Core-Shell Toner with Vinyl Polymerizable Shell

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Solution Overview

Problem

Conventional core-shell toners face issues where excessive shell removal leads to adhesion to toner-regulating blades and insufficient shell results in background smear, while external additives are embedded, affecting flowability and durability.

Innovation Solution

A toner with a core-shell structure where the shell is firmly attached to prevent adhesion to the toner-regulating blade and acts as a spacer to prevent external additive embedment, achieved by controlling the shell's removal using ultrasonic treatment and centrifugation to ensure optimal transmittance and surface coverage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a large amount of shell is formed in core-shell toners, then durability and chargeability are improved, but the shell is removed from the toner surface and adheres to the toner-regulating blade

Engineering Contradiction:
Improvedurability and chargeabilityVSAvoidshell adhesion to toner-regulating blade
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The invention changes the physical and chemical parameters of the shell material by using a specific vinyl polymerizable resin with controlled molecular weight (10,000-100,000) and functional groups. This parameter optimization allows the shell to maintain sufficient adhesion to prevent blade contamination while retaining enough removal to provide durability and chargeability benefits.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention uses a composite structure combining polyester resin core with vinyl polymerizable resin shell. This composite material approach allows each component to contribute its strengths: the core provides structural integrity and heat resistance, while the shell provides chargeability and controlled removal characteristics that prevent blade adhesion.

Inventive Principle:
Principle #40Composite materials

2Object-generated harmful factors

If the amount of shell is too small or insufficient, then shell removal does not cause adhesion to toner-regulating blade, but background smear occurs

Engineering Contradiction:
Improveprevention of shell adhesion to bladeVSAvoidbackground smear
Core Design Contradiction:
Object-generated harmful factorsVSObject-affected harmful factors

Solution Approach 1:

The invention optimizes the shell thickness and material composition parameters to achieve a critical balance. The vinyl polymerizable resin shell with specific molecular weight ranges provides just enough material to prevent background smear through proper coverage, while the controlled removal characteristics prevent excessive adhesion to the regulating blade.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The shell acts as a protective layer that copies or replicates the toner surface properties, providing a uniform coating that prevents background smear. The controlled removal of this copied layer during operation allows for proper toner regulation without blade contamination.

Inventive Principle:
Principle #26Copying

3Ease of operation

If external additives are added to improve flowability, then toner flowability is enhanced, but the additives are embedded in the toner particles causing insufficient flowability and durability

Engineering Contradiction:
ImproveflowabilityVSAvoiddurability and flowability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The vinyl polymerizable resin shell forms a flexible, porous thin film structure that allows external additives to be properly positioned on the toner surface without deep embedding. This shell structure maintains additive availability for flowability enhancement while protecting toner durability through proper surface coverage.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The shell structure incorporates porous characteristics that allow controlled interaction between external additives and the toner core. This porous structure prevents excessive embedding of additives while maintaining their functional benefits for flowability and preserving toner durability through the shell barrier.

Inventive Principle:
Principle #31Porous materials

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 solution ensures high chargeability and durability of the toner with improved fixability and reduced background smear, while maintaining the shell's spacer effect to prevent external additive embedment, enhancing overall toner performance.

Implementation Method 1

irradiating with ultrasonic waves of 20 kHz and 80 W for 5 min

Methodology Applied
Scientific EffectUltrasonic vibration: Ultrasonic Vibration

Implementation Method 2

a liquid containing the toner dispersed therein is centrifugated at 3,000 rpm for 5 min

Methodology Applied
Scientific EffectCentrifugal separation: Centrifugal Separation

Data Source

PatentEP2756355B1Latent electrostatic image developing toner
Publication Date: 2016.05.18 RICOH CO LTD
  • EP2756355B1 patent drawingFigure 1~2
  • EP2756355B1 patent drawingFigure 3~4
  • EP2756355B1 patent drawingFigure 5~6

AI summary

A toner including: a core particle containing at least a binder resin, a colorant and a releasing agent; and a shell on a surface of the core particle, wherein the toner gives a supernatant having a transmittance of 50% to 95% with respect to light having a wavelength of 800 nm, where the supernatant is formed after 3 g of the toner is added to 40 g of ion-exchange water containing 0.5% by mass of sodium dodecyl sulfate, followed by stirring for 90 min and by irradiating with ultrasonic waves of 20 kHz and 80 W for 5 min, and a liquid containing the toner dispersed therein is centrifugated at 3,000 rpm for 5 min.