Modified Polyalkylene Oxide Thickener for Cationic Surfactant Compatibility
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Solution Overview
Problem
Conventional polyurethane-based thickeners exhibit poor transparency and increased viscosity when used with cationic surfactants, leading to undesirable cosmetic products with a heavy feel and turbidity, while reducing hydrophobic groups to improve transparency results in decreased viscosity.
Innovation Solution
A modified polyalkylene oxide is synthesized by reacting a polyethylene oxide compound with a polyether monohydric alcohol and a diisocyanate, specifically a polyether monohydric alcohol comprising an ethylene oxide/propylene oxide random copolymer and a monohydric alcohol, to create a thickener that maintains transparency and high viscosity even when combined with a cationic surfactant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the number of carbon atoms at the terminal alcohol is increased to enhance thickening properties, then the association power of hydrophobic groups increases, but the affinity for water decreases causing the aqueous solution to become tacky and turbid
Solution Approach 1:
The patent applies local quality by introducing a polar group (such as carboxylic acid, sulfonic acid, or hydroxyl group) at the terminal position of the hydrophobic group. This allows the terminal region to have different properties from the main chain - the main chain retains strong hydrophobic association for thickening, while the terminal polar group provides water affinity to prevent tackiness and turbidity.
Solution Approach 2:
The patent changes the chemical parameter of the terminal group by introducing polar functional groups (carboxylic acid, sulfonic acid, or hydroxyl groups) with specific pKa values or hydroxyl characteristics. This parameter change allows the terminal to interact favorably with water while the bulk hydrophobic groups maintain association, resolving the contradiction between thickening power and solution clarity.
2Object-generated harmful factors
If the proportion of hydrophobic groups is decreased to improve transparency, then the aqueous solution becomes clearer, but the viscosity decreases when cationic surfactant is added
Solution Approach 1:
The patent maintains high proportion of hydrophobic groups throughout the chain to ensure strong association and high viscosity, while introducing polar groups only at the terminals. This local differentiation allows the bulk to provide thickening power while the terminals provide water solubility and transparency, avoiding the need to reduce overall hydrophobic content.
Solution Approach 2:
The patent creates a composite molecular structure combining hydrophobic polyether chains with polar terminal groups. This molecular-level composite allows simultaneous achievement of high viscosity (from hydrophobic association) and good transparency (from terminal polar groups enhancing water compatibility).
3Strength
If polyurethane-based thickeners are used in combination with cationic surfactant, then the liquid exhibits thickened properties, but the transparency deteriorates giving an undesirable appearance
Solution Approach 1:
The patent introduces polar terminal groups that interact favorably with water and cationic surfactants, preventing aggregate formation that would cause turbidity. The main hydrophobic chain maintains association for viscosity, while the polar terminals ensure compatibility with aqueous and surfactant environments, maintaining transparency even with cationic surfactants present.
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 modified polyalkylene oxide provides a transparent and highly viscous aqueous solution, retaining transparency and viscosity when used with cationic surfactants, outperforming conventional thickeners by maintaining both properties without the drawbacks of turbidity and reduced viscosity.
Implementation Method 1
A modified polyalkylene oxide is synthesized by reacting a polyethylene oxide compound with a polyether monohydric alcohol and a diisocyanate
Implementation Method 2
nonionic polyurethane-based thickeners that exhibit thickening properties upon aggregation of hydrophobic groups
Data Source
Figure 1~2
AI summary
The object of the present invention is to provide a modified polyalkylene oxide capable of yielding an aqueous solution excellent in transparency with high viscosity, even when combined with a cationic surfactant. The present invention provides a modified polyalkylene oxide obtained by reacting a polyalkylene oxide compound (A), a polyether monohydric alcohol (B), and a diisocyanate compound (C); wherein (A) is a polyethylene oxide represented by formula (II) HO-(CH2CH2O)n-H (II) wherein n is an integer of 130 to 680; wherein (B) comprises a random copolymer of ethylene oxide and propylene oxide, the random copolymer having a hydroxy group at one terminal and a linear-chain C15-24 alkyl group at the other terminal, and having a ratio (a/b) of 1 to 2 wherein a represents the number of moles of ethylene oxide added and b represents the number of moles of propylene oxide added; and wherein (C) is at least one member selected from the group consisting of compounds represented by formula (IV) O=C=N-R2-N=C=O (IV) wherein R2 represents methyldiphenylene, hexamethylene, methyldicyclohexylene, 3-methyl-3,5,5-trimethylcyclohexylene, dimethylphenylene, or tolylene.