Hybrid Toner Particles Core Shell Structure

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Solution Overview

Problem

Existing hybrid toner particles face challenges in high-speed monochrome printing due to variations in surface morphology and melting temperatures, leading to issues like drum contamination and increased toner usage, particularly when combining styrene-acrylate and polyester resins in emulsion aggregation processes.

Innovation Solution

A method is developed to create hybrid toner particles with a core comprising polyester or a mixture of polyester and styrene-acrylate polymers, and a shell predominantly composed of styrene-acrylate polymers, using a continuous coalescence process to enhance surface morphology and fusing performance while reducing costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If styrene-acrylate and polyester resins are combined in emulsion aggregation processes, then cost is reduced and fusing performance is improved, but surface morphology varies and melting temperature varies leading to drum contamination

Engineering Contradiction:

ImprovecostVSAvoidsurface morphology

Core Design Contradiction:

Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The toner particle is divided into a core region containing polyester resin and a shell region containing styrene-acrylate resin. This segmentation allows each resin type to be positioned in the region where it provides optimal performance, eliminating the mixing issues that cause surface morphology variation while maintaining the cost and fusing performance benefits of combining both resins.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the toner particle are assigned different resin compositions tailored to local requirements. The core contains polyester for low MFT and good fusing, while the shell contains styrene-acrylate for cost efficiency and flow properties. This local quality assignment ensures that each material performs its best function without interfering with other materials.

Inventive Principle:

Principle #3Local quality

2Reliability

If polyester resin is used as base resin, then fusing performance is improved with lower MFT, but cost increases

Engineering Contradiction:

Improvefusing performanceVSAvoidcost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The composition parameters of the toner particle are changed by distributing different resins to different regions. By placing polyester resin in the core and styrene-acrylate in the shell, the particle achieves the low MFT and good fusing performance of polyester while incorporating the cost benefits of styrene-acrylate, thus optimizing the cost-performance parameter.

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If styrene-acrylate latex is used, then cost is reduced, but melting temperature varies leading to inhomogeneous surface morphology

Engineering Contradiction:

ImprovecostVSAvoidsurface morphology uniformity

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The toner particle is segmented into core and shell regions with different resin compositions. Styrene-acrylate resin is confined to the shell region, physically separated from the polyester-containing core. This segmentation prevents the melting temperature variation of styrene-acrylate from affecting the overall surface morphology uniformity, while still allowing cost reduction through styrene-acrylate usage.

Inventive Principle:

Principle #1Segmentation

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 particles exhibit improved circularity, fusing latitude, and reduced drum contamination, achieving high-speed printing with lower toner usage and maintaining good charge relative humidity performance.

Implementation Method 1

heating the aggregated particle to a first temperature beyond its glass transition temperature in a first heat exchanger to form a coalesced particles

Methodology Applied

Scientific EffectGlass transition:

Implementation Method 2

heating the aggregated particle to a first temperature beyond its glass transition temperature in a first heat exchanger to form a coalesced particles

Methodology Applied

Scientific EffectCoalescence: Coagulation

Implementation Method 3

quenching the coalesced particles to a second temperature below the glass transition temperature after a residence time

Methodology Applied

Scientific EffectQuenching:

Data Source

PatentUS9383666B1Toner particles comprising both polyester and styrene acrylate polymers having a polyester shell

Publication Date: 2016.07.05 XEROX CORP

AI summary

Toners and processes useful in providing toners suitable for electrophotographic apparatuses, including apparatuses such as digital, image-on-image, and similar apparatuses. In particular, emulsion aggregation toners that comprise toner particles having a core composed of either polyester resin or both styrene-acrylate and polyester resins. These embodiments also comprise a shell disposed over the core, wherein the shell comprises styrene-acrylate resin.