Core-Shell Toner Resolves Crystalline Migration and Gloss
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Polyester EA ultra low melt toners exhibit high peak gloss, poor charging characteristics, and issues with toner flow and blocking due to crystalline resin migration during coalescence.
Innovation Solution
The development of toners incorporating a combination of linear, crystalline, and high molecular weight polyesters with specific solubility parameter differences, forming a core-shell configuration with a branched or cross-linked high molecular weight resin, which prevents crystalline resin migration and improves toner properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If crystalline polyester resin is used in toner formulation, then fusing properties and crease minimum fixing temperature are improved, but peak gloss becomes unacceptably high and charging characteristics deteriorate
Solution Approach 1:
The invention creates a core-shell structure where the core contains crystalline polyester resin for excellent fusing properties, while the shell contains amorphous polyester resin with specific glass transition temperature to control surface properties. This local differentiation allows the crystalline resin to provide fusing performance internally while the amorphous shell manages surface characteristics like charging and gloss.
Solution Approach 2:
The invention combines crystalline polyester resin and amorphous polyester resin in a core-shell configuration, creating a composite toner particle that leverages the advantages of both material types. The crystalline core provides thermal stability and fusing performance, while the amorphous shell controls surface properties including charging characteristics and peak gloss.
2Temperature
If crystalline polyester resin migrates to surface during coalescence, then fusing temperature is reduced, but toner flow and blocking properties deteriorate
Solution Approach 1:
The core-shell structure confines the crystalline polyester resin to the core region, preventing its migration to the particle surface during coalescence. This localized containment allows the crystalline resin to lower fusing temperature through its melting characteristics while preventing surface migration that would cause poor toner flow and blocking issues.
Solution Approach 2:
The amorphous polyester resin shell acts as an intermediary layer between the crystalline core and the external environment. It mediates the behavior of the crystalline resin by containing it within the core while providing a surface layer with appropriate glass transition temperature that ensures good toner flow and prevents blocking, thus reconciling the temperature reduction benefit with flow performance.
3Ease of manufacture
If amorphous polyester resin with low glass transition temperature is used, then charging characteristics improve, but peak gloss increases
Solution Approach 1:
The invention places amorphous polyester resin with low glass transition temperature specifically in the shell region to improve charging characteristics at the particle surface, while the crystalline core maintains structural integrity and controls gloss. The localized positioning allows charging improvement without the entire particle becoming high-gloss.
Solution Approach 2:
The composite core-shell structure combines amorphous polyester in the shell with crystalline polyester in the core. The amorphous shell component improves charging characteristics through its low glass transition temperature and surface properties, while the crystalline core component controls peak gloss, creating a balanced performance that neither material could achieve alone.
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 results in toners with enhanced charging, flow, and blocking properties, reducing peak gloss and improving overall performance under various environmental conditions.
Implementation Method 1
at least one high molecular weight polyester having a Mw greater than about 15,000 and a polydispersity index of greater than about 4, wherein the linear polyester and the high molecular weight polyester have a difference in solubility parameter of from about 0.1 to about 1
Implementation Method 2
high molecular weight polyester having a Mw of from about 20,000 to about 100,000, and a polydispersity index of from about 4 to about 100
Implementation Method 3
Emulsion aggregation (EA) is one such method. These toners may be formed by aggregating a colorant with a latex polymer formed by emulsion polymerization
Implementation Method 4
aggregating the small particles to form a plurality of larger aggregates; coalescing the larger aggregates to form particles
Implementation Method 5
the linear polyester and the high molecular weight polyester have a difference in solubility parameter of from about 0.1 to about 1
Data Source
AI summary
Toner particles are provided which may, in embodiments, include a high molecular weight branched or cross-linked polyester to decrease image gloss and to increase toner elasticity to prevent surface additives impaction. In embodiments, the toner particles may have a core-shell configuration, with the high molecular weight polyester in the core, the shell, or both.