Plasma Polymerized Contact Lens Coating for Durability
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Solution Overview
Problem
Existing contact lens materials face challenges in achieving both good water wettability and durability, particularly when subjected to extraction with organic solvents and high-pressure steam sterilization, which can lead to surface cracking and unsuitability for wear.
Innovation Solution
A method involving plasma polymerization in a mixed gas atmosphere of methane and moist air, followed by plasma treatment in a nonpolymerizable gas atmosphere, to form a coating on the contact lens surface, enhancing hydrophilicity and durability while preventing cracking during swelling and sterilization processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coating film is formed by plasma polymerization in a hydrocarbon atmosphere to enhance water wettability, then the surface hydrophilicity is improved, but the film separates and cracks during extraction and swelling steps
Solution Approach 1:
The patent changes the chemical composition parameters of the plasma polymerization gas from pure hydrocarbon to a mixed gas containing oxygen (5-50% by volume). This parameter change transforms the film properties from rigid and brittle to flexible and crack-resistant, allowing the film to withstand lens swelling without separation or cracking while maintaining water wettability.
2Stability of the object's composition
If plasma polymerization is conducted with a mixed gas of saturated hydrocarbon and oxygen, then the film flexibility is improved, but the film is etched away more rapidly requiring considerable time to achieve desired thickness
Solution Approach 1:
The patent optimizes the oxygen content parameter in the mixed gas to a specific range (5-50% by volume). Within this range, the film achieves sufficient flexibility while minimizing etching loss. The upper limit of 50% oxygen prevents excessive etching that would reduce film formation rate, thus balancing flexibility and productivity.
3Strength
If a rigid crosslinked film is formed to provide durability, then the surface durability is improved, but the lens volume swells causing film separation and cracking
Solution Approach 1:
The patent modifies the crosslinking density and chemical composition of the film by controlling oxygen content during plasma polymerization. The resulting film has intermediate crosslinking that provides durability while maintaining flexibility to accommodate lens swelling (10-50% volume increase) without separation or cracking.
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 results in a soft contact lens with a smooth, hydrophilic surface that maintains water wettability and durability, preventing surface defects and ensuring comfort during wear.
Implementation Method 1
said contact lens base material is processed by plasma polymerization in a mixed gas atmosphere of methane and moist air
Implementation Method 2
treated with plasma in a nonpolymerizable gas atmosphere, to form said coating
Data Source
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AI summary
Provided is a contact lens material having a smooth surface with good water wettability and durability. In the method of manufacturing a contact lens material comprising a contact lens base material and a coating formed on at least a portion of a surface of the above base material, the contact lens base material is processed by plasma polymerization in a mixed gas atmosphere of methane and moist air, and then treated with plasma in a nonpolymerizable gas atmosphere to form the above coating. Further provided is a method of manufacturing a soft contact lens wherein water is introduced into the contact lens material manufactured by the above method to obtain a soft contact lens.