Isotropic Liquid Detergent HEDP Stability via Amine Buffering
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Solution Overview
Problem
Isotropic aqueous liquid laundry detergents face challenges in incorporating high levels of 1-Hydroxyethane-1,1-diphosphonic Acid (HEDP) due to stability issues, particularly in concentrated compositions, which affects cleaning performance when used in low surfactant doses.
Innovation Solution
Formulating the detergent with a surfactant system comprising ethoxylated alcohol nonionic surfactant, amine oxide, linear alkyl benzene sulphonate, and soap, along with a polymer system of ethoxylated polyethyleneimine and polyethylene terephthalate polyester soil release polymer, and using monoethanolamine for pH adjustment to maintain stability and incorporate at least 1.5 wt% HEDP, ensuring the composition remains isotropic and effective.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high levels of HEDP are incorporated into concentrated liquid detergent compositions, then cleaning performance on bleachable stains is improved, but physical stability of the isotropic liquid deteriorates
Solution Approach 1:
The patent introduces a specific amine buffer system (monoethanolamine and/or diethanolamine with pH 7.0-9.0) as an intermediary between HEDP and the isotropic liquid matrix. This buffer mediator enables HEDP to remain stable at high concentrations (0.5-5.0 wt%) without causing precipitation or phase separation, thus maintaining both cleaning performance and physical stability simultaneously
Solution Approach 2:
The patent changes the pH parameter of the liquid detergent composition to specifically 7.0-9.0 using the amine buffer system. This pH adjustment optimizes HEDP solubility and stability in the concentrated isotropic liquid, allowing high levels of HEDP to be incorporated while preventing the physical instability that would otherwise occur at higher HEDP concentrations
2Stability of the object's composition
If concentrated liquid detergent compositions are formulated at lower pH (around 6.5) for polymer stability, then polymer stability is improved, but HEDP stability at high incorporation levels deteriorates
Solution Approach 1:
The patent raises the pH parameter from the conventional 6.5 (used for polymer stability) to a new optimal range of 7.0-9.0. This pH elevation, achieved through the amine buffer system, simultaneously optimizes both polymer stability and HEDP stability at high concentrations, resolving the trade-off between these two requirements
Solution Approach 2:
The patent creates a composite buffer system combining monoethanolamine and/or diethanolamine with additional amines (such as triethanolamine, disodium EDTA, or sodium citrate). This composite material provides synergistic effects that maintain both polymer integrity and HEDP stability at the required pH range of 7.0-9.0
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 isotropic liquid detergent with enhanced cleaning performance by maintaining HEDP stability at higher incorporation levels, even at elevated temperatures, effectively addressing the stability and cleaning challenges of previous compositions.
Implementation Method 1
HEDP has been found to be much harder to incorporate into isotropic liquids with acceptable physical stability compared with the prior art Dequest 2066
Implementation Method 2
a) at least 10 wt% of a surfactant system, the surfactant system comprising: a(i) at least 5 wt% ethoxylated alcohol nonionic surfactant
Implementation Method 3
c) at least 5 wt% of a polymer system comprising nonionic EPEI and nonionic PET POET polyester soil release polymer
Data Source
AI summary
An isotropic liquid laundry detergent comprising: a) at least 10 wt% of a surfactant system, the surfactant system comprising: a(i) at least 5 wt% ethoxylated alcohol nonionic surfactant, a(ii) optionally, amine oxide amphoteric surfactant, a(iii) at least 5 wt% linear alkyl benzene sulphonate formed from neutralisation of LAS acid by an amine that buffers at the pH of the composition and a second non-buffering amine that does not buffer because its pKa is at least 2 units higher than the in-bottle pH of the composition, a(iv) soap formed from the neutralisation of fatty acid by the first and second amine, and a(v) optionally, Alkyl ether sulphate; b) at least 1.5 wt% HEDP, c) at least 5 wt% of a polymer system comprising nonionic EPEI and nonionic PET POET polyester soil release polymer, and d) at least 2 enzymes. the in-bottle pH of the composition being in the range 6.0 to less than 7, preferably 6.3 to 6.7.