Core-Shell Polymer Particles for TiO2 Dispersion
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Solution Overview
Problem
The existing methods for preparing TiO2-polymer composite particles result in increased flocculation and grit formation due to bleeding of adsorbing groups from the core to the shell of 'acorn' particles, which affects the hiding efficiency and quality of coatings.
Innovation Solution
A process involving a stable aqueous dispersion of pre-formed polymer particles is contacted with a monomer emulsion under emulsion polymerization conditions, with specific monomer and polymer composition ratios to create polymer particles with a core-shell morphology, where phosphorus acid groups are predominantly located at the core, reducing grit formation and improving TiO2 compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If adsorbing functional groups are distributed throughout the polymer particles including the shell portion, then TiO2 adsorption capacity is improved, but flocculation and grit formation increase due to bridging effects
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where adsorbing functional groups are concentrated in the core portion of the particle while the shell portion has minimal adsorbing groups. This spatial differentiation allows TiO2 to adsorb effectively at the core without experiencing bridging flocculation that would occur if adsorbing groups were distributed throughout the entire particle including the shell.
Solution Approach 2:
The patent segments the polymer particle into distinct core and shell portions with different functional group distributions. The core contains the adsorbing functional groups for TiO2 binding, while the shell provides a non-adsorbing protective layer, thereby separating the adsorption function from the protective function and preventing grit formation.
2Object-generated harmful factors
If adsorbing groups are concentrated at the core portion to reduce bridging effects, then grit formation is reduced, but TiO2 adsorption efficiency may be compromised
Solution Approach 1:
The patent concentrates adsorbing functional groups specifically in the core portion of the particle, creating a localized high-density adsorption zone. This ensures efficient TiO2 adsorption at the core while the shell portion remains free of adsorbing groups, preventing bridging effects and grit formation.
3Shape
If emulsion polymerization is used to create core-shell particles, then particle morphology control is improved, but process complexity increases
Solution Approach 1:
The patent uses preliminary action by first forming polymer particles with adsorbing functional groups, then using these as seeds for a second polymerization stage that forms the shell. This stepwise approach allows precise control over core-shell morphology while managing process complexity through staged synthesis rather than attempting to form the complete structure in a single step.
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 process results in a stable aqueous dispersion of polymer particles with improved TiO2 compatibility, reducing grit formation and enhancing the hiding efficiency and quality of coatings by maintaining adsorbing groups at the core, leading to grit-free films and superior paint properties.
Implementation Method 1
the core portion being preferentially functionalized with TiO2-adsorbing groups
Implementation Method 2
contacting a stable aqueous dispersion of pre-formed polymer particles with a monomer emulsion under emulsion polymerization conditions
Data Source
AI summary
The present invention relates to a process comprising contacting a stable aqueous dispersion of pre-formed polymer particles with a monomer emulsion under emulsion polymerization conditions to form a stable aqueous dispersion of pre-formed particles protuberating from polymer particles arising from the polymerization of the monomer emulsion; these multistage polymer particles show exceptional compatibility with pigment particles. In another aspect, the present invention is a composition relating to the pre-formed particles.