Electrostatic Toner with Crystalline Resin Storage Modulus Control
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Solution Overview
Problem
Electrostatic charge image developing toners containing crystalline resins face challenges in achieving both low-temperature fixing characteristics and heat-resistant storage characteristics, as the crystalline resin can be blended with amorphous resin during heating, reducing heat resistance and causing toner aggregation, and further crystallization during storage at high temperatures affects fixing characteristics.
Innovation Solution
The toner composition includes a binder resin of amorphous polyester, crystalline resin, and amorphous vinyl resin, with specific storage modulus measurements at different temperatures to control crystallization and prevent bleed-out, ensuring stable low-temperature fixing and heat-resistant storage by optimizing the material composition and adding a mold release agent or acrylate monomer to facilitate crystallization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the toner contains a crystalline resin with low melting temperature and low melt viscosity to achieve low-temperature fixing, then the low-temperature fixing characteristics are improved, but the heat-resistant storage characteristics deteriorate due to blending with amorphous resin during heating
Solution Approach 1:
The invention changes the physical and chemical parameters of the crystalline resin by controlling its melting point to be 50-80°C and specifying the storage modulus ratio G′(Tm-10)/G′(Tm-20) to be 1.2 or less. These parameter changes ensure the resin maintains crystallinity during storage while enabling low-temperature fixing, resolving the contradiction between fixing temperature and heat-resistant storage characteristics.
Solution Approach 2:
The invention uses a composite binder resin system comprising both amorphous resin and crystalline resin in specific proportions (crystalline resin 5-50 mass%, amorphous resin 50-95 mass%). This composite structure allows the amorphous resin to provide low-temperature fixing capability while the crystalline resin maintains structural integrity and heat resistance during storage.
2Reliability
If annealing is performed to recrystallize the blended crystalline resin and improve heat-resistant storage characteristics, then the heat resistance is enhanced, but the diameter of the crystalline resin domain increases causing exposure from toner surfaces and reducing charging characteristics
Solution Approach 1:
The invention precisely controls the storage modulus ratio parameter G′(Tm-10)/G′(Tm-20) to be 1.2 or less, which serves as a critical indicator for controlling crystalline resin domain size. This parameter control prevents excessive crystallization during storage while maintaining heat-resistant characteristics, resolving the contradiction between heat resistance and crystalline domain size control.
Solution Approach 2:
The invention uses the storage modulus ratio G′(Tm-10)/G′(Tm-20) as a feedback parameter to monitor and control the crystallization state of the binder resin. By measuring this ratio, the invention ensures that annealing processes do not cause excessive crystalline domain growth that would expose crystalline resin from toner surfaces and degrade charging characteristics.
3Reliability
If further crystallization of insufficiently crystallized toner occurs during storage at high temperature, then the heat-resistant storage characteristics are improved, but the low-temperature fixing characteristics deteriorate
Solution Approach 1:
The invention optimizes the melting point of the crystalline resin to be within 50-80°C and controls the storage modulus ratio G′(Tm-10)/G′(Tm-20) to be 1.2 or less. These parameter settings create a balanced crystallization behavior that provides sufficient heat resistance during storage while preserving the low-temperature fixing characteristics, preventing the deterioration that would occur with excessive crystallization.
Solution Approach 2:
The invention applies partial crystallization control rather than complete crystallization. By controlling the crystalline resin content at 5-50 mass% and managing the storage modulus ratio, the invention achieves sufficient crystallization for heat resistance while deliberately limiting excessive crystallization that would harm low-temperature fixing characteristics.
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
This approach results in a toner with consistent low-temperature fixing characteristics and reduced bleed-out, maintaining compatibility between low-temperature fixing and heat-resistant storage even at high temperatures, enhancing the toner's overall performance and stability.
Implementation Method 1
a crystalline resin, such as a crystalline polyester resin, and has improved low-temperature fixing characteristics
Implementation Method 2
annealing of the toner at a temperature equal to or lower than the softening temperature of the toner for a long time causes recrystallization of the blended crystalline resin
Implementation Method 3
the diameter of the crystalline resin domain in the toner is increased to expose the crystalline resin from the surfaces of toner particles
Data Source
AI summary
An electrostatic charge image developing toner includes a particulate toner matrix containing a binder resin and an external additive. The binder resin includes an amorphous polyester resin, a crystalline resin, and an amorphous vinyl resin. A storage modulus G′0(t) measured before the toner is left and storage moduli G′Tm-10(t) and G′Tm-20(t) measured after the toner is left for three hours at temperatures (Tm-10)° C. and (Tm-20)° C., respectively, based on a melting point (Tm° C.) derived from the crystalline resin satisfy the relations represented by G′0(t)<G′Tm-10(t), G′0(t)<G′Tm-20(t), and G′Tm-10(x)/G′Tm-20(x)≤1.5 in a temperature range A for measurement where the storage modulus G′0(t) is 1.0×106 Pa or more. The value t represents any temperature (° C.) for measurement in the temperature range A for measurement; and the value x represents the temperature (° C.) for measurement having a maximum difference between the storage moduli G′Tm-10(t) and G′Tm-20(t).