Reactive Emulsion Toner with Epoxy Crosslinking
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Solution Overview
Problem
Existing toners lack the ability to remain permanently on image recording media, especially when subjected to bending and twisting, leading to poor document offset and crease properties, which is critical for packaging applications.
Innovation Solution
A reactive emulsion/aggregation toner is developed, comprising a styrene/acrylate resin with epoxy and carboxylic acid groups that crosslink during the fusing process at temperatures above 100°C, transforming low molecular weight resin into a high molecular weight toner with improved mechanical properties and scratch resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If low molecular weight resin is used in toner, then low minimum fixing temperature (MFT) is achieved, but document offset and crease properties are poor
Solution Approach 1:
The patent applies parameter changes by introducing functional groups (epoxy and carboxylic acid) into the resin structure that enable temperature-dependent crosslinking. At low temperatures during application, the resin remains in a low molecular weight state with low MFT. During fusing at elevated temperatures (100-200°C), the functional groups react to form crosslinked networks, transforming the resin into a high molecular weight structure with improved mechanical properties and permanent bonding to the substrate.
Solution Approach 2:
The patent creates a composite material system combining low molecular weight styrene/acrylate resin with reactive functional groups (epoxy and carboxylic acid). This composite approach allows the resin to exhibit dual characteristics: low viscosity and low MFT in the uncrosslinked state for easy application, and high strength and permanent adhesion in the crosslinked state after thermal processing.
2Reliability
If high molecular weight resin is used in toner, then document offset and crease properties are improved, but minimum fixing temperature increases
Solution Approach 1:
The patent applies preliminary action by pre-installing reactive functional groups (epoxy and carboxylic acid) into the low molecular weight resin structure during manufacturing. These groups remain dormant at low temperatures but are activated during the fusing process. This preliminary preparation allows the resin to achieve high molecular weight and improved mechanical properties only when needed, during thermal processing, while maintaining low MFT during storage and application.
3Strength
If crosslinking occurs during toner preparation, then high molecular weight and improved mechanical properties are achieved, but low molecular weight benefits are lost
Solution Approach 1:
The patent applies dynamics by making the molecular weight and crosslinking state of the resin temperature-dependent rather than fixed. The resin dynamically transitions from a low molecular weight, uncrosslinked state at low temperatures (providing low MFT and fluidity) to a high molecular weight, crosslinked state at high temperatures during fusing (providing improved mechanical properties). This dynamic behavior allows the resin to optimize its properties for each stage of the process.
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 crosslinking process enhances document offset and crease properties, providing a more permanent image that resists cracking and peeling, making the toner suitable for packaging applications.
Implementation Method 1
a reaction occurs between the epoxy group and the carboxylic acid group components such that there is crosslinking therebetween. Thus, a crosslinked toner is formed during fusing.
Implementation Method 2
after melting and curing on the image recording medium, e.g., paper product, etc., crosslinking will occur.
Data Source
AI summary
A toner is disclosed that includes a toner binder of a styrene/acrylate resin containing carboxylic acid substituents and epoxy substituents, and optionally a colorant and/or wax. The carboxylic acid substituents act as a curing agent and react with the epoxy substituents, causing rapid crosslinking of the toner. Curing occurs during the fusing process and at a temperature greater than 100° C.