Hybrid Light-Curing Composition for Shadow-Area Adhesive Cure
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Solution Overview
Problem
Existing curable compositions based on urethane (meth)acrylate oligomers face challenges in achieving complete cure in regions shadowed from radiation sources, leading to unreliable material performance and adhesive bonds over time.
Innovation Solution
A hybrid light-curing composition comprising an acid catalyzed urethane (meth)acrylate oligomer, cyanoacrylate monomer, metallocene compound, free radical polymerization inhibitor, and acidic anionic polymerization inhibitor, which allows for stable composition formation and improved cure performance, including shadowed areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional urethane (meth)acrylate oligomers are cured by visible light or ultraviolet light, then the curing process is efficient in exposed areas, but shadowed regions remain uncured leading to product reliability issues
Solution Approach 1:
The patent changes the chemical parameters of the oligomer by incorporating both hydroxyl-functional and carboxyl-functional groups, enabling the material to undergo both free radical polymerization and anionic polymerization. This dual-polymerization capability allows the composition to cure completely in both exposed and shadowed regions, eliminating uncured material and improving reliability.
Solution Approach 2:
The invention creates a composite curable composition that combines urethane (meth)acrylate oligomers with specific functional groups (hydroxyl and carboxyl) along with multiple types of photoinitiators and inhibitors. This composite material system enables simultaneous free radical and anionic polymerization, ensuring complete cure throughout the entire composition including shadowed areas.
2Productivity
If cyanoacrylate monomer is added to improve cure speed, then fast curing is achieved, but premature gelation occurs due to residual catalyst in the oligomer
Solution Approach 1:
The patent removes the harmful residual metal-based or amine-based catalysts from the urethane (meth)acrylate oligomer synthesis process. By eliminating these catalysts, the composition remains stable during storage and handling, preventing premature gelation when cyanoacrylate monomer is present, while still enabling fast curing through controlled photopolymerization.
Solution Approach 2:
The invention introduces specific functional groups (hydroxyl and carboxyl) as intermediaries that enable controlled polymerization through photoinitiated mechanisms rather than catalyst-driven mechanisms. These functional groups allow the system to achieve fast curing through light activation without the harmful side effects of residual catalysts causing premature gelation.
3Strength
If conventional photopolymerization is used, then exposed areas cure well, but shadowed regions contain uncured material that weakens adhesive bonds over time
Solution Approach 1:
The patent fundamentally changes the polymerization parameters by incorporating carboxyl-functional groups alongside hydroxyl-functional groups, enabling anionic polymerization in addition to free radical polymerization. This dual mechanism ensures that shadowed regions undergo complete curing through anionic polymerization, eliminating weak uncured material and improving long-term adhesive bond strength and reliability.
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 achieves complete or nearly complete cure in shadowed regions, enhancing material reliability and adhesive strength, even under high temperature and humidity conditions.
Implementation Method 1
curing the curable composition by exposing it to light to form the cured composition
Implementation Method 2
an acid catalyzed urethane (meth)acrylate oligomer comprising an acid catalyst
Data Source
AI summary
In an aspect, a curable composition comprises an acid catalyzed urethane (meth) acrylate oligomer comprising an acid catalyst; a cyanoacrylate monomer; a metallocene compound; a free radical polymerization inhibitor; and an acidic anionic polymerization inhibitor. In yet another aspect, a method of making a cured composition comprises forming the curable composition; and curing the curable composition by exposing it to light to form the cured composition.