Polymer Dispersion Viscosity Stabilization via Alkali Salts
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Solution Overview
Problem
Conventional protective colloid-stabilized polymer dispersions tend to experience viscosity buildup during storage, particularly when using fully saponified polyvinyl alcohols, leading to instability and reduced water resistance in application products.
Innovation Solution
Incorporating salts of earth alkali metals and di- or polyfunctional alcohols with specific functional groups into polymer dispersions, which contain fully saponified polyvinyl alcohols as protective colloids, to maintain stability and improve water resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fully saponified polyvinyl alcohol is used as a protective colloid to stabilize polymer dispersions, then the protective colloid provides effective stabilization, but the viscosity of the dispersion builds up during storage
Solution Approach 1:
Alkali metal salts serve as intermediary substances that modify the interaction between the protective colloid and polymer particles. The salts adjust the electrostatic environment, preventing excessive polymer colloid interaction that leads to viscosity buildup, while maintaining the protective colloid's stabilization function.
Solution Approach 2:
The invention changes the chemical composition parameters of the dispersion system by introducing specific alkali metal salts. This alters the physical-chemical parameters such as ionic strength and electrostatic potential, thereby controlling viscosity stability without compromising protective colloid effectiveness.
2Stability of the object's composition
If urea is added to increase storage stability of aqueous polymer dispersions, then the viscosity stability improves, but the water resistance of adhesive bonds deteriorates
Solution Approach 1:
The invention extracts urea from the formulation and replaces it with alkali metal salts. This removal eliminates the harmful effect on water resistance while achieving the desired viscosity stability through the alternative mechanism provided by the salts.
Solution Approach 2:
The invention uses simple, inexpensive alkali metal salts (such as sodium chloride, potassium chloride) as substitutes for urea. These salts provide the necessary stabilization function without the detrimental long-term effects on adhesive bond water resistance.
3Adaptability or versatility
If aluminum salts are added to modify polymer dispersion properties, then certain functional properties improve, but the storage stability deteriorates due to thickening
Solution Approach 1:
Instead of using aluminum salts (trivalent cations) that cause excessive crosslinking and thickening, the invention inverts the approach by using alkali metal salts (monovalent cations). These salts provide the necessary ionic effects without causing the harmful thickening and gelation that aluminum salts produce.
Data Source
AI summary
The invention relates to aqueous dispersions based on protective colloid-stabilized polymerisates of ethylenically unsaturated monomers. The aqueous dispersions are characterized in that they contain one or more salts of alkaline (earth) metals and one or more alcohols, said alcohols having at least one alcohol group and optionally one or more additional functional groups selected from the group comprising amine, carbamic acid, mercaptan, sulfonic acid, sulfuric acid, halide, carboxyl, alkoxy, phosphinic acid, phosphonic acid, and phosphoric acid groups, wherein the sum of the number of the alcohol groups and the additional functional groups of the alcohols ≥ 2.