Ophthalmic Lens Coating Layout for Anti-Soil and Edging Alignment
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Solution Overview
Problem
Existing ophthalmic lenses with hydrophobic and/or oleophobic coatings face challenges in maintaining effective antifouling properties while ensuring proper alignment during the edge trimming process, as the low surface energy coatings impair adhesion, leading to misalignment and difficulty in removing temporary coatings without reducing hydrophobicity.
Innovation Solution
The lenses are designed with differentiated hydrophobic properties on the front and back surfaces, where the back surface has a higher water contact angle (≥80°) and a thinner temporary layer, if any, to enhance adhesion and antifouling performance, while the front surface has a lower contact angle and thicker temporary layer for easier removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If hydrophobic and/or oleophobic coatings are applied to ophthalmic lenses to improve antifouling properties, then dirt adhesion is reduced and cleaning is easier, but the low surface energy impairs adhesion to retaining devices during edge trimming, causing misalignment
Solution Approach 1:
The lens coating is segmented into two distinct zones: a first zone (front surface) with standard hydrophobic/oleophobic coating providing moderate antifouling properties, and a second zone (rear surface) with enhanced hydrophobic coating providing superior antifouling properties. This segmentation allows each zone to be optimized for its specific function while resolving the adhesion conflict during manufacturing.
Solution Approach 2:
Different surface energy characteristics are applied to different locations on the lens. The rear surface receives a coating with lower surface energy (higher hydrophobicity) compared to the front surface, creating local quality differences that enable the retaining device to adhere properly to the front surface while the rear surface maintains enhanced dirt resistance.
2Manufacturing precision
If temporary coatings are applied to ensure proper adhesion during edge trimming, then alignment is maintained, but the temporary coatings are difficult to remove without reducing the hydrophobic properties of the lens
Solution Approach 1:
The retaining device adheres specifically to the first zone (front surface) which has standard hydrophobic properties, allowing proper adhesion during edge trimming. After manufacturing, the retaining device is removed, and since it only contacted the front surface, the enhanced hydrophobic coating on the rear surface remains completely intact and unaffected.
Solution Approach 2:
The first zone with standard hydrophobic coating acts as an intermediary surface that provides sufficient adhesion for the retaining device during manufacturing, while the second zone with enhanced hydrophobic coating serves as a protected layer that maintains its superior antifouling properties without direct interaction with the retaining device.
3Ease of manufacture
If the same hydrophobic coating is applied to both front and back surfaces, then manufacturing is simplified, but the rear surface does not provide sufficient antifouling protection despite being close to the wearer's eye and eyelashes
Solution Approach 1:
The rear surface is treated with an enhanced hydrophobic coating that provides superior antifouling properties specifically where needed near the wearer's eye and eyelashes, while the front surface maintains standard coating properties. This local quality differentiation optimizes protection where most required.
Solution Approach 2:
The lens employs a composite coating structure with two different hydrophobic/oleophobic coatings: a first coating on the front surface with standard surface energy, and a second coating on the rear surface with lower surface energy and enhanced hydrophobicity, creating a multi-layered protective system.
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 design improves antifouling properties on the back surface, reduces misalignment during edge trimming, and maintains hydrophobicity, while allowing for easy removal of temporary coatings, thus enhancing visual comfort and lens performance.
Implementation Method 1
a coating having a contact angle of at least 80° with water on its rear face
Implementation Method 2
Antifouling coatings lower the surface energy of the lens, so that dirt adhesion is reduced
Data Source
AI summary
The present invention relates to an ophthalmic lens in which the front and rear surfaces each have different hydrophobic properties. Said lens includes a substrate having a hydrophobic main front surface, and a main rear surface, the outer surface of which has a receding water contact angle of no lower than 80°, the outer surface of said main front surface having a receding water contact angle lower than that of the rear main surface. The invention provides various means for preparing said lenses, which can be obtained in particular after depositing and then removing temporary layers with different thicknesses on the two surfaces of the lens.