Silicone Hydrogel Ink Binder for Uniform Lens Hydration
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Solution Overview
Problem
Colored silicone hydrogel contact lenses often experience mechanical and rheological defects due to uneven ink domain expansion during hydration, compromising print quality and optical clarity.
Innovation Solution
A silicone hydrogel ink binder comprising colorants, solvent, and a silicone copolymer formed from a copolymerization of alkylacrylamide, hydroxyethyl acrylate, non-bulky organosilicon, and bulky siloxane monomers, with a complementary reactive functionality, is applied to form a colored film that expands uniformly with the lens during hydration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ink binders are used in colored silicone hydrogel contact lenses, then coloration is achieved, but mechanical and rheological defects occur due to uneven ink domain expansion during hydration
Solution Approach 1:
The patent modifies the chemical composition parameters of the ink binder by incorporating specific silicone copolymers with controlled hydrophilicity and crosslinking density. This changes the expansion characteristics of the ink domain during hydration, preventing uneven expansion while maintaining mechanical integrity and optical clarity.
Solution Approach 2:
The ink binder is formulated as a composite material combining silicone copolymers, hydrophilic monomers, and colorants. This composite structure allows the ink domain to expand uniformly during hydration while maintaining mechanical strength and preventing rheological defects, thus resolving the contradiction between reliability and manufacturing precision.
2Ease of manufacture
If colorants are dispersed in the lens or printed on the lens, then cosmetic enhancement is achieved, but optical clarity may be compromised due to ink domain expansion
Solution Approach 1:
The patent adjusts the polymerization parameters and composition of the ink binder to control the size and distribution of colorant-containing domains. By optimizing these parameters, the ink domains remain sufficiently small and uniformly distributed to maintain optical clarity while still providing effective coloration.
Solution Approach 2:
The ink binder creates localized color domains with specific physical and chemical properties that differ from the surrounding lens material. These localized regions are designed to maintain optical clarity while providing the desired cosmetic enhancement, resolving the contradiction between ease of manufacture and optical clarity.
3Ease of manufacture
If ink binder composition is simplified, then manufacturing cost is reduced, but oxygen permeability matching becomes difficult
Solution Approach 1:
The silicone copolymer-based ink binder serves multiple functions simultaneously: it provides colorant binding, controls domain expansion, maintains mechanical integrity, and matches oxygen permeability. This multi-functional design reduces the need for additional specialized components, simplifying manufacturing while maintaining reliability.
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 solution ensures optically clear colored silicone hydrogel contact lenses with matching oxygen permeability (Dk) and high print quality by preventing ink domain expansion, maintaining optical clarity and mechanical integrity.
Implementation Method 1
a copolymerization product of a polymerization composition comprising (1) an alkylacrylamide monomer, (2) a hydroxyethyl acrylate monomer, (3) a non-bulky organosilicon-containing monomer having an ethylenically unsaturated reactive end group, and (4) a bulky siloxane monomer having an ethylenically unsaturated reactive end group
Implementation Method 2
a monomer having a reactive functionality complementary to the hydroxyl moiety of the hydroxyethyl acrylate monomer and a polymerizable ethylenically unsaturated reactive end group
Implementation Method 3
a colored silicone hydrogel contact lens having a colored film on a surface thereof
Data Source
AI summary
A silicone hydrogel ink binder includes (a) one or more colorants, (b) a solvent, and (c) a silicone copolymer including a reaction product of (i) a copolymerization product of a polymerization composition comprising (1) an alkylacrylamide monomer, (2) a hydroxyethyl acrylate monomer, (3) a non-bulky organosilicon-containing monomer having an ethylenically unsaturated reactive end group, and (4) a bulky siloxane monomer having an ethylenically unsaturated reactive end group, with (ii) a monomer having a reactive functionality complementary to the hydroxyl moiety of the hydroxyethyl acrylate monomer and a polymerizable ethylenically unsaturated reactive end group.