Toner Viscosity Control for Image Transfer on Low Hardness Intermediate Bodies
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Solution Overview
Problem
Image forming apparatuses face challenges in achieving high transfer efficiency on uneven surfaces due to issues like white spots and fading, which occur when using toners with inappropriate viscoelasticity in conjunction with intermediate transfer bodies of low surface hardness.
Innovation Solution
An image forming apparatus that employs an electrostatic charge image developing toner with specific viscosity characteristics, including (ln η(T1)−ln η(T2))/(T1−T2)≤−0.14 and (ln η(T2)−ln η(T3))/(T2−T3)≥−0.15, where η(T1), η(T2), and η(T3) represent viscosities at different temperatures, to ensure proper adhesion and transfer on uneven surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an intermediate transfer body with low surface hardness (micro rubber hardness 45-65) is used to improve transfer efficiency on uneven surfaces, then transfer efficiency is improved, but white spots and fading occur due to improper toner adhesion
Solution Approach 1:
The patent applies parameter changes by precisely controlling the viscosity-temperature characteristics of the toner binder resin. Specifically, the resin is selected to have a glass transition temperature (Tg) between 40-80°C and a specific viscosity ratio range: (lnη(T1)-lnη(T2))/(T1-T2) between -0.20 and -0.10, where T1=60°C and T2=90°C. This parameter optimization ensures the toner maintains proper adhesion to the intermediate transfer body while preventing white spots and fading, resolving the contradiction between transfer efficiency and image quality.
Solution Approach 2:
The patent employs composite materials by formulating the toner with a specific composition: binder resin (30-80 wt%), colorant (10-40 wt%), and optional additives. The binder resin itself is a composite polymer system with specific molecular weight distribution (Mw/Mn ratio of 1.05-5.0) and crosslinking density. This composite material approach allows optimization of both adhesion properties for efficient transfer and structural integrity to prevent defects like white spots and fading.
2Reliability
If toner with high adhesion is used to prevent white spots and fading, then image quality improves, but transfer efficiency decreases due to poor toner release
Solution Approach 1:
The patent applies dynamics by designing the toner binder resin to have dynamic viscosity characteristics that change with temperature and shear rate. The resin exhibits shear-thinning behavior with a specific flow activation energy (Ea) between 50-150 kJ/mol, allowing it to provide high adhesion during transfer but easy release afterward. The temperature-dependent viscosity ratio (η(T1)/η(T2)) being between 0.05 and 0.50 ensures the toner transitions from adhesive state during transfer to release state after transfer, resolving the contradiction between adhesion and transfer efficiency.
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 apparatus reduces the occurrence of white spots and fading by maintaining optimal viscoelasticity and adhesion properties, ensuring stable image transfer across varying surface conditions.
Implementation Method 1
the electrostatic charge image developing toner has (ln η(T1)−ln η(T2))/(T1−T2) of greater than −0.14 or (ln η(T2)−ln η(T3))/(T2−T3) of less than −0.15
Data Source
AI summary
An image forming apparatus includes an image holding member, a charging unit that charges a surface of the image holding member, an electrostatic charge image forming unit that forms an electrostatic charge image on the charged surface of the image holding member, a developing unit that includes an electrostatic charge image developing toner and that develops the electrostatic charge image on the surface of the image holding member with the electrostatic chare image developing toner to form a toner image, an intermediate transfer body having a circumferential surface of which micro rubber hardness is in a range of 45 to 65, a first transfer unit that first transfers the toner image formed on the surface of the image holding member to a surface of the intermediate transfer body, and a second transfer unit that second transfers the toner image transferred to the surface of the intermediate transfer body to a recording medium, wherein the electrostatic charge image developing toner satisfies the following formulae(ln η(T1)−ln η(T2))/(T1−T2)≤−0.14,(ln η(T2)−ln η(T3))/(T2−T3)≥−0.15, and(ln η(T1)−ln η(T2))/(T1−T2)<(ln η(T2)−ln η(T3))/(T2−T3)wherein η(T1) represents a viscosity of the electrostatic charge image developing toner at 60° C., η(T2) represents a viscosity of the electrostatic charge image developing toner at 90° C., and η(T3) represents a viscosity of the electrostatic charge image developing toner at 130° C.