Core-Shell Toner with Oxazoline Shell for Formaldehyde Control
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Solution Overview
Problem
The existing toners face challenges with high-temperature preservability, low-temperature fixability, and charge retention, and they tend to generate free formaldehyde, especially in high-humidity environments due to the use of hydrophilic thermosetting resins like melamine.
Innovation Solution
The development of an electrostatic latent image developing toner with toner particles having a core-shell structure, where the shell layer contains a hydrophilic thermosetting resin with oxazoline, carbodiimide, or isocyanate groups and a hydrophobic thermoplastic resin exposed on the surface, which inhibits free formaldehyde generation and improves charge retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a hydrophilic thermosetting resin such as melamine is used to improve low-temperature fixability, then the toner can be fixed at lower temperatures, but free formaldehyde is generated and the resin absorbs water molecules in high-temperature and high-humidity environments
Solution Approach 1:
The invention changes the chemical parameters of the thermosetting resin by selecting specific functional groups (oxazoline, carbodiimide, or isocyanate groups) that do not generate free formaldehyde, while maintaining the low-temperature fixability property through appropriate glass transition temperatures (40-150°C)
Solution Approach 2:
The invention creates a composite shell layer containing both hydrophilic thermosetting resin (for low-temperature fixability) and hydrophobic thermoplastic resin (to prevent water absorption and formaldehyde generation), achieving synergistic effects that resolve the technical contradiction
2Temperature
If a hydrophilic thermosetting resin such as melamine is used to improve low-temperature fixability, then the toner can be fixed at lower temperatures, but the toner absorbs water molecules in high-temperature and high-humidity environments
Solution Approach 1:
The invention creates a composite shell layer containing both hydrophilic thermosetting resin (for low-temperature fixability) and hydrophobic thermoplastic resin (to prevent water absorption), achieving synergistic effects that resolve the technical contradiction between low-temperature fixability and high-temperature preservability
Solution Approach 2:
The invention applies different properties to different parts of the shell layer: the hydrophilic thermosetting resin provides low-temperature fixability while the hydrophobic thermoplastic resin provides water resistance, with each component performing its specific function in the composite structure
3Reliability
If toner particles are preserved at high temperature, then the toner can be stored in various conditions, but the toner particles tend to agglomerate and reduce charge amount
Solution Approach 1:
The invention forms a protective shell layer around the toner core beforehand, which prevents agglomeration of toner particles during high-temperature storage, thereby preserving charge amount and maintaining storage stability
4Reliability
If a shell layer containing thermosetting resin is formed to improve high-temperature preservability and low-temperature fixability, then the toner performance is improved, but the shell layer structure becomes more complex
Solution Approach 1:
The invention uses a composite shell layer structure combining thermosetting resin and thermoplastic resin, where each component serves a specific function: thermosetting resin for high-temperature preservability and low-temperature fixability, and thermoplastic resin for water resistance and structural integrity
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 exhibits excellent high-temperature preservability, low-temperature fixability, and charge retention with minimal free formaldehyde generation, even in high-humidity conditions, as demonstrated by the Examples and Comparative Examples.
Implementation Method 1
The hydrophobic thermoplastic resin is exposed at surfaces of the toner particles
Implementation Method 2
In the second shell layer formation process, the aqueous medium is heated to form shell layers containing the hydrophilic thermosetting resin and the hydrophobic thermoplastic resin on the surfaces of the toner cores
Data Source
AI summary
An electrostatic latent image developing toner includes toner particles each including a toner core (10) and a shell layer (20) covering a surface of the toner core (10). The shell layer (20) contains a hydrophilic thermosetting resin and a hydrophobic thermoplastic resin. The hydrophilic thermosetting resin is a resin having at least one functional group selected from the group consisting of oxazoline groups, carbodiimide groups, and isocyanate groups. The hydrophobic thermoplastic resin is exposed at surfaces of the toner particle.