Dual-Cure PU Lamination Adhesive for Ophthalmic Film Integrity
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Solution Overview
Problem
Existing adhesive technologies for functional films in ophthalmic lenses, such as photochromic and clear-to-polarized films, lack sufficient mechanical stiffness and integrity during manufacturing, handling, and casting processes, leading to issues with maintaining shape and adhesion.
Innovation Solution
The use of two-component polyurethane adhesives and dual cure polyurethane-based adhesives that provide satisfactory preliminary adhesive strength and maintain laminate integrity during lamination, suitable for batch and roll-to-roll processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If flexible thermoplastic polyurethane (TPU) or thermoplastic elastomer (TPE) films are used for functional films, then the films can be easily manufactured and handled, but the films lack mechanical stiffness and cannot maintain physical shape
Solution Approach 1:
The patent uses composite materials by combining flexible TPU/TPE films with rigid support layers (PET, PC, or TAC films) to create a laminated structure. This composite approach allows the functional film to maintain its flexibility and ease of manufacture while the support layers provide the necessary mechanical stiffness and shape maintenance capability.
2Ease of manufacture
If a adhesive is used to hold the multilayer laminate together, then the laminate can be formed and handled, but the adhesive must maintain integrity during manufacturing, handling, transport, and casting processes
Solution Approach 1:
The patent employs a two-component polyurethane adhesive system where Component A (polyol with hydroxyl groups) and Component B (polyisocyanate with NCO groups) are mixed in specific ratios and cured under controlled conditions. The adhesive parameters (composition ratio, curing temperature, curing time) are optimized to achieve sufficient green strength while maintaining flexibility for lamination processing.
3Shape
If photochromic and clear-to-polarized films are laminated to maintain shape, then the films gain mechanical support, but the adhesive must provide satisfactory preliminary adhesive strength (green strength) during the lamination process
Solution Approach 1:
The patent applies the adhesive to the support layers before the actual lamination process, allowing the adhesive to partially cure and develop preliminary bonding capability. This preliminary action ensures that when the functional films are laminated, the adhesive already has sufficient green strength to hold the multilayer structure together during handling and transport.
4Productivity
If residual injection mold heat is used to thermally attach the C2P laminate, then the process is efficient and quick, but the adhesive must withstand the thermal conditions during attachment
Solution Approach 1:
The patent formulates the polyurethane adhesive with specific thermal stability parameters, selecting polyol and polyisocyanate components that maintain their bonding properties at the temperatures generated by residual injection mold heat. The adhesive curing parameters are adjusted to ensure proper bonding occurs within the thermal window provided by the injection molding process.
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 adhesives ensure effective adhesion and integrity of functional films, enabling successful manufacturing and handling of ophthalmic lenses with photochromic and clear-to-polarized functionalities.
Implementation Method 1
a B-component comprising a polyisocyanate... reacting the A-component and the B-component with one another
Implementation Method 2
a polymerization initiator, and at least one monomer
Data Source
AI summary
Disclosed herein are a two-component polyurethane adhesive and a dual cure polyurethane-based adhesive for use in laminated films. The adhesives are particularly useful for producing photochromic and clear-to-polarized laminates for ophthalmic lens applications.