Silicone Hydrogel Lens Coating Without Solvent Extraction
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Solution Overview
Problem
Existing methods for producing silicone hydrogel contact lenses are costly, inefficient, and environmentally unfriendly due to the use of ophthalmically incompatible organic solvents, which require additional extraction and hydration processes, and result in hydrophobic surfaces that can adhere to the eye.
Innovation Solution
A method involving a polymerizable composition comprising hydrophilized polysiloxane vinylic crosslinker, hydroxyethyl methacrylate, alkoxyethyl methacrylate, and carboxyl-containing (meth)acryloxy monomer, cured to form a silicone hydrogel lens with a crosslinked hydrophilic layer, eliminating the need for extraction and hydration processes and using environmentally friendly solvents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional cast molding technique with ophthalmically incompatible organic solvents is used, then silicone hydrogel contact lenses can be produced, but production cost increases and production efficiency decreases due to additional extraction and hydration processes
Solution Approach 1:
The patent removes the harmful extraction and hydration processes from the manufacturing sequence by using water-soluble polymerizable components that eliminate the need for organic solvent extraction, directly addressing the cost and efficiency problems caused by these additional steps
Solution Approach 2:
The invention changes the solubility parameter of the polymerizable components from organic-soluble to water-soluble, fundamentally altering the manufacturing process to eliminate extraction and hydration steps, thereby reducing production cost and improving efficiency
2Ease of manufacture
If ophthalmically incompatible organic solvents are used in SiHy lens formulation, then lens production is possible, but environmental friendliness deteriorates and production cost increases
Solution Approach 1:
The patent converts the previously harmful organic solvents into beneficial water-soluble components, turning an environmentally harmful process into an eco-friendly one while simultaneously reducing production cost by eliminating extraction and hydration steps
Solution Approach 2:
The invention changes the solvent compatibility parameter from organic to water-based, fundamentally transforming the manufacturing process to be both cost-effective and environmentally friendly by eliminating the need for harmful organic solvents
3Reliability
If silicone-containing components are used in SiHy lens formulation, then oxygen permeability is improved, but compatibility with hydrophilic components deteriorates preventing formation of optically clear lens
Solution Approach 1:
The patent changes the chemical compatibility parameter of the silicone-containing components by using water-soluble polymerizable components, allowing them to be miscible with hydrophilic components and form optically clear lenses while maintaining high oxygen permeability
Solution Approach 2:
The invention creates a composite lens formulation combining silicone-containing components with hydrophilic components through water-soluble polymerizable components that provide compatibility between the two material classes, achieving both oxygen permeability and optical clarity
4Ease of manufacture
If SiHy contact lens surface is left hydrophobic, then manufacturing is simplified, but wettability deteriorates causing the lens to adhere to the eye
Solution Approach 1:
The patent incorporates hydrophilic polymerizable components into the lens formulation during the molding process, performing the wetting modification action in advance rather than requiring post-manufacturing surface treatment, thus maintaining manufacturing simplicity while achieving good wettability
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
Produces optically clear, wettable silicone hydrogel contact lenses with high oxygen permeability and reduced production costs, while minimizing environmental impact.
Implementation Method 1
curing thermally or actinically the polymerizable composition in the lens mold to form a silicone hydrogel lens precursor
Implementation Method 2
curing thermally or actinically the polymerizable composition in the lens mold
Implementation Method 3
hydrating the silicone hydrogel lens precursor obtained in step (2) in water or an aqueous solution to obtain a hydrated silicone hydrogel contact lens
Implementation Method 4
heating the silicone hydrogel lens precursor obtained in step (2) or the hydrated silicone hydrogel contact lens obtained in step (3) directly in an aqueous solution having a pH from about 6.5 to about 9.5 and including at least one water-soluble, thermally-crosslinkable hydrophilic polymeric material at a temperature from about 60° C. to about 140° C. to form a coated silicone hydrogel contact lens
Data Source
AI summary
The invention provide a method for producing coated silicone hydrogel contact lenses in a cost-effective and environmentally friendly manner. The method is free of lens extraction step and comprises: curing thermaly or acctinically in a lens mold a polymerizable composition that comprises at least one hydrophilized polysiloxane vinylic crosslinker, hydroxyethyl methacrylate, C1-C2 alkoxyethyl (meth)acrylate, at least one free-radical initiator, and at least one solvent selected from the group consisting of water, propylene glycol, and/or a low-molecular weight polyethyleneglycol; and heating the cast-molded silicone hydrogel contact lens in an aqueous coating solution to form a coated silicone hydrogel contact lens comprising a bulk silicone hydrogel material and a layer of a crosslinked hydrophilic polymeric material that is covalently attached onto the bulk silicone hydrogel material. Resultant contact lenses are optically clear and wettable and have a relatively high oxygen permeability.