Colored Silicone Hydrogel Contact Lens UV Curing Method
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Solution Overview
Problem
Current methods for producing colored silicone hydrogel contact lenses lack high ion permeability and high-quality color images, which are essential for maintaining corneal health and aesthetic appeal.
Innovation Solution
A method involving a mold assembly with a female and male mold, where a color coat containing a silicone-containing polymer binder is partially cured using high intensity UV light, followed by exposure of the mold surfaces to a second high intensity UV light before filling with a silicone-containing vinylic monomer and hydrophilic vinylic monomer, ensuring optimal ion and oxygen permeability and print quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods are used to produce colored silicone hydrogel contact lenses, then the manufacturing process is simple, but the ion permeability is low and the color image quality is poor
Solution Approach 1:
The manufacturing process is divided into distinct stages: (1) applying color coat to mold surface, (2) partial curing with first UV light, (3) exposing mold surfaces to second UV light, (4) filling with lens-forming material, and (5) final curing. This segmentation allows each step to be optimized independently, achieving high color image quality and ion permeability while maintaining process control.
Solution Approach 2:
The color coat is applied and partially cured on the mold surface before filling the lens-forming material. This preliminary action ensures that the color pattern is firmly established and will not be disturbed during subsequent processing, resulting in high-quality color images without smudging or delamination.
2Reliability
If high intensity UV light is used to cure the color coat, then the curing is complete and adhesion is good, but the ion permeability may be reduced
Solution Approach 1:
The color coat is subjected to partial curing with the first high intensity UV light rather than complete curing. This partial action is sufficient to establish good adhesion and prevent smudging, while leaving the structure less crosslinked to maintain ion permeability. The second UV exposure then treats the mold surfaces without over-curing the color coat.
3Object-generated harmful factors
If the mold surfaces are exposed to high intensity UV light before filling, then the ion permeability is enhanced, but the color coat may be damaged
Solution Approach 1:
The mold surfaces are exposed to the second high intensity UV light after the color coat has been partially cured. This timing ensures that the color coat has sufficient crosslinking to resist damage while the mold surfaces are activated to enhance ion permeability of the final lens structure.
Solution Approach 2:
Two different UV light sources with distinct emission spectra are used: the first source (higher intensity in 320-390 nm range) for color coat curing, and the second source (higher intensity in 250-260 nm range) for mold surface treatment. This parameter change allows selective curing of different components without mutual interference.
4Reliability
If conventional curing methods are used, then the process is simple, but the oxygen permeability and corneal health benefits are insufficient
Solution Approach 1:
The patent uses specific UV light sources with defined emission spectra characteristics - the first source having higher intensity in the 320-390 nm range for color coat curing, and the second source having higher intensity in the 250-260 nm range for mold surface treatment. These parameter changes enable optimization of both oxygen permeability and ion permeability while maintaining corneal health benefits.
Solution Approach 2:
The lens-forming material is formulated as a composite comprising at least one silicone-containing vinylic monomer or macromer and at least one hydrophilic vinylic monomer. This composite structure provides both high oxygen permeability (from silicone content) and high ion permeability (from hydrophilic content), achieving superior corneal health protection.
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 ion permeability and a high-quality color image with good adhesion, preventing smudging and delamination, thereby enhancing the clinical performance and cosmetic appeal of silicone hydrogel contact lenses.
Implementation Method 1
irradiating the color coat on the molding surface with a first high intensity UV light to at least partially cure the color coat
Implementation Method 2
irradiating the exposed surfaces of the female mold and the male mold with a second high intensity UV light prior to filling
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 generally relates to a method for making colored contact lenses, in particular to colored silicone hydrogel contact lenses. The present invention is also related to a method of a first high intensity UV curing the colored print on the mold and a second high intensity UV treating mold for making colored silicone hydrogel contact lenses. The present invention illustrates the right combination of the first high intensity UV exposure and the second high intensity UV exposure allows a lens that maintains good ion permeability (IP) value and a good print quality.