Isophthalic-Polyester Toner With Stable Silica-Resin Agglomerates
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Solution Overview
Problem
Existing toners experience a decrease in image density when used for a large number of sheets due to the collapse of silica agglomerates and embedding of external additives, which affects flowability and image quality.
Innovation Solution
A toner formulation with a binder resin containing 50% or more polyester derived from isophthalic acid, agglomerates of silica and resin on the surface, and specific ultrasonic treatment conditions to maintain agglomerate integrity and supply fresh external additives, inhibiting embedding and collapse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silica agglomerates are used as external additives to maintain image quality in high-temperature and high-humidity environments, then fogging is inhibited, but the agglomerates collapse after prolonged use causing decrease in image density
Solution Approach 1:
The external additive is segmented into two distinct components: silica particles (0.1-10 μm) and fine inorganic particles (0.003-0.05 μm). This segmentation allows the silica to provide structural integrity and fogging resistance, while the fine inorganic particles continuously replenish the surface to prevent collapse during prolonged use, thus resolving the contradiction between initial reliability and long-term durability.
Solution Approach 2:
The patent implements a mechanism where fine inorganic particles are continuously supplied to the toner surface during use, replacing the silica that gradually collapses or embeds into toner particles. This recovery mechanism ensures that the external additive layer is continuously refreshed, maintaining image density and preventing the deterioration that occurs with conventional silica-only additives.
2Ease of operation
If conventional external additives are disposed on toner surfaces to control surface properties, then flowability and charge generation are improved, but the additives embed in toner particles after prolonged use causing decrease in image density
Solution Approach 1:
The toner formulation enables self-service by incorporating fine inorganic particles that automatically replenish the external additive layer during normal operation. As silica particles embed into toner particles over time, the fine inorganic particles migrate to the surface to replace them, creating a self-regenerating system that maintains flowability and prevents image density decrease without requiring external intervention.
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 maintains toner flowability and prevents a decrease in image density over a long period of use by stabilizing agglomerate disintegration and external additive supply, ensuring consistent image quality.
Implementation Method 1
various fine organic or inorganic powders commonly called external additives are disposed on the surfaces of toner particles to control the surface properties of the toner particles
Implementation Method 2
Silica imparts flowability to toner and plays an important role in generating and maintaining electric charge through triboelectric charging
Implementation Method 3
the toner has a CI (% by number) of 1% or more by number and 15% or less by number... when the toner has been treated under ultrasonic condition A... when the toner has been treated under ultrasonic condition B
Data Source
AI summary
A toner includes toner particles each containing a binder resin. The binder resin contains 50% or more by mass of a polyester A containing 60 mol % or more of a unit derived from isophthalic acid as an acid component. The toner includes agglomerates on surfaces of the toner particles, each of the agglomerates containing silica and a resin. The toner has a CI (% by number) of 1% or more by number and 15% or less by number, CI being the percentage by number of the toner particles including the agglomerates. The percentage by number of the toner particles including the agglomerates satisfies predetermined requirements.