Crystalline Polyester Toner for Low-Temperature Fixing
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Solution Overview
Problem
Electrostatic latent image developing toners with low-temperature fixability suffer from thermal instability, leading to releasing agent bleed-out and image noise when stored under high-temperature and high-humidity conditions.
Innovation Solution
The toner formulation includes a binder resin with a crystalline polyester resin and a releasing agent, specifically an aliphatic acid ester wax or hydrocarbon wax with a branched structure, to control the crystallization peak and reduce the heat value ΔHc(L) to 15% or less of the total exothermic peak, ensuring low-temperature fixability without image noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a crystalline resin is added to achieve low-temperature fixability, then the melting temperature and melting viscosity of the binder resin are decreased, but the thermal stability of the toner is reduced, causing releasing agent bleed-out and image noise under high-temperature and high-humidity storage conditions
Solution Approach 1:
The invention changes the chemical composition parameters of the binder resin by specifying particular polyester resins with controlled molecular structures and compositions. This allows achieving low-temperature fixability while maintaining thermal stability through precise parameter control rather than simply adding crystalline resins.
Solution Approach 2:
The invention uses a composite binder resin system combining specific polyester resins with controlled ratios of different components. This composite structure provides both the low melting point needed for low-temperature fixing and the thermal stability required to prevent releasing agent bleed-out during storage.
2Ease of operation
If the melting temperature and melting viscosity of the binder resin are decreased to achieve low-temperature fixability, then the fixability at low temperature is improved, but the toner produces image noise after long-term storage under high-temperature and high-humidity conditions
Solution Approach 1:
The invention precisely controls the chemical composition parameters of the binder resin, including molecular weight distribution and functional group ratios, to achieve the optimal balance between low-temperature fixability and prevention of releasing agent bleed-out that causes image noise.
Solution Approach 2:
The invention replaces the use of crystalline resins with a specifically designed polyester resin composition that achieves the same low-temperature fixing effect without the long-term stability problems, effectively substituting a problematic material with a superior alternative.
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 and prevents image noise even after prolonged storage under high-temperature and high-humidity conditions by inhibiting releasing agent bleed-out, maintaining image quality.
Implementation Method 1
it is necessary to decrease a melting temperature and a melting viscosity of a binder resin
Implementation Method 2
decrease a melting temperature and a melting viscosity of a binder resin
Implementation Method 3
a heat value ΔHc(L), which is a heat value in the range of (an exothermic peak top temperature rc−7° C.) or less, is made to be 15% or less with respect to a heat value ΔHc
Data Source
AI summary
An object of the present invention is to provide an electrostatic latent image developing toner containing: a binder resin; and a releasing agent, wherein the binder resin contains a crystalline polyester resin; an endothermic peak top temperature of the electrostatic latent image developing toner is 70° C. or more measured with differential scanning calorimetry (DSC) in a heating-up period of the toner; and a heat value ΔHc(L) is 15% or less with respect to a heat value ΔHc, wherein the heat value ΔHc(L) is a heat value in the range of (an exothermic peak top temperature rc−7° C.) or less; and the heat value ΔHc is a heat value of the total exothermic peak measured with DSC in a heating-down period of the toner.