Multistage Polymer Particles for TiO2-Free Coatings
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Solution Overview
Problem
The paint industry faces challenges in reducing the high cost and environmental impact of titanium dioxide (TiO2) usage while maintaining opacity and scrub resistance in coatings, as alternatives like opaque polymer particles have limited effectiveness and are not substitutes for TiO2.
Innovation Solution
A waterborne composition comprising multistage polymer particles with a water-occluded core and a polymeric shell, along with a binder layer, which reduces or eliminates the need for TiO2 by providing superior hiding and scrub resistance when used in paint formulations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If TiO2 is used as opacifying pigment, then hiding performance is improved, but cost and environmental impact increase
Solution Approach 1:
The invention uses composite polymer particles combining a water-occluded core with polymeric shell and binder layer, creating a material that achieves TiO2-level opacity without requiring actual TiO2 pigment
Solution Approach 2:
The invention changes the refractive index parameter of the opacifying agent by using polymer compositions with tailored glass transition temperatures and molecular structures that scatter light effectively, replacing the high refractive index requirement of TiO2
2Quantity of substance
If extender is used to substitute TiO2, then TiO2 loading is reduced, but scrub resistance deteriorates
Solution Approach 1:
The invention applies different functional properties to different parts of the particle system: the core provides opacity, the shell provides structural integrity, and the binder layer provides adhesion and scrub resistance, creating localized functional zones
Solution Approach 2:
The invention uses spherical particle morphology with specific size distributions (0.1-2.0 microns) to optimize light scattering while maintaining film integrity and scrub resistance
3Quantity of substance
If opaque polymer particles are used, then TiO2 loading is reduced, but hiding performance and coating properties deteriorate
Solution Approach 1:
The invention segments the particle structure into distinct functional zones: water-occluded core for opacity, polymeric shell for structural stability, and binder layer for adhesion, with each segment optimized for its specific function
Solution Approach 2:
The invention uses a nested structure where the polymeric shell encapsulates the water-occluded core, and the binder layer encapsulates the shell, creating concentric functional layers like nested dolls
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 composition achieves excellent hiding and scrub resistance performance, making it a viable alternative to TiO2-based coatings by leveraging the properties of binder-coated and non-binder-coated opaque polymer particles, thereby reducing TiO2 loading or eliminating its need altogether.
Implementation Method 1
Titanium oxide (TiO2) is the mostly commonly used opacifying pigment in the paint industry due to its very high refractive index
Implementation Method 2
a polymeric binder layer superposing the shell, which polymeric binder layer has a Tg of not greater than 35 °C
Data Source
AI summary
The present invention relates to a waterborne composition comprising an aqueous dispersion of first and second multistage polymer particles, wherein each of the first and second polymer particles comprises a water-occluded core and a high Tg polymeric shell wherein the second multistage polymer particles further comprise a polymeric binder layer superposing the shell. The composition of the present invention is useful for reducing the load of TiO2 in paint formulations, while producing coatings with excellent hiding and scrub resistance.