Optical Film Composition for Thick Concavo-Convex Structures
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Solution Overview
Problem
Conventional photo imprinting methods for producing optical elements with concavo-convex structures face challenges in managing polymerization heat and maintaining transmittance, especially when producing thick film thicknesses, due to excessive heat generation during curing, which affects the heat resistance and optical properties of the resulting materials.
Innovation Solution
A method using a composition containing a urethane (meth)acrylate monomer and a photo initiator, with specific ratios to control heat generation and improve transmittance, allowing for the production of optical elements with a concavo-convex structure and thick film thickness while minimizing polymerization heat, using a photo-curing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photo imprinting method is used to produce thick film optical elements, then shape accuracy is improved, but polymerization heat excessively rises during curing
Solution Approach 1:
The patent changes the chemical composition parameters of the curing system by selecting specific photopolymerizable compounds (acrylates, methacrylates, vinyl monomers) and controlling photo initiator concentration (0.001-1 part by mass per 100 parts by mass of photopolymerizable compound). This parameter optimization enables thick film curing while controlling polymerization heat generation through controlled reaction kinetics.
Solution Approach 2:
The patent uses composite material systems combining multiple photopolymerizable compounds with different polymerization characteristics. By formulating compositions with specific ratios of acrylates, methacrylates, and vinyl monomers along with carefully selected photo initiators, the system achieves both thorough curing of thick films and controlled heat generation through synergistic material interactions.
2Length of stationary object
If conventional composition is used for thick film photo imprinting, then film thickness is increased, but transmittance of cured material deteriorates
Solution Approach 1:
The patent optimizes chemical composition parameters including selecting photopolymerizable compounds with appropriate molecular weights and structures, controlling photo initiator concentrations within specific ranges, and adjusting monomer ratios. These parameter changes enable the formulation to achieve complete curing throughout thick films while maintaining optical transmittance by controlling yellowing and degradation.
Solution Approach 2:
The patent employs low-concentration photo initiators (0.001-1 part by mass per 100 parts by mass of photopolymerizable compound) that are consumed during the curing process. This approach allows thorough polymerization in thick films while minimizing the accumulation of chromophoric byproducts that would deteriorate transmittance, effectively using small amounts of initiating agents to achieve complete conversion.
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 method effectively reduces warpage and waviness, enhances heat resistance, and maintains high transmittance of the cured layer, even at elevated temperatures, making it suitable for applications requiring optical elements with excellent thermal stability and optical clarity.
Implementation Method 1
forming the cured layer having the concavo-convex structure by photo-curing the pattern formative layer
Data Source
AI summary
Methods for producing an optical element having a cured layer with a concavo-convex structure are described. Such a method includes: forming a composition layer on a base material by using a composition containing a polymerizable compound and a photo initiator; forming a pattern formative layer by pressure-contacting a mold; and forming the cured layer having the concavo-convex structure by photo-curing the pattern formative layer, wherein the polymerizable compound contains (a) a urethane (meth)acrylate monomer, the composition contains 0.005 to 0.5 part by mass of the photo initiator with respect to 100 parts by mass of the polymerizable compound, and the cured layer has a film thickness of the concavo-convex structure within a range of 0.5 mm to 1 cm.