Polyester Toner with Phase-Separated Microstructure

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Solution Overview

Problem

Polylactic acid-based toners face challenges in achieving desired properties such as strength, compatibility, and thermal characteristics, leading to issues like background smear, filming, and toner scattering due to low molecular weight and poor dispersibility with other resins, which affects their durability and performance in electrophotographic processes.

Innovation Solution

A polyester resin with a controlled thermal characteristic and phase-separation structure is developed, incorporating a binder resin with a glass transition temperature between 25°C to 65°C and a specific phase difference structure observed through atomic force microscopy, ensuring both strength and storage stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If polylactic acid is used as a binder resin for toner, then environmental friendliness is improved, but toner strength and durability deteriorate

Engineering Contradiction:
Improveenvironmental friendlinessVSAvoidtoner strength
Core Design Contradiction:
Object-affected harmful factorsVSStrength

Solution Approach 1:

The invention uses a composite binder resin system comprising polylactic acid (PLA) combined with other polymer components. This composite approach allows the toner to maintain environmental benefits from PLA while gaining the strength and durability needed for practical use. The synergistic combination of materials resolves the contradiction between eco-friendliness and mechanical performance.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The invention modifies the molecular weight parameters of the polylactic acid component, specifically using high molecular weight PLA ( Mw: 100,000-1,000,000). This parameter change significantly improves toner strength and durability while maintaining the environmental benefits of using plant-derived polylactic acid as the binder resin.

Inventive Principle:
Principle #35Parameter changes

2Duration of action of stationary object

If polylactic acid is used as a binder resin, then biodegradability is improved, but compatibility and dispersibility with other resins deteriorate

Engineering Contradiction:
ImprovebiodegradabilityVSAvoidcompatibility and dispersibility
Core Design Contradiction:
Duration of action of stationary objectVSStability of the object's composition

Solution Approach 1:

The invention introduces intermediary components in the binder resin system that facilitate compatibility between polylactic acid and other resin materials. These intermediary substances act as compatibilizers, improving the dispersibility and uniform distribution of PLA within the multi-component toner formulation while preserving its biodegradable properties.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

By creating a composite binder resin system that includes polylactic acid combined with other compatible polymers and additives, the invention achieves both biodegradability and improved compatibility. The composite structure allows different materials to work synergistically, maintaining the environmental benefits while ensuring stable composition and good dispersibility.

Inventive Principle:
Principle #40Composite materials

3Device complexity

If polylactic acid is used alone for toner production, then simplicity of formulation is improved, but necessary toner properties deteriorate

Engineering Contradiction:
Improveformulation simplicityVSAvoidtoner properties
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The invention optimizes the molecular weight parameters of polylactic acid (using high molecular weight PLA with Mw: 100,000-1,000,000) to achieve necessary toner properties. This parameter modification allows the formulation to remain relatively simple while significantly improving reliability, strength, and durability characteristics.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention applies local quality enhancement by specifically targeting the molecular weight and structural characteristics of the polylactic acid component. Rather than completely redesigning the formulation, it locally optimizes the PLA properties to achieve the necessary toner performance while maintaining formulation simplicity.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP2756356B1Electrophotographic toner, developer containing the toner, and image forming apparatus
Publication Date: 2019.12.18 RICOH CO LTD
  • EP2756356B1 patent drawingFigure 1~2
  • EP2756356B1 patent drawingFigure 3~4
  • EP2756356B1 patent drawingFigure 5~6

AI summary

An electrophotographic toner including: a binder resin, wherein the binder resin has one glass transition temperature Tg and the glass transition temperature Tg of the binder resin is within 25°C to 65°C as measured in second heating with a differential scanning calorimeter at a heating rate of 5 °C/min, and wherein a phase image of the binder resin obtained with an atomic force microscope (AFM) of tapping mode contains first phase difference regions and a second phase difference region such that the first phase difference regions are dispersed in the second phase difference region, where the first phase difference regions correspond to greater phase difference regions and the second phase difference region corresponds to a smaller phase difference region when an intermediate value between a maximum value and a minimum value of the phase differences is used as a threshold.