Liquid Developer Pigment Dispersant Fixing Strength
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Solution Overview
Problem
Liquid developers for wet-type image forming based on wet electrophotography face issues with image fixity due to the presence of insulating liquid, which remains on recording materials, and basic pigment dispersants can deteriorate pigment dispersibility and increase viscosity, affecting granulation quality.
Innovation Solution
A liquid developer comprising toner particles with a resin, a pigment having an acid group, and a basic polymer dispersant including units derived from ε-caprolactone, which improves pigment dispersibility and fixing strength while maintaining suitable viscosity for high productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a basic pigment dispersant is added to improve fixing strength, then the fixing strength is improved, but the dispersibility of the pigment deteriorates and viscosity increases
Solution Approach 1:
The patent changes the chemical structure parameters of the pigment dispersant by specifying it must contain basic groups (amine, amino, imine, imino, or pyrrolidone) and specific functional groups (carboxyl, sulfonic acid, phosphoric acid, or boric acid). This parameter optimization allows the dispersant to simultaneously improve fixing strength while maintaining pigment dispersibility, resolving the contradiction between these two properties.
Solution Approach 2:
The patent creates a composite pigment dispersant system that combines multiple functional components: basic groups for fixing strength, hydrophilic groups (carboxyl, sulfonic acid, phosphoric acid, or boric acid) for dispersibility, and optional hydrophobic groups for compatibility with the insulating liquid. This composite structure enables simultaneous achievement of improved fixing strength and maintained dispersibility.
2Strength
If a basic pigment dispersant is added to improve fixing strength, then the fixing strength is improved, but the viscosity of the liquid droplet increases
Solution Approach 1:
The patent optimizes the molecular weight parameter of the basic pigment dispersant, specifying it should be in the range of 100 to 10,000. This parameter control prevents excessive viscosity increase while maintaining the fixing strength improvement function, thereby preserving granulation quality and productivity.
Solution Approach 2:
The patent introduces local quality by adding optional hydrophobic groups (alkyl, alkenyl, aryl, or aryloxy groups) to specific positions of the dispersant molecule. This local modification enhances compatibility with the insulating liquid and controls viscosity locally, preventing overall viscosity increase while maintaining fixing strength benefits.
3Ease of operation
If the liquid developer is used for image formation, then the image can be formed, but the fixity of the image is inferior due to the presence of insulating liquid
Solution Approach 1:
The patent uses the basic pigment dispersant as an intermediary substance between the pigment and the recording material. The dispersant's basic groups interact with the recording material surface while its hydrophilic groups interact with the pigment, mediating the fixation process and enabling strong image fixity despite the presence of insulating liquid.
Solution Approach 2:
The patent creates a composite toner particle structure where the pigment dispersant forms an interface layer between the pigment core and the recording material. This composite structure includes pigment particles coated with the multifunctional dispersant, enabling effective image fixation while maintaining liquid developer operability.
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 enhances pigment dispersibility and fixing strength, reduces viscosity issues, and maintains high productivity, resulting in improved image formation and handling characteristics.
Implementation Method 1
the pigment dispersant is a basic polymer dispersant including units derived from ε-caprolactone
Implementation Method 2
the resin is melted to be attached to and accordingly fixed on the recording material
Implementation Method 3
the pigment includes a pigment having an acid group, and the pigment dispersant is a basic polymer dispersant including units derived from ε-caprolactone
Data Source
AI summary
A liquid developer used for wet-type image forming apparatuses includes toner particles and an insulating liquid, the toner particles include a resin, a pigment, and a pigment dispersant, the pigment includes a pigment having an acid group, and the pigment dispersant is a basic polymer dispersant including units derived from ε-caprolactone.