Aqueous Direct Dye Formulation Stability via Membrane Purification
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Solution Overview
Problem
Existing aqueous direct dye formulations for paper dyeing face storage stability issues due to limited dye solubility and the presence of water-soluble amines and urea, leading to precipitates and nonuniform colorations, especially in blended dye mixtures.
Innovation Solution
An aqueous direct dye formulation with reduced amounts of water-soluble amines and urea, where dyes are purified using nanofiltration or ultrafiltration, and the formulation includes 50-99% of dyes obtainable by reduction or thermal treatment of Direct Yellow 11, 1-50% of blue, black, or red direct dyes, up to 0.9% of water-soluble amines, and up to 0.9% of urea, with specific membrane cutoffs and preservatives to enhance stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If water-soluble amines and urea are added to improve dye solubility, then storage stability is improved, but environmental pollution and waste treatment complexity increase
Solution Approach 1:
The patent removes harmful substances (water-soluble amines and urea) from the dye formulation while maintaining storage stability through alternative means such as optimized dye composition and pH control, thereby eliminating environmental pollution without sacrificing reliability
Solution Approach 2:
The patent changes the chemical composition parameters by reducing or eliminating water-soluble amines and urea, and instead uses alternative stabilizers and pH adjusters to maintain storage stability, thus resolving the contradiction between reliability and environmental harm
2Reliability
If high concentrations of water-soluble amines and urea are used to maintain dye solubility, then storage stability is improved, but the amount of harmful substances in waste water increases
Solution Approach 1:
The patent extracts and removes water-soluble amines and urea from the formulation, replacing them with environmentally friendly alternatives that provide the same storage stability function without contributing to harmful substance accumulation in waste water
Solution Approach 2:
The patent uses biodegradable and environmentally friendly substances that break down quickly in the environment, replacing persistent harmful substances, thus reducing the quantity of harmful substances in waste water while maintaining storage stability
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 formulation achieves stable direct dye solutions with reduced sulfate content and minimal organic waste, providing consistent coloration and improved storage stability, reducing the need for additional solubility improvers and minimizing waste treatment complexities.
Implementation Method 1
at least one of dyes (a1) and (a2) has been purified by nanofiltration or ultrafiltration, whereby nanofiltration has been carried out with a polymer nanofiltration membrane or ultrafiltration has been carried out with a polymer or ceramic membrane with a cutoff at 1000 to 5000 Dalton
Implementation Method 2
at least one of dyes (a1) and (a2) has been purified by nanofiltration or ultrafiltration, whereby nanofiltration has been carried out with a polymer nanofiltration membrane or ultrafiltration has been carried out with a polymer or ceramic membrane with a cutoff at 1000 to 5000 Dalton
Data Source
AI summary
The present invention relates to an aqueous direct dye formulation, comprising (a) 5 to 25 % by weight of a dye composition comprising (a1) 50-99 % by weight of one or more dyes obtainable by reduction or thermal treatment of Direct Yellow 11, and (a2) 1 -50 % by weight of a blue, black and/or red direct dye, (all based on the dye composition); (b) up to 0.9 % by weight of a saturated, cyclic or acyclic water-soluble amine comprising a primary, secondary or tertiary amino group and at least one further functional group selected from primary, secondary and tertiary amino groups, OH groups and ether groups; and (c) up to 0.9 % by weight of urea; and (d) water, wherein the percentages for (a), (b), and (c) relate to the total weight of the aqueous direct dye formulation. The invention moreover relates to a process for their preparation and the use thereof for the dyeing, in particular of paper, as well as paper which has been dyed with this aqueous direct dye formulation.