White Toner Composition for Charge Uniformity and Stable Printout
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Solution Overview
Problem
Existing white toners suffer from charge uniformity issues and environmental stability, leading to image defects such as fogging and inconsistent image density due to broad charge amount distribution and charging instability.
Innovation Solution
A white toner formulation containing a white pigment with a work function of 5.80 eV to 6.10 eV and an inorganic fine particle with a work function of 6.15 eV or more, in specific mass ratios, to achieve charge neutralization and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional white pigments (aluminum oxide, titanium oxide, magnesium oxide, calcium oxide) are used as negative toner, then the toner can be formed with white color, but the white pigment is likely to be positively charged causing uneven charge distribution and broad charge amount distribution
Solution Approach 1:
The patent changes the work function parameter of the white pigment to a specific range (5.80-6.10 eV) to achieve proper charge characteristics. This parameter optimization ensures the pigment remains positively charged enough for toner formation while avoiding excessive positive charge that causes uneven distribution
Solution Approach 2:
The patent creates a composite toner material combining binder resin with specifically controlled white pigment (work function 5.80-6.10 eV) and inorganic fine particle (work function ≥6.15 eV). This composite structure achieves charge neutralization between the two inorganic components while maintaining the white color and proper charge uniformity
2Illumination intensity
If two types of titanium oxide particles are used to improve whiteness and lightfastness, then the whiteness and lightfastness are improved, but the charging stability in usage environment is insufficient causing image density variation and fogging
Solution Approach 1:
The patent optimizes the work function parameter of the white pigment to a narrow range (5.80-6.10 eV) which provides both sufficient whiteness and proper charge stability. This specific parameter selection avoids the charging instability observed with conventional titanium oxide formulations
Solution Approach 2:
The inorganic fine particle with work function ≥6.15 eV acts as a charge control intermediary that neutralizes excessive positive charge from the white pigment. This intermediary component stabilizes the overall charge distribution and prevents fogging while maintaining image density consistency across different usage environments
3Illumination intensity
If white pigment with high positive charge is used to ensure white color, then the white color is achieved, but fogging phenomenon occurs in non-image portions and image density stability is poor
Solution Approach 1:
The patent converts the potentially harmful excessive positive charge of white pigment into a beneficial controlled charge distribution. By selecting work function 5.80-6.10 eV, the pigment provides sufficient positive charge for toner formation while the inorganic fine particle (work function ≥6.15 eV) balances this charge, transforming what would be harmful fogging into controlled charge neutralization that prevents both fogging and density instability
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 toner provides high charge uniformity and stable print-out of high-quality images across varying environments, reducing image defects and ensuring consistent image density.
Implementation Method 1
the white pigment has a work function of 5.80 eV or more and 6.10 eV or less, the inorganic fine particle has a work function of 6.15 eV or more
Data Source
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AI summary
The present invention provides a white toner which has high charge uniformity and enables stable print-out of high-quality images irrespective of its usage environment. The above object can be solved by a white toner including a white toner particle containing a binder resin, a white pigment and an inorganic fine particle, in which the white pigment has a work function of 5.80 eV or more and 6.10 eV or less, the content of the white pigment is 15.0 parts by mass or more and 60.0 parts by mass or less relative to 100 parts by mass of the binder resin, and the inorganic fine particle has a work function of 6.15 eV or more.