Ophthalmic Blocking Pad Torque Resistance
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Solution Overview
Problem
Advanced ophthalmic lenses with low energy surfaces are difficult to secure during shaping or edging processes due to their properties, which require improved mounting solutions that can withstand torque and maintain adhesion.
Innovation Solution
An ophthalmic blocking pad comprising a foam layer, a rigid film layer with high tensile strength, and an adhesive layer configured to exhibit high peel adhesion and torque performance, ensuring secure bonding to both the lens and shaping device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conformable substances or adhesives are used to secure lens work pieces, then the lens can be mounted in the shaping machine, but the mounting fails when the lens has low energy surfaces such as anti-reflection coatings
Solution Approach 1:
The blocking pad is divided into multiple functional layers: a foam layer for conformability and cushioning, a film layer for structural integrity and torque resistance, and an adhesive layer for bonding to the lens surface. This segmentation allows each layer to address specific requirements, enabling reliable mounting on low energy surfaces while maintaining adaptability to different lens shapes.
Solution Approach 2:
The blocking pad combines dissimilar materials (foam, film, and adhesive layers) into a composite structure that integrates the benefits of each material. The foam provides conformability, the film provides tensile strength for torque performance, and the adhesive provides bonding capability to low energy surfaces, creating a mounting solution that overcomes the limitations of single-material approaches.
2Ease of manufacture
If traditional adhesive tapes or adhesives are used to secure the lens, then mounting is simple, but they cannot withstand the large torque exerted during shaping
Solution Approach 1:
The blocking pad separates the functions of ease of mounting and torque resistance into different layers. The adhesive layer enables simple application to the lens, while the film layer provides the structural strength to withstand torque during shaping, eliminating the need for complex mounting procedures while maintaining high torque resistance.
Solution Approach 2:
The composite structure combines a compliant adhesive layer for easy bonding with a rigid film layer for torque strength. This material combination allows the blocking pad to be easily applied like traditional adhesives while providing the torque resistance previously unavailable with simple adhesive mounting methods.
3Strength
If the blocking pad uses high tensile strength film layer, then torque performance is improved, but the complexity of the pad structure increases
Solution Approach 1:
The blocking pad segments the structural requirements into distinct layers, with the film layer specifically dedicated to providing tensile strength for torque performance. This segmentation allows the use of high strength materials only where necessary, rather than requiring the entire pad structure to be complex and heavy.
Solution Approach 2:
The film layer is applied locally over the foam layer, providing high tensile strength only at the interface where torque forces are transmitted during shaping. This localized application of high strength material optimizes torque performance while minimizing overall structural complexity and material usage.
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 blocking pad provides enhanced torque and peel performance, effectively securing lenses during shaping and easy removal post-processing, even on low energy surfaces, improving the efficiency of ophthalmic lens manufacturing.
Implementation Method 1
an adhesive layer configured to exhibit a peel adhesion of at least about 4.0 lb/in (0.70 N/mm) on polypropylene
Implementation Method 2
a foam layer having a specific gravity not greater than about 0.6
Data Source
AI summary
An ophthalmic blocking pad includes a foam layer, a film layer disposed over and directly contacting the foam layer, and an adhesive layer disposed over the film layer. The film layer has a tensile strength of at least about 25 ksi (172 MPa).