Heterocyclic UV Absorbent for Polymer Stability
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Solution Overview
Problem
Current ultraviolet absorbents face limitations in long-wavelength UV-A absorption, with inorganic absorbents lacking flexibility in absorption wavelength and organic absorbents experiencing light stability issues and skin irritation concerns, while existing heterocyclic compounds are underutilized for their potential in UV protection.
Innovation Solution
Development of a novel heterocyclic compound with a specific structure that acts as a monomolecular ultraviolet absorbent, featuring a high molar extinction coefficient and excellent light fastness, which is used to enhance the UV resistance of polymer materials and prevent decomposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inorganic ultraviolet absorbents are used, then durability properties such as weather resistance and heat resistance are improved, but freedom in selecting the compound is limited and absorption wavelength is determined by band gap
Solution Approach 1:
The patent applies parameter changes by modifying the molecular structure of organic ultraviolet absorbents through chemical substitution and conjugation extension. Specifically, it uses heterocyclic compounds with extended pi-conjugation systems and introduces electron-donating or electron-withdrawing groups to precisely adjust absorption wavelengths, enabling both high durability and flexible wavelength selection.
2Adaptability or versatility
If organic ultraviolet absorbents with long-wavelength absorption are used, then absorption wavelength flexibility is improved, but light stability deteriorates and absorption capacity declines over time
Solution Approach 1:
The patent employs composite material strategy by combining heterocyclic chromophores with stable molecular frameworks. It integrates electron-donating heterocyclic rings with electron-withdrawing groups to create push-pull chromophores that enhance both absorption flexibility and photostability through intramolecular charge transfer mechanisms that prevent degradation.
Solution Approach 2:
The patent modifies molecular parameters by extending pi-conjugation length and introducing rigid heterocyclic structures to reduce molecular vibration and rotation, thereby enhancing light stability while maintaining long-wavelength absorption flexibility through controlled conjugation extension.
3Reliability
If benzophenone- and benzotriazole-based ultraviolet absorbents are used, then light stability is improved, but skin irritation and accumulation in body cause concern
Solution Approach 1:
The patent applies local quality by modifying specific regions of the molecular structure - using heterocyclic rings with electron-donating properties at specific positions to alter the electronic distribution and reduce skin penetration while maintaining UV absorption efficacy. The molecular design targets specific interaction sites to avoid harmful biological effects.
Solution Approach 2:
The patent employs a design philosophy of using molecules that are metabolically benign and readily excreted, avoiding accumulation in the body. The heterocyclic structures are designed to be photostable during use but easily metabolized afterward, eliminating long-term accumulation concerns while providing sustained UV protection.
4Illumination intensity
If ultraviolet absorbent concentration is increased to block long-wavelength light, then light blocking capability is improved, but precipitation and bleed-out occur during long-term use
Solution Approach 1:
The patent changes the molecular parameters of the ultraviolet absorbent by introducing rigid heterocyclic structures and extended conjugation systems that increase molar extinction coefficients. This allows achieving high light blocking capability at lower concentrations, preventing precipitation and bleed-out while maintaining effective UV protection.
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 novel heterocyclic compound effectively provides sustained long-wavelength UV-A absorption without precipitation or bleed-out, improving the UV resistance of polymer materials and preventing instability in UV filter applications.
Implementation Method 1
the compound exhibits a molar extinction coefficient of 75,000 or more at its maximum absorption wavelength, and the maximum absorption wavelength is 350 nm or more
Data Source
AI summary
A compound represented by formula (I-1):wherein R21, R22, R23 and R24 each independently represent a hydrogen atom or a monovalent substituent, with the proviso that compounds, in which R21, R22, R23 and R24 each are an alkylthio group, are excluded; R21 and R22 and/or R23 and R24 each may bond to each other to form a ring, with the proviso that compounds, in which the formed ring is a dithiol ring or a dithiolane ring, are excluded;R25 and R26 each independently represent a hydrogen atom or a monovalent substituent;X21, X22, X23 and X24 each independently represent a hetero atom;compounds, wherein R21, R22, R23 and R24 each represent a cyan group; X21, X22, X23 and X24 each represent a sulfur atom; and R25 and R26 each represent a hydroxyl group or a hydrogen atom, are excluded; andcompounds, wherein R21 and R23 each represent a hydrogen atom; R22 and R24 each represent an arylcarbonyl group; X21, X22, X23 and X24 each represent a sulfur atom; and R25 and R26 each represent a hydroxyl group, are excluded; and an ultraviolet absorbent, which has molecular weight of 10,000 or less and molar extinction coefficient at the maximum absorption wavelength of the ultraviolet absorbent of 80,000 or more.