Ionic Silicone Hydrogel Contact Lenses Wettability

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Solution Overview

Problem

Existing silicone hydrogels for contact lenses face challenges such as poor wettability, high modulus, hydrolytic instability, and high cost, with difficulties in achieving excellent clarity, low modulus, and desirable oxygen permeability while using inexpensive commercially available monomers.

Innovation Solution

The development of ionic silicone hydrogels formed from a reaction mixture comprising 37 to 75 wt% slow-reacting hydrophilic monomers, including at least one ionic component, and a silicone-containing component with a kinetic half-life ratio of at least 2, which allows for stable modulus and improved processing characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If polymeric wetting agents such as PVP and acyclic polyamides are used to improve wettability, then wettability is improved, but device complexity increases due to requirement for special compatibilizing components that need custom manufacturing

Engineering Contradiction:

ImprovewettabilityVSAvoidcomplexity

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The patent extracts the wetting function from complex polymeric wetting agents and compatibilizing components, achieving wettability through simple ionic monomers (NVP, VMA, EGVE) that are readily available and do not require custom-manufactured compatibilizers, thereby reducing device complexity while maintaining improved wettability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces expensive, complex polymeric wetting agents with inexpensive, readily available ionic monomers that can be easily incorporated into the silicone hydrogel formulation, reducing both cost and manufacturing complexity while achieving the desired wettability

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Strength

If polyfunctional silicone monomers or macromers are used as crosslinking agents to improve structural integrity, then structural integrity is improved, but modulus increases

Engineering Contradiction:

Improvestructural integrityVSAvoidmodulus

Core Design Contradiction:

StrengthVSForce

Solution Approach 1:

The patent changes the crosslinking approach by using monofunctional silicone monomers with controlled reaction kinetics instead of polyfunctional crosslinking agents, adjusting the reaction parameters to achieve adequate structural integrity while maintaining lower modulus through controlled crosslinking density

Inventive Principle:

Principle #35Parameter changes

3Illumination intensity

If anionic monomers such as MAA are added to reduce haze and improve clarity, then clarity is improved, but hydrolytic instability occurs

Engineering Contradiction:

ImproveclarityVSAvoidhydrolytic stability

Core Design Contradiction:

Illumination intensityVSStability of the object's composition

Solution Approach 1:

The patent converts the potential harm of ionic monomers causing hydrolytic instability into a benefit by carefully selecting ionic monomers with appropriate kinetic half-lives that provide clarity improvement without compromising hydrolytic stability, turning a previously problematic class of monomers into a safe and effective option

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

4Reliability

If silicone content is increased to achieve desirable oxygen permeability, then oxygen permeability is improved, but cost of raw materials increases

Engineering Contradiction:

Improveoxygen permeabilityVSAvoidcost

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent changes the approach to achieving oxygen permeability by optimizing the reaction kinetics parameters and monomer selection rather than simply increasing silicone content, achieving desirable oxygen permeability through controlled polymerization and crosslinking of ionic silicone monomers while using more cost-effective raw materials

Inventive Principle:

Principle #35Parameter changes

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 resulting silicone hydrogels exhibit exceptional balance of properties including stability, haze, water content, and oxygen permeability, with stable modulus and enhanced drug uptake efficiency, making them suitable for biomedical devices like contact lenses.

Implementation Method 1

a reaction mixture comprising about 37 to about 75 wt % of a mixture of slow-reacting hydrophilic monomers, each having a slow-reacting hydrophilic monomer kinetic half life

Methodology Applied

Scientific EffectPolymerization: Photopolymerisation

Implementation Method 2

The resulting silicone hydrogels exhibit exceptional balance of properties including stability, haze, water content, and oxygen permeability

Methodology Applied

Scientific EffectHydrogen bonding: Chemical Bonding

Data Source

PatentUS9125808B2Ionic silicone hydrogels

Publication Date: 2015.09.08 JOHNSON & JOHNSON VISION CARE INC

AI summary

The present invention relates to ionic silicone hydrogel contact lenses which comprise at least one pharmaceutical or nutriceutical component and are formed from reaction mixtures comprising a mixture of slow-reacting hydrophilic monomers, including at least one slow-reacting ionic monomer, at least one silicone-containing component and at least one hydroxyl-containing component, wherein the ratio of the slow-reacting hydrophilic component half lives to the silicone-containing component half life is at least 2.