Core-Shell Toner for Single Component Development
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Solution Overview
Problem
Existing emulsion aggregation toner technologies face challenges in achieving high gloss and low fusing temperatures while maintaining anti-blocking and storage characteristics, especially in single component development systems, where toner particles need to exhibit high transfer efficiency and low cohesivity.
Innovation Solution
A method involving the formation of emulsion aggregation toner particles using a styrene acrylate polymer binder resin with specific molecular weights, combined with polypropylene or polyethylene wax, and a second polymer binder resin to create a core-shell structure, which is then coalesced to achieve desired size and shape, resulting in toner particles with improved glass transition temperature and circularity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If emulsion aggregation toner technologies use conventional resin formulations, then the process is simpler, but the anti-blocking and storage characteristics deteriorate
Solution Approach 1:
The invention divides the toner particle into a core-shell structure with distinct functional regions. The core contains the styrene acrylate polymer binder resin with specific molecular weights (Mw 50-100K, Mn 10-30K) providing anti-blocking properties, while the shell provides structural integrity and storage stability. This segmentation allows each region to be optimized for its specific function, resolving the contradiction between reliability and process complexity.
Solution Approach 2:
The invention uses composite material formulation by combining styrene acrylate polymer binder resin with specific wax content (5-20% by weight) and colorant within the core, surrounded by a shell layer. This composite structure provides synergistic effects where the polymer matrix prevents blocking while the shell maintains storage characteristics, overcoming the limitations of conventional single-material formulations.
2Reliability
If toner particles are designed for high transfer efficiency, then image quality improves, but particle cohesivity increases causing blocking
Solution Approach 1:
The invention applies local quality by creating a core-shell structure where the core region has high surface energy and controlled cohesivity for efficient transfer, while the shell region provides a protective barrier that prevents excessive particle aggregation. The styrene acrylate polymer in the core with controlled molecular weight distribution ensures local optimization of transfer properties without compromising overall particle stability.
Solution Approach 2:
The invention changes critical parameters including the molecular weight distribution of the styrene acrylate polymer (Mw 50-100K, Mn 10-30K) and wax content (5-20% by weight) to optimize the balance between transfer efficiency and particle cohesivity. By controlling the glass transition temperature and molecular weight parameters, the toner achieves high transfer efficiency while maintaining low cohesivity to prevent blocking.
3Use of energy by moving object
If fusing temperature is reduced for low cost operation, then energy consumption decreases, but gloss and fix properties deteriorate
Solution Approach 1:
The invention changes the thermal parameters of the toner formulation by using styrene acrylate polymer with controlled molecular weight and glass transition temperature, combined with specific wax content (5-20% by weight). This parameter optimization allows the toner to achieve proper melting and flow at lower fusing temperatures, reducing energy consumption while maintaining high gloss and fix properties through controlled phase transition behavior.
Solution Approach 2:
The invention exploits phase transitions by designing the core-shell structure with styrene acrylate polymer and wax that undergo controlled melting and solidification at specific temperature ranges. During fusing, the toner undergoes phase transition from solid to semi-fluid state, allowing it to flow and conform to the substrate for high gloss finish, then solidifies upon cooling to provide durable fixation. This controlled phase transition enables low-temperature fusing while maintaining image quality.
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 approach results in toner particles with enhanced anti-blocking and storage characteristics, improved release from fuser members, and high transfer efficiency, making them suitable for single component developer systems with high gloss and low fusing temperatures.
Implementation Method 1
aggregating the blend by heating at a temperature at or above the glass transition temperature of the styrene acrylate polymer binder resin to form an aggregated toner core
Implementation Method 2
coalescing the core-shell toner by heating at a temperature above the glass transition temperature of the second latex
Data Source
AI summary
A method for developing toner for use in a single component development system, wherein the process includes a) contacting a styrene acrylate polymer binder resin having a weight average molecular weight (Mw) of from about 50 to about 100 Kpse, and a number average molecular weight (Mn) of from about 10 to about 30 Kpse, a wax selected from the group consisting of polypropylene and polyethylene, and at least one colorant to produce a toner blend, b) aggregating the blend by heating at a temperature at or above the glass transition temperature of the styrene acrylate resin to form an aggregated toner core; c) adding a second binder resin to the aggregated toner core to form a shell over said toner core thereby forming a core-shell toner; d) growing said core-shell toner to a desired size; e) coalescing the core-shell toner by heating at a temperature above the glass transition temperature of the second latex; and f) recovering toner particles, wherein the toner particles have an onset glass transition temperature of from about 50° C. to about 60° C., and a circularity of from about 0.950 to about 0.990.