Aqueous Dye Dispersion Stability via Free Acid Form
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Solution Overview
Problem
Current technologies face challenges in producing stable aqueous dye dispersions of anionic direct dyes in their acid form, which are cost-effective and ecologically friendly, with high color strength, and in achieving highly concentrated dispersions that can be easily diluted.
Innovation Solution
An aqueous dye dispersion comprising 2.0 to 30.0% by weight of a dye with a coupling component from the acetoacetanilide, pyridone, or pyrimidine series, 0.1 to 20.0% by weight of additives such as wetting agents, dispersing agents, rheology modifiers, and preservatives, and 50.0 to 97.9% by weight of water, where the dye is in its free acid form, stabilized using ultrafiltration and suitable additives to prevent sedimentation and improve viscosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If highly concentrated dispersions of direct dye salts are prepared, then color strength is improved, but dilution speed decreases and stability worsens
Solution Approach 1:
The patent changes the chemical form of the dye from salt to free acid, which fundamentally alters solubility and dilution characteristics. The free acid form enables rapid dilution while maintaining high concentration stability, resolving the contradiction between concentration and dilution speed
Solution Approach 2:
The patent introduces specific additives as intermediaries that facilitate the dissolution and stabilization of highly concentrated free acid dye dispersions. These additives act as mediators between the concentrated dye and water, enabling easy dilution without compromising stability
2Object-affected harmful factors
If free acid form of anionic direct dyes is used, then ecological compatibility is improved, but water solubility worsens leading to sedimentation
Solution Approach 1:
The patent uses specifically selected additives as intermediaries that bridge the free acid dye and water, preventing sedimentation while maintaining the ecological benefits of the acid form. These additives enable solubilization without requiring harsh chemicals
Solution Approach 2:
The patent creates a composite dispersion system combining free acid dye with specially selected stabilizing additives. This composite approach maintains the ecological advantages of the acid form while achieving enhanced stability through synergistic interactions between components
3Stability of the object's composition
If conventional salt forms of direct dyes are used, then water solubility is improved, but ecological impact worsens and color strength decreases
Solution Approach 1:
The patent changes the fundamental chemical parameter from salt form to free acid form, which simultaneously improves ecological compatibility and color strength while maintaining adequate solubility through the use of specific additives and optimized formulation parameters
4Quantity of substance
If highly concentrated dye dispersions are prepared, then shipping costs are reduced, but obtaining such concentrated dispersions becomes more difficult
Solution Approach 1:
The patent changes the dye form to free acid and optimizes formulation parameters to enable the preparation of highly concentrated dispersions through simple mixing processes, making high-concentration production both feasible and economical
Solution Approach 2:
The patent employs specific additives as intermediaries that facilitate the preparation of highly concentrated dispersions by improving wetting and dispersion characteristics, thereby simplifying the manufacturing process despite the high concentration target
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 solution results in stable, non-sedimenting dye dispersions with improved color strength, faster dyeing capabilities, and reduced organic waste, allowing for higher concentration and easier dilution, while maintaining long shelf life and reducing the need for certain additives.
Implementation Method 1
by azo coupling one or more aromatic diazonium salts with one or more couplers
Implementation Method 2
adding to the aqueous slurry a viscosity enhancing agent in an amount sufficient to obtain a viscosity of 500 to 5000 centipoise
Implementation Method 3
Ultrafiltration is carried out in order to remove salts and synthesis byproducts
Data Source
AI summary
The present invention relates to storage stable aqueous dye dispersions, comprising (a) 2.0 to 30.0 % by weight, based on the sum of (a), (b) and (c), of a dye of the formula (3) in which KK is a residue of a coupling component; (b) 0.1 to 20.0 % by weight, based on the sum of (a), (b) and (c), of at least one additive selected from the group consisting of wetting agents, dispersing agents, rheology modifiers, and preservatives; and (c) 50.0 to 97.9 % by weight, based on the sum of (a), (b) and (c), of water. The invention moreover relates to a process for their preparation and the use thereof for the dyeing, in particular of paper.