Photochromic Optical Coating Composition for Strong Layer Adhesion
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Solution Overview
Problem
Existing optical articles with photochromic layers face challenges in achieving excellent adhesion between the photochromic layer and adjacent layers, which affects the durability and performance of the optical article.
Innovation Solution
A polymerizable composition comprising an acyclic methacrylate with a molecular weight of 500 or more and a hydroxy group-containing (meth)acrylate is used to form a photochromic layer, enhancing adhesion with adjacent layers through the inclusion of specific components like polyalkylene glycol dimethacrylate and hydroxy group-containing (meth)acrylate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional photochromic coating is used, then the photochromic layer can be formed, but the adhesion between the photochromic layer and adjacent layers is insufficient
Solution Approach 1:
The patent uses a composite polymerizable composition containing multiple specific components: a photochromic compound, a polymerizable compound with a specific structure (containing both a methacryloyl group and a hydroxy group), and optionally a silane coupling agent. This composite material approach creates a photochromic layer with enhanced adhesion to adjacent layers while maintaining manufacturability through a systematic formulation method.
Solution Approach 2:
The patent specifies precise parameter ranges for the polymerizable composition, including the molecular weight of the polymerizable compound (500-2000), the ratio of hydroxy group-containing (meth)acrylate to total (meth)acrylate (5-50 mass%), and the content of silane coupling agent (0.1-10 mass%). By optimizing these parameters, the adhesion performance is significantly improved without excessive complexity in the manufacturing process.
2Strength
If the photochromic layer is made thicker to improve durability, then the layer strength increases, but the adhesion to adjacent layers deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the photochromic layer by incorporating specific polymerizable compounds with controlled molecular weights and hydroxy group contents. This allows the layer to achieve both sufficient thickness for durability and enhanced adhesion through chemical bonding mechanisms, resolving the contradiction between thickness and adhesion.
Solution Approach 2:
The patent introduces a silane coupling agent as an intermediary substance that chemically bonds the photochromic layer to adjacent layers. This mediator enables strong adhesion even when the photochromic layer is made thicker, as the silane coupling agent creates chemical bridges between the photochromic layer and surrounding materials.
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 composition enables the formation of a photochromic layer with superior adhesion to adjacent layers, improving the durability and performance of optical articles such as spectacle lenses by ensuring strong bonding.
Implementation Method 1
A photochromic compound is a compound having a property of developing a color under emission of light in a wavelength range having photoresponsivity and fading without light emission (photochromic properties)
Implementation Method 2
a method in which a coating containing a photochromic compound and a polymerizable compound is provided on a substrate, and the coating is cured to form a cured layer having photochromic properties
Data Source
AI summary
Provided is a polymerizable composition for an optical article including a photochromic compound, a component A: an acyclic methacrylate having a molecular weight of 500 or more, and a component B: a hydroxy group-containing (meth)acrylate.