Developing Roll Surface Topology to Suppress Toner Fusion
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Solution Overview
Problem
In electrophotographic devices, the lack of appropriate surface roughness on developing rolls leads to increased toner fusion and filming due to excessive ground contact area with photoreceptors and layer-forming blades, causing inefficiencies in toner conveyance and transfer.
Innovation Solution
A developing roll with a shaft body and an elastic body layer featuring large protruding parts of 3.0 to 12 μm width and height, and small protruding parts forming convex-concavities with a ten-point average roughness of 2.0 to 4.0 μm on the side surfaces, manufactured by forming a base layer with a carbon-carbon double bond polymer and impregnating it with chlorinated isocyanuric acid to create the desired surface topology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the surface of the developing roll is not imparted with appropriate roughness, then the ground contact area with the photoreceptor or layer-forming blade becomes large, but toner fusion occurs on the photoreceptor or layer-forming blade due to physical pressing
Solution Approach 1:
The invention applies different surface characteristics to different regions: large protruding parts (3.0-12 μm width/height) create ground contact area reduction, while small protruding parts on the side surfaces (forming convex-concavities with Rz 2.0-4.0 μm) prevent toner adhesion. This local differentiation resolves the contradiction by simultaneously achieving reliable toner transfer and preventing toner fusion.
Solution Approach 2:
The surface structure is segmented into two distinct levels: large protruding parts that reduce ground contact area and small protruding parts on their side surfaces that prevent toner adhesion through the lotus effect. This segmentation allows each level to perform its specific function, resolving the contradiction between maintaining contact area and preventing toner fusion.
2Reliability
If particles that form roughness are blended into the surface layer, then roughness is imparted to the surface, but protruding parts where particles exist are easily scraped and toner is easily fused from this point
Solution Approach 1:
Instead of uniformly blending particles throughout the surface layer, the invention creates localized small protruding parts specifically on the side surfaces of large protruding parts. These localized structures provide the necessary roughness while maintaining structural integrity and preventing toner fusion at critical locations.
Solution Approach 2:
The invention uses a composite surface structure combining large protruding parts (providing ground contact area reduction) with small protruding parts on their side surfaces (providing toner release through lotus effect). This composite structure achieves both surface stability and toner fusion prevention without the drawbacks of particle blending.
3Reliability
If any method of imparting roughness is used, then surface roughness is achieved, but toner is easily fused because the toner is deposited in recessed parts between protruding parts
Solution Approach 1:
The invention converts the potential harm of recessed parts (where toner would be trapped and fused) into a benefit by forming small protruding parts on the side surfaces of large protruding parts. These small protruding parts create convex-concavities that actively repel toner through the lotus effect, transforming the recessed areas from toner traps to toner-release zones.
Solution Approach 2:
The invention applies different surface characteristics to different locations: the tops of large protruding parts maintain smooth surfaces for toner conveyance, while the side surfaces have small protruding parts creating convex-concavities with Rz 2.0-4.0 μm that prevent toner adhesion. This local differentiation prevents toner deposition in recessed parts while maintaining necessary surface roughness.
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
This configuration reduces the ground contact area, suppresses toner fusion and filming, and ensures effective toner transferability by utilizing the lotus effect of the small protruding parts on the side surfaces of the large protruding parts, maintaining optimal toner conveyance and preventing adhesion between the large protruding parts.
Implementation Method 1
a step of impregnating the surface of the base layer with chlorinated isocyanuric acid, and curing the surface of the base layer impregnated with the chlorinated isocyanuric acid
Implementation Method 2
curing the surface of the base layer impregnated with the chlorinated isocyanuric acid so as to form a plurality of small protruding parts
Implementation Method 3
ensures effective toner transferability by utilizing the lotus effect of the small protruding parts on the side surfaces of the large protruding parts
Data Source
AI summary
Provided are a developing roll for an electrophotographic device and a method for manufacturing a developing roll for an electrophotographic device, with which toner fusion and toner filming are suppressed. A developing roll for an electrophotographic device includes a shaft body and an elastic body layer formed on an outer circumference of the shaft body. The surface of the elastic body layer has a plurality of large protruding parts having a width of 3.0 to 12 μm and a height of 3.0 to 12 μm, and the side surface of the large protruding part 16 has a plurality of small protruding parts which form convex-concavity having a ten-point average roughness Rz of 2.0 to 4.0 μm.