Corona-Treated Mold Surface for Predictable Contact Lens Adhesion
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Solution Overview
Problem
In the full-mold process for contact lens production, it is unpredictable which mold half the polymerized contact lens will adhere to, requiring a manual check after opening the mold, which complicates the process and reduces efficiency.
Innovation Solution
Applying a corona discharge treatment to the back surface of the mold increases the surface hydrophilicity, ensuring the contact lens adheres reliably to one mold half, reducing lens tearing and allowing for automated processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If no surface treatment is applied to the mold, then the manufacturing process is simple, but the contact lens adhesion is unpredictable requiring manual checks
Solution Approach 1:
The mold surface is pre-treated with corona discharge before the contact lens manufacturing process to create a hydrophilic surface layer. This preliminary action ensures predictable lens adhesion to the treated mold half, eliminating the need for manual checks after molding while maintaining process simplicity
Solution Approach 2:
The surface properties of the mold are modified by changing the hydrophobicity parameter through corona discharge treatment. This creates a hydrophilic surface that reliably attracts and retains the hydrogel contact lens material, making adhesion predictable without adding complex process steps
2Productivity
If manual checks are performed after mold opening, then lens adhesion can be verified, but production efficiency is reduced
Solution Approach 1:
The mold surface is pre-treated with corona discharge to create a hydrophilic surface that guarantees predictable lens adhesion. This preliminary action allows the process to proceed automatically without manual verification, improving productivity while maintaining reliable adhesion consistency
Solution Approach 2:
The corona-treated mold surface self-regulates lens adhesion through its hydrophilic properties. The lens naturally adheres to the treated mold half without requiring external intervention or manual checks, enabling automated high-speed production while ensuring consistent adhesion
3Extent of automation
If corona discharge treatment is applied to the mold, then lens adhesion becomes predictable and automation is enabled, but additional processing step is required
Solution Approach 1:
The mold surface is pre-treated with corona discharge to create a hydrophilic surface layer before lens manufacturing. This one-time preliminary action enables subsequent automated production runs without requiring additional steps during each manufacturing cycle, balancing automation capability with manufacturing simplicity
Solution Approach 2:
The mold surface properties are permanently modified by corona discharge treatment to create a hydrophilic surface. This parameter change enables reliable lens adhesion and process automation while requiring only a single treatment step, maintaining ease of manufacture
4Manufacturing precision
If no surface treatment is used, then manufacturing is simpler, but lens tearing occurs due to unreliable adhesion
Solution Approach 1:
The mold surface is pre-treated with corona discharge to create a hydrophilic surface that ensures reliable lens adhesion during manufacturing. This preliminary action prevents lens tearing by guaranteeing strong, predictable bonding between the lens and mold, improving lens integrity without adding complex process steps
Solution Approach 2:
The surface hydrophobicity parameter of the mold is changed through corona discharge treatment to create a hydrophilic surface. This parameter change ensures strong, predictable lens adhesion that prevents lens tearing during removal, maintaining manufacturing precision while keeping the process simple
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 corona discharge treatment consistently retains the contact lens on the treated mold half, minimizing lens tearing and enabling automated processing without the need for post-opening checks, thus enhancing production efficiency and quality.
Implementation Method 1
applying a corona discharge on one of the first and second back surfaces
Implementation Method 2
increases the surface hydrophilicity, ensuring the contact lens adheres reliably to one mold half
Data Source
Figure 1
AI summary
The invention provides a method of making ophthalmic lenses with an enhanced quality and enhanced yield achieved by using molds having been treated on back surface of mold with corona discharge technique. The method comprises the steps of obtaining a mold for cast-molding contact lenses from a lens formulation, wherein the mold comprises a first mold half having a first molding surface and a first back surface, a second mold half having a second molding surface and a second back surface, wherein when the first and second mold are configured to receive each other such that a lens forming cavity is formed between the first molding surface and the second molding surface and applying a corona discharge on one of the first and second back surfaces so that the molding surface of the mold with the treated back surface has an average water contact angle smaller than the molding surface of the mold with untreated mold by about 0.1 degrees to about 6 degrees.