Ophthalmic Lens Mold Coating for Print-on-Mold and Release
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Solution Overview
Problem
The manufacture of ophthalmic lenses, particularly colored contact lenses, faces challenges such as 'bubbling' and 'sticking' due to inadequate mold surface wettability and reactivity, as well as 'no print' defects in the print-on-mold process, which affect the quality and yield of lens production.
Innovation Solution
A mold assembly with a mateable pair of glass or quartz mold parts, where at least one cavity surface is coated with a uniform and continuous inorganic protective coating, typically silicon oxide, to enhance non-reactivity and wettability, applied using plasma treatment or silicone pad methods, ensuring a water dynamic contact angle between 60° to 100° for improved mold release and print-on-mold properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If glass or quartz molds are used, then durability, transparency, and dimensional stability are improved, but cost increases
Solution Approach 1:
The patent applies this principle by providing a protective coating on glass or quartz molds that can be removed and replaced. When the mold becomes damaged or contaminated beyond repair, rather than discarding the entire expensive mold, only the relatively inexpensive protective coating is removed and a new one is applied, effectively creating a disposable protective layer on a permanent mold substrate.
2Ease of operation
If mold surface is treated to improve wettability, then mold release is improved, but chemical reactivity with monomers increases
Solution Approach 1:
The patent applies this principle by introducing a protective coating as an intermediary layer between the mold surface and the lens monomers. This coating layer provides the desired wettability and mold release properties while simultaneously acting as a barrier that prevents harmful chemical interactions between the monomers and the mold substrate, thus resolving the contradiction between improved release and reduced chemical reactivity.
3Object-affected harmful factors
If protective coating is applied to mold, then chemical resistance is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies this principle by changing the surface parameters of the mold through application of a protective coating with specific properties (wettability, chemical resistance, thickness). The coating transforms the mold surface characteristics to achieve the desired chemical resistance and mold release properties, while the systematic approach to coating application and removal manages the manufacturing complexity.
4Productivity
If mold is reused after cleaning, then productivity is improved, but quality consistency deteriorates
Solution Approach 1:
The patent applies this principle by applying a fresh protective coating to the mold before each production run. This preliminary action ensures that the mold surface is in optimal condition for each lens manufacturing cycle, preventing contamination and ensuring consistent quality. The coating is applied in advance and maintained throughout production, eliminating the quality deterioration that occurs with repeated cleaning and reuse.
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 solution significantly reduces lens rejection rates due to 'no print' and 'sticking' issues, maintaining consistent molding quality and increasing the overall yield of high-quality colored contact lenses, with the coated molds capable of withstanding multiple manufacturing cycles with minimal defects.
Implementation Method 1
The coating, during molding of the ophthalmic article, is essentially inert or non-reactive with the lens monomers or lens surface that is formed in the mold assembly
Implementation Method 2
enhance non-reactivity and wettability, applied using plasma treatment or silicone pad methods, ensuring a water dynamic contact angle between 60° to 100° for improved mold release
Implementation Method 3
The preferred technique for applying a protective coating to the mold employs plasma-enhanced chemical vapor deposition (PECVD)
Data Source
Figure 1~2
AI summary
This invention is directed to improved lens molds (1) for the production of ophthalmic lenses, in particular colored contact lenses. The invention involves protective coatings (3) for extended use and repair of reusable glass or quartz molds as well as for improved mold release and print-on-mold properties. The invention is also directed to a method of making the improved lens molds and their use in the manufacture of ophthalmic lenses, in particular colored contact lenses.