Silicone Hydrogel Contact Lens Marking via UV Curing
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Solution Overview
Problem
Existing methods for marking contact lenses, such as printing and laser marking, face issues with durability and readability, leading to reduced mechanical strength and comfort due to dye flow-off, discoloration, or laser ablation, necessitating a method for silicone hydrogel contact lenses with identifying marks that maintain comfort and mechanical integrity.
Innovation Solution
A method involving a mold assembly with a silicone-containing polymer binder ink, partially cured with high-intensity UV light, followed by exposure of mold surfaces to a second UV light before filling with a silicone-containing vinylic monomer and hydrophilic monomer, ensuring high ion permeability and clear or colored identifying marks that adhere well without smudging or delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional printing method with dyestuff in organic medium is used, then identifying marks can be applied to contact lens surfaces, but the dyestuffs may be flowed off, discolored, or peeled off due to repeated cleaning and disinfection treatments
Solution Approach 1:
The patent changes the chemical parameters of the marking medium by replacing organic solvent-based dyestuffs with water-soluble or water-dispersible dyestuffs. This parameter change allows the marks to remain stable during repeated cleaning and disinfection treatments while maintaining ease of application through printing methods.
Solution Approach 2:
The patent uses composite material systems combining water-soluble/dispersible dyestuffs with specific binders or polymers that provide adhesion to the contact lens surface. This composite approach ensures both the ease of application and the durability against flow-off, discoloration, and peeling during repeated treatments.
2Reliability
If laser radiation marking method is used, then identifying marks can be printed or engraved on lens or mold, but the lens material is ablated or thickness is reduced, reducing mechanical strength
Solution Approach 1:
The patent replaces the mechanical/thermal laser ablation process with a chemical deposition process using water-soluble or water-dispersible dyestuffs. This substitution eliminates material removal and associated strength reduction while maintaining mark readability through conventional printing methods applied to the lens surface or mold.
3Reliability
If high intensity UV light is used to cure identifying mark coat, then mark adhesion and durability are improved, but lens material may be affected by UV exposure
Solution Approach 1:
The patent applies local quality by using water-soluble or water-dispersible dyestuffs specifically in the marking areas rather than throughout the entire lens material. This localized approach allows UV curing to be applied to enhance mark adhesion and durability without subjecting the bulk lens material to harmful UV effects, as the dyestuffs are confined to specific surface regions.
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 method achieves high-quality, durable identifying marks on silicone hydrogel contact lenses with enhanced ion permeability and mechanical strength, preventing smudging and delamination, while maintaining lens comfort and clarity.
Implementation Method 1
irradiating the identifying mark coat on the molding surface with a first high intensity UV light to at least partially cure the identifying mark coat
Implementation Method 2
irradiating the exposed surfaces of the female mold half and the male mold half with a second high intensity UV light prior to filling a lens-forming fluid material
Implementation Method 3
exposing the mold assembly and the lens-forming fluid material to an energy source, wherein the energy source polymerizes the lens-forming fluid material
Data Source
AI summary
The present invention is related to a method for making silicone hy- drogel contact lenses with an identifying mark, by irradiating the iden¬ tifying mark coat on the molding surface with a first and a second high intensity UV light prior to filling the lens-forming fluid material; exposing the mold assembly and the lens-forming fluid material to an energy source which polymerizes the lens-forming fluid materi¬ al wherein the emission spectrum of the first high intensity UV light has a higher intensity in the wavelength range of 320-390 nm by at least 200 mW/cm<2> and a lower intensity in the wavelength range of 250-260 nm by at least 10 mW/cm<2> than the second high inten¬ sity UV light.