Opacifying Pigment Dispersion for One-Coat Hide and Whiteness
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Solution Overview
Problem
Existing architectural coatings struggle to achieve one-coat hiding with high hiding and whiteness due to the crowding effect of high TiO2 levels, which reduces scattering efficiency and Y-reflectance.
Innovation Solution
Aqueous dispersion of multistage polymer particles with a water-occluded core, a polymeric shell, and a superposing binder layer, combined with an opacifying inorganic pigment and a colorant that absorbs light in the range of 500-600 nm, within specific weight and concentration ranges, to enhance hiding and whiteness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high levels of TiO2 are used to achieve high hiding, then hiding is improved, but scattering efficiency is reduced due to the crowding effect
Solution Approach 1:
The patent divides the opacifying function into multiple components: a core polymer particle structure, a shell layer, and multiple binder layers with different Tg values. This segmentation allows each layer to contribute differently to hiding and scattering, avoiding the crowding effect of high TiO2 while maintaining high hiding performance through the multifunctional particle design.
Solution Approach 2:
The patent creates composite polymer particles with a core-shell-binder layer structure, combining materials with different properties. The core provides structural integrity, the shell provides opacity, and the binder layers provide adhesion and flexibility. This composite structure achieves high hiding and maintains scattering efficiency without relying solely on high TiO2 loading.
2Reliability
If light absorption is increased to improve hiding, then hiding is improved, but whiteness (Y-reflectance) is attenuated
Solution Approach 1:
The patent applies local quality by creating distinct layers with different functions: the core layer provides structural support, the shell layer provides opacity through light scattering, and the binder layers provide adhesion. This localized functional distribution allows the shell to handle whiteness maintenance through scattering while other layers handle hiding through absorption and adhesion, resolving the contradiction between hiding and whiteness.
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 a one-coat hide with a contrast ratio of at least 99.5% and Y-reflectance of at least 91.0% in films applied at 2-4 mil thickness, surpassing the requirements for one-coat hiding.
Implementation Method 1
a colorant that absorbs light in the range of from 500 nm to 600 nm
Implementation Method 2
Hiding and whiteness are achieved using high refractive index particles such as TiO2 particles
Data Source
AI summary
The present invention relates to a composition comprising 1) an aqueous dispersion of multistage opacifying polymer particles with a superposing binder layer; 2) a colorant; and 3) inorganic opacifying pigment particles. The composition of the present invention is useful for one coat hide paint formulations.