Amphoteric Polymer Spacing TiO2 in Associative Coatings
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Solution Overview
Problem
Paints containing associative rheology modifiers like HEUR, HASE, and HMHEC thickeners cause titanium dioxide (TiO2) particles to self-associate, reducing hiding efficiency compared to compositions thickened with non-associative thickeners.
Innovation Solution
An amphoteric polymer with pendant acid groups or salts and pendant mono- or dialkylamino ethylene oxide groups is used to improve the spacing of TiO2 particles, creating a network that enhances hiding efficiency by interacting with both the TiO2 and the associative thickener or latex surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If associative rheology modifiers (HEUR, HASE, HMHEC) are used as thickeners, then viscosity control and flow properties are improved, but TiO2 particles self-associate and crowd together, reducing hiding efficiency
Solution Approach 1:
The patent introduces a dispersant as an intermediary substance that mediates between the associative thickener and TiO2 particles. The dispersant adsorbs onto TiO2 particle surfaces and provides steric or electrostatic repulsion, preventing particle aggregation while allowing the associative thickener to maintain its viscosity-enhancing function. This mediator resolves the contradiction by decoupling the thickening mechanism from the particle aggregation problem.
Solution Approach 2:
The patent modifies surface parameters of TiO2 particles through dispersant adsorption, changing surface charge, hydrophobicity, or steric characteristics. These parameter changes alter particle-particle interaction forces, preventing aggregation caused by associative thickeners while maintaining the desired rheological properties of the coating system.
2Strength
If TiO2 particles are allowed to self-associate with associative thickeners, then viscosity is enhanced, but particle spacing decreases and hiding performance deteriorates
Solution Approach 1:
The dispersant acts as a mediator that interferes with the direct association between TiO2 particles and associative thickener molecules. By adsorbing onto particle surfaces, the dispersant creates a protective layer that prevents the thickener from inducing particle crowding, thereby maintaining both viscosity enhancement and particle dispersion necessary for hiding performance.
Solution Approach 2:
The patent creates a composite system consisting of TiO2 particles, associative thickener, and dispersant working together. The dispersant-modified particle surface forms a composite structure that maintains individual particle separation while allowing the associative thickener to provide viscosity control, achieving both rheological strength and optical hiding properties.
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 amphoteric polymer effectively improves hiding efficiency in coatings containing TiO2 and associative rheology modifiers by creating an ideal spacing of TiO2 particles, leading to enhanced hiding performance.
Implementation Method 1
amphoteric polymer having pendant acid groups, or salts thereof
Implementation Method 2
associative rheology modifiers create a network with the binder in the paint system
Data Source
AI summary
The present invention relates to a composition comprising an amphoteric polymer having pendant acid groups, or salts thereof, and pendant mono- or dialkylamino ethylene oxide groups or alkylammonium ethylene oxide groups characterized by either of the following formulas:where R1-R3 and X− are as defined herein. The composition of the present invention improves hiding efficiency for coating compositions formulated using associative rheology modifiers, binders, and titanium dioxide.