Microcapsule Imaging Sheets With Reactive Diluent Crosslinking
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Solution Overview
Problem
Conventional microcapsule imaging systems suffer from poor temperature latitude, mid-tone rendition, and slow color development, leading to poor image quality and resolution due to the use of photopolymerizable leuco dyes and solvents.
Innovation Solution
Incorporating a non-photopolymerizable reactive diluent, such as an epoxide compound, which reacts with leuco dye developers to improve image resolution and edge sharpness by crosslinking with phenol or carboxylic groups, enhancing film integrity and color development rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a non-polymerizable inert solvent or diluent is added to improve leuco dye solubility and reduce internal phase viscosity, then color development is enhanced, but non-uniform image quality, poor film integrity, and delamination occur
Solution Approach 1:
The patent changes the chemical reactivity parameter of the diluent from inert to reactive. By using a reactive diluent that can form crosslinks with the photopolymer matrix, the system maintains improved color development (through reduced viscosity) while preventing film delamination and non-uniform image quality through enhanced crosslinking density and matrix stability.
Solution Approach 2:
The patent creates a composite internal phase system combining leuco dye, photopolymerizable monomer, photoinitiator, and reactive diluent. The reactive diluent forms crosslinks with the photopolymer matrix, creating a composite structure that simultaneously achieves low viscosity for fast color development and high mechanical integrity to prevent delamination.
2Quantity of substance
If high concentration of leuco dyes is included to increase color density, then color saturation is improved, but leuco dyes precipitate at low storage or operation temperatures, resulting in poor image quality
Solution Approach 1:
The patent changes the physical parameters of the internal phase by incorporating a reactive diluent that forms crosslinks with the photopolymer matrix. This crosslinking network maintains dye solubility at high concentrations while preventing precipitation at low temperatures, thereby improving both color density and temperature latitude simultaneously.
Solution Approach 2:
The reactive diluent acts as an intermediary substance that mediates between the photopolymer matrix and the leuco dye. It forms crosslinks with the matrix while maintaining dye solubility, preventing direct precipitation of the dye at low temperatures while allowing high color density.
3Quantity of substance
If high concentration of leuco dyes is included to increase color density, then color saturation is improved, but mobility of leuco dyes is poor due to high viscosity of internal phase, causing loss of mid-tone details
Solution Approach 1:
The patent changes the viscosity parameter of the internal phase by incorporating a reactive diluent. The diluent reduces the viscosity of the internal phase, enabling better dye mobility even at high dye concentrations, thereby improving mid-tone rendition while maintaining high color density.
Solution Approach 2:
The reactive diluent creates local variations in crosslinking density within the internal phase. This allows different regions to have different viscosities, improving dye mobility in mid-tone regions while maintaining high dye concentration for saturation in highlight and shadow regions.
4Quantity of substance
If maximum color density is achieved, then color saturation is improved, but leuco dyes spread extensively, causing deterioration of image resolution, particularly with respect to edge sharpness
Solution Approach 1:
The patent changes the crosslinking parameter of the internal phase by using a reactive diluent. The crosslinks formed by the reactive diluent act as physical barriers that limit dye spread, thereby maintaining image resolution and edge sharpness even at maximum color density.
Solution Approach 2:
The reactive diluent acts as an intermediary that forms crosslinks with the photopolymer matrix, creating a network structure that mediates between dye concentration and dye spread. This network allows high color saturation while preventing excessive dye migration that would degrade edge sharpness.
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 use of a non-photopolymerizable reactive diluent results in improved image resolution, edge sharpness, and film integrity without compromising image quality, achieving high color saturation and faster color development.
Implementation Method 1
the epoxide released from the ruptured microcapsules reacts and crosslinks with the phenol or carboxylic group of the developers
Implementation Method 2
a photoinitiator; and a polymerizable or crosslinkable monomer or oligomer
Data Source
AI summary
Microcapsules including a polymeric shell and an internal phase including a non-photopolymerizable reactive diluent are provided for use in microcapsule imaging sheets. Imaging sheets including microcapsules which include a non-photopolymerizable reactive diluent, and which exhibit improvements in color development (Dmax), discoloration (yellowing) resistance, mechanical properties (e.g., peel strength), and temperature latitude of imaging sheets including leuco dyes.