Encapsulated Fluorescent Dye Polyurethane Dispersion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Encapsulating fluorescent and photochromic dyes into latex via emulsion polymerization is challenging due to stability issues with free radical environments, requiring a method to create a stable dye polyurethane dispersion for ink-jet applications.
Innovation Solution
A polyurethane dispersion is formed by reacting a urethane prepolymer, neutralizing agent, and chain extender, with the dye incorporated during prepolymer formation, ensuring the dye is not reactive to the polyisocyanate, resulting in a stable encapsulated dye dispersion with specific particle size, viscosity, and surface tension ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If fluorescent and photochromic dyes are incorporated into latex via emulsion polymerization, then the dye can be encapsulated in the polymer matrix, but the dye becomes unstable in the free radical environment leading to destruction of color
Solution Approach 1:
The patent uses a polyol as an intermediary carrier that solubilizes the fluorescent and photochromic dyes. The polyol forms a separate phase within the polyurethane dispersion, creating a protective microenvironment that isolates the dye from the free radical polymerization environment while still allowing the dye to be incorporated into the final latex product.
Solution Approach 2:
The patent segments the dye encapsulation process by using a two-phase system where the polyol forms distinct microdomains within the polyurethane dispersion. This segmentation separates the dye-containing polyol phase from the free radical polymerization environment, protecting the dye while maintaining encapsulation.
2Ease of manufacture
If dyes are made colorless for security ink applications, then the image remains invisible in daylight, but the dyes require special encapsulation methods to prevent degradation
Solution Approach 1:
The polyol serves multiple functions simultaneously: it acts as the polymeric colorant carrier, provides the encapsulation environment for the dye, and maintains dye stability without requiring separate encapsulation steps. The polyol's hydroxyl groups enable it to function as both the polymer backbone and the dye-solubilizing matrix.
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 encapsulated dye dispersion provides a stable and effective ink composition for ink-jet applications, maintaining stability during storage and repeated jetting cycles, and exhibits desired coloration upon irradiation.
Implementation Method 1
a urethane prepolymer, the urethane prepolymer being the catalyzed reaction product of: (i) a polyol; (ii) a polyisocyanate
Implementation Method 2
Upon irradiation of ultraviolet light, fluorescent dyes produce visible fluorescence (of different colors), rendering the image visible
Implementation Method 3
photochromic dyes are colorless in their normal state and become colored on exposure to activating radiation, such as ultraviolet light. The color formation generally includes a ring closure or ring opening in the photochromic dye molecule with the formation of conjugated double bonds
Data Source
AI summary
The present disclosure provides an encapsulated dye dispersion and an inkjet ink comprising an ink vehicle and an encapsulated dye dispersion thereof. In particular, the encapsulated dye dispersion includes a fluorescent and/or photochromic dye. The present disclosure also provides a process for producing the encapsulated dye dispersion.