Hydrolyzable Silicone Hydrogel Contact Lens Prepolymer
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Solution Overview
Problem
Conventional cast-molding techniques for producing silicone hydrogel contact lenses face challenges such as high production costs, inefficiencies due to the need for organic solvents, and dimensional variations in disposable plastic molds, leading to inconsistent lens properties and complex design fidelity issues.
Innovation Solution
Development of actinically crosslinkable prepolymers comprising vinylic monomers with hydrolyzable silicone groups, hydrophilic monomers, and siloxane-containing compounds, which are cured in high-precision reusable molds without the need for post-curing surface treatments, allowing for hydrolysis to achieve a hydrophilic surface and improved lens consistency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional cast-molding technique with disposable plastic molds is used, then production process is simple, but dimensional variations occur leading to low manufacturing precision
Solution Approach 1:
The patent replaces expensive reusable metal molds with disposable plastic molds that are cheaper and easier to manufacture. Although disposable molds have dimensional variations, the invention compensates through a purified prepolymer system that reduces sensitivity to mold imperfections, maintaining acceptable manufacturing precision while dramatically simplifying the manufacturing process and reducing costs.
Solution Approach 2:
The invention changes the material parameters by using a purified prepolymer composition with specific molecular weight distribution and functional group content. This parameter optimization makes the lens material less sensitive to mold dimensional variations, thereby maintaining manufacturing precision even with disposable molds.
2Ease of manufacture
If conventional cast-molding with monomer mixtures is used, then lens extraction is required, but this increases production cost and decreases productivity
Solution Approach 1:
The invention performs preliminary purification of the prepolymer before lens manufacturing, removing unpolymerizable monomers and impurities in advance. This preliminary action eliminates the need for post-manufacturing lens extraction, thereby increasing production efficiency and reducing costs without compromising lens quality.
Solution Approach 2:
The invention extracts and removes unpolymerizable monomers and impurities from the prepolymer composition before lens formation. By taking out these problematic components beforehand, the process eliminates the need for subsequent extraction steps, improving both productivity and cost-effectiveness.
3Ease of manufacture
If actinically crosslinkable prepolymers with hydrolyzable silicone groups are used, then hydrophilic surface is achieved without post-treatment, but additional monomer components are required
Solution Approach 1:
The invention merges multiple functions into the prepolymer composition: bulk polymerization, crosslinking, and surface hydrophilization are all achieved through the integrated action of hydrolyzable silicone-containing monomers and actinically crosslinkable groups. This consolidation eliminates separate surface treatment steps while managing composition complexity through synergistic component selection.
Solution Approach 2:
The prepolymer composition is designed with multi-functionality: the hydrolyzable silicone groups provide both bulk oxygen permeability and surface hydrophilicity upon hydrolysis, while the actinically crosslinkable groups enable UV-curing. This universal design achieves multiple objectives simultaneously, offsetting the increased composition complexity with process simplification.
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 reduces production costs, enhances lens design fidelity, and achieves a hydrophilic surface without additional surface treatments, improving the oxygen and ion permeability of silicone hydrogel contact lenses.
Implementation Method 1
curing under a spatial limitation of actinic radiation (e.g., UV)
Implementation Method 2
actinically crosslinkable groups
Implementation Method 3
monomer with a hydrolyzable silicone-containing group
Data Source
AI summary
The invention provides a silicone hydrogel contact lens including a hydrolyzable units. The hydrolyzable units can be converted by hydrolysis into a hydrophilic units which is capable of imparting the silicone hydrogel contact lens a hydrophilic surface without post-curing surface treatment. The invention also provides an actinically crosslinkable prepolymer including hydrolyzable units and use of the prepolymer of the invention. In addition, the invention provides a method for making wettable silicone hydrogel contact lens without posterior surface treatments other than hydrolysis.