Polyurethane-Urea Optical Adhesive Delamination Resistance
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Solution Overview
Problem
Existing optical lenses formed from multilayered laminate structures, including polarized lenses, often suffer from delamination under high humidity, high temperature, and high stress conditions, and require complicated surface treatment processes for production, making them costly and time-consuming to produce.
Innovation Solution
A crosslinked polyurethane-urea optical adhesive system is developed, comprising a reactive prepolymer composition of aliphatic isocyanates, polyols, and a crosslinking agent, formed in-situ from isocyanate groups and water, which is used to bond transparent and optically functional films, eliminating the need for complex surface treatments and enhancing durability and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multilayered laminate structures are used to form optical lenses, then different optical functional characteristics can be imparted to the lens, but delamination occurs under high humidity, high temperature and high stress conditions
Solution Approach 1:
The patent employs a composite adhesive system comprising polyurethane, polyisocyanate, and silane components that work synergistically to bond optical layers. This composite material approach provides both strong adhesion and flexibility, allowing the laminate to maintain integrity under high humidity, temperature, and stress conditions while supporting multiple optical functional layers with different characteristics.
Solution Approach 2:
The patent utilizes silane crosslinking chemistry that undergoes parameter changes through moisture-curing reactions. The silane components react with water to form crosslinked gel structures, transforming the adhesive from a flexible precursor state to a rigid, highly crosslinked network state. This parameter change enables the adhesive to achieve superior delamination resistance while maintaining initial processability.
2Reliability
If surface treatments such as etching and coupling agent coating are applied to substrate surfaces, then lamination can be achieved, but the production process becomes complicated and time-consuming
Solution Approach 1:
The patent extracts and eliminates the need for separate surface treatment steps by incorporating adhesion-promoting functionality directly into the adhesive composition. The silane and polyisocyanate components provide inherent surface bonding capability, allowing the adhesive to bond effectively to optical substrates without requiring prior etching or coupling agent treatment, thus simplifying the overall production process.
Solution Approach 2:
The adhesive composition serves multiple functions simultaneously: it provides bulk adhesion, surface bonding through silane crosslinking, flexibility through polyurethane segments, and moisture curing capability. This multi-functionality eliminates the need for separate surface treatment processes while achieving reliable lamination.
3Reliability
If high heat and pressure autoclave process is used for lamination, then bonding can be achieved, but the process is not suitable for roll-to-roll coating or laminate production
Solution Approach 1:
The patent replaces the mechanical high heat and pressure autoclave bonding system with a chemical bonding system based on silane crosslinking and polyisocyanate reactions. These chemical reactions proceed at lower temperatures and ambient pressures, enabling the lamination process to be adapted to continuous roll-to-roll production methods while maintaining reliable bonding.
Solution Approach 2:
The patent changes the bonding parameters from high temperature and high pressure mechanical conditions to lower temperature chemical reaction conditions. The silane crosslinking reaction proceeds effectively at moderate temperatures, and the moisture-curing mechanism allows bonding under ambient pressure conditions suitable for roll-to-roll production.
4Reliability
If aromatic isocyanate containing polyurethane is used to bond laminate layers, then bonding can be achieved, but the adhesive requires complicated surface treatment processes
Solution Approach 1:
The patent uses a composite adhesive system that combines polyisocyanate, silane, and polyurethane components. The aliphatic polyisocyanate provides strong surface bonding without the yellowing issues of aromatic isocyanates, while the silane component provides crosslinking for enhanced adhesion. This composite approach achieves reliable bonding without requiring complicated surface treatment processes.
Solution Approach 2:
The patent extracts and eliminates the need for surface treatment processes by incorporating adhesion-promoting silane and polyisocyanate chemistry directly into the adhesive formulation. This allows the adhesive to bond effectively to optical substrates through its inherent chemical properties rather than relying on pre-treated surfaces.
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 crosslinked polyurethane-urea adhesive system provides durable, stress-tolerant, and cost-efficient optical film laminates and lenses with improved resistance to delamination, facilitating easier production and enhanced performance under various environmental conditions.
Implementation Method 1
a crosslinked polyurethane-urea formed from a composition comprising: a reactive prepolymer composition formed of a mixture comprising at least two different polyols and an aliphatic isocyanate; a chain extender; and a crosslinking agent; the polyurethane-urea formed in-situ from reaction between isocyanate groups and water
Implementation Method 2
a crosslinked polyurethane-urea formed from a composition comprising: a reactive prepolymer composition formed of a mixture comprising at least two different polyols and an aliphatic isocyanate; a chain extender; and a crosslinking agent
Data Source
AI summary
The present invention pertains to polyurethane-urea based optical adhesives for formation of optical film laminates, optically functional film laminates, and ophthalmic or eyeglass lenses employing the same and methods for producing the same.