Cleaning Blade Hardness and Surface Composition for Image Quality
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Solution Overview
Problem
Existing image forming apparatuses face issues with toner filming on the intermediate transfer belt and the occurrence of stapler marks in images, particularly when using toners with unevenly distributed wax and conventional cleaning blades with specific hardness ratios or surface compositions.
Innovation Solution
The image forming apparatus employs a cleaning blade with a two-layer structure, where the edge layer and back surface layer are made of polyurethane resin, with a hardness ratio of 0.84 to 0.93 and a surface composition that includes a high concentration of F and Si within 200 nm from the surface, which contacts the intermediate transfer belt.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional cleaning blade with specific hardness ratio or surface composition is used, then the cleaning function is provided, but toner filming on the intermediate transfer belt and stapler marks in images occur
Solution Approach 1:
The cleaning blade is designed with a two-layer structure where the edge layer and back surface layer have different hardness values. The edge layer has a specific hardness (Ha) and the back surface layer has a different hardness (Hb), creating a localized property distribution that optimizes both cleaning effectiveness and image quality by preventing toner filming and stapler marks
Solution Approach 2:
The cleaning blade combines two different polyurethane resin materials with distinct hardness characteristics to form a composite structure. This composite design allows the blade to simultaneously achieve effective toner removal and prevent harmful effects like filming and stapler marks that occur with conventional single-material blades
2Ease of manufacture
If the hardness ratio (Hb/Ha) is outside the range of 0.84 to 0.93, then manufacturing flexibility is improved, but toner filming and stapler marks occur
Solution Approach 1:
The invention specifies a precise parameter range for the hardness ratio (Hb/Ha) between 0.84 and 0.93, along with specific hardness values for the edge layer (Ha: 85-95°) and back surface layer (Hb: 75-85°). By controlling these physical parameters within defined ranges, the cleaning blade achieves optimal performance that prevents toner filming and stapler marks while maintaining manufacturability
3Ease of manufacture
If the surface composition of the cleaning blade does not have high F and Si concentration within 200 nm, then material selection is simplified, but toner filming occurs
Solution Approach 1:
The edge layer of the cleaning blade is designed with a specific surface composition characterized by high concentrations of F and Si elements within 200 nm from the surface. This localized compositional property enhances the blade's ability to prevent toner filming on the intermediate transfer belt while maintaining overall manufacturing feasibility
Data Source
AI summary
An image forming apparatus includes an image holder; a charging unit that charges a surface of the image holder; an electrostatic charge image forming unit that forms an electrostatic charge image on the charged surface of the image holder; a developing unit that accommodates an electrostatic charge image developer containing a toner having toner particles and that develops an electrostatic charge image formed on the surface of the image holder as a toner image by the electrostatic charge image developer, in which a release agent present in a region within 800 nm from a surface of the toner particles is 70% or more of a release agent in entire toner particles and a melting temperature of the release agent is 65° C. or higher and 80° C. or lower; an intermediate transfer belt that has an outer peripheral surface to which the toner image is to be transferred; a primary transfer unit that has a primary transfer member performing primary transfer of the toner image formed on the surface of the image holder to the outer peripheral surface of the intermediate transfer belt; a secondary transfer unit that has a secondary transfer member performing secondary transfer of the toner image transferred to the outer peripheral surface of the intermediate transfer belt by the primary transfer to a surface of a recording medium; and a cleaning device having a cleaning blade that is brought into contact with and cleans the outer peripheral surface of the intermediate transfer belt and that has a two-layer structure including an edge layer and a back surface layer, in which the edge layer and the back surface layer are constituted of a polyurethane resin, a ratio (Hb/Ha) of a hardness Hb of the edge layer to a hardness Ha of the back surface layer is 0.84 or more and 0.93 or less, and a total amount of F and Si present within 200 nm from the surface of the cleaning blade, which is brought into contact with the intermediate transfer belt of the edge layer, accounts for 75% or more of a total amount of F and Si present within 5 μm from the surface.