Core-Shell Toner with Dense Shell and Low-Temperature Fixation
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Solution Overview
Problem
Existing electrostatic image developing toners face challenges in achieving both low-temperature fixation performance and blocking resistance, as increasing the shell-to-core ratio for better blocking resistance often compromises low-temperature fixation, and methods like core-shell structures can result in non-coated areas or expose the core, leading to insufficient performance.
Innovation Solution
A core-shell structure is implemented where a resin coating layer of a water-soluble resin is applied to the core particles, followed by a shell layer of resin particles with a higher glass transition temperature, ensuring a high coating ratio and effective blocking resistance while maintaining low-temperature fixation performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the shell-to-core ratio is increased to improve blocking resistance, then blocking resistance is improved, but low-temperature fixation performance deteriorates
Solution Approach 1:
The invention applies local quality by creating a core-shell structure where the shell layer (with high Tg resin particles) provides blocking resistance at the toner surface, while the core (with low Tg binder resin) maintains low-temperature fixation performance. The shell layer thickness is controlled to be 0.01-5 μm to locally provide heat resistance without compromising the core's fixation capability.
Solution Approach 2:
The invention uses composite materials by combining resin particles with different glass transition temperatures. The shell layer contains resin particles with Tg of 80°C or higher (such as polystyrene, poly(methyl methacrylate), or polyacrylonitrile), while the core contains binder resin with lower Tg, creating a composite structure that simultaneously achieves blocking resistance and low-temperature fixation.
2Ease of manufacture
If heating at high temperature is applied to form core-shell structure, then shell particles adhere to core particles, but shell particles are buried and non-coated parts form, causing insufficient blocking resistance
Solution Approach 1:
The invention applies preliminary action by pre-forming the core particles with binder resin, colorant, and other components before adding the shell layer. The shell layer is then formed by incorporating resin particles with high Tg into the toner composition, which naturally adhere to the core particle surfaces during the granulation process, avoiding the need for post-adhesion heating that would bury the shell particles.
3Reliability
If the shell component is made large to improve blocking resistance, then blocking resistance is improved, but low-temperature fixation performance is disturbed
Solution Approach 1:
The invention applies parameter changes by precisely controlling the shell layer thickness to be 0.01-5 μm and the resin particle size in the shell layer to be 0.1-10 μm. This controlled parameter range ensures sufficient blocking resistance while maintaining enough low Tg binder resin in the core for effective low-temperature fixation, avoiding the trade-off between shell size and fixation performance.
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 novel core-shell structure effectively achieves both low-temperature fixation and blocking resistance by ensuring a thin, dense shell layer on the core particles, enhancing the toner's overall performance.
Implementation Method 1
a resin coating layer of a water-soluble resin is applied to the core particles, followed by a shell layer of resin particles
Implementation Method 2
a shell layer on the resin coating layer, the shell layer is formed of a particle comprising a resin as a main ingredient... a glass transition temperature of the polymer primary particle to constitute the core particle is referred to as Tg1, and a glass transition temperature of the particle to constitute the shell layer is referred to as Tg2, the Tg1 and Tg2 satisfy the following relationship: 25° C.≦Tg1≦45° C., 55° C.≦Tg2, Tg2−Tg1≧20
Data Source
AI summary
The object of the present invention is to provide an electrostatic image developing toner excellent in providing high image quality and excellent in low-temperature fixation performance and environmental stability. The present invention is an electrostatic image developing toner having a toner base particle containing at least a binder resin and a colorant, and an external additive, wherein the toner base particle has a core-shell structure having a core particle and a shell layer, the toner base particle has a resin coating layer of a water-soluble resin on the surface of the core particle, and has the shell layer on the resin coating layer.