Toner Resin Particles with Crystalline Polyester Shell
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Solution Overview
Problem
Existing toner manufacturing methods, such as kneading and milling, face challenges in achieving high low-temperature fixability and heat-resistant storage stability due to issues like particle size irregularity, broad particle size distribution, and contamination from release agents, which affect image quality and equipment performance.
Innovation Solution
Resin particles comprising a binder resin, a crystalline polyester resin, and a release agent with a domain diameter of 1 μm or less, where over 80% of the release agent surface is covered by crystalline polyester resin with a higher melting point, enhancing low-temperature fixability and heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a release agent is added to improve fixability, then low-temperature fixability is improved, but the toner cracks at the interface with the release agent during milling, resulting in a large amount of release agent on the toner surface and deposition on equipment
Solution Approach 1:
The release agent is internalized within the toner particle structure, forming a core-shell configuration where the release agent domain is nested inside the toner particle. This prevents the release agent from being exposed on the surface and causing deposition on equipment, while still providing the necessary releasing effect during fixation.
Solution Approach 2:
The release agent is localized to specific domains within the toner particle rather than being uniformly distributed. This creates distinct regions with different functions: the release agent domains provide releasing capability while the surrounding toner matrix maintains structural integrity and prevents cracking during milling.
2Object-generated harmful factors
If the release agent is internalized to prevent deposition, then equipment contamination is reduced, but the toner strength is significantly reduced especially when stored at high temperature due to phase-separated structure
Solution Approach 1:
The release agent is nested within the toner particle as internal domains rather than being externally applied or surface-coated. This nesting structure protects the release agent from exposure while maintaining toner particle integrity through the surrounding toner matrix.
Solution Approach 2:
The toner is designed as a composite material system with distinct phases: the toner matrix (binder resin and polyester resin) and the internal release agent domains. This composite structure allows each component to fulfill its function while maintaining overall particle strength, particularly through the crystalline polyester resin that provides structural support.
3Temperature
If crystalline polyester resin and amorphous polyester resin are both melted to achieve low-temperature fixability, then fixing temperature is reduced, but most amorphous polyester resin does not melt yet since crystalline polyester resin melts first
Solution Approach 1:
The toner particle has a heterogeneous structure with distinct crystalline and amorphous regions. The crystalline polyester resin domains melt first at lower temperatures to initiate the fixing process, while the amorphous polyester resin continues to soften and flow at slightly higher temperatures to complete the fixation, ensuring both low-temperature capability and complete melting.
Solution Approach 2:
The fixing process occurs in stages: first the crystalline polyester resin melts to enable initial toner flow and adhesion, then the amorphous polyester resin continues to soften and complete the fusion. This sequential melting behavior ensures complete resin transformation while maintaining low overall fixing temperatures.
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 solution provides resin particles with improved low-temperature fixability, heat-resistant storage stability, and stable image quality by ensuring the release agent is finely dispersed and protected within the toner, preventing softening and seepage during high-temperature storage.
Implementation Method 1
the resin and the release agent are incompatible with each other and have a phase-separated structure in the form of sea islands
Implementation Method 2
a melting point of the crystalline polyester resin is higher than a melting point of the release agent
Data Source
AI summary
A resin particle may comprise a binder resin, a crystalline polyester resin; and a release agent being in a plurality of domains, which have a domain diameter of 1 μm or less; wherein more than 80% of a surface of each of the plurality of domains of the release agent is covered with the crystalline polyester resin, and a melting point of the crystalline polyester resin is higher than a melting point of the release agent.