Toner Base Particles with Surface Polyester Gradient and Silica

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Solution Overview

Problem

Toner development using polyester and vinyl resins faces challenges with moisture absorption and charge retention due to the migration of polyester resin to the surface, leading to decreased transfer rates, especially at high humidity.

Innovation Solution

The development of an electrostatic charge image toner with toner base particles containing both polyester and vinyl resins, where the polyester resin concentration is higher on the surface than inside, and sol-gel silica with an average circularity of 0.75 to 0.9 is applied to suppress moisture absorption and maintain charge stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If polyester resin is used in toner particles, then low-temperature fixability is improved, but moisture absorption increases at high humidity

Engineering Contradiction:

Improvefixing temperatureVSAvoidmoisture absorption

Core Design Contradiction:

TemperatureVSObject-affected harmful factors

Solution Approach 1:

The patent creates a non-uniform distribution of polyester resin within the toner particles, with higher concentration at the surface and lower concentration in the core. This local quality variation allows the surface to have moisture-resistant properties while the core maintains low-temperature fixability, resolving the contradiction between these two requirements.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent combines polyester resin and vinyl resin in a composite structure with specific concentration gradients. This composite material approach allows the toner to simultaneously achieve low-temperature fixability (from polyester resin) and moisture resistance (from vinyl resin dominance in the core), resolving the contradiction between these opposing properties.

Inventive Principle:

Principle #40Composite materials

2Stability of the object's composition

If sol-gel silica is added to toner particles, then charge stability is improved, but particle shape irregularity increases

Engineering Contradiction:

Improvecharge stabilityVSAvoidparticle circularity

Core Design Contradiction:

Stability of the object's compositionVSShape

Solution Approach 1:

The patent specifies a particular circularity range (0.75 to 0.9) for sol-gel silica particles to optimize the balance between charge stability and particle shape regularity. By controlling this geometric parameter within a specific range, the patent achieves sufficient charge stability while minimizing negative effects on particle shape and flow properties.

Inventive Principle:

Principle #35Parameter changes

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

This configuration enhances the toner's ability to maintain charge and transfer rate by preventing moisture absorption and reducing the migration of sol-gel silica, thereby improving the toner's performance in humid environments.

Implementation Method 1

sol-gel silica that has an average circularity of from 0.75 to 0.9, on the surface of the toner base particles

Methodology Applied

Scientific EffectAdsorption: Adsorption

Implementation Method 2

reducing the migration of sol-gel silica

Methodology Applied

Scientific EffectDiffusion Barrier: Diffusion Barrier

Data Source

PatentUS8956796B2Electrostatic charge image developing toner, electrostatic charge image developer, toner cartridge, developing device, image forming apparatus, and image forming method

Publication Date: 2015.02.17 FUJIFILM BUSINESS INNOVATION CORP

AI summary

Provided is an electrostatic charge image developing toner including toner base particles which contain a polyester resin and a vinyl resin and does not have a coating layer and wherein the concentration of the polyester resin on the particle surface is higher than the concentration of the polyester resin in the inside of the particles, and a sol-gel silica which has an average circularity of from 0.75 to 0.9, on the surface of the toner base particles.