PEG Polyurethane Contact Lenses Oxygen Clarity
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Solution Overview
Problem
Current contact lens materials, particularly those based on PEG polyurethanes, face challenges such as opacity, poor oxygen permeability, and instability due to the incorporation of silicone, which affects their clarity, comfort, and shelf life, making them unsuitable for high-performance ophthalmic applications.
Innovation Solution
A polyurethane polymer composition is developed using a mixture of poly(ethylene glycol) (PEG) compounds, block copolymers, di- or polyisocyanates, and a chain extender with specific functional groups, reacted under anhydrous conditions to create a transparent and stable polymer suitable for thermoplastic or thermoset manufacturing processes, including reaction cast moulding and injection/compression moulding techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high levels of silicone-containing compounds are incorporated into polyurethane polymers to increase oxygen permeability, then oxygen permeability is improved, but the polymer becomes opaque or semi-opaque
Solution Approach 1:
The patent applies parameter changes by carefully controlling the concentration of silicone-containing compounds within a specific range (0.1-10 wt%) and adjusting the molecular weight of PEG compounds (200-10,000 Da) to optimize both oxygen permeability and optical clarity. This quantitative parameter optimization resolves the contradiction between these two properties.
Solution Approach 2:
The patent creates a composite polyurethane polymer system combining PEG compounds, silicone-containing compounds, and isocyanate compounds. This composite approach allows the material to achieve both high oxygen permeability (DK ≥ 30) and optical clarity by synergistically integrating multiple components with complementary properties.
2Use of energy by moving object
If silicone-containing compounds are added to polyurethane polymers, then oxygen permeability increases, but the polymer stability and shelf life decrease
Solution Approach 1:
The patent optimizes the concentration parameter of silicone-containing compounds (0.1-10 wt%) to achieve sufficient oxygen permeability while maintaining polymer stability. This controlled parameter adjustment prevents excessive silicone content from causing instability, thereby extending shelf life while meeting oxygen transmission requirements.
Solution Approach 2:
The patent applies local quality by selecting specific types of silicone-containing compounds with particular molecular structures and properties. Rather than using any silicone compound, the invention specifies compounds that provide oxygen permeability benefits while maintaining compatibility and stability with the polyurethane matrix.
3Ease of operation
If PEG compounds of moderately high molecular weight are used in polymer mixtures, then hydrophilicity increases, but transparency decreases
Solution Approach 1:
The patent applies parameter changes by optimizing the molecular weight of PEG compounds within a broad range (200-10,000 Da) and adjusting their concentration in the polymer mixture. This parameter optimization allows the formulation to achieve adequate hydrophilicity for comfort while maintaining optical transparency through careful balance of molecular weight and composition.
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 solution provides highly transparent, stable, and comfortable contact lenses with high oxygen permeability, maintaining structural integrity and clarity even after hydration and sterilization, addressing the limitations of previous materials by ensuring compatibility and transparency with high silicone content.
Implementation Method 1
A polyurethane polymer composition is developed using a mixture of poly(ethylene glycol) (PEG) compounds, block copolymers, di- or polyisocyanates, and a chain extender with specific functional groups, reacted under anhydrous conditions
Implementation Method 2
The polymer may be crosslinked and/or branched, and the reactant mixture may comprise 0.01 to 5 wt % of at least one compound having an average functionality greater than two
Data Source
AI summary
The present invention provides a poly(ethylene) glycol based polyurethane polymer composition, particularly useful in the production of contact lenses. Generally the reactant mixture used to form the polymer includes a branched chain extender. There is also provided a method of manufacturing a contact lens formed from such a polymer.