Optical Brightener Salt Composition for Storage-Stable Aqueous Solutions
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Solution Overview
Problem
The paper and board industry requires stable, concentrated aqueous solutions of optical brighteners without solubilizing auxiliaries for improved whiteness and handling, as existing solutions rely on additives that contaminate effluent and lack storage stability across temperature ranges.
Innovation Solution
A specific salt form of anilino-substituted bistriazinyl derivatives of 4,4′-diaminostilbene-2,2′-disulphonic acid is used, formed through a process involving conversion to a mixed salt with (CH3)2NH+CH2CH2OH ions, allowing for stable solutions without additional solubilizing agents, and further processed using membrane filtration for purity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solubilising auxiliaries such as urea or ethylene glycol are added to optical brightener solutions, then storage stability is improved, but effluent contamination increases
Solution Approach 1:
The invention extracts and eliminates the harmful solubilising auxiliaries (urea, ethylene glycol) from the optical brightener solution while maintaining storage stability through the use of specific salt forms of the optical brightener molecules themselves
Solution Approach 2:
The optical brightener molecules are modified to serve their own solubilisation needs through the incorporation of salt forms with enhanced water solubility, eliminating the need for external solubilising auxiliaries
2Ease of operation
If optical brighteners are supplied as concentrated aqueous solutions, then ease of handling and metering is improved, but storage stability over wide temperature ranges deteriorates
Solution Approach 1:
The invention changes the chemical parameters of the optical brightener by converting it to specific salt forms (sodium, potassium, ammonium, or organic ammonium salts) which fundamentally alter the solution's storage stability characteristics across temperature ranges while maintaining concentrated aqueous form for ease of handling
3Quantity of substance
If anilino-substituted bistriazinyl derivatives with sulphonic acid groups are used, then water solubility is improved, but affinity for cellulose fibres deteriorates
Solution Approach 1:
The invention applies local quality modification by introducing salt-forming functional groups at specific locations on the optical brightener molecule, creating a balance between water-soluble regions (salt forms) and cellulose-affine regions (anilino-substituted bistriazinyl core structure)
Data Source
AI summary
The instant invention relates to storage stable solutions of optical brighteners based on certain salt forms of anilino-substituted bistriazinyl derivatives of 4,4′-diaminostilbene-2,2′-disulphonic acid which do not need extra solubilising additives.