Radiation Curable Lens Sheet Resin Adhesion Shape Recovery
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Solution Overview
Problem
Existing radiation curable resin compositions for lens sheets face challenges in achieving excellent adhesion to plastic substrates, shape recovery properties, mechanical strength, and moldability while maintaining a high refractive index, with issues such as indentation creep and insufficient shape retention.
Innovation Solution
A radiation curable resin composition comprising epoxy (meth)acrylate, bifunctional (meth)acrylates expressed by specific formulas, a bifunctional (meth)acrylate obtained from (meth)acrylic acid and an aliphatic dihydric alcohol with an oxyalkylene structure, and a thermoplastic resin, which provides improved adhesion, shape recovery, mechanical strength, and refractive index when cured on a plastic substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a high proportion of monofunctional reactive monomer (40-70 mass %) is used to achieve satisfactory adhesion to plastic substrate and high refractive index, then adhesion and refractive index are improved, but crosslink density becomes low resulting in indentation creep and insufficient shape retention
Solution Approach 1:
The patent changes the chemical composition parameters by introducing specific bifunctional (meth)acrylates with defined molecular structures (formulas 1 and 2) and controlling their proportions relative to monofunctional monomers. This adjusts the crosslink density and network structure to achieve both good adhesion and shape retention without indentation creep.
Solution Approach 2:
The patent creates a composite resin system combining epoxy (meth)acrylate, multiple types of bifunctional (meth)acrylates, and monofunctional (meth)acrylate in specific proportions. This composite approach balances the competing requirements of adhesion (from monofunctional monomers) and shape retention (from bifunctional crosslinking).
2Stability of the object's composition
If polymer content is increased to improve shape recovery properties and shape retention, then shape retention is improved, but moldability such as casting efficiency and shape reproducibility deteriorates
Solution Approach 1:
The patent optimizes the polymer content parameter within a specific range (5-50 mass %) and adjusts the molecular structure parameters of the bifunctional (meth)acrylates. This balances the viscosity and flow characteristics for good moldability while maintaining sufficient shape retention through controlled crosslinking.
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 composition enhances the lens sheet's resistance to contact pressure, facilitates easier handling during assembly, and allows for the design of shorter focus lenses with improved optical performance.
Implementation Method 1
a molded layer performing a lens function and made of a cured resin material is provided on a plastic substrate
Data Source
AI summary
The present invention relates to a radiation curable resin composition which comprises epoxy (meth)acrylate, a monofunctional (meth)acrylate, a bifunctional (meth)acrylate having a specific structure, and a bifunctional (meth)acrylate obtained from an aliphatic dihydric alcohol having an oxyalkylene structure and (meth)acrylic acid and further contains a thermoplastic resin, thereby causing satisfactory adhesion to plastic substrates, sufficient shape retention, and excellent shape recovery properties, and satisfaction in moldability including casting efficiency and shape reproducibility, as well as a high refractive index and appropriateness for use as a lens sheet.