Benzodithiolane UV Agent with Acid Groups for Aqueous Stability
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Solution Overview
Problem
Current water-soluble ultraviolet absorbing agents face challenges in maintaining stability and solubility in aqueous media, particularly when exposed to long-wavelength ultraviolet rays, leading to issues like haze and precipitation due to crystallization.
Innovation Solution
A novel ultraviolet absorbing agent with a benzodithiolane skeleton and acid groups, such as sulfonic acid or carboxylic acid, is developed, which has improved solubility and stability in water, suppressing crystallization and aggregation, and is formulated into a composition with a water-soluble polymer for enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a water-soluble ultraviolet absorbing agent is used to absorb long-wavelength ultraviolet rays (380-400 nm), then the ultraviolet absorbing ability is improved, but the stability in aqueous medium deteriorates due to precipitation and aggregation
Solution Approach 1:
The patent modifies the molecular structure parameters of the ultraviolet absorbing agent by introducing specific acid groups (sulfonic acid, carboxylic acid, or phosphoric acid) and controlling the number of aromatic rings (1-3 rings) to achieve optimal balance between water solubility and UV absorbing ability. The molecular weight is controlled within 200-500 Da, and the agent must exhibit at least one acid group with pKa 2.0-6.0, which resolves the contradiction by changing chemical parameters to enhance both stability and functionality.
Solution Approach 2:
The patent creates a composite ultraviolet absorbing agent that combines the benzodithiolane skeleton with specific acid groups (sulfonic acid, carboxylic acid, or phosphoric acid) and optional aromatic rings. This composite structure integrates multiple functional elements: the benzodithiolane core for UV absorption, acid groups for water solubility, and controlled aromatic content for stability, thereby achieving both high ultraviolet absorbing ability and stability in aqueous media.
2Stability of the object's composition
If the solubility in water is increased to prevent precipitation, then the stability is improved, but the ultraviolet absorbing ability in the 380-400 nm range deteriorates
Solution Approach 1:
The patent optimizes the balance between solubility and UV absorption by precisely controlling molecular parameters: introducing 1-3 acid groups (sulfonic, carboxylic, or phosphoric acid) to enhance water solubility while limiting aromatic rings to 1-3 units to maintain UV absorbing ability in the 380-400 nm range. The molecular weight is constrained to 200-500 Da, ensuring sufficient solubility without compromising the chromophoric properties needed for effective UV absorption.
Solution Approach 2:
The patent applies local quality by strategically placing acid groups at specific positions on the benzodithiolane skeleton to maximize water solubility while preserving the core UV-absorbing structure. The acid groups are introduced at positions that enhance solubility without interfering with the electronic structure responsible for long-wavelength UV absorption, thus achieving local optimization of both solubility and UV absorbing ability.
3Stability of the object's composition
If a phenylbenzimidazole compound with sulfonic acid group is used as ultraviolet absorbing agent, then water solubility is achieved (0.01% or more), but the solubility degree is insufficient for stable presence in aqueous medium alone
Solution Approach 1:
The patent significantly enhances water solubility by introducing multiple acid groups (1-3 groups of sulfonic, carboxylic, or phosphoric acid) with pKa values between 2.0-6.0, exceeding the solubility of conventional phenylbenzimidazole compounds. This parameter change ensures the agent can stably present in aqueous medium alone without requiring additional solubilizing agents or forming emulsions, thereby achieving both high solubility and stable presence.
4Reliability
If the ultraviolet absorbing agent is aged in aqueous medium or water-soluble polymer, then the maintenance of ultraviolet absorbing ability is good, but haze increases due to precipitation or aggregation
Solution Approach 1:
The patent controls molecular parameters to prevent aggregation and precipitation during aging: molecular weight is limited to 200-500 Da, and the agent must contain 1-3 acid groups with specific pKa values (2.0-6.0). These parameter constraints ensure the molecule remains sufficiently hydrophilic and sterically hindered against aggregation, maintaining both UV absorbing ability and low haze even after prolonged aging in aqueous media or water-soluble polymers.
Solution Approach 2:
The patent incorporates acid groups (sulfonic, carboxylic, or phosphoric acid) with pKa values of 2.0-6.0 into the molecular structure beforehand, which act as cushioning elements that prevent precipitation and aggregation during aging. These pre-installed functional groups ensure the agent maintains stability and prevents haze formation even when exposed to environmental conditions over time, cushioning against the harmful effects of aggregation.
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 agent effectively absorbs ultraviolet rays in the 380-400 nm range with improved stability and reduced haze in aqueous media, maintaining performance even after aging, and is used in films and laminates for effective UV protection.
Implementation Method 1
an ultraviolet absorbing agent having an ultraviolet absorbing ability in a wavelength range of at least 380 nm to 400 nm
Data Source
AI summary
Provided are an ultraviolet absorbing agent represented by General Formula (1) and an application thereof. In General Formula (1), R11 represents a monovalent substituent. n is 1 or 2. W1 and W2 each independently represent a hydrogen atom, a cyano group, a carbamoyl group, a sulfamoyl group, a nitro group, an acyl group, an alkylsulfonyl group, an arylsulfonyl group, an alkylsulfinyl group, an arylsulfinyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkyl group, an aryl group, or a heterocyclic group, where at least one of W1 or W2 represents a substituent having a Hammett's substituent constant σp value of 0.2 or more. W1 and W2 may be bonded to each other to form a ring.