Core-Shell Styrene-Acrylate Toner for Storage Stability

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Solution Overview

Problem

Current toner compositions, particularly styrene-acrylate toners, face challenges in meeting requirements for hot offset, gloss, aging, and storage stability, especially in single-component development machines, particularly for black toner applications.

Innovation Solution

The development of toner particles with a core-shell structure comprising specific styrene-acrylate copolymers, a wax, and an optional colorant, where the core and shell have defined molecular weights and glass transition temperatures, and the use of a flocculant and chelating agent to control aggregation and coalescence processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If styrene-acrylate toner compositions are used to meet machine requirements for hot offset, gloss, aging, and storage stability, then storage stability and durability are improved, but the complexity of achieving all requirements simultaneously creates formulation challenges

Engineering Contradiction:
Improvestorage stabilityVSAvoidformulation complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent employs composite materials by combining styrene-acrylate copolymer with specific molecular weights (32,000-38,000 g/mol) and controlled glass transition temperatures (57-61°C) with carefully selected waxes and colorants. This composite formulation achieves multiple performance requirements (hot offset resistance, gloss, aging stability, storage stability) simultaneously while managing formulation complexity through systematic component selection and ratio optimization.

Inventive Principle:
Principle #40Composite materials

2Illumination intensity

If core-shell structure with specific molecular weight copolymers is used, then gloss and low-melt properties are improved, but manufacturing precision requirements increase

Engineering Contradiction:
ImproveglossVSAvoidmolecular weight control
Core Design Contradiction:
Illumination intensityVSManufacturing precision

Solution Approach 1:

The patent applies parameter changes by specifying precise molecular weight ranges (32,000-38,000 g/mol for first copolymer, 52,000-58,000 g/mol for second copolymer) and controlled glass transition temperatures (57-61°C and 53-57°C respectively). These parameter specifications enable the core-shell structure to achieve desired gloss and low-melt properties while providing clear manufacturing guidelines to manage precision requirements.

Inventive Principle:
Principle #35Parameter changes

3Strength

If aggregation and coalescence processes are controlled using flocculant and chelating agent, then particle morphology and durability are improved, but process complexity increases

Engineering Contradiction:
ImprovedurabilityVSAvoidprocess complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent uses flocculant and chelating agent as intermediary substances to control the aggregation and coalescence processes. These intermediaries facilitate the formation of particles with desired morphology and enhance durability by controlling the interaction between copolymer components during processing, while adding manageable steps to the overall process.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 resulting toner composition exhibits improved storage stability, durability, and gloss characteristics, while maintaining low-melt properties and triboelectric charging characteristics, suitable for single-component development machines, particularly for black toner applications.

Implementation Method 1

the first core styrene-acrylate copolymer has a weight average molecular weight of from about 32,000 g/mol to about 38,000 g/mol and an onset glass transition temperature of from about 57.0° C. to about 61.0° C.

Methodology Applied
Scientific EffectGlass transition:

Implementation Method 2

The aggregation/coalescence process may include adding a flocculant

Methodology Applied
Scientific EffectFlocculation: Flocculation

Implementation Method 3

raising the temperature to a second temperature that is higher than the first temperature to coalesce the aggregated particles

Methodology Applied
Scientific EffectHeating: Heating

Data Source

PatentUS12066790B2Styrene-acrylate toner composition
Publication Date: 2024.08.20 XEROX CORP

AI summary

Toner particles including a core and a shell thereover; wherein the core comprises at least one styrene-acrylate copolymer selected from styrene-acrylate copolymer 1, styrene-acrylate copolymer 2, and styrene-acrylate copolymer 3, and combinations thereof a wax; and an optional colorant; wherein the shell comprises at least one styrene-acrylate copolymer selected from styrene-acrylate copolymer 1, styrene acrylate copolymer 2, styrene acrylate copolymer 3, and combinations thereof.