Crosslinked Polyester Toner for Gloss-Free Decolorization

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Solution Overview

Problem

Conventional decolorizable toners suffer from insufficient decolorization performance, resulting in noticeable gloss in decolorized regions and poor low-temperature fixability.

Innovation Solution

An electrophotographic toner composition comprising an electron donating color developable agent, an electron accepting color developing agent, and a crosslinked polyester resin binder, with microencapsulation and a temperature control agent to control decolorization, ensuring a smooth surface and effective color removal without gloss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional decolorizable toner is used, then the toner can be decolorized by heating, but the decolorization performance is insufficient and gloss is noticeable in decolorized regions

Engineering Contradiction:

Improvedecolorization performanceVSAvoidgloss in decolorized region

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent modifies the chemical structure of the color developable agent by introducing specific substituents (electron-donating groups at positions 2 and 6 of the fluoran ring) to optimize the decolorization characteristics. This structural parameter change enables complete color removal while controlling the surface properties to minimize gloss in decolorized regions.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The toner is formulated as a composite system containing the fluoran-based color developable agent, color developing agent, and binder resin. This composite approach allows the color developable agent to provide decolorization functionality while the binder resin maintains surface integrity, preventing excessive gloss in decolorized areas.

Inventive Principle:

Principle #40Composite materials

2Temperature

If conventional decolorizable toner is used, then the toner can be removed by heating, but low-temperature fixability is poor

Engineering Contradiction:

Improvefixing temperatureVSAvoidlow-temperature fixability

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The fluoran-based color developable agent is designed with specific chemical parameters that allow it to remain stable at low fixing temperatures. The electron-donating substituents at positions 2 and 6 enhance the thermal stability of the colored form, enabling reliable color fixation at lower temperatures while maintaining decolorization capability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The toner formulation creates different thermal response characteristics in different components: the binder resin provides adhesion at low temperatures, while the fluoran-based color developable agent maintains color stability. This local differentiation of thermal properties enables both low-temperature fixability and reliable color retention.

Inventive Principle:

Principle #3Local quality

3Illumination intensity

If the color developable agent has strong color development, then the image quality is improved, but the decolorization becomes incomplete

Engineering Contradiction:

Improvecolor intensityVSAvoiddecolorization completeness

Core Design Contradiction:

Illumination intensityVSReliability

Solution Approach 1:

The fluoran-based color developable agent uses specific substituent parameters (electron-donating groups at positions 2 and 6) that create a balanced electronic structure. This structure enables strong color development through electron donation while maintaining susceptibility to decolorization by heating, achieving both high color intensity and complete decolorization.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The fluoran ring structure acts as an intermediary between the color developing agent and the binder resin. It accepts electrons from the color developing agent to form intense color, but the specific substituent pattern allows this colored intermediate to be readily decolorized by thermal energy, completing the decolorization cycle.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 toner achieves reliable decolorization with minimal gloss and maintains low-temperature fixability, allowing for efficient reuse of printed materials.

Implementation Method 1

The color developable agent is an electron donating compound

Methodology Applied

Scientific EffectElectron donation: Redox Reactions

Implementation Method 2

The color developing agent is an electron accepting compound

Methodology Applied

Scientific EffectElectron acceptance: Redox Reactions

Implementation Method 3

a decolorizable toner, which is decolorized by heating

Methodology Applied

Scientific EffectThermal decolorization: Thermolysis

Data Source

PatentUS9164408B2Electrophotographic toner

Publication Date: 2015.10.20 TOSHIBA TEC KK

AI summary

An electrophotographic toner contains an electron donating color developable agent, an electron accepting color developing agent, and a polyester resin binder which is a polyester resin obtained by polycondensation of a carboxylic acid component and an alcohol component and has a crosslinked structure formed of a crosslinking component including at least either one of a trivalent or higher valent carboxylic acid and a trihydric or higher hydric alcohol, and is decolorized by heating.