Toner with Boric Acid Crosslinking and Shell Barrier
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Solution Overview
Problem
Existing toners face challenges in achieving both low-temperature fixability and heat-resistant storage stability due to surface migration of low-molecular-weight resins and release agents, leading to decreased charging characteristics and image defects in high-temperature and high-humidity environments.
Innovation Solution
A toner composition comprising a binder resin and boric acid, where boric acid forms a crosslinked structure with the binder resin, and a fatty acid metal salt is applied on the toner surface to prevent boric acid exudation, maintaining low-temperature fixability and heat-resistant storage stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the glass transition temperature (Tg) of the binder resin is lowered to enable low-temperature fixing, then low-temperature fixability is improved, but low-molecular-weight resin and release agent migrate to the toner surface, causing decreased heat-resistant storage stability
Solution Approach 1:
A shell layer comprising a polyester resin and a polyol is introduced as an intermediary between the binder resin core and the external environment. This shell layer has high affinity for low-molecular-weight resins and release agents through hydrogen bonding, acting as a barrier that prevents their migration to the toner surface while allowing the binder resin to maintain low Tg for low-temperature fixing
Solution Approach 2:
The toner is structured as a composite material with a core-shell architecture: the core contains the binder resin with low Tg for low-temperature fixing, while the shell contains polyester resin and polyol components that provide heat-resistant storage stability by suppressing surface migration of low-molecular-weight substances
2Reliability
If a shell is formed on the toner core particle surface to suppress migration of low-molecular-weight resin and release agent, then heat-resistant storage stability is improved, but low-temperature fixability is lowered due to inhibition of fixing
Solution Approach 1:
The shell layer parameters are precisely controlled: the polyester resin has a specific melting point range (60-100°C) and the polyol has a specific glass transition temperature range (-50-0°C). By adjusting these parameters, the shell provides sufficient stability at storage temperatures while remaining permeable enough to allow fixing at low temperatures
3Reliability
If boric acid is incorporated into the toner particle to form a crosslinked structure with the binder resin, then both heat-resistant storage stability and low-temperature fixability are achieved, but the crosslinked structure collapses in high-temperature and high-humidity environment, causing free boric acid to exude onto the surface and reduce charging characteristics
Solution Approach 1:
The shell layer acts as an intermediary barrier that prevents free boric acid from migrating to the toner surface. The polyester resin and polyol in the shell have high affinity for boric acid through hydrogen bonding, trapping it within the shell structure and preventing exudation onto the surface in high-temperature and high-humidity environments
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 effectively suppresses deterioration of charging characteristics, enabling the formation of high-quality electrophotographic images with excellent low-temperature fixability and heat-resistant storage stability even in harsh environments, with a long service life.
Implementation Method 1
the boric acid and the functional groups of the binder resin in the toner particle form a crosslinked structure
Implementation Method 2
a fatty acid metal salt on a surface of the toner particle... preventing boric acid exudation
Data Source
AI summary
A toner comprising a toner particle, the toner particle comprising a binder resin and a boric acid, wherein, where the toner particle is subjected to ATR-IR analysis by using germanium as an ATR crystal in an ATR method, a peak corresponding to the boric acid is detected, the toner comprises a fatty acid metal salt on a surface of the toner particle, and a presence ratio of an boron element on the surface of the toner particle is 0.01 atomic % or less as measured by X-ray photoelectron spectroscopy.