Core-Shell Toner Particles for Low Melt Fixing

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Solution Overview

Problem

Current ultra low melt (ULM) polyester-based toners achieve a reduction in minimum fix temperature (MFT) but compromise electrical performance due to the degradation of crystalline resin properties when increasing crystalline resin content, leading to poor charge maintenance and conductivity.

Innovation Solution

The development of toner particles with a core-shell morphology, where a crystalline resin core is encapsulated within an amorphous resin shell, combined with additional amorphous resins to form a nanoparticle, which is then mixed with other reagents to create a toner with reduced MFT without degrading electrical performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If crystalline resin content is increased to reduce minimum fix temperature further, then MFT is reduced, but electrical performance degrades

Engineering Contradiction:
Improveminimum fix temperatureVSAvoidelectrical performance
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The toner particle is segmented into distinct functional zones: a core containing amorphous resin and charge control agents, and an outer shell containing crystalline resin. This segmentation allows each zone to perform its specialized function without interference, enabling the crystalline shell to reduce MFT while the amorphous core preserves electrical performance

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the toner particle are assigned different material compositions and properties. The core uses amorphous resin with high electrical conductivity and charge control agents, while the shell uses crystalline resin with low melting point. This local differentiation allows simultaneous optimization of electrical performance in the core and thermal properties in the shell

Inventive Principle:
Principle #3Local quality

2Temperature

If crystalline resin is added to reduce MFT, then fusing temperature is lowered, but conductivity and charge maintenance deteriorate

Engineering Contradiction:
Improvefusing temperatureVSAvoidconductivity and charge maintenance
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The toner particle is constructed as a composite material system combining amorphous resin in the core with crystalline resin in the shell. This composite structure leverages the complementary properties of both materials: the amorphous core provides electrical conductivity and charge stability, while the crystalline shell provides low-temperature melting and fusion

Inventive Principle:
Principle #40Composite materials

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

This approach maintains electrical performance and reduces MFT effectively, allowing for a broader fusing latitude while preventing crystalline resin degradation, especially at higher crystalline resin content levels.

Implementation Method 1

a crystalline resin core is encapsulated within an amorphous resin shell

Methodology Applied
Scientific EffectEncapsulation: Physical Containment

Implementation Method 2

reduced minimum fix temperature (MFT)... The toner can have a minimum fixing temperature of from about 100° C. to about 130° C.

Methodology Applied
Scientific EffectPhase transition: Phase Change

Implementation Method 3

Any one or more second amorphous resins and any toner particle shell serve to contain the crystalline resin within the toner particle so as to insulate the nanoparticle and the crystalline resin therein from the toner particle surface

Methodology Applied
Scientific EffectPhysical barrier formation: Physical Containment

Data Source

PatentUS8685605B2Low melt toner
Publication Date: 2014.04.01 XEROX CORP

AI summary

Toners containing encapsulated crystalline resin have lower minimum fix temperatures without charge degradation.