Core-Shell Toner Particles with Charge Control Shell
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Solution Overview
Problem
Conventional toner processes incorporating crystalline polyester exhibit reduced charging properties in varying environmental conditions, which can be detrimental in high and low temperature and humidity environments.
Innovation Solution
Incorporating a charge control agent, such as a copolymer containing charge control agent recurring units, into the shell of toner particles formed through an emulsion aggregation process, where non-crosslinked latex particles are aggregated with a polyester and a wax in the presence of a coagulant, and additional resin is added to form a shell around the aggregates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If crystalline polyester is incorporated into toner particles, then desirable relative humidity sensitivity is maintained, but charging properties are reduced in varying environmental conditions
Solution Approach 1:
The patent applies local quality by creating a multi-layered particle structure where the core contains crystalline polyester for humidity sensitivity, while the shell incorporates charge control agents for improved charging properties. This allows different regions of the same particle to have specialized functions, resolving the contradiction between maintaining humidity sensitivity and improving charging reliability.
Solution Approach 2:
The patent uses composite materials by combining crystalline polyester with charge control agents in a core-shell structure. The composite nature allows the toner to simultaneously exhibit the humidity sensitivity of polyester and the enhanced charging properties of the charge control agents, particularly in extreme temperature and humidity conditions.
2Reliability
If charge control agent is added to improve charging properties, then triboelectrical properties are enhanced, but minimum fixing temperature increases
Solution Approach 1:
The patent applies parameter changes by carefully controlling the type, amount, and distribution of charge control agents in the shell structure. By optimizing these parameters, the patent achieves improved charging properties while minimizing the impact on minimum fixing temperature, as the shell structure allows for controlled interaction between the charge control agents and the polyester core.
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 effectively counters reduced charging properties while maintaining desirable relative humidity sensitivity, providing toners with improved triboelectrical properties and reduced minimum fixing temperature, suitable for xerographic processes.
Implementation Method 1
The solution effectively counters reduced charging properties while maintaining desirable relative humidity sensitivity, providing toners with improved triboelectrical properties
Implementation Method 2
non-crosslinked latex particles are aggregated with a polyester, such as a crystalline polyester, optional crosslinked latex particles, such as latexes containing crosslinked vinyl polymeric particles, a wax and colorants, in the presence of a coagulant like a polymetal halide
Data Source
AI summary
A toner composition includes core toner particles and a shell formed over the core toner particles. The core toner particles include a resin substantially free of cross linking, an optional cross linked resin, a polyester resin, and a colorant. The shell includes a resin containing charge control agent recurring units.