Core-Shell Toner Production via Shell Layer Adhesion
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Solution Overview
Problem
Conventional core-shell toner production methods face challenges in achieving both low-temperature fixing performance and blocking resistance due to unreacted binder resin particles from the shell layers remaining as floating particles, especially when the binder resin particles in the core and shell layers have different acidic groups, leading to poor adhesion and stability.
Innovation Solution
A process involving a mixing step for binder resin, colorant, and release agent dispersions, followed by agglomeration, metal salt loading, shell adhering, and fusion to ensure the binder resin particles from the shell layers adhere uniformly to the core particles, preventing unreacted particles and achieving both low-temperature fixing and blocking resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If binder resin particles making up shell layers are added to form shell layers, then low-temperature fixing performance is improved, but unreacted particles remain as floating particles causing poor adhesion and stability
Solution Approach 1:
The patent changes the chemical parameter of the binder resin by introducing a specific acidic group (carboxyl group with pKa of 3.0-6.0) into the shell layer resin. This parameter change enables the resin to maintain both low glass transition temperature (for low-temperature fixing) and sufficient adhesion to core particles, resolving the contradiction between fixing temperature and adhesion stability.
Solution Approach 2:
The patent creates a composite structure where the shell layer consists of a copolymer containing both hydrophobic monomer units (providing low Tg) and hydrophilic monomer units containing carboxyl groups (providing adhesion). This composite material approach allows simultaneous achievement of low-temperature fixing performance and stable adhesion to core particles.
2Ease of manufacture
If binder resin particles making up shell layers are added supplementally, then shell layers are formed on core particles, but fine particles do not successfully adhere and remain as floating particles
Solution Approach 1:
The patent specifies precise parameter ranges for the acidic group content (0.1-10 mmol/g) and glass transition temperature (0-60°C) of the shell layer resin. These parameter optimizations ensure that the resin particles adhere uniformly to core particles during the fusion step, preventing formation of floating particles while maintaining manufacturability.
Solution Approach 2:
The patent applies different properties to different parts of the toner structure: the core particles contain binder resin with specific properties, while the shell layer contains a different binder resin with tailored properties (specific acidic group content and Tg range). This local quality differentiation ensures proper adhesion at the core-shell interface while maintaining overall toner performance.
3Stability of the object's composition
If binder resin particles making up shell layers have higher dispersion stability, then they can more not easily come to agglomerate, but adhesion to core particles deteriorates
Solution Approach 1:
The patent optimizes the balance between dispersion stability and adhesion by controlling the carboxyl group content (0.1-10 mmol/g) and glass transition temperature (0-60°C) of the shell layer resin. This parameter optimization allows the resin to maintain sufficient dispersion stability during processing while ensuring strong adhesion to core particles through the acidic group interactions.
Solution Approach 2:
The patent ensures homogeneous distribution of the acidic groups throughout the shell layer resin structure. This homogeneity in chemical composition allows uniform adhesion behavior across all shell layer particles, preventing both aggregation and poor adhesion, thereby balancing dispersion stability with adhesion strength.
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 process produces a core-shell toner with improved low-temperature fixing performance and blocking resistance by ensuring uniform adhesion of shell layers to core particles, preventing unreacted resin particles and maintaining stability during the fusion step.
Implementation Method 1
a dispersion of a binder resin used for cores and a dispersion of a colorant are mixed and thereafter the mixture is made to agglomerate by heating, pH control and/or addition of an agglomerating agent until particles come to have the desired particle diameter
Implementation Method 2
the core-shell agglomerated particles obtained are heated to a temperature not lower than the glass transition temperature of the binder resin to effect fusion to produce the toner
Data Source
AI summary
A process for producing a core-shell toner is provided in which the toner has core particles containing at least a binder resin (1), a colorant and a release agent and shell layers which contain at least a resin (2) and with which the core particles are covered; and the process including the steps of (A) mixing a binder resin-(1) dispersion, a colorant dispersion and a release agent dispersion, (B) adding to a mixed dispersion thus obtained an agglomerating agent to effect agglomeration, (C) adding to core agglomerated particles thus formed a mixture prepared by mixing the resin-(2) dispersion and a metal salt to make the resin (2) adhere to the surfaces of the core agglomerated particles, and (D) heating core-shell agglomerated particles thus formed to a temperature not lower than the glass transition temperatures of the binder resin (1) and resin (2) to effect fusion thereof.