Photochromic Coating Composition Balancing Hardness and Fast Switching
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Solution Overview
Problem
Existing curable photochromic compositions face a challenge in achieving a balance between hardness and photochromic performance, with hard matrices resulting in slower transformation kinetics and reduced hardness in soft matrices.
Innovation Solution
A curable photochromic composition comprising a photochromic compound, a hydrazide functional material with multiple hydrazide groups, a (meth)acrylate polymer with reactive carbonyl groups, and optionally a second carbonyl-functional component or non-reactive component, to form a photochromic layer with improved hardness without compromising photochromic performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a hard matrix is used in cured photochromic films, then hardness is improved, but photochromic transformation kinetics deteriorates (slower transformation)
Solution Approach 1:
The patent changes the chemical composition parameters of the matrix by incorporating specific functional materials (hydrazide-functional materials and carbonyl-functional components) that create a unique molecular structure. This allows the matrix to achieve both hardness and fast photochromic transformation kinetics by modifying the chemical environment around the photochromic compound, enabling simultaneous improvement of both hardness and transformation speed.
2Speed
If a soft matrix is used in cured photochromic films, then photochromic transformation kinetics is improved (faster transformation), but hardness deteriorates (reduced hardness)
Solution Approach 1:
The patent creates a composite matrix system combining hydrazide-functional materials with carbonyl-functional components. This composite structure provides both the flexibility needed for fast photochromic transformation and the structural integrity for hardness, resolving the contradiction between softness for kinetics and hardness for strength.
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 achieves a balance between hardness and photochromic performance by utilizing hydrazide and carbonyl-functional components to create a durable photochromic layer with fast transformation kinetics.
Implementation Method 1
a hydrazide functional material having at least two hydrazide groups that are reactive with carbonyl groups
Implementation Method 2
photochromic compounds, such as indeno-fused naphthopyrans, typically undergo a transformation from one form or state to another form, with each form having a characteristic or distinguishable absorption spectrum associated therewith
Data Source
AI summary
The present invention relates to, a curable photochromic composition that includes: (a) a photochromic compound; (b) a hydrazide functional material having at least two hydrazide groups that are reactive with carbonyl groups selected from ketone groups and aldehyde groups; (c) a first carbonyl-functional component including a (meth)acrylate polymer having at least two carbonyl groups that are reactive with hydrazide groups; and (d) at least one of, (d1) a second carbonyl-functional component having at least one carbonyl group that is reactive with hydrazide groups, and/or (d2) a non-reactive component. The non-reactive component is free of functional groups that are reactive with the hydrazide functional material, the first carbonyl-functional component, and the second carbonyl-functional component. The present invention also relates to an article that includes: a substrate; and a photochromic layer over at least one surface of the substrate, where the photochromic layer is formed from the curable photochromic composition of the present invention.