Optical Brightening Solutions With Low Anionic Charge Stability
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Solution Overview
Problem
The paper industry faces challenges with optical brightening agents (OBAs) due to their low solubility in water and high anionic charge, which interferes with recycling processes and requires costly membrane filtration or additional steps to achieve storage-stable aqueous solutions.
Innovation Solution
Concentrated aqueous solutions of triazinyl-stilbene-based optical brighteners with balanced anionic and cationic charges, prepared without solubilizing auxiliaries or membrane filtration, providing superior fluorescent whitening effects for paper applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If optical brightening agents are used in concentrated aqueous solutions, then solubility and storage stability are improved, but anionic charge builds up during repulping which interferes with cationic chemicals
Solution Approach 1:
The patent changes the chemical structure of the optical brightening agent by using a tertiary amine group instead of an amino acid residue, which fundamentally alters the charge characteristics. This structural parameter change reduces the anionic charge while maintaining solubility and storage stability in concentrated aqueous solutions.
2Object-generated harmful factors
If membrane filtration is used to remove inorganic salts, then anionic charge is reduced, but process time and cost increase
Solution Approach 1:
The patent extracts the problematic amino acid residue component from the optical brightening agent structure and replaces it with a tertiary amine group. This extraction eliminates the source of high anionic charge at the molecular level, making subsequent membrane filtration unnecessary and reducing process time.
Solution Approach 2:
The patent performs preliminary structural modification of the optical brightening agent during synthesis to reduce anionic charge before the repulping process. By addressing the charge issue in advance through molecular design rather than through post-processing filtration, the method eliminates time-consuming membrane filtration steps.
3Stability of the object's composition
If amino acid residues are used to improve solubility, then storage stability is enhanced, but anionic charge increases which interferes with papermaking chemicals
Solution Approach 1:
The patent changes the functional group parameter from amino acid residue to tertiary amine group in the optical brightening agent structure. This parameter change simultaneously maintains storage stability while reducing anionic charge, eliminating the trade-off between these two properties.
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 exhibit enhanced storage stability and improved solubility, reducing anionic charge interference and eliminating the need for additional processing steps, resulting in superior fluorescent whitening effects on paper surfaces.
Implementation Method 1
provide superior fluorescent whitening effects when applied to the surface of paper
Data Source
Figure 1
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).