Fixing Device Abrasive Reformer and Crystalline Toner for Low-Temp Fixing
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Solution Overview
Problem
Current toners face challenges in achieving low-temperature fixability while preventing sheet ejection blocking and image streaks, with existing solutions either leading to aggregation in high-humidity environments or causing image defects due to surface roughness from polishing.
Innovation Solution
The development of a toner with a crystalline polyester resin and a fixing device featuring an abrasive grain abutting layer with specific size and roughness characteristics, along with a fixing surface reformer, to enhance low-temperature fixability, prevent sheet ejection blocking, and maintain image gloss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a toner containing crystalline polyester resin is used to achieve low-temperature fixability, then the toner melts more rapidly at low temperatures, but the toner is likely to aggregate in high-temperature high-humidity environments
Solution Approach 1:
The toner is formulated as a composite material containing crystalline polyester resin (3-15 mass%), amorphous polyester resin (85-97 mass%), and fluorinated compound (0.1-5 mass%). This composite structure combines the low-temperature melting advantage of crystalline polyester with the storage stability of amorphous polyester and the moisture resistance of fluorinated compound, resolving the contradiction between low-temperature fixability and high-temperature high-humidity storage stability.
2Reliability
If the surface of the fixing member is polished to reduce roughness and prevent abnormal images, then surface scratching is reduced, but polishing streaks are formed on the fixing surface
Solution Approach 1:
The invention changes the surface roughness parameter of the fixing member to a specific range (Ra: 0.03-0.15 μm) that optimizes both image quality and prevents polishing streaks. Additionally, the toner formulation with controlled gel fraction (5-20%) and specific resin composition modifies how the toner interacts with the fixing surface, allowing acceptable image quality without requiring extremely smooth surfaces that cause streaking.
3Productivity
If sheets are stacked on the sheet ejection tray after fixing, then printing productivity increases, but sheet ejection blocking occurs due to pressure and residual heat causing toner images to stick together
Solution Approach 1:
The toner's viscoelastic properties are optimized by controlling the gel fraction (5-20%) and using a specific resin composition with crystalline and amorphous polyesters. This parameter optimization ensures the toner solidifies rapidly after fixing, maintaining sufficient rigidity at ejection temperature to prevent sheet sticking while allowing high-speed printing.
4Manufacturing precision
If abrasive grains with smaller size are used in the abutting layer to maintain image gloss, then surface roughness is reduced, but the ability to reform the fixing surface decreases
Solution Approach 1:
The invention optimizes the abrasive grain size parameter to a specific range (2.0-6.5 μm average grain size) that balances surface reforming capability with image gloss maintenance. This parameter optimization allows the abutting layer to effectively reform the fixing surface while minimizing the formation of polishing streaks that would degrade image quality.
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 effectively achieves low-temperature fixability, resistance to sheet ejection blocking, and prevention of image streaks, ensuring high-quality image formation without compromising gloss or stability.
Implementation Method 1
a fixing surface reformer having an abutting layer to abut the fixing surface. The abutting layer contains abrasive grains having an average grain size of from 2.0 to 6.5 μm on a surface thereof which abuts the fixing surface
Implementation Method 2
an endothermic peak indicating an amount of heat absorption of from 2.0 to 8.0 J/g, derived from the crystalline polyester resin, in a first temperature rising in a differential scanning calorimetry (DSC)
Implementation Method 3
The fixing device is configured to fix the visible image on a recording medium
Implementation Method 4
a storage elastic modulus G′ of 1.0×107 Pa or lower at 70° C. in a temperature rising in a viscoelasticity measurement, a storage elastic modulus G′ of 1.0×107 Pa or higher at 70° C. in a temperature falling in the viscoelasticity measurement
Data Source
AI summary
An image forming apparatus including a developing device and a fixing device is provided. The fixing device includes a fixing rotator having a fixing surface, an opposing rotator opposing the fixing rotator to form a nip portion therebetween, and a fixing surface reformer having an abutting layer to abut the fixing surface. The abutting layer contains abrasive grains having an average grain size of 2.0-6.5 μm on a surface which abuts the fixing surface. The toner comprises a crystalline polyester resin and exhibits G′ (storage elastic modulus) of 1.0×107 Pa or lower at 70° C. in a temperature rising in a viscoelasticity measurement, G′ of 1.0×107 Pa or higher at 70° C. in a temperature falling in the viscoelasticity measurement, and an endothermic peak indicating an amount of heat absorption of from 2.0 to 8.0 J/g, derived from the crystalline polyester resin, in a first temperature rising in DSC.