Photochromic Adhesive Composition for Optical Sheets
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Solution Overview
Problem
Existing photochromic adhesive compositions for bonding optical sheets, especially those made of polycarbonate resin, face challenges in maintaining high photochromic characteristics and adhesiveness at high temperatures, and often suffer from issues like peeling and optical strain in optical articles.
Innovation Solution
A photochromic adhesive composition is developed, comprising a photochromic compound with a molecular chain of 300 or more as a substituent, combined with an adhesive urethane (urea) resin having a specific softening point of 140 to 220°C, which enhances both adhesiveness and heat resistance while maintaining excellent photochromic performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a photochromic coating material prepared by adding a photochromic agent to an acrylate copolymer is used, then the photochromic characteristics are achieved, but the adhesiveness to the polycarbonate film is insufficient
Solution Approach 1:
The invention changes the chemical composition parameters of the adhesive layer by using a polyurethane resin containing specific groups (carboxyl, hydroxyl, or amine groups) instead of conventional acrylate copolymer. This parameter change enables both strong adhesion to polycarbonate and good photochromic characteristics through the specific chemical groups that facilitate bonding while allowing photochromic agent incorporation.
Solution Approach 2:
The invention creates a composite adhesive material combining polyurethane resin with specific functional groups (carboxyl, hydroxyl, or amine groups) and photochromic agents. This composite structure provides both the adhesive properties needed for bonding optical sheets and the photochromic functionality, resolving the contradiction between adhesion and photochromic performance.
2Ease of manufacture
If a polyurethane resin composition containing a solvent such as tetrahydrofuran or toluene is used, then the resin layer can be formed, but the transparent sheet may dissolve causing poor appearance and degradation of photochromic characteristics
Solution Approach 1:
The invention extracts and removes the harmful solvent (tetrahydrofuran or toluene) from the polyurethane resin composition. By using a solvent-free or low-solvent formulation with specific functional groups (carboxyl, hydroxyl, or amine groups), the adhesive maintains manufacturability while preventing dissolution of the transparent sheet and preserving photochromic characteristics.
Solution Approach 2:
The invention converts the potential harm of solvent-based formulations (which cause dissolution and degradation) into a benefit by using alternative functional groups (carboxyl, hydroxyl, or amine groups) that provide adhesion without requiring harmful solvents. This approach maintains resin layer formation capability while eliminating the harmful effects of solvent-induced dissolution.
3Reliability
If a laminate sheet bonded with a polycarbonate sheet via a photochromic dye-containing polyurethane resin adhesive layer is used, then the photochromic characteristics are achieved, but the adhesiveness and heat resistance are insufficient causing peeling or optical strain
Solution Approach 1:
The invention changes the chemical structure parameters of the polyurethane resin by incorporating specific functional groups (carboxyl, hydroxyl, or amine groups) that enhance both adhesion and heat resistance. This parameter modification allows the adhesive layer to maintain strong bonding and thermal stability while preserving photochromic characteristics, eliminating peeling and optical strain issues.
Solution Approach 2:
The invention develops a composite adhesive material combining polyurethane resin with specific functional groups (carboxyl, hydroxyl, or amine groups) and photochromic agents. This composite structure simultaneously provides enhanced adhesion, heat resistance, and photochromic performance, resolving the contradiction between photochromic characteristics and mechanical/thermal 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 firm bonding of optical sheets even at high temperatures, minimizes molding failures like peeling, and ensures excellent photochromic characteristics in the resulting optical articles.
Implementation Method 1
photochromic plastic sunglasses which can control the antiglareness by changing a transparency depending on the surrounding brightness by combination with a photochromic dye
Implementation Method 2
a photochromic adhesive composition having adhesiveness... capable of bonding optical sheets to each other
Data Source
Figure 1~2
AI summary
The present invention includes: a photochromic adhesive composition containing (A) a photochromic compound having, as a substituent, a molecular chain having a molecular weight of 300 or more, and (B) an adhesive urethane (urea) resin, and having a softening point of 140 to 220°C, and a photochromic laminate using the adhesive composition. The invention provides the photochromic adhesive composition that functions as an adhesive layer for bonding optical sheets, and the photochromic laminate using the composition exhibits excellent photochromic characteristics, adhesiveness and workability