Photochromic Primer Layer Composition for Stable Adhesion
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Solution Overview
Problem
Existing photochromic articles face challenges in achieving strong adhesive properties between the photochromic layer and the substrate, particularly due to the viscosity increase of moisture-curable polyurethane resins during storage.
Innovation Solution
A primer layer formed from a polymer composition containing a polymer with hydroxy groups and (meth)acryloyl groups, along with a blocked isocyanate, is introduced between the photochromic layer and the substrate to enhance adhesion, preventing viscosity increase during storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a moisture-curable polyurethane resin layer is formed between the substrate and the photochromic layer to improve adhesion, then the adhesive property is improved, but the liquid viscosity increases during storage due to reaction with moisture in the air
Solution Approach 1:
The patent uses a primer layer as an intermediary between the substrate and the photochromic layer. This primer layer contains a blocked isocyanate that prevents direct moisture curing of the polyurethane resin during storage, thereby maintaining low viscosity while still providing adhesion promotion. The blocked isocyanate acts as a mediator that delays the curing reaction until the desired time.
Solution Approach 2:
The patent changes the chemical state of the isocyanate group by using a blocked isocyanate instead of a free isocyanate. This parameter change (from reactive to blocked state) prevents premature reaction with moisture during storage, maintaining the resin in a low-viscosity liquid state until application, when the blocking is removed to allow curing.
2Stability of the object's composition
If a primer layer with blocked isocyanate is used to suppress viscosity increase during storage, then the liquid viscosity stability is improved, but the adhesive property must be maintained through specific polymer composition
Solution Approach 1:
The patent creates a composite primer layer composition that combines a polymer with both hydroxy groups and (meth)acryloyl groups, along with a blocked isocyanate. This composite material approach allows the system to achieve both viscosity stability during storage and adequate adhesion, as the dual-functional polymer provides both crosslinking capability and adhesion promotion without requiring overly complex formulations.
3Stability of the object's composition
If the isocyanate group is protected by a blocking agent to suppress reaction during storage, then the viscosity stability is improved, but the curing capability must be restored after storage
Solution Approach 1:
The patent applies preliminary action by blocking the isocyanate group before storage to prevent premature curing. The blocking agent is specifically chosen to be removable under storage conditions, allowing the isocyanate to become active again when needed for adhesion and curing. This preliminary blocking action ensures stability during storage while preserving the curing capability for later use.
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 provides a photochromic article with excellent adhesive properties between the photochromic layer and the substrate, ensuring durability and stability over time.
Implementation Method 1
The isocyanate contained in the primer layer forming polymer composition is a blocked isocyanate in which the isocyanate group is protected by a blocking agent, so that the reaction during storage of the hydroxy group and the isocyanate group possessed by the polymer can be suppressed.
Implementation Method 2
A photochromic compound is a compound having a property of developing a color under irradiation with a light in a wavelength range having a photoresponsiveness, and fading without light irradiation (photochromic property).
Data Source
AI summary
Provided is a photochromic article having a substrate, a primer layer formed from a primer layer forming polymer composition, and a photochromic layer containing a photochromic compound in this order. The primer layer forming polymer composition contains a polymer having a hydroxy group and a (meth) acryloyl group, and a blocked isocyanate.