Ophthalmic Lens Primer Coating for Thermoplastic Adhesion
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Solution Overview
Problem
The integration of thermoplastic functional elements into thermoset ophthalmic lenses faces challenges due to compatibility issues with the lens casting material, leading to damage, delamination, and reduced adhesion during manufacturing and finishing processes, particularly with polycarbonate substrates.
Innovation Solution
A primer coating comprising reactive monomers and a photoactive catalyst is applied to the surface of thermoplastic functional elements, enhancing adhesion to thermoset lens substrates by promoting chemical bonding and protecting the functional elements from degradation during the casting process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If thermoplastic functional elements are integrated into thermoset ophthalmic lenses, then added functions (light filtering, optical functions) are achieved, but compatibility issues arise causing damage, delamination, and poor adhesion during manufacturing and finishing processes
Solution Approach 1:
A primer coating is applied as an intermediary layer between the thermoplastic functional element and the thermoset lens substrate. This primer contains reactive monomers that chemically bond to both the functional element surface and the casting monomer, creating a stable adhesive interface that prevents delamination during manufacturing and finishing processes
Solution Approach 2:
The system uses a composite structure consisting of the thermoplastic functional element, the primer coating layer, and the thermoset lens substrate. This multi-material composite approach allows each layer to contribute its specific properties while the primer ensures interfacial compatibility and bonding between the thermoplastic and thermoset components
2Adaptability or versatility
If thin PVA polarizing films (30 μm) are used for polarized lenses, then light filtering function is achieved, but the films are susceptible to damage during manual handling and production steps
Solution Approach 1:
The thin PVA polarizing film is laminated between more durable thermoplastic films (such as TAC or polycarbonate) to create a composite polarizing element. This sandwich structure provides the light filtering function of the PVA film while the surrounding thermoplastic layers provide mechanical strength and damage resistance during handling and manufacturing
Solution Approach 2:
The solution uses thin functional films (PVA) for optical function while enclosing them within more robust thermoplastic film layers. The outer thermoplastic shells protect the thin inner functional film from mechanical damage while allowing the thin film to perform its optical function effectively
3Strength
If industrial primers are used with polycarbonate/PVA/polycarbonate laminates, then adhesion is attempted, but the primers damage the optical quality by hazing the laminate and do not provide adequate adhesion
Solution Approach 1:
The primer formulation uses specifically selected reactive monomers with appropriate molecular weights, functional groups, and reactivity parameters. The primer contains photoactive catalysts and is cured under controlled UV exposure parameters to achieve complete curing without overheating or damaging the polycarbonate laminate, thus maintaining optical clarity while providing strong adhesion
Solution Approach 2:
The primer is applied as a thin, localized coating only on the surfaces requiring adhesion (the thermoplastic film surfaces contacting the lens substrate). This localized application ensures adequate adhesion strength at the interface while minimizing the amount of primer material that could potentially haze the laminate, preserving optical quality in the bulk material
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 primer coating ensures robust adhesion and consistent light filtering performance across various lens substrates, reducing manufacturing complexity and maintaining optical clarity by preventing haziness and damage to the functional elements.
Implementation Method 1
the primer coating includes at least one first reactive monomer, at least one second reactive monomer, and at least one photoactive catalyst
Data Source
AI summary
An ophthalmic lens including a substrate-independent adhesive primer for joining a functional element to a lens substrate. In particular, the ophthalmic lens includes at least one polymerized lens substrate including at least one thermoset monomer, a functional component including at least one thermoplastic layer, a surface of the at least one thermoplastic layer facing the polymerized lens substrate, and a primer coating deposited onto the surface of the at least one thermoplastic film facing the polymerized lens substrate.