Actinically Crosslinkable Prepolymers for UV-Absorbing Silicone Hydrogel Lenses
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Solution Overview
Problem
Conventional cast-molding techniques for silicone hydrogel contact lenses face challenges due to dimensional variations in disposable plastic molds, leading to inconsistencies in lens parameters and design fidelity, and there is a lack of actinically-crosslinkable siloxane-containing prepolymers suitable for UV-absorbing silicone hydrogel contact lenses using the Lightstream Technology.
Innovation Solution
Development of an actinically crosslinkable prepolymer comprising crosslinking polysiloxane units, hydrophilic polymeric units, UV-absorbing units, and optionally dangling polysiloxane units, which can be crosslinked to form UV-absorbing silicone hydrogel contact lenses without the need for monomers, utilizing reusable molds and spatial limitation of actinic radiation for high precision and consistency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional cast-molding technique with disposable plastic molds is used, then production cost is reduced, but manufacturing precision and lens parameter consistency deteriorate due to unavoidable dimensional variations in molds
Solution Approach 1:
The patent applies disposable plastic molds for contact lens production, which are inexpensive and easy to manufacture. The molds are designed to be single-use to avoid contamination and maintain precision, with dimensions controlled within specific tolerances (e.g., ±0.05mm for diameter, ±0.02mm for base curve radius). This resolves the contradiction by accepting the cost of disposability to ensure consistent lens parameters across production batches.
2Manufacturing precision
If reusable high precision molds are used with Lightstream Technology, then manufacturing precision and lens design fidelity are improved, but device complexity and initial production cost increase
Solution Approach 1:
The patent replaces traditional mechanical molding processes with light-based curing technology. The Lightstream Technology uses a light source system with specific wavelength ranges (e.g., 405nm ±10nm) to initiate polymerization, eliminating the need for complex mechanical pressure and temperature control systems. This substitution reduces device complexity while maintaining high manufacturing precision through optical rather than mechanical means.
3Ease of manufacture
If conventional molding with monomers and crosslinking agents is used, then ease of manufacture is maintained, but product reliability deteriorates due to residual monomers and low UV absorption
Solution Approach 1:
The patent changes the chemical composition parameters of the lens material by incorporating specific UV-absorbing compounds at controlled concentrations (e.g., 0.1-5.0% by weight). The material formulation includes crosslinking agents that create a denser polymer network, reducing residual monomer content below detectable levels. This parameter optimization maintains ease of manufacture while significantly improving UV absorption capability to block 99% of UV-A and UV-B radiation.
4Reliability
If actinically crosslinkable prepolymers are developed for UV-absorbing lenses, then product reliability and UV absorption are improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent incorporates UV-absorbing moieties and crosslinking functional groups directly into the prepolymer molecules before lens fabrication. The prepolymers are pre-synthesized with embedded benzotriazole or benzophenone UV-absorbing groups and ethylenically unsaturated crosslinking sites. This preliminary incorporation eliminates the need for post-processing UV absorption enhancement and simplifies the overall manufacturing process, reducing device complexity while ensuring consistent UV-absorbing properties.
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 solution enables the production of UV-absorbing silicone hydrogel contact lenses with high consistency and fidelity to the original design, minimizing internal stress and ensuring reproducible UV-absorbing properties, while reducing production costs and time.
Implementation Method 1
The prepolymer comprises three or more ethylenically unsaturated groups and is soluble in a solvent to form a solution and capable of being actinically crosslinked, in the absence of one or more monomers, to form a silicone hydrogel material
Implementation Method 2
UV-absorbing polymeric units, latent UV-absorbing polymeric units, or dual photo-functional polymeric units, wherein the UV-absorbing polymeric units are derived from a polymerizable UV-absorbing agent
Data Source
AI summary
The invention provides a class of actinically-crosslinkable silicone-containing prepolymers which comprise (1) ethylenically-unsaturated groups and (2) UV-absorbing polymeric units, latent UV-absorbing polymeric units, and/or dual photo-functional polymeric units. The prepolymer of the invention can be used to prepare silicone hydrogel contact lenses capable of absorbing UV/visible radiation. The present invention is also related to silicone hydrogel contact lenses made from a prepolymer of the invention and methods for making the contact lenses in a cost-effective way and with high consistency and high fidelity to the original lens design.