Reactive Demolding Agents for Silicone Hydrogel Lens Production
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Solution Overview
Problem
The difficulty in separating polar resin mold members used in the production of silicone hydrogel contact lenses, which are less deformable and more challenging to work with compared to non-polar resin molds, leading to issues in demolding and delensing without damaging the lenses.
Innovation Solution
Incorporating chemically reactive demolding agents into the silicone hydrogel lens precursor composition to facilitate the separation of polar resin mold members and the delensing of polymerized lenses, reducing the effort required for demolding and delensing without affecting the lens properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polar resin molds are used to produce silicone hydrogel contact lenses with ophthalmically acceptable surface wettabilities, then the lens surface wettability is improved, but the ease of separating mold members deteriorates
Solution Approach 1:
A demolding agent is introduced as an intermediary substance between the polar resin mold and the silicone hydrogel lens. The demolding agent reduces the adhesion forces between the mold and lens, enabling easy separation while maintaining the polar resin mold's ability to produce lenses with good surface wettability. The agent acts as a mediator that temporarily modifies the interface properties during demolding without affecting the final lens quality.
Solution Approach 2:
The surface properties of the mold or lens interface are temporarily changed by applying a demolding agent. This agent modifies the surface energy or friction characteristics at the mold-lens interface, reducing adhesion forces during demolding. The parameter change is localized and temporary, affecting only the demolding process while leaving the final lens properties unchanged.
2Reliability
If complex demolding processes like ultrasonic energy or temperature differentials are used to separate polar resin mold members, then the completeness of demolding is improved, but the device complexity and energy consumption increase
Solution Approach 1:
The demolding agent serves as a chemical intermediary that simplifies the demolding process. Instead of requiring complex physical methods like ultrasonic vibration or temperature cycling, the agent chemically or physically modifies the interface to enable simple mechanical separation. This reduces both device complexity and energy consumption while achieving complete demolding.
Solution Approach 2:
The complex mechanical and thermal demolding systems (ultrasonic devices, temperature control systems) are replaced by a simpler chemical approach using a demolding agent. The agent creates conditions that allow easy mechanical separation without requiring sophisticated equipment or energy-intensive processes.
3Ease of operation
If non-polar resin molds are used for production, then the ease of separating mold members is improved, but the lens surface wettability deteriorates
Solution Approach 1:
The demolding agent acts as a mediator that decouples the relationship between mold polarity and demolding ease. By introducing this intermediate substance, the mold can maintain its polar properties for producing high-wettability lenses while the agent temporarily modifies the interface to enable easy separation, effectively resolving the contradiction between mold polarity and demolding ease.
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
Enables easier and more efficient separation of polar resin mold members and delensing of silicone hydrogel contact lenses, improving production efficiency and reducing the need for complex demolding processes like ultrasonic energy or temperature differentials, while maintaining ophthalmically acceptable properties.
Implementation Method 1
Incorporating chemically reactive demolding agents into the silicone hydrogel lens precursor composition to facilitate the separation of polar resin mold members and the delensing of polymerized lenses
Data Source
AI summary
Compositions and methods for improving demolding polar resin molds used in the production of silicone hydrogel materials are described. The present compositions and methods include the use of one or more reactive demolding agents. The reactive demolding agents react with components of a polymerization mixture to produce a polymerized silicone hydrogel device containing a reactant product of the demolding agent and the other components of the polymerization mixture. Polar resin molds used during the polymerization of the polymerization mixture are more easily separated than substantially identical molds used in the polymerization of a substantially identical material without a reactive demolding agent. The present compositions and methods may be used in the manufacture of silicone hydrogel lenses, such as contact lenses. The demolding aids may also be useful as delensing aids.