Soft Lens Surface Treatment for Hydrophilicity and Oxygen Permeability
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Solution Overview
Problem
Existing soft contact lenses with silicone monomers suffer from high hydrophobicity, leading to discomfort and reduced oxygen permeability, and current surface treatments either compromise stability or require costly, controlled production.
Innovation Solution
A surface treatment agent comprising a reaction product of poly(meth)acrylic acid and a copolymer with specific molecular weight and monomer ratios, enhancing hydrophilicity and reducing dryness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a silicone monomer is blended with the soft contact lens material to increase oxygen permeability, then oxygen permeation is improved, but hydrophobicity increases causing dryness and discomfort
Solution Approach 1:
The invention applies local quality by creating a hydrophilic surface layer on the contact lens while maintaining the bulk silicone hydrogel composition. The surface treatment agent containing carboxy group-containing polymer and crosslinking agent forms a hydrophilic coating only on the lens surface, providing moisture retention where needed while preserving the oxygen permeability of the silicone-based bulk material.
Solution Approach 2:
The invention uses composite materials by combining silicone hydrogel bulk material with a hydrophilic surface coating. The surface treatment agent creates a composite structure where the inner layer is oxygen-permeable silicone hydrogel and the outer layer is a hydrophilic polymer coating with carboxy groups that provides moisture retention and comfort.
2Object-affected harmful factors
If a hydrophilic monomer with carboxy group is blended with silicone monomer to improve hydrophilicity, then surface hydrophilicity is enhanced, but hydrolysis reaction increases reducing stability
Solution Approach 1:
The invention applies preliminary action by pre-forming a stable polymer backbone structure using commercial polymer powders with controlled molecular weights and carboxy group contents. The polymer is partially hydrolyzed in advance to generate carboxy groups, and then crosslinked on the lens surface before use, preventing further unwanted hydrolysis during wear and improving long-term stability.
Solution Approach 2:
The invention uses parameter changes by controlling the degree of hydrolysis and crosslinking density to optimize the balance between hydrophilicity and stability. By adjusting the carboxy group content (0.1-10 mmol/g) and crosslinking conditions, the invention achieves sufficient surface hydrophilicity while maintaining compositional stability during extended wear.
3Object-affected harmful factors
If copolymer with reactive groups is chemically bound to give hydrophilicity to the surface, then surface hydrophilicity is improved, but production complexity and cost increase
Solution Approach 1:
The invention extracts the complex copolymer synthesis step and replaces it with simpler commercial polymer powders that already contain the necessary carboxy groups. Instead of producing a copolymer with both hydrophilic and reactive groups in one complex step, the invention uses pre-made polymers with carboxy groups and adds crosslinking functionality separately, greatly simplifying production equipment requirements.
Solution Approach 2:
The invention uses commercially available polymer powders as disposable starting materials that can be directly applied to lenses. These commercial polymers replace the need for expensive, highly controlled copolymer production equipment, making the process economically viable while achieving the same hydrophilic surface effect.
4Object-affected harmful factors
If a hydrophilic layer is formed on the surface of contact lens to improve wearing feeling, then hydrophilicity is enhanced, but oxygen permeability is lowered
Solution Approach 1:
The invention applies local quality by creating a thin hydrophilic surface layer that provides comfort only where it contacts the eye, while the bulk of the lens maintains high oxygen permeability. The surface treatment agent forms a coating of controlled thickness that delivers hydrophilicity at the surface without significantly impeding oxygen transmission through the lens body.
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 treatment significantly improves hydrophilicity, reducing discomfort and maintaining oxygen permeability while being economically viable.
Implementation Method 1
a surface treatment agent for a soft contact lens, containing a reaction product obtained through a reaction between poly(meth)acrylic acid and a copolymer (P)
Implementation Method 2
containing a reaction product obtained through a reaction between poly(meth)acrylic acid and a copolymer (P) to give hydrophilicity to the surface of contact lens
Data Source
AI summary
The present invention relates to a surface treatment agent for soft contact lens, containing a reaction product obtained through a reaction between a poly(meth)acrylic acid which has an average molecular weight of 1,000 to 2,000,000, and a copolymer (P) which is obtained through polymerization of a specified hydrophilic monomer (nA) and a specified reactive monomer (nB), wherein in the copolymer, the hydrophilic monomer (nA) is 80 to 99 mol %, the reactive monomer (nB) is 1 to 20 mol %, and a weight average molecular weight is 10,000 to 5,000,000. The surface treatment agent tremendously enhances surface hydrophilicity of a soft contact lens to improve discomfort.