Concentrated Optical Brightener Solutions With Reduced Anionic Charge
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Solution Overview
Problem
The paper industry faces challenges with optical brightening agents (OBAs) having low water solubility due to inorganic salts formed during manufacturing, leading to high anionic charge issues that interfere with recycling processes and require costly membrane filtration steps.
Innovation Solution
Concentrated aqueous solutions of triazinyl-stilbene-based optical brighteners with balanced cationic and anionic charges are prepared without additional process steps or solubilizing agents, using a stepwise reaction of cyanuric halides with amines and di-n-propylamine in the presence of water, resulting in stable solutions suitable for paper sizing and coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If conventional OBAs are used in concentrated aqueous solutions, then high anionic charge is generated which interferes with cationic chemicals, but the patent uses specific triazinyl-stilbene compounds with reduced anionic charge to eliminate this interference
Solution Approach 1:
The patent changes the chemical structure parameters of the OBA by using specific triazinyl-stilbene compounds with particular substituents (formula I with specific R groups and p values) to reduce the anionic charge from typical high levels to reduced levels, thereby eliminating interference with cationic chemicals in recycling processes
Solution Approach 2:
The patent creates a simplified version of conventional OBAs by using compounds that naturally possess reduced anionic charge without requiring additional processing steps like membrane filtration, thus copying the essential brightening function while eliminating the harmful anionic charge characteristic
2Stability of the object's composition
If membrane filtration is used to remove inorganic salts, then storage stability is improved, but the process becomes time- and cost-consuming
Solution Approach 1:
The patent extracts the problematic inorganic salts from the system during the manufacturing process itself, creating a final product that is inherently free of salts requiring no additional filtration steps, thus achieving both storage stability and process efficiency
Solution Approach 2:
The patent performs salt removal as a preliminary action during the manufacturing process rather than as a subsequent step, ensuring that the final concentrated aqueous solution is already purified and stable without requiring additional membrane filtration operations
3Quantity of substance
If amino acid residues are used in OBA compounds, then water solubility is improved, but anionic charge increases interfering with cationic chemicals
Solution Approach 1:
The patent changes the substituent parameters in the OBA molecular structure from amino acid residues (which provide solubility but high anionic charge) to alternative groups in formula (I) that maintain or improve water solubility while reducing anionic charge, achieving both solubility and reduced harmful effects simultaneously
4Device complexity
If concentrated aqueous solutions are prepared without membrane filtration, then process complexity is reduced, but storage stability is compromised
Solution Approach 1:
The patent performs purification as a preliminary action during manufacturing, ensuring that the concentrated aqueous solution is already free of inorganic salts and other impurities before storage, thereby achieving both process simplicity and long-term storage stability without requiring complex filtration equipment or 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 solutions provide superior fluorescent whitening effects with reduced anionic charge, improved solubility, and storage stability, eliminating the need for membrane filtration and auxiliaries, thus enhancing operational efficiency and cost-effectiveness.
Implementation Method 1
provide superior fluorescent whitening effects when applied to the surface of paper
Data Source
AI summary
Concentrated storage stable aqueous solutions (S) comprising components (a), (b) and (c), wherein component (a) is at least one optical brightening agent of formula (1), in which the anionic charge on the brightener is balanced by a cationic charge composed of one or more cations selected from the group consisting of hydrogen, alkali metal cation, alkaline earth metal cation, ammonium, ammonium which is mono-, di- or trisubstituted by a C1-4 linear or branched alkyl radical and ammonium which is mono-, di- or trisubstituted by a C1-4 linear or branched hydroxyalkyl radical, and the concentration of component (a) is 0.08 to 0.3 mol per kg, based on the total weight of the concentrated storage-stable aqueous solutions (S), component (b) is at least one inorganic salt (SA), in a concentration of 2 to 15% by weight, based on the total weight of the concentrated storage-stable aqueous solutions (S), and component (c) is water, in a concentration of 10% to 88% by weight, based on the total weight of the concentrated storage-stable aqueous solutions (S).