Amphoteric Polymer Particles for Coating Hiding Power
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Solution Overview
Problem
Existing opacifying coatings face challenges in achieving high hiding power and whiteness while minimizing pigment usage, as higher pigment levels lead to light scattering inefficiencies due to particle crowding, and current polymer-based solutions do not adequately address these issues.
Innovation Solution
A stable aqueous dispersion of multiphase amphoteric polymer particles with specific monomer compositions and structural units, including phosphorus acid, carboxylic acid, and amine groups, is used to enhance adsorption and create composite particles that improve hiding efficiency and gloss in dried coatings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If higher levels of opacifying pigment are used to achieve desired hiding and whiteness, then hiding power is improved, but light scattering efficiency is reduced due to particle crowding
Solution Approach 1:
The patent introduces polymer particles containing dihydrogen phosphate functional groups as intermediaries between the opacifying pigment particles and the coating medium. These polymer particles adsorb onto the pigment surfaces, creating a steric barrier that maintains optimal spacing between pigment particles, thereby preventing crowding while achieving desired hiding power at reduced pigment levels.
Solution Approach 2:
The patent changes the chemical and physical parameters of the coating system by incorporating polymer particles with specific functional groups (dihydrogen phosphate) and controlled concentrations (0.1-10% of total coating weight). This parameter change allows for reduced pigment levels (5-20% reduction) while maintaining or improving hiding efficiency through optimized particle spacing.
2Object-affected harmful factors
If lower levels of opacifying pigment are used to maximize light scattering efficiency, then light scattering capability is improved, but hiding power and whiteness are insufficient
Solution Approach 1:
The polymer particles act as mediators that enable lower pigment concentrations to achieve sufficient hiding. By adsorbing onto pigment surfaces and providing steric stabilization, they allow pigment particles to be spaced optimally for light scattering while still achieving the necessary cumulative scattering effect for adequate hiding and whiteness.
Solution Approach 2:
The patent creates a composite coating system combining opacifying pigment particles with polymer particles containing dihydrogen phosphate functional groups. This composite approach leverages the light scattering properties of the pigment while utilizing the polymer's adsorption and spacing capabilities to enhance overall hiding efficiency at reduced pigment levels.
3Quantity of substance
If polymer particles are added to promote adsorption to pigment particles, then hiding efficiency is improved, but formulation complexity increases
Solution Approach 1:
The patent simplifies the formulation approach by focusing on a key parameter change: incorporating polymer particles with dihydrogen phosphate functional groups at specific concentration ranges (0.1-10% of total coating weight). This targeted parameter change provides predictable adsorption and spacing effects without requiring complex multi-component polymer formulations.
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 multiphase amphoteric polymer particles effectively adhere to inorganic pigment particles, reducing crowding and enhancing light scattering, resulting in improved hiding power, whiteness, and gloss in opacifying coatings with reduced pigment usage.
Implementation Method 1
polymer particles containing select chemical groups that promote adsorption to the opacifying pigment particle
Data Source
AI summary
The present invention relates to a stable aqueous dispersion of multiphase amphoteric polymer particles comprising a crosslinked polymer phase comprising structural units of a phosphorus acid monomer, a carboxylic acid monomer, a multiethylenically unsaturated monomer, and an ethylenically unsaturated nonionic monomer; and a second polymer phase comprising a carboxylic acid monomer and an ethylenically unsaturated nonionic monomer. The present invention also relates to composites of the particles and pigment particles such as TiO2. The composition is useful for preparing dried coatings with improved hiding.