Silicone Hydrogel Lens Extraction Tray Reciprocating Motion
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Solution Overview
Problem
Current methods for producing contact lenses, particularly silicone hydrogel lenses, often result in optical defects such as tray marks and dimples due to the extraction process, which requires multiple stages of solvent extraction and large spaces, making them costly and inefficient for pilot plant development.
Innovation Solution
A method involving a single process tank with at least two extracting stages using different solvents, followed by a reciprocating motion during water refilling to minimize tray marks and dimples, significantly reducing optical defects in silicone hydrogel contact lenses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple stages of extraction with changing solvent concentrations are used, then unreacted monomer or solvent is effectively extracted, but the process requires large space and significant financial resources
Solution Approach 1:
The patent combines multiple extraction stages into a single process tank by implementing a recirculating system where extraction medium flows through multiple chambers sequentially. The lens remains in one location while the extraction medium circulates through different concentration zones, merging the function of multiple tanks into one compact unit.
Solution Approach 2:
The extraction system nests multiple extraction chambers within a single process tank structure. The medium flows through nested chambers with decreasing solvent concentrations, allowing multi-stage extraction to occur within a compact, space-efficient configuration.
2Reliability
If traditional extraction process is used, then unreacted monomer is extracted, but optical defects such as tray marks and dimples are formed on the contact lenses
Solution Approach 1:
The patent introduces dynamic motion to the traditionally static extraction process. The process tank undergoes controlled reciprocating motion (back-and-forth movement) during extraction, which prevents the lens from adhering to the tray and eliminates tray marks and dimples while maintaining effective monomer extraction.
3Productivity
If pilot plant production is implemented, then product development evaluation can be conducted, but the cost and space requirements are prohibitively large
Solution Approach 1:
The patent merges multiple extraction stages and functions into a single integrated process tank, creating a compact pilot plant system that requires minimal space while maintaining full product development evaluation capabilities.
Solution Approach 2:
The single process tank performs multiple functions: it serves as the extraction chamber, the circulation system, and the motion control unit. This multi-functional design eliminates the need for separate equipment for each extraction stage, reducing overall plant space requirements.
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 effectively reduces optical defects by up to 85% in silicone hydrogel contact lenses, enhancing the efficiency and cost-effectiveness of the extraction process, allowing for more precise and economical production in a smaller space.
Implementation Method 1
subjecting the extraction tray for the formed silicone hydrogel contact lenses to a reciprocating lowering and raising motion thereof to obtain the silicone hydrogel contact lenses
Implementation Method 2
extracting the formed silicone hydrogel contact lenses with a first extracting medium, wherein the first extracting medium is a first solvent or a mixture of the first solvent and water
Implementation Method 3
applying thermal energy or ultraviolet radiation to polymerize the lens forming material
Implementation Method 4
curing thermally or actinically the polymerizable lens-forming material in the lens mold to form a silicone hydrogel contact lens
Data Source
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Figure 3~4
AI summary
The present invention generally relates to a method for producing silicone hydrogel contact lenses having less optical defects or free of optical defects by subjecting the extraction tray for the formed silicone hydrogel contact lenses to a reciprocating lowering and raising motion thereof to obtain the silicone hydrogel contact lenses.