Positively Chargeable Toner Core-Shell Structure for Stable Image Quality
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Solution Overview
Problem
Existing toner technologies face challenges in maintaining consistent charge characteristics, leading to increased fogging density and reduced image quality over time, particularly when used in electrostatic latent image development.
Innovation Solution
A positively chargeable toner with a core-shell structure, where the shell layer contains a first resin with an amide group and a second resin with a quaternary ammonium cation, ensuring a stable charge distribution and improved charge rise characteristics, is developed. This toner is designed to maintain a charge amount of 20 μC/g or more after 3 minutes and a charge amount distribution with a coefficient of variation of 3.5 or less, minimizing fogging and enhancing image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a quaternary ammonium compound is used as a charge control agent to improve charge characteristics, then charge amount increases, but charge distribution uniformity deteriorates leading to increased fogging density
Solution Approach 1:
The charge control function is segmented between two distinct components: a quaternary ammonium compound (providing charge amount) and an amide compound (providing charge distribution uniformity). This segmentation allows each component to optimize its specific function without interfering with the other, resolving the contradiction between achieving high charge amount and maintaining uniform charge distribution.
Solution Approach 2:
The toner employs a composite charge control system combining a quaternary ammonium compound and an amide compound in specific proportions. This composite approach leverages the complementary properties of both compounds: the quaternary ammonium compound ensures sufficient charge amount while the amide compound maintains charge distribution uniformity, thereby preventing fogging density increase.
2Reliability
If stirring time is extended to achieve saturated charge amount, then charge completeness improves, but productivity decreases due to longer processing time
Solution Approach 1:
The toner particles are pre-engineered with a specific composition including quaternary ammonium compound and amide compound in optimized ratios, along with a core-shell structure that facilitates rapid charge acquisition. This preliminary preparation enables the toner to achieve saturated charge amount in just 3 minutes of stirring, rather than requiring extended stirring times, thus maintaining both charge completeness and productivity.
3Measurement precision
If charge amount is increased to improve image formation, then image quality improves, but fogging density increases due to unstable charge characteristics
Solution Approach 1:
The invention optimizes the parameters of the charge control system by specifying precise proportions: 0.1-10 parts by mass of quaternary ammonium compound and 0.1-10 parts by mass of amide compound per 100 parts by mass of toner. Additionally, the core-shell structure with specific glass transition temperature ranges (core: 50-150°C, shell: 30-100°C) is designed to stabilize charge characteristics. These parameter optimizations enable high charge amount (20 μC/g or more after 3 minutes) while maintaining stable charge distribution, thereby improving image quality without increasing fogging density.
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 achieves stable high-quality image formation with low fogging density, as demonstrated by the toner's ability to maintain charge characteristics over time, resulting in improved image quality and reduced fogging density even after printing 10,000 sheets.
Implementation Method 1
A positively chargeable toner contains a plurality of toner particles each containing a core, and a shell layer disposed over a surface of the core. The shell layer contains a first resin and a second resin. The first resin contains at least one repeating unit having an amide group. The second resin contains at least one repeating unit having a quaternary ammonium cation.
Implementation Method 2
the toner attains, in the first mixture, a charge amount Q3 after stirring for 3 minutes and attains a charge amount Q30 after stirring for 30 minutes, and both relationships of 'Q30≦Q3' and '20 μC/g≦Q3' are satisfied
Data Source
AI summary
A positively chargeable toner contains plural toner particles each containing a core, and a shell layer disposed over the core. The shell layer contains a first resin containing at least one repeating unit having an amide group, and a second resin containing at least one repeating unit having a quaternary ammonium cation. The toner attains a charge amount Q3 after stirring for 3 minutes and attains a charge amount Q30 after stirring for 30 minutes, and “Q30≦Q3” and “20 μC/g≦Q3” are both satisfied. Assuming that a second mixture of 100 parts by mass of the standard carrier and 10 parts by mass of the toner charged to a saturated charge amount is born on a development roller to measure a charge amount distribution, an arithmetic mean X and a standard deviation Y of the charge amount distribution satisfy “Y/X≦3.5”.