Solvent-Free Silicone Hydrogel Contact Lens Manufacturing
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Solution Overview
Problem
Current methods for manufacturing contact lenses face challenges in achieving high oxygen permeability and water content without compromising mechanical strength, often resulting in decreased toughness and surface texture issues due to solvent evaporation during the molding process.
Innovation Solution
A method involving a mixture of siloxane macromers, hydrophilic monomers, a crosslinking agent, and an initiator, which is processed using UV or thermal treatment without solvents, to create contact lenses with enhanced oxygen permeability and water content, while maintaining mechanical strength and simplifying the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the water content of contact lenses is increased to improve oxygen permeability, then oxygen permeability is improved, but mechanical strength and toughness decrease
Solution Approach 1:
The patent uses a composite material system consisting of siloxane macromers (providing oxygen permeability) and hydrophilic monomers (providing water content and comfort). This composite approach allows the contact lens to achieve high oxygen permeability (DK>80) and high water content (30-80%) simultaneously while maintaining mechanical strength through the synergistic interaction of the two material components.
Solution Approach 2:
The patent changes the chemical composition parameters by incorporating specific siloxane macromers with defined molecular weights (1,000-10,000) and hydrophilic monomer ratios. By adjusting these parameters, the formulation achieves optimal balance between oxygen permeability, water content, and mechanical properties without compromising toughness.
2Ease of manufacture
If thermal reaction is used to process silicon hydrogel, then the material can be formed, but manufacturing time increases and solvent evaporation causes surface texture issues
Solution Approach 1:
The patent replaces the thermal reaction system with a photo-polymerization system using UV or visible light initiators. This substitution eliminates the need for high-temperature thermal processing (100-120°C for 2-3 hours), enabling rapid curing at room temperature within seconds to minutes, thereby significantly reducing manufacturing time and eliminating solvent evaporation issues.
Solution Approach 2:
The patent utilizes the phase transition of the photoinitiator upon light absorption to trigger polymerization. The photoinitiator absorbs UV or visible light and undergoes a phase/energy transition that initiates the polymerization reaction, enabling rapid material formation without thermal heating and associated solvent evaporation problems.
3Ease of manufacture
If solvent is used in the manufacturing process, then material processing is facilitated, but mass evaporation during molding creates surface texture problems
Solution Approach 1:
The patent extracts and eliminates the solvent component from the manufacturing formulation, using a solvent-free system consisting of siloxane macromers, hydrophilic monomers, crosslinking agents, and photoinitiators. This extraction eliminates the harmful effect of solvent evaporation during molding, ensuring smooth surface texture and high manufacturing precision while maintaining ease of processing through the liquid monomer mixture.
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 contact lenses with oxygen permeability exceeding 80 and water content greater than 30%, reducing manufacturing costs and eliminating surface texture issues, while maintaining mechanical integrity.
Implementation Method 1
The mixture is injected into a mold of contact lens and a UV irradiating treatment or a thermal treatment is conducted to the mixture to form contact lenses
Implementation Method 2
The mixture is injected into a mold of contact lens and a UV irradiating treatment or a thermal treatment is conducted to the mixture to form contact lenses
Data Source
AI summary
The invention provides a method for manufacturing contact lenses, including: (a) mixing a siloxane macromer represented by formula (I), a siloxane macromer represented by formula (II), a hydrophilic monomer, a crosslinking agent and an initiator to form a mixture for manufacturing contact lenses, wherein the mixture for manufacturing contact lenses is free of solvent; and (b) injecting the mixture into a mould of contact lenses and conducting a UV irradiating treatment or a thermal treatment to form contact lenses, wherein formula (I) and formula (II) are shown in following:in formula (I), R1, R2 and R3 are C1-C4 alkyl groups and m is an integer of 10-40, and in formula (II), R4, R5 and R6 are C1-C4 alkyl groups or alcohol groups, R7 is a C1-C4 alkyl group, and n is an integer of 10-130. Also provided are the contact lenses manufactured from the method.