Lens Blank Temporary Grip Coating for Adhesion
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Solution Overview
Problem
Existing methods for bonding ophthalmic lens blanks to lens support blocks in continuous on-block manufacturing processes face challenges due to the hydrophobic and oleophobic top coatings reducing adhesion, leading to a risk of the lens blank detaching during processing, especially with thermoelastic materials like CR 39, where the temporary metallic fluoride grip systems lose surface energy over time.
Innovation Solution
A lens blank with a fully finished first face featuring a hydrophobic, oleophobic, and dirt-repelling top coating, covered by a temporary grip coating made from the same material as the outermost layer of the antireflection coating, which provides sufficient adhesion to the block piece even after storage, and a block piece with a plasma-treated workpiece mounting face for enhanced bonding, using a UV or visible light-curable blocking material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a hydrophobic, oleophobic top coating is applied to the lens blank to provide dirt repelling properties, then the surface properties are improved, but the adhesion at the interface between the blocking material and the lens blank is reduced
Solution Approach 1:
The patent segments the coating system into three distinct layers: the hydrophobic/oleophobic top coating (TC) for dirt repelling properties, a temporary grip coating (GC) for adhesion during processing, and the antireflection coating (AR) as the outermost layer. This segmentation allows each layer to perform its specific function without interfering with the adhesion of the blocking material.
Solution Approach 2:
The patent introduces the temporary grip coating (GC) as an intermediary layer between the blocking material and the top coating (TC). This intermediary layer provides the necessary adhesion for the blocking material while allowing the top coating to maintain its dirt repelling properties. The grip coating acts as a mediator that resolves the conflict between adhesion and surface properties.
2Reliability
If a temporary metallic fluoride grip coating is applied over the top coating to improve adhesion, then the adhesion is improved, but the surface energy is lost over time during storage
Solution Approach 1:
The patent changes the material parameter of the outermost coating layer from metallic fluoride to a material compatible with the antireflection coating (such as silicon oxide, titanium oxide, or zinc oxide). This parameter change allows the grip coating to maintain its adhesion properties over extended storage periods without losing surface energy, while still providing sufficient grip for the blocking material.
3Ease of manufacture
If the first face of the lens blank is fully finished including top coating before blocking, then the manufacturing process is simplified, but the adhesion to the blocking material is compromised
Solution Approach 1:
The patent applies the complete coating sequence (antireflection coating and top coating) to the first face of the lens blank before the blocking step. This preliminary action allows the lens blank to be fully coated in advance, simplifying the manufacturing process. The temporary grip coating is then applied over the top coating to ensure adhesion during processing, resolving the conflict between process simplification and adhesion reliability.
4Object-affected harmful factors
If protective foils are used to protect the lens blank during processing, then the lens is protected, but the handling and processing time are increased
Solution Approach 1:
The patent makes the temporary grip coating serve dual functions: it provides adhesion for the blocking material during processing and simultaneously acts as a protective layer for the top coating. This self-service approach eliminates the need for separate protective foils, reducing handling steps and processing time while maintaining protection of the lens blank.
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 solution ensures reliable adhesion during processing steps, reduces the risk of lens blank detachment, maintains the hydrophobic properties, and simplifies the manufacturing process by eliminating the need for protective foils and deblocking steps, allowing for efficient production of high-quality spectacle lenses with reduced handling and processing time.
Implementation Method 1
the temporary grip coating GC serving to achieve sufficient adhesion at an interface between the lens blank and a blocking material on a block piece
Implementation Method 2
a block piece with a plasma-treated workpiece mounting face for enhanced bonding
Implementation Method 3
using a UV or visible light-curable blocking material
Implementation Method 4
a top coating TC on top of the antireflection coating AR, wherein the top coating TC is selected from a group comprising hydrophobic, oleophobic and dirt repelling coatings
Data Source
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AI summary
A lens blank (SFB) is proposed, having a first face (cx), an opposite, second face (cc), and an edge (E) inbetween, the first face possessing a final curvature and being coated, in this order, with an antireflection coating (AR), a top coating (TC), and a temporary grip coating (GC). The antireflection coating comprises a stack of alternating antireflection layers (HIL, LIL) with an outermost layer, whereas the top coating is selected from a group comprising hydrophobic, oleophobic and dirt repelling coatings. The temporary grip coating and the outermost layer of the antireflection coating are comprised of one and the same coating material. In this way the temporary grip coating effectively serves to provide sufficient adhesion to the blocking material (M) on the block piece (B) in the processing steps, and can easily be removed from the processed lens upon deblocking without degrading the repelling properties of the top coating.