Electrophotographic Toner Copper Ratio UV Stability

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Solution Overview

Problem

Conventional electrophotographic toners suffer from discoloration and decoloration issues, particularly with magenta and yellow colors, due to ultraviolet radiation, which affects image stability and longevity, especially in natural color regions with low toner density.

Innovation Solution

Incorporating a copper compound into the toner, with a specific copper-to-carbon content ratio, to prevent discoloration and decoloration by stabilizing the colorants and using an ultraviolet absorbent to further enhance light resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a toner is used for electrophotographic image formation, then image formation capability is achieved, but discoloration and decoloration occur due to ultraviolet radiation

Engineering Contradiction:

Improveimage stabilityVSAvoidultraviolet radiation damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A copper compound is introduced as an intermediary substance between the ultraviolet radiation and the colorant molecules. The copper compound absorbs or scatters the ultraviolet radiation before it can reach and decompose the colorant molecules, thereby preventing discoloration and decoloration while allowing the electrophotographic image formation to proceed normally.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The copper compound, which may have been considered an additive without primary function, is discovered to provide ultraviolet protection. The harmful ultraviolet radiation that would normally decompose colorant molecules is instead utilized to excite the copper compound, which then protects the colorant through energy transfer or absorption mechanisms.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Adaptability or versatility

If magenta and yellow colorants are used for natural color reproduction, then color reproduction capability is improved, but discoloration tendency increases

Engineering Contradiction:

Improvecolor reproduction capabilityVSAvoidcolor stability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The copper compound is specifically positioned in relation to the magenta and yellow colorants within the toner particle structure. By localizing the copper compound near these particular colorants, the protection against ultraviolet radiation is applied selectively where it is most needed, while maintaining the overall color reproduction capabilities of the toner system.

Inventive Principle:

Principle #3Local quality

3Adaptability or versatility

If toner density is reduced for natural color regions, then image quality is improved, but discoloration becomes more conspicuous

Engineering Contradiction:

Improvenatural color reproductionVSAvoiddiscoloration visibility

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The copper compound serves as a protective intermediary that is distributed throughout the toner particle, providing ultraviolet protection even in regions with low toner density. This ensures that natural color regions with minimal toner coverage still receive adequate protection against discoloration, maintaining both image quality and color stability.

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 copper compound effectively prevents discoloration and decoloration of yellow and magenta colorants, ensuring stable image reproduction and longevity, particularly in natural color regions with low toner density, while the ultraviolet absorbent enhances light resistance.

Implementation Method 1

a compound having an ultraviolet ray absorbing capability is contained in a toner along with a pigment to reduce irradiation of the pigment with an ultraviolet ray

Methodology Applied

Scientific EffectUltraviolet absorption: Absorption (EM radiation)

Implementation Method 2

an ultraviolet ray is absorbed, and the light energy thus absorbed is converted to vibration energy within molecules, whereby affection thereof to the other materials in the toner is suppressed

Methodology Applied

Scientific EffectEnergy conversion:

Data Source

PatentUS7303846B2Electrophotographic toner, process for producing the same, and process for forming image

Publication Date: 2007.12.04 FUJIFILM BUSINESS INNOVATION CORP

AI summary

An electrophotographic toner contains at least a binder resin and a colorant, and log10{[Cu]/[C]} satisfies the following equation (1):−5.0≦log10{[Cu]/[C]}≦−3.5 (1)in which, [C] represents a carbon content (%) and [Cu] represents a copper content (%), measured with fluorescent X-ray. An electrophotographic developer containing the toner, a method for producing the toner, and a method for forming an image by using the toner are also provided.