Toner Fixing via Viscoelastic Modulus Control
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Solution Overview
Problem
Toner formulations face challenges in achieving balanced low-temperature fixability, separability, and heat-resistant storability, as existing waxes with high compatibility with binder resins tend to compromise either fixability or storability, and ester waxes do not adequately improve melt viscosity or maintain high melting points.
Innovation Solution
A toner composition incorporating an amorphous resin and a wax, where the dynamic viscoelastic properties are optimized by controlling the loss elastic modulus and tan δ values within specific ranges to ensure both low-temperature fixability and heat-resistant storability, with a coat layer having low compatibility with the wax to enhance separability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a wax is added to plasticize a binder resin to improve low-temperature fixability, then the viscosity in a toner-molten state is lowered and low-temperature fixability is improved, but the toner tends to attach to a fixing member (separability is lowered)
Solution Approach 1:
The invention changes the chemical parameters of the binder resin by selecting specific resins with defined glass transition temperatures (Tg between -50°C to 0°C for amorphous resin A and Tm between 50°C to 80°C for semi-crystalline resin B) and controlling the wax content (5-20 mass%) to achieve optimal viscosity characteristics that balance low-temperature fixability with separability
Solution Approach 2:
The invention uses a composite binder resin system combining amorphous resin A and semi-crystalline resin B in specific proportions (mass ratio A:B of 9:1 to 1:9) to create a material that exhibits both low-temperature flow properties for fixability and sufficient structural integrity for separability
2Temperature
If a wax with high compatibility with binder resin is used to improve low-temperature fixability, then the viscosity is lowered, but during storage under high temperature environment, a part of the wax may melt and be exuded on the surface, deteriorating storability
Solution Approach 1:
The invention adjusts the melting point parameter of the wax to be between 60°C to 90°C, which is high enough to prevent exudation during storage but low enough to provide plasticizing effect during fixing, and controls the wax content at 5-20 mass% to balance compatibility and stability
Solution Approach 2:
The invention creates different functional zones within the toner particle by selecting resins with specific Tg and Tm ranges that create a gradient structure, where the amorphous resin A provides low-temperature flexibility and the semi-crystalline resin B provides high-temperature structural stability
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 toner achieves excellent low-temperature fixability, improved separability, and enhanced heat-resistant storability by controlling the elastic modulus and tan δ values, reducing the likelihood of paper winding on the fixing member and maintaining image integrity.
Implementation Method 1
a toner that melts rapidly at a lower temperature, that is, that has excellent low-temperature fixability is preferable
Implementation Method 2
in dynamic viscoelasticity measurement of the toner, when the temperature at which the loss elastic modulus G'' measured at a frequency of 1 Hz becomes 1.00×10^6 Pa is set as T(1 Hz)
Data Source
AI summary
Toner, including: a toner particle that contains a binder resin and a wax, wherein the binder resin includes an amorphous resin A, and, in dynamic viscoelasticity measurement of the toner, when the temperature at which the loss elastic modulus G″ measured at a frequency of 1 Hz becomes 1.00×106 Pa is set as T(1 Hz), when the temperature at which the loss elastic modulus G″ measured at a frequency of 20 Hz becomes 1.00×106 Pa is set as T(20 Hz), and when the maximum value of the ratio (tan δ) of the loss elastic modulus G″ with respect to the storage elastic modulus G′, measured at a frequency of 20 Hz, in a range of from 60° C. to 90° C. is set as tan δ(P), the toner satisfies T(20 Hz)−T(1 Hz)≤7.0° C., 0.80≤tan δ(P)≤1.90, 60° C.≤T(1 Hz)≤80° C., and 60° C.≤T(20 Hz)≤80° C.