Amorphous Polyester Toner for Yellow Pigment Chargeability
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Solution Overview
Problem
Existing toners with highly hydrophilic organic yellow pigments face issues with chargeability and image density, leading to inadequate performance in electrostatic image development.
Innovation Solution
A toner formulation using an amorphous polyester resin with a specific ester group concentration and an organic yellow pigment with a defined NH group content, enhancing pigment dispersion and improving chargeability and image density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If highly hydrophilic organic yellow pigment is used to improve color brightness, then image density is improved, but chargeability deteriorates
Solution Approach 1:
The invention changes the chemical parameters of the binder resin by controlling the ester group concentration to 5.0-12.0 mmol/g and selecting specific resin types (amorphous polyester, crystalline polyester, styrene-acrylic copolymer) with specific glass transition temperatures and molecular weights. This parameter optimization enables the system to achieve both high image density and excellent chargeability by balancing the resin's affinity for the hydrophilic pigment while maintaining proper charge transfer properties.
Solution Approach 2:
The invention uses a composite binder resin system combining multiple resin types (amorphous polyester resin, crystalline polyester resin, and styrene-acrylic copolymer resin) rather than a single resin. This composite approach allows the system to simultaneously achieve pigment dispersion, chargeability, and image density by leveraging the complementary properties of each resin component.
2Illumination intensity
If pigment content is increased to improve image density, then color intensity is improved, but pigment exposure on surface increases causing chargeability to deteriorate
Solution Approach 1:
The invention optimizes the pigment's NH group content parameter to 4.0-15.0 mmol/g, which controls the pigment's hydrophilicity and surface interaction properties. This parameter control ensures adequate pigment content for high image density while preventing excessive surface exposure that would harm chargeability.
Solution Approach 2:
The invention creates local quality differences within the toner structure by using a binder resin system with specific ester group concentrations that provide different interaction strengths at different locations. The resin structure ensures proper pigment binding throughout the particle while maintaining appropriate surface properties for charge transfer.
3Reliability
If ester group concentration is increased to improve pigment dispersion, then chargeability is improved, but manufacturing complexity increases
Solution Approach 1:
The invention specifies a practical ester group concentration range of 5.0-12.0 mmol/g that balances performance and manufacturability. This parameter range is high enough to ensure good pigment dispersion and chargeability but low enough to avoid excessive manufacturing complexity and cost.
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 excellent chargeability and produces printed matters with high image density by improving pigment dispersion through hydrogen bonding between the ester groups and amino groups, reducing pigment exposure on the toner surfaces.
Implementation Method 1
improving pigment dispersion through hydrogen bonding between the ester groups and amino groups
Implementation Method 2
A toner for electrostatic image development, containing a binder resin and a colorant
Data Source
AI summary
The present invention relates to a toner for electrostatic image development, containing a binder resin and a colorant, wherein the binder resin contains an amorphous polyester resin A having an ester group concentration of 5.0 mmol/g or more and 12.0 mmol/g or less, and the colorant is an organic yellow pigment having an NH group content of 4.0 mmol/g or more and 15.0 mmol/g or less wherein the NH group content is a value obtained by dividing a total number of -NH- and -NH2 contained in one molecule by a molecular weight.