Self-Dispersing Polymer Ink for Dischargeability and Head Repellency
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Solution Overview
Problem
Aqueous ink compositions for inkjet recording face challenges in achieving satisfactory dischargeability and maintaining liquid repellency of inkjet head members, with existing solutions failing to provide both high-quality image formation and long-term ink ejection performance.
Innovation Solution
An inkjet ink composition incorporating self-dispersing polymer particles with specific structural units, colloidal silica, and colorant particles, optimized with a glass transition temperature of 120°C or higher, I/O value between 0.20 and 0.55, and pH between 7.5 and 10, to enhance dischargeability and prevent liquid repellency deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional dispersion methods are used for aqueous ink, then the formulation process is simple, but pigment dispersibility is poor and product quality is unsatisfactory
Solution Approach 1:
The invention uses composite polymer particles comprising a water-insoluble polymer and a water-soluble polymer in a specific ratio (0.1-10 parts water-soluble polymer per 1 part water-insoluble polymer). This composite structure allows the water-insoluble polymer to provide good pigment dispersibility while the water-soluble polymer ensures adequate water solubility and dischargeability, resolving the contradiction between simple formulation and effective pigment dispersion.
2Object-affected harmful factors
If aqueous ink composition is used, then environmental protection and resource conservation are improved, but dischargeability and liquid repellency maintenance are insufficient compared to oil-based inks
Solution Approach 1:
The invention carefully controls the molecular weight of the water-soluble polymer (1,000-100,000) and its ratio to the water-insoluble polymer (0.1-10:1), as well as the ink composition pH (7.5-10.0). These parameter optimizations enable aqueous ink to achieve dischargeability comparable to oil-based inks while maintaining environmental advantages.
Solution Approach 2:
The composite polymer particle structure combines the hydrophobic properties of water-insoluble polymer (good for pigment binding) with the hydrophilic properties of water-soluble polymer (good for water compatibility and dischargeability), enabling aqueous ink to overcome its inherent dischargeability limitations.
3Strength
If polymer particles are added to improve image quality, then image scratch resistance is enhanced, but liquid repellency of inkjet head member deteriorates
Solution Approach 1:
The invention optimizes the glass transition temperature of the water-insoluble polymer (80-200°C) and controls the particle size (0.01-10 μm). These parameter controls ensure that polymer particles provide sufficient image strength and scratch resistance without excessive adhesion to the inkjet head, thereby maintaining liquid repellency.
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 ink composition ensures excellent dischargeability and maintains the liquid repellency of inkjet head members, improving image scratch resistance and stability over time.
Implementation Method 1
self-dispersing polymer particles, each of the self-dispersing polymer particles including a structural unit derived from a hydrophilic monomer and a structural unit derived from a hydrophobic monomer
Implementation Method 2
colloidal silica
Implementation Method 3
a glass transition temperature of 120°C or higher
Data Source
AI summary
The present invention provides an inkjet ink composition including: self-dispersing polymer particles, each of the self-dispersing polymer particles including a structural unit derived from a hydrophilic monomer and a structural unit derived from a hydrophobic monomer; colloidal silica; and colorant particles, the inkjet ink composition having excellent dischargeability and suppressing the deterioration of the liquid repellency of an inkjet head member.