Core-Shell Toner Resin Structure for Low-Temp Fusing and Storage Stability
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Solution Overview
Problem
Existing toners for electrophotography fail to simultaneously achieve excellent low-temperature fusing properties and heat-resistant storage stability, as they often compromise on one aspect at the expense of the other.
Innovation Solution
A core-shell toner structure is produced through a process involving the aggregation and coalescence of resin particles, where the core contains a polyester resin with a propyleneoxide adduct of bisphenol A and a vinyl-based resin segment, and the shell contains a polyester resin with an ethyleneoxide adduct of bisphenol A, ensuring low compatibility between the core and shell to maintain the core-shell structure and enhance stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a core-shell toner structure is used to improve low-temperature fusing properties, then fusing performance is enhanced, but heat-resistant storage stability deteriorates
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the core and shell have different resin compositions optimized for their specific functions. The core contains polyester resin with propyleneoxide adduct for low-temperature fusing, while the shell contains polyester resin with ethyleneoxide adduct for heat resistance and storage stability. This localized differentiation of material properties resolves the contradiction between low-temperature fusing performance and heat-resistant storage stability.
Solution Approach 2:
The patent uses composite materials by combining two different polyester resin systems with distinct chemical compositions. The core uses polyester resin (a) with propyleneoxide adduct of bisphenol A, while the shell uses polyester resin (b) with ethyleneoxide adduct of bisphenol A. This composite approach allows simultaneous achievement of low-temperature fusing properties from the core and heat-resistant storage stability from the shell.
2Manufacturing precision
If resin particles are aggregated and coalesced to form core-shell structure, then particle size distribution is narrowed, but compatibility between core and shell layers deteriorates
Solution Approach 1:
The patent applies parameter changes by carefully controlling the glass transition temperatures and chemical compositions of the core and shell resins. The core polyester resin (a) and shell polyester resin (b) are designed with specific glass transition temperature differences and chemical composition ratios to ensure low compatibility that maintains the core-shell structure during aggregation and coalescence, while achieving narrow particle size distribution.
3Reliability
If the shell layer is formed to maintain structural integrity, then storage stability is improved, but wax exposure to outer surface increases
Solution Approach 1:
The patent applies the flexible shell principle by creating a shell layer with specific thickness and composition that acts as a controlled barrier. The shell layer is designed to be sufficiently thin and compatible to allow controlled release of wax to the outer surface while maintaining structural integrity and storage stability. This resolves the contradiction between storage stability and preventing harmful wax exposure.
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 resulting toner exhibits improved low-temperature fusing properties and heat-resistant storage stability, maintaining a homogeneous shell layer and preventing wax exposure, thus enhancing charge distribution and developability.
Implementation Method 1
aggregating and coalescing method (emulsification-aggregation method or aggregation-coalescence method) in which fine resin particles, etc., are aggregated and coalesced together in an aqueous medium
Data Source
AI summary
The present invention relates to a process for producing a toner for development of electrostatic images, including the following steps (1) to (3): Step (1): aggregating resin particles (X) containing a composite resin that contains a segment constituted of a polyester resin (a) obtained by polycondensing an alcohol component containing 80 mol% or more of a propyleneoxide adduct of bisphenol A and a polycarboxylic acid component, and a vinyl-based resin segment containing a constitutional unit derived from a styrene-based compound, in an aqueous medium, to obtain aggregated particles (1); Step (2): aggregating the aggregated particles (1) obtained in the step (1) with resin particles (Y) containing a polyester resin (b) obtained by polycondensing an alcohol component containing 80 mol% or more of an ethyleneoxide adduct of bisphenol A and a polycarboxylic acid component to obtain aggregated particles (2); and Step (3): coalescing the aggregated particles (2) obtained in the step (2).