Silicone Hydrogel Contact Lens Curing via Spatially Limited UV
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Solution Overview
Problem
Conventional cast molding techniques for producing silicone hydrogel contact lenses suffer from dimensional variations in plastic molds, leading to inconsistencies in lens parameters and design fidelity, and require longer curing times, which increase production costs and can result in undesirable physical properties.
Innovation Solution
A method using a monomer mixture comprising hydrophilic amide-type vinylic monomers, siloxane-containing (meth)acrylamide monomers, and polysiloxane vinylic monomers, cured under spatial limitation of actinic radiation, such as UV light, to produce silicone hydrogel contact lenses with high consistency and reduced curing time.
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 dimensional variations in molds
Solution Approach 1:
The patent applies disposable plastic molds for contact lens production, which are inexpensive and easily replaceable. These molds have unavoidable dimensional variations due to injection-molding fluctuations and non-uniform shrinking, leading to variations in lens parameters such as peak refractive index, diameter, basic curve, and central thickness. The disposable nature allows continuous replacement without investing in high-precision reusable molds.
2Device complexity
If conventional cast molding technique is used, then device complexity is reduced, but productivity deteriorates due to longer curing times
Solution Approach 1:
The patent employs a monomer mixture formulation with specific components including hydrophilic amide-type vinylic monomers, siloxane-containing (meth)acrylamide monomers, and polysiloxane vinylic monomers or macromers. This composition is designed to cure rapidly under spatially limited actinic radiation, reducing curing time to about 120 seconds or less while maintaining lens quality and edge definition.
3Reliability
If longer curing time is used in conventional technique, then complete polymerization is achieved, but lens edge quality deteriorates and production costs increase
Solution Approach 1:
The patent replaces conventional thermal or bulk curing methods with spatially limited actinic radiation curing. This allows precise control over the curing process, enabling complete polymerization of the monomer mixture while maintaining sharp lens edges and high quality. The spatial limitation of radiation ensures that curing occurs only where needed, preventing over-curing and edge degradation.
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
This approach enables the production of contact lenses with high lens edge quality and reduced production costs due to shorter curing times, while maintaining high fidelity to the original design and optical clarity.
Implementation Method 1
irradiating, under a spatial limitation of actinic radiation, the lens-forming material in the mold for a time period of about 120 seconds or less, so as to crosslink the lens-forming material
Data Source
AI summary
The invention provide a method for making silicone hydrogel based on the Lightstream Technology from a monomer mixture with a curing time of less than about 100 seconds. The present invention is also related to silicone hydrogel contact lenses made according to methods of the invention.