pH-Responsive Thickener Blend for Low Viscosity Storage
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Solution Overview
Problem
Existing blends of pH-independent soluble associative thickeners with ASE or HASE thickeners in their low pH emulsion form have excessively high viscosity, making them impractical for use at practical weight solids, and the addition of cyclodextrin compounds increases costs.
Innovation Solution
An aqueous thickener blend composition comprising an acid-suppressible associative thickener with hydrophobic groups such as secondary or tertiary amines, combined with HASE or ASE thickeners, where the pH is adjusted to reduce viscosity and allow for pourable blends without cyclodextrin, using a backbone like polyoxyalkylene or poly(meth)acrylamide, and additives like organic co-solvents or surfactants to control viscosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pH-independent soluble associative thickeners are blended with ASE or HASE thickeners in their low pH emulsion form, then the thickening capability is improved, but the viscosity becomes excessively high making the blend impractical for use
Solution Approach 1:
The patent applies parameter changes by adjusting the pH of the blend to a higher range (pH 7-10) where ASE and HASE thickeners become soluble or swellable, transforming them from their insoluble emulsion form. This pH adjustment fundamentally changes the physical state and viscosity characteristics of the thickener blend, making it pourable while maintaining thickening capability.
Solution Approach 2:
The patent creates a composite thickener system by combining pH-independent soluble associative thickeners (HEUR) with alkali-soluble/alkali-swellable emulsion thickeners (ASE/HASE) in a specific formulation. This composite approach allows the blend to achieve both low viscosity at storage pH and high thickening efficiency at application pH, resolving the contradiction between ease of operation and thickening capability.
2Ease of operation
If cyclodextrin compounds are added to the blend composition, then the viscosity is reduced and pourability is improved, but the cost increases significantly
Solution Approach 1:
The patent replaces expensive cyclodextrin compounds with a more economical approach using pH adjustment and conventional thickeners. By controlling pH to manage viscosity and relying on the inherent properties of the thickener blend rather than adding costly viscosity-modifying agents like cyclodextrins, the formulation achieves pourability without significant cost increase.
Solution Approach 2:
Instead of adding expensive additives like cyclodextrin to reduce viscosity, the patent uses parameter changes (pH adjustment) to control the viscosity of the blend. This approach manages the viscosity problem through fundamental chemical parameter control rather than expensive additive incorporation.
3Ease of operation
If the active solids concentration is reduced to decrease viscosity, then the product becomes more pourable, but the formulation latitude in terms of weight solids is limited
Solution Approach 1:
The patent creates a dynamic thickener blend where the viscosity and thickening properties can adapt to different pH conditions. The blend maintains low viscosity at storage pH for easy handling but exhibits high thickening efficiency at application pH, providing both pourability and formulation flexibility without compromising active solids concentration.
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 provides a pourable blend with low viscosity and high active thickener solids, effectively thickening aqueous systems when the pH is adjusted, improving flow and leveling performance without the added cost of cyclodextrin.
Implementation Method 1
the pH of the aqueous acid-suppressible associative thickener composition is below a value of the pKa of the secondary amine, or the tertiary amine, or the tertiary phosphine, or combination thereof, thereby substantially protonating the secondary amine, or the tertiary amine, or the tertiary phosphine, or combination thereof
Implementation Method 2
sufficient acid to reduce the pH of the aqueous associate thicjener composition below the value of the pKa of the secondary amine, or tertiary amine, or tertiary phosphone, or combination thereof, thereby substantially protonating the secondary amine, or the tertiary amine, or the tertiary phosphine, or combination thereof
Implementation Method 3
Associative thickeners are so called because the mechanism by which they thicken is believed to involve hydrophobic associations between the hydrophobic moieties in the thickener molecules and/or between the hydrophobic moieties in the thickener molecules and other hydrophobic surfaces
Data Source
AI summary
A thickener blend composition, and method for thickening aqueous systems, comprising an associative thickener wherein the same group that is attached to or within the backbone of the associative thickener is reversibly switched between being hydrophilic and hydrophobic in nature. When the group that is attached to or within the backbone is rendered hydrophilic, the aqueous thickener is pourable and readily incorporated into aqueous polymer compositions. When this group is rendered hydrophobic, the thickener performs its thickening function efficiently. Switching is readily accomplished by adjusting the pH of the associative thickener composition and the aqueous polymer composition being thickened.