Toner Formulation with Controlled Molecular Weight for Offset Resistance

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Solution Overview

Problem

Toner offset issues in image forming apparatuses due to poor compatibility between hydrocarbon wax and polyester resin, leading to agglomeration and inadequate releasing properties, result in degraded flowability and filming resistance.

Innovation Solution

A toner formulation comprising an amorphous polyester resin with an SP value of 11.0 to 11.5 (cal/cm3)1/2, a styrene resin with an SP value of 9.5 to 10.5 (cal/cm3)1/2, and hydrocarbon wax, with controlled molecular weight distribution to enhance dispersibility and filming resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If hydrocarbon wax is added to toner to prevent offset, then offset resistance is improved, but compatibility with polyester resin deteriorates leading to poor dispersion

Engineering Contradiction:

Improveoffset resistanceVSAvoiddispersion uniformity

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent changes the molecular weight parameter of the polyester resin to a specific range (3,000-6,000) to optimize the compatibility and dispersion of hydrocarbon wax in the toner composition

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite toner system combining polyester resin, hydrocarbon wax, and optional styrene resin to achieve both offset resistance and uniform dispersion through synergistic material interactions

Inventive Principle:

Principle #40Composite materials

2Reliability

If hydrocarbon wax with large dispersion diameter is used, then releasing property is improved, but toner particle agglomeration occurs degrading flowability

Engineering Contradiction:

Improvereleasing propertyVSAvoidflowability

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent optimizes the molecular weight parameter of polyester resin to control the dispersion diameter of hydrocarbon wax within an optimal range that prevents agglomeration while maintaining releasing properties

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent ensures uniform distribution of hydrocarbon wax throughout the toner particle structure, preventing localized concentration that would cause agglomeration while maintaining surface releasing properties

Inventive Principle:

Principle #3Local quality

3Ease of operation

If hydrocarbon wax with small dispersion diameter is used, then flowability is improved, but releasing property becomes insufficient

Engineering Contradiction:

ImproveflowabilityVSAvoidreleasing property

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent sets the molecular weight of polyester resin within a specific range (3,000-6,000) to achieve optimal dispersion diameter for hydrocarbon wax that balances flowability and releasing property

Inventive Principle:

Principle #35Parameter changes

4Reliability

If hydrocarbon wax is added to toner, then offset resistance is improved, but filming occurs over long period of use

Engineering Contradiction:

Improveoffset resistanceVSAvoidfilming resistance

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent optimizes the molecular weight parameter of polyester resin and controls the dispersion characteristics of hydrocarbon wax to prevent filming while maintaining offset resistance over extended usage periods

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent achieves homogeneous distribution of hydrocarbon wax throughout the toner composition to prevent localized accumulation and filming on surfaces during long-term operation

Inventive Principle:

Principle #33Homogeneity

Data Source

PatentUS20240012344A1Toner, developing agent, toner accommodating unit, image forming apparatus, and image forming method

Publication Date: 2024.01.11 RICOH CO LTD

AI summary

A toner contains an amorphous polyester resin with an SP value of from 11.0 to 11.5 (cal/cm3)1/2, a styrene resin with an SP value of from 9.5 to 10.5 (cal/cm3)1/2, and a hydrocarbon wax, wherein the molecular weight distribution of the toner soluble in tetrahydrofuran has the main peak between 3,500 to 5,500 as measured by gel permeation chromatography.