Tri-layer adhesive system for laminated optical lens
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Solution Overview
Problem
Existing adhesive systems for laminating ophthalmic lenses and films often result in uneven adhesive layers and poor adhesion, particularly with high-index epi-sulfur materials and polarized films, leading to optical and mechanical performance issues.
Innovation Solution
A multi-adhesive layer system comprising a latex layer on both the film and lens, with a hot melt adhesive (HMA) layer in the middle, applied via spin coating, to ensure strong and even bonding between the lens and film, which can be laminated using hot press equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single layer of UV curable adhesive or hot melt adhesive is used, then the lamination process is simple, but the adhesion strength is insufficient and the adhesive layer is uneven
Solution Approach 1:
The adhesive system is divided into three distinct layers: a first latex adhesive layer applied to the film, a middle hot melt adhesive layer, and a second latex adhesive layer applied to the lens. This segmentation allows each layer to perform its specific function optimally, with the latex layers providing strong bonding to the substrates and the hot melt layer providing strong inter-layer adhesion, thereby resolving the contradiction between system simplicity and adhesion strength.
Solution Approach 2:
The invention uses a composite adhesive system combining two different types of adhesives (latex and hot melt) in a three-layer structure. This composite approach leverages the complementary strengths of each adhesive type: latex adhesive's ability to bond to polarized films and plastic lenses, and hot melt adhesive's strong cohesive strength and rapid setting properties, achieving superior overall adhesion that neither single adhesive could provide alone.
2Reliability
If thermal or UV curable glue is used, then adhesion can be achieved, but the adhesive layer thickness is uneven causing optical defects
Solution Approach 1:
The latex adhesive layers are applied to the film and lens surfaces before the actual lamination process. This preliminary application allows the adhesive to be evenly distributed on the substrates in advance, ensuring uniform thickness and avoiding optical defects during the subsequent hot press lamination step, while still achieving strong adhesion.
3Ease of manufacture
If conventional adhesive methods are used, then the process is straightforward, but delamination occurs during edging and surfacing processes
Solution Approach 1:
The three-layer adhesive system segments the bonding functions, with the outer latex layers providing strong initial adhesion to the substrates and the middle hot melt layer providing robust inter-layer bonding. This segmentation creates a more durable composite adhesive structure that resists delamination during subsequent edging and surfacing processes, while maintaining ease of manufacture through the standardized lamination process.
4Reliability
If a thick adhesive layer is used to ensure coverage, then complete bonding is achieved, but optical quality deteriorates due to unevenness
Solution Approach 1:
The adhesive system is segmented into three thin layers rather than one thick layer. This segmentation allows each layer to be applied at a controlled, thin thickness that maintains optical quality, while the combined three-layer structure provides complete bonding coverage and superior adhesion strength that a single thick layer could not achieve without compromising optical performance.
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 multi-adhesive layer system achieves the strongest adhesion between polarized films and plastic lenses, maintaining optical quality and mechanical performance, and is compatible with various edging processes, preventing delamination during surfacing and edging.
Implementation Method 1
a first latex layer (16a) and a second HMA layer (16b) can be applied on a functionalized film and a third latex layer (16c) can be applied on lens (12) in advance
Implementation Method 2
the two parts are laminated together by hot press equipment in few minutes
Implementation Method 3
All three layers are water based polymers that can be easily spin coated on the film and lens before lamination
Data Source
Figure 1~2
Figure 3A~3B
AI summary
A method for laminating a functional film on to an optical base element and a tri-layer adhesive system for use in the method. The tri-layer adhesive includes a first latex adhesive layer disposed on the functional film and a second latex adhesive layer disposed on the optical base element. An HMA layer is disposed in between the latex layers to form a tri-layer adhesive to permanently retain the functionalized film on the optical base element. The method includes first coating a latex adhesive on the functional film and second coating a latex adhesive on the optical base element. An HMA is then coated on to one of the dried latex adhesive layers. The film is hot pressed on to the optical base element with the HMA sandwiched in between the latex layers to form a laminated optical device.