Fixing Unit Belt and Toner Rheology for Low-Temperature Offset
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Solution Overview
Problem
Current image forming apparatuses face challenges in achieving low-temperature fixing while maintaining offset resistance and glossiness, with existing toners either degrading in storage stability or requiring high temperatures, and fixing devices experiencing inefficiencies in heat transfer and warm-up times.
Innovation Solution
An image forming apparatus using a toner composition with an amorphous polymer, crystalline resin, and releasing agent, where the toner has specific rheological properties allowing for efficient low-temperature fixing and reduced offset resistance, combined with a fixing unit featuring a flexible endless belt and heat source for effective heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional toners are used for low-temperature fixing, then fixing temperature can be reduced, but offset resistance and glossiness deteriorate
Solution Approach 1:
The invention changes the rheological parameters of the toner by controlling the storage modulus at specific temperatures. By adjusting the storage modulus G'(100) to be 20,000 Pa or less and G'(150) to be 500 Pa or more with a gradient a of 0.035 or less, the toner achieves optimal viscosity characteristics for low-temperature fixing while maintaining offset resistance and glossiness.
Solution Approach 2:
The invention uses a composite binder resin system combining amorphous polymer and crystalline resin in specific proportions. This composite structure allows the toner to exhibit both low-temperature flowability (from amorphous polymer) and high-temperature stability (from crystalline resin), resolving the contradiction between low fixing temperature and offset resistance.
2Temperature
If conventional toners are used for low-temperature fixing, then fixing temperature can be reduced, but glossiness deteriorates
Solution Approach 1:
The invention changes the rheological parameters of the toner by controlling the storage modulus at specific temperatures. By adjusting the storage modulus G'(100) to be 20,000 Pa or less and G'(150) to be 500 Pa or more with a gradient a of 0.035 or less, the toner achieves optimal viscosity characteristics for low-temperature fixing while maintaining offset resistance and glossiness.
3Device complexity
If existing fixing devices are used, then structure can be maintained, but warm-up time and energy consumption increase
Solution Approach 1:
The invention changes the thermal properties of the toner by optimizing its rheological parameters. The controlled storage modulus gradient allows the toner to respond more efficiently to heat input, achieving proper fixing at lower temperatures and shorter times, thereby reducing the warm-up time and energy consumption of existing fixing devices without requiring structural modifications.
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 enables rapid heat application at low temperatures, reducing warm-up times and improving offset resistance, resulting in high-quality images with consistent glossiness and efficient energy use.
Implementation Method 1
a fixing unit featuring a flexible endless belt and heat source for effective heat transfer
Implementation Method 2
the toner has specific rheological properties allowing for efficient low-temperature fixing
Data Source
AI summary
An image forming apparatus including: image bearing member; latent image forming unit; developing unit; transfer unit; fixing unit, wherein toner in the developing unit contains amorphous polymer, crystalline resin and releasing agent, when the toner is measured for G′ at 40° C. to 210° C. with rheometer at 1 Hz and 1 deg, G′(100) is ≦20,000 and G′(150) is ≧500 Pa, and straight line drawn by connecting points of the G′(100) and G′(110) on curve of the G′ has gradient of ≦0.035, the gradient being “a” expressed by: a=|log10G′(100)−log10G′(110)|/10, and the fixing unit includes: heating member containing flexible endless belt; heat source fixed within the flexible endless belt; and press member in contact with the belt to form nip portion, and the fixing unit is configured to heat/press the medium passing through the nip portion to fix the image on the medium.