Silicone Hydrogel Contact Lens Monomer Composition for Mold Compatibility
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Solution Overview
Problem
Existing contact lenses lack sufficient breaking elongation and surface hydrophilicity, particularly when produced using hydrophobic molds like polypropylene without surface hydrophilic treatments, which can lead to lens discomfort and reduced oxygen permeability.
Innovation Solution
A monomer composition containing a siloxanyl group-containing itaconic acid diester monomer, amide group-containing monomers, hydroxy group-containing monomers, siloxanyl group-containing (meth)acrylate, and a cross-linking agent, in specific mass ratios, is used to create a polymer that enhances breaking elongation and surface hydrophilicity, even when produced with hydrophobic molds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a polypropylene mold is used to produce silicone hydrogel contact lenses, then the mold is easy to manufacture and process, but the lens surface becomes hydrophobic leading to lipid and protein adhesion
Solution Approach 1:
The patent applies preliminary action by incorporating hydrophilic monomers (NVP, DMAA, MVA, or N-vinylpyrrolidinone) into the monomer composition before polymerization. This allows the hydrophilic groups to be built into the lens matrix during manufacturing, creating a hydrophilic environment that prevents lipid and protein adhesion from the outset, rather than applying surface treatments after lens production.
Solution Approach 2:
The patent uses composite materials by combining silicone monomers (for oxygen permeability) with hydrophilic monomers (NVP, DMAA, MVA, or N-vinylpyrrolidinone) in a copolymerization system. This creates a composite polymer network that simultaneously provides both oxygen permeability and surface hydrophilicity, eliminating the need for separate surface treatments while maintaining mold compatibility.
2Object-affected harmful factors
If surface treatments are applied to improve lens surface hydrophilicity, then lipid and protein adhesion is prevented, but the manufacturing process becomes complex
Solution Approach 1:
The patent merges the functions of lens formation and surface hydrophilicity creation into a single polymerization step. By incorporating hydrophilic monomers into the base polymer composition, the patent combines what would traditionally be separate processes (lens molding followed by surface treatment) into one integrated manufacturing step, thereby simplifying the overall process while maintaining effectiveness.
Solution Approach 2:
The patent applies self-service by enabling the lens material itself to provide the hydrophilic properties needed to prevent adhesion. The hydrophilic monomers become part of the lens matrix, allowing the lens to self-regulate its surface properties through its inherent composition rather than requiring external surface treatments or additional processing steps.
3Object-affected harmful factors
If hydrophilic monomers like NVP, DMAA, MVA, or N-vinylpyrrolidinone are added to improve surface hydrophilicity, then some hydrophilicity is achieved, but sufficient hydrophilicity and breaking elongation cannot be obtained
Solution Approach 1:
The patent applies parameter changes by optimizing the concentration ranges of multiple monomer components simultaneously. Specifically, it controls the silicone monomer content (30-70 mass%), hydrophilic monomer content (5-40 mass%), and crosslinking agent content (1-20 mass%), creating a balanced composition that achieves both sufficient surface hydrophilicity and adequate breaking elongation properties that cannot be achieved with single monomer additions.
Solution Approach 2:
The patent uses composite materials by creating a multi-component copolymer system that combines silicone monomers, hydrophilic monomers (NVP, DMAA, MVA, or N-vinylpyrrolidinone), and crosslinking agents. This composite polymer network achieves synergistic effects where the combined components provide both the required surface hydrophilicity and mechanical strength properties that individual components cannot achieve alone.
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 resulting contact lenses exhibit excellent breaking elongation and surface hydrophilicity, preventing lipid and protein adhesion and maintaining mechanical strength and comfort, without the need for additional surface treatments.
Implementation Method 1
Silicone hydrogel contact lenses are recognized as safer lenses that supply more oxygen to a cornea of an eye than conventional hydrogel contact lenses containing no silicone
Implementation Method 2
A method is known in which a hydrophilic polymer wetting agent such as polyvinylpyrrolidone (PVP) is added to a monomer composition and the composition is polymerized to obtain a silicone hydrogel contact lens
Implementation Method 3
there is a concern that the wetting agent may be eluted from the lens during an alcohol extraction step after the polymerization
Data Source
AI summary
Provided is a contact lens that can exhibit excellent breaking elongation and surface hydrophilicity even when produced using a hydrophobic mold made of polypropylene or the like without performing a surface hydrophilic treatment. Further provided are a monomer composition and a polymer that can be suitably used for obtaining the contact lens. This monomer composition contains (A) a siloxanyl group-containing itaconic acid diester monomer, (B) an amide group-containing monomer, (C) a hydroxy group-containing monomer, (D) a siloxanyl group-containing (meth)acrylate, and (E) a cross-linking agent in a specific ratio.