composition is less susceptible to reduction in friction coefficient μ and has a proper hardness, a smaller permanent elongation and an excellent abrasion resistance after crosslinking. Therefore, the rubber composition is suitable for a sheet conveying roller and an image forming apparatus incorporating the sheet conveying roller.