Silicone Hydrogel Lens De-molding via Thermal Hydration
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Solution Overview
Problem
Conventional methods for producing silicone hydrogel contact lenses face challenges such as strong adhesion between the lens and mold, requiring excessive force for separation, which can damage the lens and reduce production yield, and the use of organic solvents for deblocking, which complicates handling and increases costs.
Innovation Solution
The method involves using hot water to hydrate and dislodge the lens from the mold, reducing the need for excessive force and minimizing damage, and subsequent use of room temperature or cold water to facilitate further separation, thereby reducing tackiness and improving handling and extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If mechanical force is applied to separate mold halves after curing, then the lens can be removed from the mold, but lens damage such as fracture and tear occurs due to strong adhesion and vacuum seal
Solution Approach 1:
The patent applies preliminary action by introducing a release agent into the mold cavity before polymerization occurs. This release agent creates a non-stick barrier between the lens and mold surfaces in advance, preventing strong adhesion from developing during curing. As a result, the mold halves can be separated without requiring excessive mechanical force, thereby avoiding lens fracture and tear while maintaining high lens integrity
Solution Approach 2:
The patent employs an intermediary substance (release agent) that mediates between the lens and mold surfaces. This release agent forms a intermediate layer that prevents direct contact and strong bonding between the polymerizing lens material and the mold. The intermediary layer allows for easy separation of mold halves without transmitting damaging mechanical forces to the lens, thus resolving the contradiction between removal efficiency and lens integrity
2Ease of operation
If organic solvent is used for extraction and deblocking, then the lens can be removed from the mold half, but handling becomes difficult and costs increase due to lens tackiness
Solution Approach 1:
The release agent acts as an intermediary that prevents direct adhesion between the lens and mold, eliminating the need for organic solvent extraction and deblocking steps. By preventing tackiness at the source through the release agent barrier, the lens remains easy to handle throughout the process without requiring complex solvent-based removal procedures
Solution Approach 2:
The patent takes out (eliminates) the need for organic solvent extraction and deblocking steps by using the release agent prevention approach. Instead of requiring subsequent removal steps with complex solvents, the release agent prevents adhesion from the beginning, simplifying the overall process and improving ease of lens handling while reducing procedural complexity
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
This approach allows for the efficient dislodging of silicone hydrogel contact lenses from molds with minimal force, reducing lens damage, increasing production yield, and decreasing the need for organic solvents, thus enhancing the overall manufacturing process.
Implementation Method 1
the mold with the molded contact lens therein is soaked in hot water for a time sufficiently long to allow the hot water to get into the mold and hydrate the molded contact lens
Implementation Method 2
allow the hot water to get into the mold and hydrate the molded contact lens
Implementation Method 3
subsequent use of room temperature or cold water to facilitate further separation, thereby reducing tackiness
Data Source
Figure 1~2
AI summary
The invention provides an improved process for manufacturing silicone-hydrogel contact lenses by the use of room-temperature or cold water in the steps of separating a mold into a male mold half and female mold half and dislodging (or removing or de-blocking) a lens from its adhering mold half after the lens being cured and before lens extraction.