Stilbene Optical Brighteners With Reduced Anionic Charge
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Solution Overview
Problem
Stilbene optical brightening agents used in the paper industry have high solubility in water but generate a high anionic charge, which interferes with recycling processes and cationic chemicals, leading to a need for compounds with reduced anionic charge while maintaining fluorescent whitening effects.
Innovation Solution
Development of stilbene optical brightening agents with specific structural modifications, including the use of hydrogen, alkali metal cations, or ammonium, and specific alkyl groups, which are synthesized through a stepwise reaction of cyanuric halides with diamines and amines under controlled pH and temperature conditions, resulting in compounds with reduced anionic charge and high water solubility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If stilbene optical brightening agents with amino acid residues are used to achieve high water solubility and fluorescent whitening effects, then solubility in water is improved, but anionic charge increases causing interference with recycling processes and cationic chemicals
Solution Approach 1:
The patent changes the chemical structure parameters of the optical brightening agent by replacing amino acid residues with specific amino groups (formula II) that have different charge characteristics. This structural parameter change reduces the anionic charge while maintaining water solubility through the sulfonate groups, thereby resolving the contradiction between solubility and harmful anionic charge.
Solution Approach 2:
The patent creates a composite molecular structure combining stilbene core, sulfonate groups for solubility, and specific amino groups for reduced charge. This composite approach integrates multiple functional components within a single molecule to simultaneously achieve high water solubility and reduced anionic charge interference.
2Reliability
If optical brighteners are used in repulping processes to maintain whiteness, then fluorescent whitening effects are maintained, but anionic charge builds up interfering with cationic chemicals for sizing and retention
Solution Approach 1:
The patent modifies the charge parameter of the optical brightening agent by using amino groups with lower anionic charge characteristics. This allows the brightener to maintain its fluorescent whitening function in repulping processes while generating less anionic charge build-up, thus not interfering with subsequent cationic chemical treatments for sizing and retention.
3Illumination intensity
If conventional optical brightening agents are used to achieve high whiteness in coated papers, then fluorescent whitening effects are improved, but solubility and charge characteristics create processing difficulties
Solution Approach 1:
The patent optimizes the balance between fluorescent whitening performance and processing characteristics by adjusting the molecular parameters - specifically the amino group structure and sulfonate content. This enables the brightener to deliver high whiteness while maintaining excellent water solubility and reduced anionic charge for easier processing in paper coating operations.
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 modified stilbene optical brightening agents provide superior fluorescent whitening effects while reducing anionic charge, enabling effective use in paper production without interfering with recycling processes or cationic chemicals, and are suitable for use in size-press and pigmented coating compositions.
Implementation Method 1
The compounds of formula (1) are prepared by stepwise reaction of a cyanuric halide with a) a diamine of formula (2), b) an amine of formula (3) and c) an amine of formula (4)
Implementation Method 2
providing superior fluorescent whitening effects when applied to the surface of paper
Data Source
AI summary
The instant invention relates to stilbene optical brightening agents which combine a high solubility in water while providing superior fluorescent whitening effects when applied to the surface of paper in either the size-press or in a pigmented coating composition and which show a reduced anionic charge. The instant optical brighteners may also be used for finishing of textiles.