Curable Ink Composition for High Refractive Index Optical Coatings
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Solution Overview
Problem
The challenge in optical devices is to achieve high refractive index coatings with optical clarity and precision, particularly in multilayer structures where the mismatch of refractive indices between layers leads to undesirable refraction or reflection of light, and existing solutions face issues with the use of solvents and the dispersion of high refractive index inorganic nanoparticles.
Innovation Solution
A curable ink composition comprising a curable aromatic monomer and surface-treated metal oxide nanoparticles, where the nanoparticles are treated with a mixture of silane-functional surface treatment agents, allowing for inkjet printing without solvents and achieving a refractive index of 1.55 or greater with optical clarity, and an inorganic barrier layer is deposited on the cured layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If high refractive index inorganic nanoparticles are used to achieve high refractive index coatings, then the refractive index is improved, but the optical clarity and dispersion of nanoparticles deteriorate
Solution Approach 1:
Silane-functional surface treatment agents act as intermediaries between the inorganic metal oxide nanoparticles and the organic polymer matrix. These surface treatment agents modify the nanoparticle surfaces to improve dispersion within the polymer, preventing aggregation that would compromise optical clarity. The silane groups form a transition layer that is compatible with both inorganic and organic phases, enabling high refractive index while maintaining transparency.
Solution Approach 2:
The invention creates a composite material system combining inorganic metal oxide nanoparticles with organic polymer matrices, where the nanoparticles provide high refractive index and the polymer provides optical clarity and flexibility. The composite structure allows the beneficial properties of both materials to be realized simultaneously, with the inorganic particles enhancing optical properties while the organic matrix maintains clarity and processability.
2Ease of manufacture
If solvent-based methods are used to achieve proper viscosity for inkjet printing, then the ease of manufacture is improved, but the long-term stability and consistency of the ink composition deteriorates
Solution Approach 1:
The invention extracts and eliminates the solvent component from the ink composition entirely. Instead of using solvent-based formulations, the patent develops a solvent-free system where the curable monomer composition and surface-treated nanoparticles are dispersed directly in a suitable vehicle that does not require evaporation. This removes the source of long-term instability while maintaining printability through controlled viscosity.
Solution Approach 2:
The invention changes the fundamental parameters of the ink composition by transitioning from a solvent-based to a solvent-free formulation. This parameter change affects viscosity, stability, and curing characteristics. The curable monomer composition provides both the vehicle and the final matrix, eliminating the need for separate solvent evaporation steps and ensuring long-term compositional stability while maintaining ease of inkjet printing.
3Adaptability or versatility
If layers of differing refractive indices are placed adjacent to each other in multilayer optical devices, then the functional performance is improved, but the refraction and reflection of light at interfaces increases
Solution Approach 1:
The invention applies local quality by creating a gradient in refractive index at the interface between layers. By incorporating metal oxide nanoparticles with varying concentrations or using composite materials with spatially varying properties, the refractive index transitions smoothly across the interface rather than abruptly. This local variation in material composition reduces refraction and reflection losses while maintaining the functional performance of the multilayer device.
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 enables the formation of thin, optically clear layers with precise thickness and low surface roughness, suitable for applications like OLED devices, while avoiding the limitations of solvent-based methods and ensuring long-term stability and consistency of the ink composition.
Implementation Method 1
surface treated metal oxide nanoparticles comprise metal oxide nanoparticles that have been surface treated with a mixture of at least two silane-functional surface treatment agents
Implementation Method 2
curable ink composition comprises a curable aromatic monomer composition, and surface treated metal oxide nanoparticles... the cured layer comprises a cured organic matrix comprising at least one aromatic (meth)acrylate
Implementation Method 3
The curable ink composition is inkjet printable, having a viscosity of 30 centipoise or less at a temperature of from room temperature to 60° C.
Data Source
AI summary
Curable ink compositions include a curable aromatic monomer composition, and surface treated metal oxide nanoparticles. The surface treated metal oxide nanoparticles are surface treated with a mixture of at least two silane-functional surface treatment agents, at least one aromatic-containing silane-functional surface treatment agent and at least one silane-functional surface treatment agent comprising a co-polymerizable group. The curable ink composition is inkjet printable, having a viscosity of 30 centipoise or less at a temperature of from room temperature to 60° C., and is free from solvents. The curable ink composition, when printed and cured, has a refractive index of 1.55 or greater, and is optically clear.